AUTOMATIC ACQUISITION OF CT RADIATION DOSE DATA: USING THE DIAGNOSTIC REFERENCE LEVEL FOR RADIATION DOSE OPTIMIZATION

AUTOMATIC ACQUISITION OF CT RADIATION DOSE DATA: USING THE DIAGNOSTIC REFERENCE LEVEL FOR... Abstract The present work describes that we try to construct a system that collects dose information that performed CT examination from multiple facilities and unified management. The results of analysis are compared with other National diagnostic reference level (DRL), and the results are fed back to each facility and the cause of the abnormal value is investigated for dose optimization. Medical information collected 139 144 tests from 33 CT devices in 13 facilities. Although the DRL of this study is lower than that of Japan DRL, it was higher than the DRL of each country. When collecting all the examination, it is thought that the variation of the dose due to the error other than the intended imaging site is large. In future, we should continue to collect information in order to DRL renewal and we also think that it is desirable to collect information on physique and detailed scan region as well. INTRODUCTION Computed tomography (CT) is about 40 years old. Japan’s annual medical radiation dose per capita is the world’s largest, and most of the exposure is from CT examinations(1). Diagnostic reference level (DRL) recommendations to restrict exposure to that which is medically necessary have been made by the International Commission on Radiological Protection (ICRP)(2, 3). Regarding the role of DRL, if the typical dose used in the institution exceeds DRL, it is necessary to review to determine whether the dose is optimized unless there is a clinically valid cause is there. In general, investigate the performance and examination protocols (procedures) of the equipment used, find the cause of high dose (low dose), and take countermeasures to use a more appropriate dose. After taking countermeasures, dose optimization is achieved by reassessing the typical dose of the facility and confirming that it is lower than DRL. DRLs of CT examinations are expressed as volume CT dose index (CTDIvol, mGy) and dose-length products (DLP, mGy cm); for pediatrics, limits may be extrapolated from adult values, or set using pediatric phantoms(4–17). DRLs for Japan were published in 2015 using the 75th percentile of dosimetry data collected by questionnaire(18). There are three types of DRL: national DRL (NDRL), set at the national level; regional DRL (RDRL), set at the regional/academic level; and local DRL (LDRL), set at the individual center level(19). Dose indices from many centers are required to establish NDRL and RDRL, but rules on how to determine NDRL and RDRL have not been finalized. Modern radiographic diagnostic equipment records information including patient demographics, scan parameters and dose index. It is important to collect information on radiological examinations from several centers(20), and to build a dose management system capable of calculating RDRL and aggregating and managing dose information. There are several methods of collecting dosimetry data: Digital Imaging and Communications in Medicine (DICOM) headers(21, 22). Reading dose information from an image file containing data from the CT device(23). DICOM modality performed procedure step (MPPS)(24). DICOM structured report (DICOM SR)(25). We can easily read patient information and scan parameter information from a DICOM header, but the information on the dose index is often not recorded. The data recorded in the CT scanner of each manufacturers vary, and the examination information, the patient information, and the dose information are recorded as image data called ‘Dose report’ or ‘Dose sheet’. MPPS is a protocol for managing the information of the examination. The types of tags that can be handled are small in number and insufficient for dose management. DICOM standardized ‘CT Radiation Dose Reporting (Dose SR)’ in 2007 for the purpose of unifying the information output format used for dose management(26). And defined a template structure for the information to be output at DICOM part 16: content mapping resource(27). This template structure was summarizing different exposure doses and related information for each device into a unit called Information Object Definition (IOD) and defined as ‘CT Radiation Dose SR IOD templates’ (Figure 1). Furthermore, the International Electrotechnical Commission (IEC) was recommended outputting dose information according to the Dose SR standard for CT device in 2012(28). Figure 1. View largeDownload slide Fundamental structure of ‘CT radiation dose SRa Information Object Description (IOD) templates’. This is part of the CT dose SR template. The templates have a hierarchical structure, and there are other contents showing X-ray, mammography and fluoroscopy. As the hierarchy progresses, scan parameters other than dose information and patient information are also described. aSR = structured report; bTID = template ID. Figure 1. View largeDownload slide Fundamental structure of ‘CT radiation dose SRa Information Object Description (IOD) templates’. This is part of the CT dose SR template. The templates have a hierarchical structure, and there are other contents showing X-ray, mammography and fluoroscopy. As the hierarchy progresses, scan parameters other than dose information and patient information are also described. aSR = structured report; bTID = template ID. We collected RDSR on dose index for CT examination and attempted to construct an aggregation system that collects dose information and scan parameter of multiple facilities by collecting information by image capture of dose sheet for noncompliant CT devices. For dose optimization, we set regional DRL and the results of analysis were compared with other National DRL, and the results were fed back to each facility and the cause of the abnormal value was investigated. METHODS AND MATERIALS Patients This retrospective study was approved by the National Institute of Radiological Sciences (NIRS) and the ethics committees of the target centers. Target patients were those who underwent CT examination from October 2014 to December 2015. Patients 0 to ≤15 years of age were classified as pediatric, and were subdivided into 0–≤1 year old, 1–≤6 years old, 6–≤11 years old and 11–≤15 years old groups. Patients over 15 years old were classified as adults. Protocols All centers had CT scanners with >16 detectors, adjusted to the most appropriate scan parameters according to age, physique and examination(17). About protocol name, in the case of RDSR we referred to ‘Target region’ mentioned in CT irradiation event data of TID10013 and the case of Dose sheet we referred to ‘Body part examination’ of DICOM header. For the dose index, the collected data included contrast-enhanced examinations when a patient underwent an examination with >2 scans (i.e. three-phase contrast examination) both CTDIvol and DLP were calculated from the mean dose. Data acquisition Two types of collection tools were used, corresponding to Japan Dose Index Registry (J-DIR). One is the National Institute of Radiological Sciences Tool ‘NIRS Tool’ (Carestream Health, Tokyo, Japan) that we developed originally. It corresponds to collection of RDSR and information collection by image capture of CT Dose sheet. The other is a commercially available ‘Dose Manager’ (Cure Hope, Osaka, Japan), which supports collection of only RDSR. Both tools collect RDSR for a certain period and output, there is no difference in accuracy. For facilities that use models that cannot output RDSR from CT, we used the image capture version of NIRS Tool. The collection tool connected to each center’s network and acquires information in real time by collecting the RDSRs or dose sheets outputted from the CT device (Figure 2). We selected 13 centers equipped with CT scanners with different manufacturers roughly representative of the distribution throughout Japan (Figure 3). The collection period of each center varied depending on the permission of the center and the burden on the personnel (Table 1). Figure 2. View largeDownload slide RDSR acquisition system. This is the connection diagram of the Tool used in this study. We collected SR data from CT or PACS in real time. CT scanners not equipped to issue SRs were handled by image capture of the dose sheet. The acquisition data was compressed and anonymized the current day between 0 o’clock and 3 o’clock every day. In addition, we made anonymization that data cannot be concatenated. The technician uploads the anonymized data on SafeSync. NIRS aggregates the SR data from each facility to the server and uploads the analysis data again. Figure 2. View largeDownload slide RDSR acquisition system. This is the connection diagram of the Tool used in this study. We collected SR data from CT or PACS in real time. CT scanners not equipped to issue SRs were handled by image capture of the dose sheet. The acquisition data was compressed and anonymized the current day between 0 o’clock and 3 o’clock every day. In addition, we made anonymization that data cannot be concatenated. The technician uploads the anonymized data on SafeSync. NIRS aggregates the SR data from each facility to the server and uploads the analysis data again. Figure 3. View largeDownload slide Distribution of CT venders. (a) Distribution of CT venders in Japan(29), n = 11 349. (b) Distribution of CT venders in this study, n = 33. Figure 3. View largeDownload slide Distribution of CT venders. (a) Distribution of CT venders in Japan(29), n = 11 349. (b) Distribution of CT venders in this study, n = 33. Table 1. Collection period and examination number, age of adult and pediatric patients. Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 aN, NIRS Tool; Ncap, NIRS Tool capture version; D, Dose Manager. bThe value is total examination number per acquisition period day and scaner number. cThe center is a university hospital. dThe value is mean value ± SD. View Large Table 1. Collection period and examination number, age of adult and pediatric patients. Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 aN, NIRS Tool; Ncap, NIRS Tool capture version; D, Dose Manager. bThe value is total examination number per acquisition period day and scaner number. cThe center is a university hospital. dThe value is mean value ± SD. View Large The NIRS tool compresses and anonymizes the current day’s RDSR between midnight and 3:00 am. Also, performs anonymization that cannot be concatenated. The information acquired from each facilities should be aggregated in the RDSR server in NIRS via the network, but it was impossible to realize because the clinical network did not allow connection with the external network due to facility policy problem. Therefore, as a method of acquiring information collected by each facility, we thought that it was safe to share it with NIRS by another PC connected to the virtual private network (VPN). Sharing is one to one with NIRS and each facility, and facility sharing is not done. In order to realize these sharing we used SafeSync (Trend Micro Incorporated, Tokyo, Japan). The data were aggregated into the RDSR System of a dedicated server. Dose Manager was able to output RDSR collected from CT at all times in anonymous state and shared by SafeSync. Data analysis The data of each center aggregated in the RDSR System were output with comma separated values (csv) and analyzed with spreadsheet software (Excel 2013, Microsoft Office, Redmond WA, USA). Data are expressed as mean ± standard deviation (SD). We used the VPN to summarize each center on a spreadsheet, and examined analytic data from each center. Comparison of dose-related data to DRLs RDSR and dose sheets included CTDIvol and DLP for the dose index, calculated the mean and SD for each anatomical region in adults and children, the representative value of each center. For CTDIvol and DLP of ‘Head and Brain’, ‘Circle of Willis’, ‘Eye region’ and ‘Orbit region’ in adults, the dose index value normalized to a 16-cm phantom standard is shown. For the other anatomical regions, it shows the values normalized to a 32-cm phantom. For the CTDIvol and DLP of pediatric patients, the values derived with the 32-cm phantom were doubled to simulate a 16-cm phantom(17). The mean and SD values, minimum value, 25th percentile, 50th percentile, 75th percentile and maximum value were calculated from the dose indices of each center. The mean value of each center was used as a representative value, and its 75th percentile values were taken as adult and pediatric DRLs in this study. We compared our findings with DRLs of the head, chest, abdomen and heart in adults from data published by 10 countries. The pediatric DRL was compared with DRLs of head, chest and abdominal CT published from six countries. RESULTS The total number of centers participating in the survey was 13, of which four were university hospitals. The number of beds was 227 in the smallest center and 1225 in the largest (Table 1). There were 134 876 examinations of patients over 15 years old (males: 76 452, females: 58 424) with RDSR obtained during the survey period from October 2014 to December 2015, and there were 2134 examinations of patients ≤15 years old (males: 1278, females: 856). There were 84 203 adult (males: 47 213, females: 36 990) and 1316 pediatric (males: 745, females: 571) subjects. The mean value for all centers was 32.8 ± 19.15 cases per day. The mean value for pediatric cases at all centers was 0.6 cases. The mean age of adults was 65.5 ± 15.92 years and the mean age of pediatric subjects was 7.5 ± 0.43 years. Figure 4 shows the age ranges in more detail. Figure 4. View largeDownload slide Distribution of examinations by age and sex. Figure 4. View largeDownload slide Distribution of examinations by age and sex. The total number of CT devices targeted for collection was 33, and all had more than 16 rows of detectors. Figure 3 shows the vendor breakdown and departures from the average. No Hitachi scanners were included. Table 2 shows the 20 target regions acquired from all the centers. ‘Unknown’ cases were excluded from the analysis. Table 2. Acquisition of CT target region and patient number of adult and pediatric patients. Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 aSRT is structured reporting templates. Table 2. Acquisition of CT target region and patient number of adult and pediatric patients. Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 aSRT is structured reporting templates. Table 3 shows the ranges and values of the CTDIvol and DLP of each target region at each center as a representative value in adults. Table 4 shows the pediatric values. Table 3. CTDIvol and DLP for single scan of each anatomical region for adult. Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 aSRT is structured reporting templates. bCTDIvol and DLP values adjusted to 16-cm PMMA phantom. Table 3. CTDIvol and DLP for single scan of each anatomical region for adult. Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 aSRT is structured reporting templates. bCTDIvol and DLP values adjusted to 16-cm PMMA phantom. Table 4. CTDIvol and DLP for single scan of each anatomical region for pediatric. Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 aSRT is structured reporting templates. bThe values adjusted to 16-cm PMMA phantom. Table 4. CTDIvol and DLP for single scan of each anatomical region for pediatric. Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 aSRT is structured reporting templates. bThe values adjusted to 16-cm PMMA phantom. Table 5 compares the 75th percentiles of adult head, chest, abdomen and heart CTs of this study with DRLs published from 10 countries and their mean values. Table 6 compares the 75th percentiles in the head, chest and abdomen of pediatric cases with the DRLs of seven countries with their mean values. Table 5. Comparison of CTDIvol and DLP for adult in each anatomical region with other countries. Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. cThe values adjusted to 32-cm PMMA phantom. Table 5. Comparison of CTDIvol and DLP for adult in each anatomical region with other countries. Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. cThe values adjusted to 32-cm PMMA phantom. Table 6. Comparison of CTDIvol and DLP for pediatric in each anatomical region with other countries. Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. Table 6. Comparison of CTDIvol and DLP for pediatric in each anatomical region with other countries. Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. DISCUSSION In this study, we introduced a series of systems that automatically collect RDSR or dose sheet output from CT, and summarized scan parameters and scan dose. The output formats of RDSR are unified, making it possible to collect information on recorded dose indices and imaging conditions(30). However, the equipment compatible with the output of RDSR is limited to the latest models. The IEC issued the 2012 Dose SR Standard for CT apparatus in IEC 60601-2-44, recommending collection of dose data from CT scans(28). In addition, it has been reported that the accuracy of reading text is 95% because information is collected only by the method of image capture of dose sheets, and each manufacturer has various display formats(31). For more detailed scan parameters, it is a disadvantage that it cannot be captured only from the dose sheet. In Table 2, the targets from the RDSR collection were 20 regions, but in reality, each center was conducting daily inspections using a more specific detailed protocol, e.g. in the case of multiphase scanning of the abdomen (T-D4000, SRT). Furthermore, because RDSR and dose sheet cannot directly obtain information on body type such as body weight and height of patients, and the AEC automatically adjusts for habitus, various ages and body types, are considered to be the cause of differences between centers. Although it has also been reported that the patients undergoing abdominal CT with body mass index (BMI) < 30 that the CTDIvol and DLP of patients who exceeded NDRL was under 0.5% and under 0.8%, respectively(20). DRL is based on standard patients in each country, making it desirable to collect body type information, such as the height and weight. From Table 3, it is conceivable that the CTDIvol of the adult chest–abdominal CT is higher than that of the abdomen–pelvis CT, because some CT scanners include devices that calculate the CTDI value from the maximum, and not the mean, tube current. In addition, CT angiography was included in the chest and abdomen studies, and there is a difference in the dose index due to angiography’s lower pitch setting. From Table 5, in comparison with the DRL of each Japanese study, the CTDIvol and DLP of the head and chest were both higher than those of the other countries, and the values in the abdomen and heart were all lower than the mean values of each country. In automatic collection of data, there are possibilities that local protocols unique to various centers may be included, and that is considered one aspect which cannot be compared with the NDRL of each country. From Table 6, in pediatric DRL, head and chest CT showed higher results than in the other countries. This may be due to the scan range in head CT being set wider in Japan than in other countries by up to ~4 cm, in order to maintain the head within the field of view. As children are more radiosensitive than adults, we should actively adopt methods that can calculate tube current for each age recommended by the Image Gently Program of the American Society of Pediatric Radiology (SPR)(32). The National Radiology Data Registry (NRDR) of the American College of Radiology (ACR) has been collecting large-scale RDSRs throughout North America as a Dose Index Registration (DIR) since 2011(33). The collected dose information is divided into detailed scan regions by a Radlex playbook ID (RPID) code, transmitted anonymously to ACR, and the results of comparative evaluation with the whole are fed back to each center. The size-specific dose estimates (SSDE) taking into consideration the body shape is beginning to be introduced in addition to CTDI and DLP in the dose index, we think that dose optimization is possible in the future(34). Even in Japan, the JJ 1017 code, which codes modality and scan region, is under development. This should lead to higher precision(35). We plan to continue to collect dosage data and to periodically compare, discover and investigate specific causes, and review protocols with the goal of dose optimization. Currently, we are sharing data with a limited collection of equipment. Constructing a cloud-based collection will allow sampling from more centers in the future. We hope this will eliminate disparities among centers and facilitate the optimization of dosimetry. REFERENCES 1 Brenner , D. J. and Hall , E. J. Computed tomography—an increasing source of radiation exposure . N. Engl. J. Med. 357 ( 22 ), 2277 – 2284 ( 2007 ) 10.1056/NEJMra072149 . 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J. 3 ( 2 ), e26 ( 2007 ) 10.2349/biij.3.2.e26 . Google Scholar CrossRef Search ADS PubMed 22 Nakada , Y. , Fujiwara , M. and Yakami , M. Optimised paediatric CT dose at a tertiary children’s hospital in Japan: a 4-y single-centre analysis . Radiat. Prot. Dosim. 168 ( 1 ), 61 – 71 ( 2016 ) 10.1093/rpd/ncv004 . Google Scholar CrossRef Search ADS 23 Cook , T. S. , Zimmerman , S. L. , Steingall , S. R. , Maidment , A. D. , Kim , W. and Boonn , W. W. RADIANCE: An automated, enterprise-wide solution for archiving and reporting CT radiation dose estimates . Radiographics 31 ( 7 ), 1833 – 1846 ( 2011 ) 10.1148/rg.317115048 . Google Scholar CrossRef Search ADS PubMed 24 Noumeir , R. Benefits of the DICOM modality performed procedure step . J. Digit. Imaging 18 ( 4 ), 260 – 269 ( 2005 ) 10.1007/s10278-005-6702-3 . Google Scholar CrossRef Search ADS PubMed 25 Dave , J. K. and Gingold , E. L. Extraction of CT dose information from DICOM metadata: automated Matlab-based approach . AJR Am. J. Roentgenol. 200 ( 1 ), 142 – 145 ( 2013 ) 10.2214/AJR.12.8501 . Google Scholar CrossRef Search ADS PubMed 26 DICOM diagnostic x-ray radiation dose reporting (Dose SR). 27 DICOM part 16 content mapping resource. 28 International Electrotechnical Commission . Medical electrical equipment, Part 2-44: Particular requirements for the safety of X-ray equipment for computed tomography. Geneva: IEC; ( 2012 ). IEC 60601-2-44. 29 Data book of medical devices & systems, Iryokiki sytem hakusho 2016, MEshinkoukyokai 2015. 30 DICOM Standards Committee, Working Group 6, Base Standard. Supplement 94: radiation dose report, NEMA 2004. Available on http://dicom.nema.org/dicom/geninfo/strategy.pdf#search=%2728.+DICOM+Standards+Committee%2C+Working+Group+6%2C+Base+Standard.+Supplement+150%27. Accessed on 21 March 2017. 31 Li , X. , Zhang , D. and Liu , B. Automated extraction of radiation dose information from CT dose report images . AJR Am. J. 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Accessed on 22 January 2017. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Radiation Protection Dosimetry Oxford University Press

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Abstract

Abstract The present work describes that we try to construct a system that collects dose information that performed CT examination from multiple facilities and unified management. The results of analysis are compared with other National diagnostic reference level (DRL), and the results are fed back to each facility and the cause of the abnormal value is investigated for dose optimization. Medical information collected 139 144 tests from 33 CT devices in 13 facilities. Although the DRL of this study is lower than that of Japan DRL, it was higher than the DRL of each country. When collecting all the examination, it is thought that the variation of the dose due to the error other than the intended imaging site is large. In future, we should continue to collect information in order to DRL renewal and we also think that it is desirable to collect information on physique and detailed scan region as well. INTRODUCTION Computed tomography (CT) is about 40 years old. Japan’s annual medical radiation dose per capita is the world’s largest, and most of the exposure is from CT examinations(1). Diagnostic reference level (DRL) recommendations to restrict exposure to that which is medically necessary have been made by the International Commission on Radiological Protection (ICRP)(2, 3). Regarding the role of DRL, if the typical dose used in the institution exceeds DRL, it is necessary to review to determine whether the dose is optimized unless there is a clinically valid cause is there. In general, investigate the performance and examination protocols (procedures) of the equipment used, find the cause of high dose (low dose), and take countermeasures to use a more appropriate dose. After taking countermeasures, dose optimization is achieved by reassessing the typical dose of the facility and confirming that it is lower than DRL. DRLs of CT examinations are expressed as volume CT dose index (CTDIvol, mGy) and dose-length products (DLP, mGy cm); for pediatrics, limits may be extrapolated from adult values, or set using pediatric phantoms(4–17). DRLs for Japan were published in 2015 using the 75th percentile of dosimetry data collected by questionnaire(18). There are three types of DRL: national DRL (NDRL), set at the national level; regional DRL (RDRL), set at the regional/academic level; and local DRL (LDRL), set at the individual center level(19). Dose indices from many centers are required to establish NDRL and RDRL, but rules on how to determine NDRL and RDRL have not been finalized. Modern radiographic diagnostic equipment records information including patient demographics, scan parameters and dose index. It is important to collect information on radiological examinations from several centers(20), and to build a dose management system capable of calculating RDRL and aggregating and managing dose information. There are several methods of collecting dosimetry data: Digital Imaging and Communications in Medicine (DICOM) headers(21, 22). Reading dose information from an image file containing data from the CT device(23). DICOM modality performed procedure step (MPPS)(24). DICOM structured report (DICOM SR)(25). We can easily read patient information and scan parameter information from a DICOM header, but the information on the dose index is often not recorded. The data recorded in the CT scanner of each manufacturers vary, and the examination information, the patient information, and the dose information are recorded as image data called ‘Dose report’ or ‘Dose sheet’. MPPS is a protocol for managing the information of the examination. The types of tags that can be handled are small in number and insufficient for dose management. DICOM standardized ‘CT Radiation Dose Reporting (Dose SR)’ in 2007 for the purpose of unifying the information output format used for dose management(26). And defined a template structure for the information to be output at DICOM part 16: content mapping resource(27). This template structure was summarizing different exposure doses and related information for each device into a unit called Information Object Definition (IOD) and defined as ‘CT Radiation Dose SR IOD templates’ (Figure 1). Furthermore, the International Electrotechnical Commission (IEC) was recommended outputting dose information according to the Dose SR standard for CT device in 2012(28). Figure 1. View largeDownload slide Fundamental structure of ‘CT radiation dose SRa Information Object Description (IOD) templates’. This is part of the CT dose SR template. The templates have a hierarchical structure, and there are other contents showing X-ray, mammography and fluoroscopy. As the hierarchy progresses, scan parameters other than dose information and patient information are also described. aSR = structured report; bTID = template ID. Figure 1. View largeDownload slide Fundamental structure of ‘CT radiation dose SRa Information Object Description (IOD) templates’. This is part of the CT dose SR template. The templates have a hierarchical structure, and there are other contents showing X-ray, mammography and fluoroscopy. As the hierarchy progresses, scan parameters other than dose information and patient information are also described. aSR = structured report; bTID = template ID. We collected RDSR on dose index for CT examination and attempted to construct an aggregation system that collects dose information and scan parameter of multiple facilities by collecting information by image capture of dose sheet for noncompliant CT devices. For dose optimization, we set regional DRL and the results of analysis were compared with other National DRL, and the results were fed back to each facility and the cause of the abnormal value was investigated. METHODS AND MATERIALS Patients This retrospective study was approved by the National Institute of Radiological Sciences (NIRS) and the ethics committees of the target centers. Target patients were those who underwent CT examination from October 2014 to December 2015. Patients 0 to ≤15 years of age were classified as pediatric, and were subdivided into 0–≤1 year old, 1–≤6 years old, 6–≤11 years old and 11–≤15 years old groups. Patients over 15 years old were classified as adults. Protocols All centers had CT scanners with >16 detectors, adjusted to the most appropriate scan parameters according to age, physique and examination(17). About protocol name, in the case of RDSR we referred to ‘Target region’ mentioned in CT irradiation event data of TID10013 and the case of Dose sheet we referred to ‘Body part examination’ of DICOM header. For the dose index, the collected data included contrast-enhanced examinations when a patient underwent an examination with >2 scans (i.e. three-phase contrast examination) both CTDIvol and DLP were calculated from the mean dose. Data acquisition Two types of collection tools were used, corresponding to Japan Dose Index Registry (J-DIR). One is the National Institute of Radiological Sciences Tool ‘NIRS Tool’ (Carestream Health, Tokyo, Japan) that we developed originally. It corresponds to collection of RDSR and information collection by image capture of CT Dose sheet. The other is a commercially available ‘Dose Manager’ (Cure Hope, Osaka, Japan), which supports collection of only RDSR. Both tools collect RDSR for a certain period and output, there is no difference in accuracy. For facilities that use models that cannot output RDSR from CT, we used the image capture version of NIRS Tool. The collection tool connected to each center’s network and acquires information in real time by collecting the RDSRs or dose sheets outputted from the CT device (Figure 2). We selected 13 centers equipped with CT scanners with different manufacturers roughly representative of the distribution throughout Japan (Figure 3). The collection period of each center varied depending on the permission of the center and the burden on the personnel (Table 1). Figure 2. View largeDownload slide RDSR acquisition system. This is the connection diagram of the Tool used in this study. We collected SR data from CT or PACS in real time. CT scanners not equipped to issue SRs were handled by image capture of the dose sheet. The acquisition data was compressed and anonymized the current day between 0 o’clock and 3 o’clock every day. In addition, we made anonymization that data cannot be concatenated. The technician uploads the anonymized data on SafeSync. NIRS aggregates the SR data from each facility to the server and uploads the analysis data again. Figure 2. View largeDownload slide RDSR acquisition system. This is the connection diagram of the Tool used in this study. We collected SR data from CT or PACS in real time. CT scanners not equipped to issue SRs were handled by image capture of the dose sheet. The acquisition data was compressed and anonymized the current day between 0 o’clock and 3 o’clock every day. In addition, we made anonymization that data cannot be concatenated. The technician uploads the anonymized data on SafeSync. NIRS aggregates the SR data from each facility to the server and uploads the analysis data again. Figure 3. View largeDownload slide Distribution of CT venders. (a) Distribution of CT venders in Japan(29), n = 11 349. (b) Distribution of CT venders in this study, n = 33. Figure 3. View largeDownload slide Distribution of CT venders. (a) Distribution of CT venders in Japan(29), n = 11 349. (b) Distribution of CT venders in this study, n = 33. Table 1. Collection period and examination number, age of adult and pediatric patients. Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 aN, NIRS Tool; Ncap, NIRS Tool capture version; D, Dose Manager. bThe value is total examination number per acquisition period day and scaner number. cThe center is a university hospital. dThe value is mean value ± SD. View Large Table 1. Collection period and examination number, age of adult and pediatric patients. Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 Center Bed Scanner number Toola Acquisition period Examination number of adult Nunmber/scanner/dayb Age (year old) Examination number of pediatric Nunmber/scanner/dayb Age (year old) Start End Male Female Total Mean ± SD Male Female Total Mean ± SD A 749 2 N 1/16/15 4/9/15 4575 3415 7990 48 64.07 ± 16.56 96 61 157 0.9 6.66 ± 4.84 B 712 1 N 7/9/15 12/30/15 7138 5335 12 473 72 66.48 ± 17.36 219 118 337 1.9 6.55 ± 4.88 Cc 740 3 N 7/8/15 12/31/15 7572 4588 12 160 23 64.21 ± 15.43 259 145 404 0.8 6.55 ± 4.48 D 676 2 N 8/19/15 9/29/15 902 752 1654 20 66.29 ± 17.61 23 12 35 0.4 6.49 ± 4.94 E 227 1 N 9/15/15 12/30/15 1306 1301 2607 25 68.81 ± 14.65 33 29 62 0.6 5.21 ± 4.54 F 715 2 Ncap 12/18/14 1/30/15 1205 910 2115 25 64.66 ± 15.03 11 17 28 0.3 8.96 ± 4.86 G 580 2 N 1/20/15 12/31/15 26 785 20 806 47 591 69 66.6 ± 15.53 264 144 408 0.6 9.54 ± 3.88 H 388 1 D 4/20/15 7/28/15 1596 1331 2927 30 64.87 ± 17.38 49 25 74 0.7 7.11 ± 4.76 Ic 600 2 D 11/18/15 12/31/15 1040 788 1828 21 61.46 ± 17.02 28 32 60 0.7 8.53 ± 4.49 J 269 2 N 9/29/15 12/31/15 2109 2041 4150 22 71.23 ± 14.57 6 0 6 0.03 11.17 ± 2.93 K 1001 6 N 10/29/15 12/30/15 4412 3526 7938 21 67.47 ± 14.26 28 13 41 0.1 9.07 ± 4.53 Lc 1225 4 N 10/28/14 2/2/15 8648 6958 15 606 40 60.93 ± 16.90 165 125 290 0.7 7.63 ± 4.34 Mc 600 5 N 2/19/15 12/31/15 9164 6673 15 837 10 65.24 ± 14.96 97 135 232 0.1 7.56 ± 4.79 Total 652.5 ± 271.27d 33 10/28/14 12/31/15 76 452 58 424 134 876 32.8 ± 19.15d 65.50 ± 15.92 1278 856 2134 0.62 ± 0.49 d 7.52 ± 0.43 aN, NIRS Tool; Ncap, NIRS Tool capture version; D, Dose Manager. bThe value is total examination number per acquisition period day and scaner number. cThe center is a university hospital. dThe value is mean value ± SD. View Large The NIRS tool compresses and anonymizes the current day’s RDSR between midnight and 3:00 am. Also, performs anonymization that cannot be concatenated. The information acquired from each facilities should be aggregated in the RDSR server in NIRS via the network, but it was impossible to realize because the clinical network did not allow connection with the external network due to facility policy problem. Therefore, as a method of acquiring information collected by each facility, we thought that it was safe to share it with NIRS by another PC connected to the virtual private network (VPN). Sharing is one to one with NIRS and each facility, and facility sharing is not done. In order to realize these sharing we used SafeSync (Trend Micro Incorporated, Tokyo, Japan). The data were aggregated into the RDSR System of a dedicated server. Dose Manager was able to output RDSR collected from CT at all times in anonymous state and shared by SafeSync. Data analysis The data of each center aggregated in the RDSR System were output with comma separated values (csv) and analyzed with spreadsheet software (Excel 2013, Microsoft Office, Redmond WA, USA). Data are expressed as mean ± standard deviation (SD). We used the VPN to summarize each center on a spreadsheet, and examined analytic data from each center. Comparison of dose-related data to DRLs RDSR and dose sheets included CTDIvol and DLP for the dose index, calculated the mean and SD for each anatomical region in adults and children, the representative value of each center. For CTDIvol and DLP of ‘Head and Brain’, ‘Circle of Willis’, ‘Eye region’ and ‘Orbit region’ in adults, the dose index value normalized to a 16-cm phantom standard is shown. For the other anatomical regions, it shows the values normalized to a 32-cm phantom. For the CTDIvol and DLP of pediatric patients, the values derived with the 32-cm phantom were doubled to simulate a 16-cm phantom(17). The mean and SD values, minimum value, 25th percentile, 50th percentile, 75th percentile and maximum value were calculated from the dose indices of each center. The mean value of each center was used as a representative value, and its 75th percentile values were taken as adult and pediatric DRLs in this study. We compared our findings with DRLs of the head, chest, abdomen and heart in adults from data published by 10 countries. The pediatric DRL was compared with DRLs of head, chest and abdominal CT published from six countries. RESULTS The total number of centers participating in the survey was 13, of which four were university hospitals. The number of beds was 227 in the smallest center and 1225 in the largest (Table 1). There were 134 876 examinations of patients over 15 years old (males: 76 452, females: 58 424) with RDSR obtained during the survey period from October 2014 to December 2015, and there were 2134 examinations of patients ≤15 years old (males: 1278, females: 856). There were 84 203 adult (males: 47 213, females: 36 990) and 1316 pediatric (males: 745, females: 571) subjects. The mean value for all centers was 32.8 ± 19.15 cases per day. The mean value for pediatric cases at all centers was 0.6 cases. The mean age of adults was 65.5 ± 15.92 years and the mean age of pediatric subjects was 7.5 ± 0.43 years. Figure 4 shows the age ranges in more detail. Figure 4. View largeDownload slide Distribution of examinations by age and sex. Figure 4. View largeDownload slide Distribution of examinations by age and sex. The total number of CT devices targeted for collection was 33, and all had more than 16 rows of detectors. Figure 3 shows the vendor breakdown and departures from the average. No Hitachi scanners were included. Table 2 shows the 20 target regions acquired from all the centers. ‘Unknown’ cases were excluded from the analysis. Table 2. Acquisition of CT target region and patient number of adult and pediatric patients. Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 aSRT is structured reporting templates. Table 2. Acquisition of CT target region and patient number of adult and pediatric patients. Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 Target region (SRTa) Adult examination number Pediatric examination number M F Total M F Total Head (T-D1100), brain (T-A0100) 14 302 11 826 26 128 535 374 909 Circle of Willis (T-45526) 0 9 9 0 0 0 Eye region (T-D0801) 1002 977 1979 83 45 128 Orbit region (T-D0801) 297 245 542 30 21 51 Neck (T-D1600) 2177 1580 3757 49 24 73 Heart (T-32000) 182 97 279 0 0 0 Chest (T-D3000) 29 726 22 592 52 318 193 145 338 Abdomen (T-D4000) 19 745 14 145 33 890 110 80 190 Chest and abdomen (R-FAB55) 3974 3355 7329 50 41 91 Chest, abdomen and pelvis (R-FAB56) 1940 1143 3083 82 33 115 Entire body (T-D0010) 216 90 306 22 16 38 Pelvis (T-D6000) 311 356 667 11 4 15 Lumbar spine (T-11503) 551 437 988 11 8 19 Spine (T-D0146) 13 22 35 2 0 2 Extremity (T-D0300) 537 556 1093 23 13 36 Arm (T-D8200) 26 23 49 4 1 5 Shoulder (T-D2220) 519 257 776 17 8 25 Leg (T-D9400) 116 67 183 12 7 19 Unknown (00001,99GEMS) 818 647 1465 44 36 80 Total examination number 76 452 58 424 134 876 1278 856 2134 aSRT is structured reporting templates. Table 3 shows the ranges and values of the CTDIvol and DLP of each target region at each center as a representative value in adults. Table 4 shows the pediatric values. Table 3. CTDIvol and DLP for single scan of each anatomical region for adult. Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 aSRT is structured reporting templates. bCTDIvol and DLP values adjusted to 16-cm PMMA phantom. Table 3. CTDIvol and DLP for single scan of each anatomical region for adult. Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 Target region (SRTa) Center number Examination number CTDIvol (mGy) DLP (mGy cm) Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max Head (T-D1100)b, Brain (T-A0100)b 13 26 128 68.9 11.26 47 62 67 78 88 1170.7 268.81 655 1059 1174 1292 1684 Circle of Willis (T-45526)b 1 9 29.2 0 29 29 29 29 29 558.3 0 558 558 558 558 558 Eye region (T-D0801)b 4 1979 35.0 11.52 20 29 37 44 45 624.3 205.52 344 563 658 720 836 Orbit region (T-D0801)b 5 542 39.9 19.15 19 29 36 46 69 719.2 636.24 293 351 520 596 1836 Neck (T-D1600) 13 3757 20.1 12.85 9 12 18 24 58 566.3 376.04 236 392 513 553 1741 Heart (T-32000) 3 279 41.6 27.12 18 27 36 54 71 983.6 292.97 653 871 1089 1149 1210 Chest (T-D3000) 13 52 318 16.3 14.66 8 11 12 15 63 721.5 337.52 290 587 659 689 1660 Abdomen (T-D4000) 13 33 890 15.4 15.03 8 10 11 12 65 641.3 344.54 351 485 549 640 1706 Chest and abdomen (R-FAB55) 2 7329 36.4 41.28 7 22 36 51 66 1039.3 963.45 358 699 1039 1380 1721 Chest, abdomen and pelvis (R-FAB56) 2 3083 17.0 0.73 17 17 17 17 18 877.3 20.63 863 870 877 885 892 Entire body (T-D0010) 2 306 61.7 19.39 48 55 62 69 75 1779.9 217.16 1626 1703 1780 1857 1934 Pelvis (T-D6000) 11 667 19.9 14.01 8 13 15 21 57 854.9 379.42 335 637 740 1031 1514 Lumbar spine (T-11503) 7 988 20.4 8.39 10 17 19 20 37 641.8 67.45 529 611 655 673 740 Spine (T-D0146) 1 35 7.6 0 8 8 8 8 8 346.6 0 347 347 347 347 347 Extremity (T-D0300) 10 1093 12.8 7.16 7 8 11 12 29 544.7 172.83 144 488 542 685 722 Arm (T-D8200) 2 49 17.9 4.95 14 16 18 20 21 602.4 118.05 519 561 602 644 686 Shoulder (T-D2220) 8 776 18.3 7.25 5 16 21 23 26 439.1 175.34 126 348 538 558 581 Leg (T-D9400) 5 183 22.2 25.15 4 9 10 22 66 692.5 448.17 228 529 553 724 1428 aSRT is structured reporting templates. bCTDIvol and DLP values adjusted to 16-cm PMMA phantom. Table 4. CTDIvol and DLP for single scan of each anatomical region for pediatric. Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 aSRT is structured reporting templates. bThe values adjusted to 16-cm PMMA phantom. Table 4. CTDIvol and DLP for single scan of each anatomical region for pediatric. Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 Age group (years) Target region (SRTa) Center number Examination number CTDIvol (mGy)b DLP (mGy cm)b Mean SD Min 25th 50th 75th Max Mean SD Min 25th 50th 75th Max 0 to <1 Head (T-D1100), brain (T-A0100) 11 85 35.0 13.92 14 27 35 43 60 529.1 261.03 180 351 509 739 928 Neck (T-D1600) 3 5 8.8 3.06 5 8 10 11 11 119.8 59.72 70 87 103 145 186 Chest (T-D3000) 9 49 9.2 8.87 1 4 9 10 31 117.5 125.02 2 51 79 123 406 Abdomen (T-D4000) 6 18 5.2 3.50 1 3 4 7 11 105.6 76.39 18 60 81 161 213 Chest and abdomen (R-FAB55) 2 13 31.0 34.19 7 19 31 43 55 384.5 445.91 69 227 385 542 700 1 to <6 Head (T-D1100), brain (T-A0100) 11 239 42.1 20.76 6 32 39 56 82 708.5 295.03 242 577 667 863 1320 Neck (T-D1600) 6 19 11.4 4.63 6 8 11 14 18 128.5 69.53 70 80 104 153 251 Chest (T-D3000) 9 104 15.1 18.33 4 6 9 13 63 180.0 145.15 69 83 117 236 507 Abdomen (T-D4000) 7 48 14.4 23.23 2 4 7 8 67 211.5 236.66 37 108 126 184 734 Chest and abdomen (R-FAB55) 2 19 25.4 27.38 6 16 25 35 45 343.7 331.91 109 226 344 461 578 6 to <11 Head (T-D1100), brain (T-A0100) 13 311 59.9 22.10 26 48 59 67 103 950.8 417.27 226 692 911 1249 1706 Neck (T-D1600) 8 22 19.7 11.13 7 11 17 27 36 300.6 250.77 62 146 187 433 725 Chest (T-D3000) 9 87 16.3 19.03 4 5 8 12 57 328.5 400.11 70 94 157 215 1192 Abdomen (T-D4000) 10 51 12.9 15.82 3 5 8 12 57 196.7 188.33 30 99 125 242 683 Chest and abdomen (R-FAB55) 2 27 41.8 48.17 8 25 42 59 76 467.5 514.75 104 286 467 649 831 11 to <15 Head (T-D1100), brain (T-A0100) 13 274 59.8 23.31 1 52 64 71 92 1090.0 398.56 436 799 1056 1278 1733 Neck (T-D1600) 5 27 38.4 19.27 19 23 33 57 60 704.6 350.26 180 508 901 967 967 Chest (T-D3000) 10 98 31.3 33.76 8 12 17 25 103 530.1 343.12 226 282 376 702 1117 Abdomen (T-D4000) 13 73 15.9 8.72 4 10 13 22 32 396.1 246.51 10 198 439 622 780 Chest and abdomen (R-FAB55) 2 32 40.3 43.42 10 25 40 56 71 730.7 395.64 274 617 959 959 959 aSRT is structured reporting templates. bThe values adjusted to 16-cm PMMA phantom. Table 5 compares the 75th percentiles of adult head, chest, abdomen and heart CTs of this study with DRLs published from 10 countries and their mean values. Table 6 compares the 75th percentiles in the head, chest and abdomen of pediatric cases with the DRLs of seven countries with their mean values. Table 5. Comparison of CTDIvol and DLP for adult in each anatomical region with other countries. Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. cThe values adjusted to 32-cm PMMA phantom. Table 5. Comparison of CTDIvol and DLP for adult in each anatomical region with other countries. Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 Anatomical region Dose index This study EU UK Norway Switzerland Germany Kenya Ireland Italy Finland Japan Mean ± SDa 2004 [5] 2005 [6] 2009 [7] 2010 [8] 2010 [9] 2012 [10] 2012 [11] 2014 [12] 2015 [13] 2015 [18] Headb CTDIvol 78 60 65 75 65 65 65 66 69 55 85 67.0 ± 8.2 DLP 1292 990 930 1000 1000 950 760 940 1312 800 1350 1003 ± 191.0 DLP/CTDI 16.6 16.5 14.3 13.3 15.4 14.6 11.7 14.2 19.0 14.5 15.9 15.0 ± 1.95 Chestc CTDIvol 15 12 13 15 10 12 13 9 15 9 15 12.3 ± 2.36 DLP 689 430 580 400 400 400 580 390 569 290 550 459 ± 102.3 DLP/CTDI 45.9 35.8 44.6 26.7 40.0 33.3 44.6 43.3 37.9 32.2 36.7 37.3 ± 5.85 Abdomenc CTDIvol 12 16 14 15 15 20 14 12 18 12 20 15.6 ± 2.91 DLP 640 726 560 710 650 900 470 600 920 560 1000 710 ± 177.3 DLP/CTDI 53 45 40 47 43 45 34 50 51 47 50 45.5 ± 5.31 Heartc CTDIvol 54 — — — 50 — — — 61 — 90 67.0 ± 20.66 DLP 1149 — — — 1000 — — — 1208 — 1400 1203 ± 200.1 DLP/CTDI 21.3 — — — 20.0 — — — 19.8 — 15.6 18.0 ± 2.51 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. cThe values adjusted to 32-cm PMMA phantom. Table 6. Comparison of CTDIvol and DLP for pediatric in each anatomical region with other countries. Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. Table 6. Comparison of CTDIvol and DLP for pediatric in each anatomical region with other countries. Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 Anatomical region Age group (years) Dose index This study UK Germany Switzerland France Thai Japan Japan Mean ± SDa 2005 [6] 2007 [14] 2008 [15] 2009 [16] 2012 [17] 2015 [22] 2015 [18] Headb 0 to <1 CTDIvol 43 30 33 20 30 25 30 38 29.4 ± 5.71 DLP 739 270 390 270 420 400 404 500 379 ± 82.9 DLP/CTDI 17.2 9.0 11.8 13.5 14.0 16.0 13.5 13.2 12.9 ± 2.16 1 to <6 CTDIvol 56 45 40 30 40 30 40 47 38.9 ± 6.64 DLP 863 470 520 420 600 570 624 660 552 ± 86.3 DLP/CTDI 15.4 10.4 13.0 14.0 15.0 19.0 15.6 14.0 14.2 ± 2.61 6 to <11 CTDIvol 67 50 50 40 50 40 45 60 47.9 ± 6.99 DLP 1249 620 710 560 900 610 734 850 712 ± 127.0 DLP/CTDI 18.6 12.4 14.2 14.0 18.0 15.3 16.3 14.2 14.9 ± 1.82 11 to <15 CTDIvol 71 65 60 60 — 45 53 — 56.6 ± 7.77 DLP 1278 930 920 1000 — 800 869 — 904 ± 74.5 DLP/CTDI 18.0 14.3 15.3 16.7 — 17.8 16.4 — 16.0 ± 1.33 Chestb 0 to <1 CTDIvol 10 12 3.5 5 6 4.5 5 11 6.7 ± 3.36 DLP 123 200 55 110 60 80 104 210 117 ± 63.5 DLP/CTDI 12.3 16.7 15.7 22.0 10.0 17.8 20.8 19.1 17.4 ± 3.96 1 to <6 CTDIvol 13 13 5.5 8 7 5.7 5 14 8.3 ± 3.69 DLP 236 230 110 200 126 140 127 300 176 ± 70.0 DLP/CTDI 18.2 17.7 20.0 25.0 18.0 24.6 25.4 21.4 21.2 ± 3.30 6 to <11 CTDIvol 12 20 8.5 10 11 10 5 15 11.4 ± 4.84 DLP 215 370 210 220 274 305 137 410 275 ± 95.3 DLP/CTDI 17.9 18.5 24.7 22.0 24.9 30.5 27.4 27.3 24.2 ± 3.93 11 to <15 CTDIvol 25 14 14 12 — 15.6 11 — 13.3 ± 1.82 DLP 702 580 205 460 — 470 359 — 415 ± 141.0 DLP/CTDI 28.1 41.4 14.6 38.3 — 30.1 32.6 — 31.4 ± 10.40 Abdomenb 0 to <1 CTDIvol 7 20 5 7 8 7.7 7 11 9.4 ± 5.01 DLP 161 170 145 130 160 220 126 220 167 ± 39.2 DLP/CTDI 23.0 8.5 29.0 18.6 20.0 28.6 18.0 20.0 17.8 ± 6.97 1 to <6 CTDIvol 8 25 8 9 9 9 7 16 11.9 ± 6.49 DLP 184 250 255 300 242 275 209 400 276 ± 61.5 DLP/CTDI 23.0 10.0 31.9 33.3 26.9 30.6 29.9 25.0 23.3 ± 7.93 6 to <11 CTDIvol 12 30 13 13 14 14 7 17 15.4 ± 7.09 DLP 242 500 475 380 490 560 346 530 469 ± 78.0 DLP/CTDI 20.2 16.7 36.5 29.2 35.0 40.0 49.4 31.2 30.4 ± 10.1 11 to <15 CTDIvol 22 14 20 16 — 17 13 — 16.0 ± 2.74 DLP 622 560 1000 500 — 765 549 — 675 ± 208.2 DLP/CTDI 28.3 40.0 50.0 31.3 — 45.0 42.2 — 42.2 ± 6.93 aThe values were calculated at DRL which excluded this study. bThe values adjusted to 16-cm PMMA phantom. DISCUSSION In this study, we introduced a series of systems that automatically collect RDSR or dose sheet output from CT, and summarized scan parameters and scan dose. The output formats of RDSR are unified, making it possible to collect information on recorded dose indices and imaging conditions(30). However, the equipment compatible with the output of RDSR is limited to the latest models. The IEC issued the 2012 Dose SR Standard for CT apparatus in IEC 60601-2-44, recommending collection of dose data from CT scans(28). In addition, it has been reported that the accuracy of reading text is 95% because information is collected only by the method of image capture of dose sheets, and each manufacturer has various display formats(31). For more detailed scan parameters, it is a disadvantage that it cannot be captured only from the dose sheet. In Table 2, the targets from the RDSR collection were 20 regions, but in reality, each center was conducting daily inspections using a more specific detailed protocol, e.g. in the case of multiphase scanning of the abdomen (T-D4000, SRT). Furthermore, because RDSR and dose sheet cannot directly obtain information on body type such as body weight and height of patients, and the AEC automatically adjusts for habitus, various ages and body types, are considered to be the cause of differences between centers. Although it has also been reported that the patients undergoing abdominal CT with body mass index (BMI) < 30 that the CTDIvol and DLP of patients who exceeded NDRL was under 0.5% and under 0.8%, respectively(20). DRL is based on standard patients in each country, making it desirable to collect body type information, such as the height and weight. From Table 3, it is conceivable that the CTDIvol of the adult chest–abdominal CT is higher than that of the abdomen–pelvis CT, because some CT scanners include devices that calculate the CTDI value from the maximum, and not the mean, tube current. In addition, CT angiography was included in the chest and abdomen studies, and there is a difference in the dose index due to angiography’s lower pitch setting. From Table 5, in comparison with the DRL of each Japanese study, the CTDIvol and DLP of the head and chest were both higher than those of the other countries, and the values in the abdomen and heart were all lower than the mean values of each country. In automatic collection of data, there are possibilities that local protocols unique to various centers may be included, and that is considered one aspect which cannot be compared with the NDRL of each country. From Table 6, in pediatric DRL, head and chest CT showed higher results than in the other countries. This may be due to the scan range in head CT being set wider in Japan than in other countries by up to ~4 cm, in order to maintain the head within the field of view. As children are more radiosensitive than adults, we should actively adopt methods that can calculate tube current for each age recommended by the Image Gently Program of the American Society of Pediatric Radiology (SPR)(32). The National Radiology Data Registry (NRDR) of the American College of Radiology (ACR) has been collecting large-scale RDSRs throughout North America as a Dose Index Registration (DIR) since 2011(33). The collected dose information is divided into detailed scan regions by a Radlex playbook ID (RPID) code, transmitted anonymously to ACR, and the results of comparative evaluation with the whole are fed back to each center. The size-specific dose estimates (SSDE) taking into consideration the body shape is beginning to be introduced in addition to CTDI and DLP in the dose index, we think that dose optimization is possible in the future(34). Even in Japan, the JJ 1017 code, which codes modality and scan region, is under development. This should lead to higher precision(35). We plan to continue to collect dosage data and to periodically compare, discover and investigate specific causes, and review protocols with the goal of dose optimization. Currently, we are sharing data with a limited collection of equipment. Constructing a cloud-based collection will allow sampling from more centers in the future. We hope this will eliminate disparities among centers and facilitate the optimization of dosimetry. REFERENCES 1 Brenner , D. J. and Hall , E. J. Computed tomography—an increasing source of radiation exposure . N. Engl. J. Med. 357 ( 22 ), 2277 – 2284 ( 2007 ) 10.1056/NEJMra072149 . 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Accessed on 22 January 2017. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

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Radiation Protection DosimetryOxford University Press

Published: Feb 7, 2018

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