TY - JOUR
AU - Panayiotakis, George, S
AB - Abstract Dose audit is important towards optimisation of patients’ radiation protection in diagnostic radiography. In this study, the effect of the body mass index (BMI) on radiation dose received by 1869 adult patients undergoing chest, abdomen, lumbar spine, kidneys and urinary bladder (KUB) and pelvis radiography in an X-ray room with a digital radiography system was investigated. Patients were categorised into three groups (normal, overweight and obese) based on the BMI values. The patients’ entrance surface air kerma (ESAK) and the effective dose (ED) were calculated based on the X-ray tube output, exposure parameters and technical data, as well as utilising appropriate conversion coefficients of the recorded kerma area product (KAP) values. The local diagnostic reference levels (LDRLs) were established at the 75th percentile of the distribution of ESAK and KAP values. Statistically, a significant increase was found in ESAK, KAP and ED values, for all examinations, both for overweight and obese patients compared to normal patients (Mann–Whitney test, p < 0.0001). Regarding the gender of the patients, a statistically significant increase was found in the dose values for male patients compared to female patients, except for the chest LAT examinations (Mann–Whitney test, p = 0.06). The percentage increase for chest PA, chest LAT, abdomen AP, lumbar spine AP, lumbar spine LAT, pelvis AP and KUB AP in overweight patients was 75%, 100%, 136%, 130%, 70%, 66% and 174% for median ESAK, 67%, 81%, 135%, 134%, 85%, 63% and 172% for median KAP, as well as 89%, 54%, 146%, 138%, 82%, 57% and 183% for median ED values, respectively. For obese patients, the corresponding increases were 200%, 186%, 459%, 345%, 203%, 150% and 785% for median ESAK, 200%, 185%, 423%, 357%, 227%, 142% and 597% for median KAP, as well as 222%, 156%, 446%, 363%, 218%, 136% and 625% for median ED. The corresponding LDRLs for overweight patients were 0.17 mGy, 1.21 mGy, 3.74 mGy, 7.70 mGy, 7.99 mGy, 4.07mGy, 5.03 mGy and 0.13 Gy cm2, 0.69 Gy cm2, 2.35 Gy cm2, 2.10 Gy cm2, 2.59 Gy cm2, 2.13 Gy cm2, 2.49 Gy cm2 in terms of ESAK and KAP values, respectively, while in the case of obese patients were 0.28 mGy, 1.82 mGy, 7.26 mGy, 15.10 mGy, 13.86 mGy, 6.89 mGy, 13.40 mGy and 0.21 Gy cm2, 1.10 Gy cm2, 4.68 Gy cm2, 4.01 Gy cm2, 4.80 Gy cm2, 3.27 Gy cm2, 6.02 Gy cm2, respectively. It can be concluded that overweight and obese patients received a significantly increased radiation dose. Careful adjustment of imaging protocols is needed for these patients to reduce patient dose, while keeping the image quality at an acceptable level. Additional studies need to be conducted for these patient groups, that could further contribute to the development of radiation protection culture in diagnostic radiography. INTRODUCTION Presently, medical X-ray examinations provide by far the largest contribution to the population radiation dose from artificial sources(1). Each examination in diagnostic radiography implies exposure of the patient to ionising radiation, which raises concerns about the stochastic and deterministic effects of radiation. To minimise these effects an international system of radiation protection has been developed(2). Patient radiation protection is based on the justification and optimisation principles. The goal of the optimisation process is to provide an acceptable image quality by keeping the corresponding radiation dose as low as reasonably achievable (ALARA)(3). Patient dose audits are critical towards optimisation of radiation protection. The monitoring of patients’ dose during diagnostic X-ray examinations should be established in the national legislation of all European countries(4). It is necessary for each institution to develop protocols for dose measurements that could contribute to both the establishment of local diagnostic reference levels (LDRLs), as well as in the evaluation of the local radiographic practice. Patients’ size and equipment technology are some of the major factors that determine the radiation dose received by the patient and the corresponding image quality(5–7). In a digital radiography system using the automatic brightness control (ABC), the tube voltage, tube current and exposure time increase with respect to the patients’ body thickness, to obtain consistent image quality(8). Thus, in the case of patients with larger thickness in the anatomical area to be imaged (overweight or obese patients) more photons are attenuated inside the body, resulting in an increase of exposure parameters and consequently in a higher radiation dose compared to normal patients(9–11). Several studies have investigated the patient dose during diagnostic radiography, in terms of kerma area product (KAP) and entrance surface air kerma (ESAK) values, measured either directly or indirectly(7, 12–26). Both these values could be converted to the organs’ absorbed doses and effective dose (ED) utilising appropriate conversion coefficients or Monte Carlo based softwares(27, 28). The third quartiles of KAP and ESAK distributions of limited samples of normal-sized patients were adopted as DRLs(29). The standardised reference levels are based on a 70-kg person and those over 90 Kg and under 50 kg are excluded. Since a large number of patients referred for a radiographic examination are overweight, or obese, the standardised DRLs need to be adjusted in order to take into account the patients’ body mass index (BMI)(10). The radiation doses for these patient’ groups need careful monitoring and adherence to the ALARA principle. In this direction, each institution should establish LDRLs and optimise radiation protection for these patient groups. In addition, it is essential to estimate the ED during such examinations, since this quantity is more meaningful than KAP or ESAK values regarding the biological effects of radiation(23). In Greece, the Greek Atomic Energy Commission (GAEC) recently established national DRLs for common radiographic examinations against which the X-ray facilities can compare their performance, however, are only applicable for normal-sized patients(30). Considering the importance of BMI-dependent dose towards the optimisation of radiation protection, the purpose of the current study was to evaluate the effect of BMI on patient dose during digital radiographic examinations performed at the Radiology Department of the University Hospital of Patras and to establish LDRLs for normal, overweight and obese patients. MATERIALS AND METHODS Patients’ data and examinations 1869 adult patients (1011 men and 858 women) who underwent chest posterior–anterior (PA), chest lateral (LAT), lumbar spine AP, lumbar spine LAT, pelvis AP, abdomen AP, kidneys and urinary bladder (KUB) AP radiographs during the period between June 2017 to February 2018 participated in the study. This study focused on the investigation of the effect of the BMI on the radiation dose received by adult patients undergoing these radiographic examinations, since these regions of the human body are quite different among patients with different body habitus with respect to the tissue size, shape and composition. Consequently, this results to quite different exposure conditions regarding the geometry and technical parameters, compared to those associated with smaller regions, such as the cranium or cervical spine. Patients were categorised into three different groups according to their BMI values: normal (18.5–24.99 kg/m2), overweight (25–29.99 kg/m2) and obese (>30 kg/m2)(31). All the examinations were performed by experienced radiographers in the same X-ray room with a digital radiography system. Chest and abdomen radiographs were acquired in standing position, while lumbar spine, pelvis and KUB radiographs in supine position. For each patient, age, sex, weight, height, thickness and BMI data were recorded. The BMI was calculated by dividing the patient’s weight by patient’s height square(31). During each examination, focus skin distance (FSD), focus detector distance (FDD), tube voltage, tube load, field size (FS) and KAP were also recorded. To calculate the FSD for each projection, patient thickness was subtracted from FDD. The dosimetric quantities used for the evaluation of patient dose were KAP, ESAK and ED per projection(32, 33). The majority of the previously published studies reported DRLs only for standard-sized patients(13–16) without any classification of the patients according to their anatomical characteristics(10). Thus, within the framework of the quality assurance program in our institution, this study investigated the patient dose in the case of normal, overweight and obese patients undergoing these radiographic examinations and reported LDRLs as a local comparator, in view of the lack of national DRLs for overweight and obese patients(29). Radiography system The radiography system utilised was a Philips Digital Diagnost (Philips Medical Systems, Netherlands, BV), equipped with a standard X-ray tube (RSO 33 100 ROT 350), an 80 kW X-ray generator (Philips Optimus) and a flat panel detector. The X-ray tube consists of a high speed rotating anode with a dual focal spot with dimensions of 0.6 and 1.2 mm. It features automatic selection of four filter combinations (0 mm Al, 2 mm Al, 1 mm Al + 0.1 mm Cu and 1 mm Al + 0.2 mm Cu) depending on the automatic programmed radiography (APR) protocols. In this study, the available APR protocol with 0 mm Al filtration was used for the abdomen, pelvis, KUB and lumbar spine radiographs, while for the chest radiographs the APR with 1 mm Al + 0.1 mm Cu filtration was used. The exposure parameters (tube voltage and tube load) were selected through automatic exposure control (AEC), to provide adequate image quality with respect to the anatomical region to be imaged. The system is under a systematic quality assurance program by the Medical Physics Department of the hospital, to ensure the consistency of the equipment performance, the reliability and reproducibility of the exposure and the dosimetric parameters. The quality control (QC) tests included the tube voltage accuracy and reproducibility, half value layer and current–time product (mAs) linearity, the measurement of the X-ray tube output and total filtration(34). The X-ray tube output was measured under a scatter free geometry at a source chamber distance of 100 cm, for the tube voltages between 40 and 140 kVp (with 10 kVp increments) and for the filtration modes used, depending on the APR protocol for each examination. This ensures that there is compliance with the X-ray quality used in clinical practice. Measurements were performed using the Radcal Accu Pro 9096 dosimeter (Radcal, Monrovia, CA, USA). The dosimeter was calibrated to the secondary standard laboratory of the GAEC. The QC tests were performed at regular intervals throughout the study, to detect if some factors influencing the radiation dose were out of appropriate limits, due to equipment malfunction. Dose measurements The radiography system was equipped with an integrated KAP metre (Diamentor E2, PTW), to provide a real-time indication of the patient dose based on the X-ray generator data (tube voltage, tube load, filtration and the FS). To achieve adequate accuracy of the KAP measurements, the KAP metre was calibrated in situ, by using a diagnostic dosimeter (Radcal Accu Pro, 9096, Monrovia, CA, USA) and a cylindrical ionisation chamber (model 10 × 6-6), according to the method provided by the International Atomic Energy Agency (IAEA) code of practice(33). The actual KAP value for each examination was calculated by multiplying the calibration coefficient with the reading of the clinical KAP metre. Dose calculations The patients’ ESAK was calculated based on the recorded exposure parameters and the X-ray tube output of the radiography system using the following formula: ESAK(μGy)=TubeOutput(μGy/mAs)×TubeLoad(mAs)×(100FSD(cm))2×BSF (1) where, BSF is the backscatter factor(32) and FSD is the focus to skin distance used. The X-ray tube output for each filtration mode used was calculated based on the function: TubeOutput(μGy/mAs)=a×(TubeVoltage(kVp))2+b×(TubeVoltage(kVp))+c (2) where a, b, c are the fitting factors derived from the plotting of the tube output measurements against the tube voltage. ED values were estimated based on the recorded KAP, using appropriate conversion coefficients(12): ED(mSv)=KAP(Gycm2)×CCED,KAP(mSvGy−1cm−2) (3) where CCED,KAP is the KAP to ED conversion coefficient. The KAP to ED conversion coefficients used were 0.16 mSv Gy−1 cm−2 for chest PA, 0.13 mSv Gy−1cm−2 for chest LAT, 0.18 mSv Gy−1 cm−2 for abdomen AP, 0.22 mSv Gy−1 cm−2 for lumbar spine AP, 0.092 mSv Gy−1 cm−2 for lumbar spine LAT, 0.18 mSv Gy−1 cm−2 for KUB AP and 0.14 mSv Gy−1 cm−2 for pelvis AP examinations. The LDRLs for normal, overweight and obese patients were estimated at the 75th percentile of the ESAK and KAP distributions. A sample of at least 10 patients was selected for each examination and patient group to fulfil the requirements of national and international guidelines. The LDRLs were defined at the 75th percentile to further assist in the optimisation process by providing a local comparator linked to the digital technology of the single X-ray room, to accommodate for the variations in the radiographic technique utilised by the various radiographers, as well as due to the lack of national DRLs for overweight and obese patients(29). Patients that underwent AP/PA and LAT projections, were considered as separate cases, to estimate the patient dose for each projection. Only radiographs that were considered diagnostic by the radiographers were accepted in this study. This ensured that all dose levels used were representative of the diagnostic quality. Microsoft excel software was used for data handling, ESAK, ED and LDRL calculations. Statistical analysis Descriptive statistics (mean, median and range of values) were utilised for expressing values of the patient data (age weight, height, BMI), technical data (FDD, FSD, FS), exposure parameters (tube voltage, tube load), dose estimates (ESAK, KAP, ED), as well as the LDRLs. The normality of the dosimetric data was tested with the Kolmogorov–Smirnov goodness-of-fit test. The Mann–Whitney U test (non-parametric test) was used for investigating the existence of statistical significant difference of the dosimetric data between normal and overweight or obese patients, and also between male and female patients for each examination. The Spearman’s Rho correlation test was applied to evaluate the correlation of KAP, ESAK and ED values with BMI. Statistical analysis was performed with SPSS v.21 statistical package (IBM Corp, Armonk, NY). A p-value of <0.05 (p < 0.05) was considered statistically significant. RESULTS AND DISCUSSION The patient data (age, weight, height, BMI), as well as technical (FDD, FSD, FS) and exposure parameters (tube voltage, tube load) for normal, overweight and obese patients, for all examinations are presented in Tables 1 and 2, respectively. Of the 1869 patients that participated in this study, 787 were normal (42.1%), 851 were overweight (45.6%) and 231 were obese (12.3%). The number of underweight patients for each examination was relatively low during the specific time period and thus were not included in this study. Generally, these patients receive significantly lower doses compared to larger patients, due to the lower exposures required to produce acceptable image quality. Additionally, the percentage of the larger patients referred to the Radiology Departments requiring radiologic evaluation has been increased significantly in the last years(10). Thus, from the point of view of radiation protection, it is of critical importance to report doses for overweight and obese patients. The mean values for the age and BMI were 51 years and 22.9 kg/m2 for normal patients, 57 years and 26.9 kg/m2 for overweight patients, as well as 64 years and 32.0 kg/m2 for obese patients. All the radiographs were of diagnostic quality acceptable by the radiographers during the examinations and by the radiologists during diagnosis. In this way, a link was achieved between the patient doses and a clinically acceptable image quality, which is essential so that the dose values can be used towards establishing LDRLs. The radiographs were acquired at a predefined tube voltage, while the tube load values were automatically adjusted, according to the thickness of the anatomical region irradiated. Thus, an increase 60–118% and 158–700% was observed in the median tube load values for overweight and obese patients, respectively, for all examinations studied. For example, Uppot(9) reported that the standard chest X-ray dose is tube voltage of 90–95 kVp and tube load of 2–2.5 mAs, but for obese patients these values should be increased manually to 100 kVp and 4 mAs in order to obtain acceptable image quality. For chest radiography, a maximum exposure time of 20 ms is recommended, to reduce motion unsharpness(35). However, for larger patients and low tube voltages the necessary tube load can only be achieved with prolonged exposures. For example, an X-ray generator capable of providing maximum current 500 mA due to space charge effects provides a tube load of only 10 mAs for 20 ms exposure time, resulting to longer exposure times if a low kV technique is used(18). Table 1. Patient data classified per projection for all examinations studied. Parameters Patients Chest PA Chest LAT Lumbar spine AP Lumbar spine LAT Pelvis AP Abdomen AP KUB AP Sample Size Normal 144 47 143 112 102 188 51 Overweight 198 67 71 86 202 176 51 Obese 33 33 45 43 35 31 11 Age (years) Normal 49/47 (17–87) 50/47 (19–87) 52/50 (19–91) 54/54 (21–84) 58/57 (23–88) 47/45 (18–89) 47/44 (18–88) Overweight 57/58 (18–90) 59/59 (20–88) 57/56 (27–90) 58/61 (23–90) 64/66 (20–92) 56/55 (23–95) 49/48 (26–77) Obese 68/70 (36–93) 63/66 (30–92) 63/63 (38–85) 58/56 (28–81) 67/71 (30–91) 61/60 (36–86) 65/67 (49/76) Weight (kg) Normal 66/65 (50–83) 67/69 (50–81) 69/70 (52–89) 66/67 (50–83) 66/66 (52–80) 67/66 (50–81) 65/64 (49–80) Overweight 79/78 (62–110) 79/80 (64–98) 78/77 (66–94) 78/78 (63–94) 78/78 (62–96) 79/79 (68–96) 81/80 (64–100) Obese 90/87 (77–120) 91/90 (77–115) 90/90 (76–115) 89/87 (74–115) 90/90 (76–115) 94/95 (81–111) 95/95 (89–106) Height (m) Normal 1.70/1.70 (1.56–1.95) 1.71/1.72 (1.56–1.90) 1.71/1.70 (1.58–1.90) 1.69/1.69 (1.59–1.91) 1.69/1.68 (1.55–1.86) 1.73/1.73 (1.56–1.90) 1.70/1.70 (1.55–1.89) Overweight 1.71/1.72 (1.52–1.97) 1.72/1.73 (1.56–1.83) 1.70/1.70 (1.59–1.88) 1.70/1.70 (1.57–1.83) 1.70/1.70 (1.55–1.85) 1.72/1.72 (1.58–1.85) 1.75/1.76 (1.58–1.96) Obese 1.66/1.63 (1.57–1.85) 1.68/1.67 (1.60–1.85) 1.68/1.67 (1.59–1.85) 1.68/1.65 (1.55–1.80) 1.67/1.67 (1.57–1.85) 1.72/1.70 (1.61–1.87) 1.72/1.72 (1.69–1.75) BMI (kg/m2) Normal 22.7/22.6 (19.7–24.97) 22.9/23.0 (20.0–24.96) 23.6/24.1 (18.9–24.98) 23.2/23.7 (18.6–24.98) 23.1/23.5 (19.3–24.98) 22.4/22.4 (18.6–24.93) 22.4/22.4 (19.3–24.86) Overweight 26.7/26.4 (25–29.98) 26.8/26.7 (25–29.8) 27.1/26.9 (25.1–29.7) 27.2/26.9 (25.1–29.7) 27.1/26.9 (25–29.8) 26.7/26.4 (25–29.96) 26.5/26.3 (25.1–29.98) Obese 32.3/31.2 (30.1–44.9) 32.1/31.2 (30.1–44.9) 31.8/31.2 (30.1–38.5) 31.8/31.2 (30.1–38.5) 32.2/31.6 (30.1–38.5) 31.9/31.7 (30.1–36.3) 32.4/32.0 (30.4–37.1) Parameters Patients Chest PA Chest LAT Lumbar spine AP Lumbar spine LAT Pelvis AP Abdomen AP KUB AP Sample Size Normal 144 47 143 112 102 188 51 Overweight 198 67 71 86 202 176 51 Obese 33 33 45 43 35 31 11 Age (years) Normal 49/47 (17–87) 50/47 (19–87) 52/50 (19–91) 54/54 (21–84) 58/57 (23–88) 47/45 (18–89) 47/44 (18–88) Overweight 57/58 (18–90) 59/59 (20–88) 57/56 (27–90) 58/61 (23–90) 64/66 (20–92) 56/55 (23–95) 49/48 (26–77) Obese 68/70 (36–93) 63/66 (30–92) 63/63 (38–85) 58/56 (28–81) 67/71 (30–91) 61/60 (36–86) 65/67 (49/76) Weight (kg) Normal 66/65 (50–83) 67/69 (50–81) 69/70 (52–89) 66/67 (50–83) 66/66 (52–80) 67/66 (50–81) 65/64 (49–80) Overweight 79/78 (62–110) 79/80 (64–98) 78/77 (66–94) 78/78 (63–94) 78/78 (62–96) 79/79 (68–96) 81/80 (64–100) Obese 90/87 (77–120) 91/90 (77–115) 90/90 (76–115) 89/87 (74–115) 90/90 (76–115) 94/95 (81–111) 95/95 (89–106) Height (m) Normal 1.70/1.70 (1.56–1.95) 1.71/1.72 (1.56–1.90) 1.71/1.70 (1.58–1.90) 1.69/1.69 (1.59–1.91) 1.69/1.68 (1.55–1.86) 1.73/1.73 (1.56–1.90) 1.70/1.70 (1.55–1.89) Overweight 1.71/1.72 (1.52–1.97) 1.72/1.73 (1.56–1.83) 1.70/1.70 (1.59–1.88) 1.70/1.70 (1.57–1.83) 1.70/1.70 (1.55–1.85) 1.72/1.72 (1.58–1.85) 1.75/1.76 (1.58–1.96) Obese 1.66/1.63 (1.57–1.85) 1.68/1.67 (1.60–1.85) 1.68/1.67 (1.59–1.85) 1.68/1.65 (1.55–1.80) 1.67/1.67 (1.57–1.85) 1.72/1.70 (1.61–1.87) 1.72/1.72 (1.69–1.75) BMI (kg/m2) Normal 22.7/22.6 (19.7–24.97) 22.9/23.0 (20.0–24.96) 23.6/24.1 (18.9–24.98) 23.2/23.7 (18.6–24.98) 23.1/23.5 (19.3–24.98) 22.4/22.4 (18.6–24.93) 22.4/22.4 (19.3–24.86) Overweight 26.7/26.4 (25–29.98) 26.8/26.7 (25–29.8) 27.1/26.9 (25.1–29.7) 27.2/26.9 (25.1–29.7) 27.1/26.9 (25–29.8) 26.7/26.4 (25–29.96) 26.5/26.3 (25.1–29.98) Obese 32.3/31.2 (30.1–44.9) 32.1/31.2 (30.1–44.9) 31.8/31.2 (30.1–38.5) 31.8/31.2 (30.1–38.5) 32.2/31.6 (30.1–38.5) 31.9/31.7 (30.1–36.3) 32.4/32.0 (30.4–37.1) Mean/Median values. The range is indicated in parenthesis. Table 1. Patient data classified per projection for all examinations studied. Parameters Patients Chest PA Chest LAT Lumbar spine AP Lumbar spine LAT Pelvis AP Abdomen AP KUB AP Sample Size Normal 144 47 143 112 102 188 51 Overweight 198 67 71 86 202 176 51 Obese 33 33 45 43 35 31 11 Age (years) Normal 49/47 (17–87) 50/47 (19–87) 52/50 (19–91) 54/54 (21–84) 58/57 (23–88) 47/45 (18–89) 47/44 (18–88) Overweight 57/58 (18–90) 59/59 (20–88) 57/56 (27–90) 58/61 (23–90) 64/66 (20–92) 56/55 (23–95) 49/48 (26–77) Obese 68/70 (36–93) 63/66 (30–92) 63/63 (38–85) 58/56 (28–81) 67/71 (30–91) 61/60 (36–86) 65/67 (49/76) Weight (kg) Normal 66/65 (50–83) 67/69 (50–81) 69/70 (52–89) 66/67 (50–83) 66/66 (52–80) 67/66 (50–81) 65/64 (49–80) Overweight 79/78 (62–110) 79/80 (64–98) 78/77 (66–94) 78/78 (63–94) 78/78 (62–96) 79/79 (68–96) 81/80 (64–100) Obese 90/87 (77–120) 91/90 (77–115) 90/90 (76–115) 89/87 (74–115) 90/90 (76–115) 94/95 (81–111) 95/95 (89–106) Height (m) Normal 1.70/1.70 (1.56–1.95) 1.71/1.72 (1.56–1.90) 1.71/1.70 (1.58–1.90) 1.69/1.69 (1.59–1.91) 1.69/1.68 (1.55–1.86) 1.73/1.73 (1.56–1.90) 1.70/1.70 (1.55–1.89) Overweight 1.71/1.72 (1.52–1.97) 1.72/1.73 (1.56–1.83) 1.70/1.70 (1.59–1.88) 1.70/1.70 (1.57–1.83) 1.70/1.70 (1.55–1.85) 1.72/1.72 (1.58–1.85) 1.75/1.76 (1.58–1.96) Obese 1.66/1.63 (1.57–1.85) 1.68/1.67 (1.60–1.85) 1.68/1.67 (1.59–1.85) 1.68/1.65 (1.55–1.80) 1.67/1.67 (1.57–1.85) 1.72/1.70 (1.61–1.87) 1.72/1.72 (1.69–1.75) BMI (kg/m2) Normal 22.7/22.6 (19.7–24.97) 22.9/23.0 (20.0–24.96) 23.6/24.1 (18.9–24.98) 23.2/23.7 (18.6–24.98) 23.1/23.5 (19.3–24.98) 22.4/22.4 (18.6–24.93) 22.4/22.4 (19.3–24.86) Overweight 26.7/26.4 (25–29.98) 26.8/26.7 (25–29.8) 27.1/26.9 (25.1–29.7) 27.2/26.9 (25.1–29.7) 27.1/26.9 (25–29.8) 26.7/26.4 (25–29.96) 26.5/26.3 (25.1–29.98) Obese 32.3/31.2 (30.1–44.9) 32.1/31.2 (30.1–44.9) 31.8/31.2 (30.1–38.5) 31.8/31.2 (30.1–38.5) 32.2/31.6 (30.1–38.5) 31.9/31.7 (30.1–36.3) 32.4/32.0 (30.4–37.1) Parameters Patients Chest PA Chest LAT Lumbar spine AP Lumbar spine LAT Pelvis AP Abdomen AP KUB AP Sample Size Normal 144 47 143 112 102 188 51 Overweight 198 67 71 86 202 176 51 Obese 33 33 45 43 35 31 11 Age (years) Normal 49/47 (17–87) 50/47 (19–87) 52/50 (19–91) 54/54 (21–84) 58/57 (23–88) 47/45 (18–89) 47/44 (18–88) Overweight 57/58 (18–90) 59/59 (20–88) 57/56 (27–90) 58/61 (23–90) 64/66 (20–92) 56/55 (23–95) 49/48 (26–77) Obese 68/70 (36–93) 63/66 (30–92) 63/63 (38–85) 58/56 (28–81) 67/71 (30–91) 61/60 (36–86) 65/67 (49/76) Weight (kg) Normal 66/65 (50–83) 67/69 (50–81) 69/70 (52–89) 66/67 (50–83) 66/66 (52–80) 67/66 (50–81) 65/64 (49–80) Overweight 79/78 (62–110) 79/80 (64–98) 78/77 (66–94) 78/78 (63–94) 78/78 (62–96) 79/79 (68–96) 81/80 (64–100) Obese 90/87 (77–120) 91/90 (77–115) 90/90 (76–115) 89/87 (74–115) 90/90 (76–115) 94/95 (81–111) 95/95 (89–106) Height (m) Normal 1.70/1.70 (1.56–1.95) 1.71/1.72 (1.56–1.90) 1.71/1.70 (1.58–1.90) 1.69/1.69 (1.59–1.91) 1.69/1.68 (1.55–1.86) 1.73/1.73 (1.56–1.90) 1.70/1.70 (1.55–1.89) Overweight 1.71/1.72 (1.52–1.97) 1.72/1.73 (1.56–1.83) 1.70/1.70 (1.59–1.88) 1.70/1.70 (1.57–1.83) 1.70/1.70 (1.55–1.85) 1.72/1.72 (1.58–1.85) 1.75/1.76 (1.58–1.96) Obese 1.66/1.63 (1.57–1.85) 1.68/1.67 (1.60–1.85) 1.68/1.67 (1.59–1.85) 1.68/1.65 (1.55–1.80) 1.67/1.67 (1.57–1.85) 1.72/1.70 (1.61–1.87) 1.72/1.72 (1.69–1.75) BMI (kg/m2) Normal 22.7/22.6 (19.7–24.97) 22.9/23.0 (20.0–24.96) 23.6/24.1 (18.9–24.98) 23.2/23.7 (18.6–24.98) 23.1/23.5 (19.3–24.98) 22.4/22.4 (18.6–24.93) 22.4/22.4 (19.3–24.86) Overweight 26.7/26.4 (25–29.98) 26.8/26.7 (25–29.8) 27.1/26.9 (25.1–29.7) 27.2/26.9 (25.1–29.7) 27.1/26.9 (25–29.8) 26.7/26.4 (25–29.96) 26.5/26.3 (25.1–29.98) Obese 32.3/31.2 (30.1–44.9) 32.1/31.2 (30.1–44.9) 31.8/31.2 (30.1–38.5) 31.8/31.2 (30.1–38.5) 32.2/31.6 (30.1–38.5) 31.9/31.7 (30.1–36.3) 32.4/32.0 (30.4–37.1) Mean/Median values. The range is indicated in parenthesis. Table 2. Technical and exposure parameters classified per projection for all examinations studied. Parameters Patients Chest PA Chest LAT Lumbar Spine AP Lumbar Spine LAT Pelvis AP Abdomen AP KUB AP Tube Voltage (kVp) Normal 125 125 77 90 77 81 81 Overweight 125 125 77 90 77 81 81 Obese 125 125 77 90 77 81 81 Tube Load (mAs) Normal 1.6/1.5 (1.0–5.7) 7.6/6.2 (1.8–21.3) 26/24 (10–67) 20/19 (5–56) 17/15 (7–42) 33/28 (6–117) 14/11 (4–32) Overweight 2.6/2.4 (1.2–5.8) 13/12 (4–28) 51/52 (16–107) 34/31 (19–86) 28/26 (9–82) 65/61 (7–156) 28/24 (13–59) Obese 3.9/4.1 (1.9–6.1) 21/17 (6–46) 103/90 (46–309) 65/49 (30–289) 49/39 (21–213) 134/137 (97–156) 88/88 (45–172) FDD (cm) Normal 180 180 114/110 (99–132) 115/113 (105–134) 115/111 (104–132) 180 113/110 (97–138) Overweight 180 180 114/111 (105–134) 114/110 (101–134) 114/111 (99–135) 180 114/110 (102–132) Obese 180 180 115/114 (107–134) 113/110 (106–127) 116/110 (106–136) 180 118/110 (109–132) FSD (cm) Normal 159/160 (152–165) 149/147 (140–162) 92/90 (74–112) 87/86 (73–109) 94/92 (83–112) 160/160 (153–165) 93/92 (79–117) Overweight 157/157 (151–162) 145/145 (139–153) 89/87 (78–111) 83/81 (69–105) 91/89 (72–114) 156/156 (151–162) 90/88 (78–110) Obese 155/155 (151–158) 142/142 (138–146) 88/87 (79–107) 80/77 (72–94) 88/84 (77–109) 152/152 (150–154) 88/83 (74–104) FS* (cm × cm) Normal 40 × 43 37 × 43 20 × 43 25 × 43 43 × 43 38 × 43 40 × 43 Overweight 43 × 43 38 × 43 23 × 43 27 × 43 43 × 43 40 × 43 43 × 43 Obese 43 × 43 38 × 42 24 × 43 27 × 43 43 × 43 43 × 43 43 × 43 Parameters Patients Chest PA Chest LAT Lumbar Spine AP Lumbar Spine LAT Pelvis AP Abdomen AP KUB AP Tube Voltage (kVp) Normal 125 125 77 90 77 81 81 Overweight 125 125 77 90 77 81 81 Obese 125 125 77 90 77 81 81 Tube Load (mAs) Normal 1.6/1.5 (1.0–5.7) 7.6/6.2 (1.8–21.3) 26/24 (10–67) 20/19 (5–56) 17/15 (7–42) 33/28 (6–117) 14/11 (4–32) Overweight 2.6/2.4 (1.2–5.8) 13/12 (4–28) 51/52 (16–107) 34/31 (19–86) 28/26 (9–82) 65/61 (7–156) 28/24 (13–59) Obese 3.9/4.1 (1.9–6.1) 21/17 (6–46) 103/90 (46–309) 65/49 (30–289) 49/39 (21–213) 134/137 (97–156) 88/88 (45–172) FDD (cm) Normal 180 180 114/110 (99–132) 115/113 (105–134) 115/111 (104–132) 180 113/110 (97–138) Overweight 180 180 114/111 (105–134) 114/110 (101–134) 114/111 (99–135) 180 114/110 (102–132) Obese 180 180 115/114 (107–134) 113/110 (106–127) 116/110 (106–136) 180 118/110 (109–132) FSD (cm) Normal 159/160 (152–165) 149/147 (140–162) 92/90 (74–112) 87/86 (73–109) 94/92 (83–112) 160/160 (153–165) 93/92 (79–117) Overweight 157/157 (151–162) 145/145 (139–153) 89/87 (78–111) 83/81 (69–105) 91/89 (72–114) 156/156 (151–162) 90/88 (78–110) Obese 155/155 (151–158) 142/142 (138–146) 88/87 (79–107) 80/77 (72–94) 88/84 (77–109) 152/152 (150–154) 88/83 (74–104) FS* (cm × cm) Normal 40 × 43 37 × 43 20 × 43 25 × 43 43 × 43 38 × 43 40 × 43 Overweight 43 × 43 38 × 43 23 × 43 27 × 43 43 × 43 40 × 43 43 × 43 Obese 43 × 43 38 × 42 24 × 43 27 × 43 43 × 43 43 × 43 43 × 43 Mean/Median values. The range is indicated in parenthesis. *Median values. Table 2. Technical and exposure parameters classified per projection for all examinations studied. Parameters Patients Chest PA Chest LAT Lumbar Spine AP Lumbar Spine LAT Pelvis AP Abdomen AP KUB AP Tube Voltage (kVp) Normal 125 125 77 90 77 81 81 Overweight 125 125 77 90 77 81 81 Obese 125 125 77 90 77 81 81 Tube Load (mAs) Normal 1.6/1.5 (1.0–5.7) 7.6/6.2 (1.8–21.3) 26/24 (10–67) 20/19 (5–56) 17/15 (7–42) 33/28 (6–117) 14/11 (4–32) Overweight 2.6/2.4 (1.2–5.8) 13/12 (4–28) 51/52 (16–107) 34/31 (19–86) 28/26 (9–82) 65/61 (7–156) 28/24 (13–59) Obese 3.9/4.1 (1.9–6.1) 21/17 (6–46) 103/90 (46–309) 65/49 (30–289) 49/39 (21–213) 134/137 (97–156) 88/88 (45–172) FDD (cm) Normal 180 180 114/110 (99–132) 115/113 (105–134) 115/111 (104–132) 180 113/110 (97–138) Overweight 180 180 114/111 (105–134) 114/110 (101–134) 114/111 (99–135) 180 114/110 (102–132) Obese 180 180 115/114 (107–134) 113/110 (106–127) 116/110 (106–136) 180 118/110 (109–132) FSD (cm) Normal 159/160 (152–165) 149/147 (140–162) 92/90 (74–112) 87/86 (73–109) 94/92 (83–112) 160/160 (153–165) 93/92 (79–117) Overweight 157/157 (151–162) 145/145 (139–153) 89/87 (78–111) 83/81 (69–105) 91/89 (72–114) 156/156 (151–162) 90/88 (78–110) Obese 155/155 (151–158) 142/142 (138–146) 88/87 (79–107) 80/77 (72–94) 88/84 (77–109) 152/152 (150–154) 88/83 (74–104) FS* (cm × cm) Normal 40 × 43 37 × 43 20 × 43 25 × 43 43 × 43 38 × 43 40 × 43 Overweight 43 × 43 38 × 43 23 × 43 27 × 43 43 × 43 40 × 43 43 × 43 Obese 43 × 43 38 × 42 24 × 43 27 × 43 43 × 43 43 × 43 43 × 43 Parameters Patients Chest PA Chest LAT Lumbar Spine AP Lumbar Spine LAT Pelvis AP Abdomen AP KUB AP Tube Voltage (kVp) Normal 125 125 77 90 77 81 81 Overweight 125 125 77 90 77 81 81 Obese 125 125 77 90 77 81 81 Tube Load (mAs) Normal 1.6/1.5 (1.0–5.7) 7.6/6.2 (1.8–21.3) 26/24 (10–67) 20/19 (5–56) 17/15 (7–42) 33/28 (6–117) 14/11 (4–32) Overweight 2.6/2.4 (1.2–5.8) 13/12 (4–28) 51/52 (16–107) 34/31 (19–86) 28/26 (9–82) 65/61 (7–156) 28/24 (13–59) Obese 3.9/4.1 (1.9–6.1) 21/17 (6–46) 103/90 (46–309) 65/49 (30–289) 49/39 (21–213) 134/137 (97–156) 88/88 (45–172) FDD (cm) Normal 180 180 114/110 (99–132) 115/113 (105–134) 115/111 (104–132) 180 113/110 (97–138) Overweight 180 180 114/111 (105–134) 114/110 (101–134) 114/111 (99–135) 180 114/110 (102–132) Obese 180 180 115/114 (107–134) 113/110 (106–127) 116/110 (106–136) 180 118/110 (109–132) FSD (cm) Normal 159/160 (152–165) 149/147 (140–162) 92/90 (74–112) 87/86 (73–109) 94/92 (83–112) 160/160 (153–165) 93/92 (79–117) Overweight 157/157 (151–162) 145/145 (139–153) 89/87 (78–111) 83/81 (69–105) 91/89 (72–114) 156/156 (151–162) 90/88 (78–110) Obese 155/155 (151–158) 142/142 (138–146) 88/87 (79–107) 80/77 (72–94) 88/84 (77–109) 152/152 (150–154) 88/83 (74–104) FS* (cm × cm) Normal 40 × 43 37 × 43 20 × 43 25 × 43 43 × 43 38 × 43 40 × 43 Overweight 43 × 43 38 × 43 23 × 43 27 × 43 43 × 43 40 × 43 43 × 43 Obese 43 × 43 38 × 42 24 × 43 27 × 43 43 × 43 43 × 43 43 × 43 Mean/Median values. The range is indicated in parenthesis. *Median values. The mean, median and the range of KAP values for normal, overweight and obese patients are presented in Table 3. The median KAP values for overweight patients increased 67% for chest PA, 81% for chest LAT, 135% for abdomen AP, 134% for lumbar spine AP, 85% for lumbar spine LAT, 172% for KUB AP and 63% for pelvis AP radiographs compared to normal patients, while for obese patients the increase values were 200%, 185%, 423%, 357%, 227%, 597% and 142%, respectively. The mean, median and the range of ESAK values for normal, overweight and obese patients are presented in Table 4. The median ESAK values for overweight patients increased 75% for chest PA, 100% for chest LAT, 136% for abdomen AP, 130% for lumbar spine AP, 70% for lumbar spine LAT, 174% for KUB AP and 66% for pelvis AP radiographs compared to normal patients, while for obese patients the increase values were 200%, 186%, 459%, 345%, 203%, 785% and 150%, respectively. There was a statistically significant difference with respect to both KAP and ESAK values, either for overweight (Mann–Whitney test, p < 0.0001) or obese patients (Mann–Whitney test, p < 0.0001) compared to normal patients, for all examinations studied. Regarding the gender of the patients, male patients showed a statistically significant increase for both KAP and ESAK values (Mann–Whitney test, p < 0.05), except for the chest LAT examinations (Mann–Whitney test, p = 0.06). The increase in dose values with the increase of BMI is mainly attributed to the increase of tube load values, as previously mentioned (Table 2). The increase in ESAK values may also be explained due to the shorter FSDs in overweight and obese patients (Table 2), regarding that FDD values remained almost constant between the patients’ groups. Additionally, the FSD was calculated taking into consideration the actual patient thicknesses measured, instead of standard thicknesses provided for each examination(26, 35, 36). This estimation is preferred more for overweight and obese patients to avoid underestimation of the ESAK values, due to larger FSDs obtained with standard thicknesses (20 cm for AP/PA and 30 cm for LAT projection), while for normal patients the standard and the actual thicknesses were roughly the same (Table 2). In general, the use of optimum FDD is of critical importance, since shorter FDDs are associated with higher patients’ doses and decreased geometric sharpness(17). This poses the question as to whether it is possible to optimise radiographic procedures for overweight and obese patients by only considering the performance of an average patient(18). A further point is the potential for dose reduction resulting from the increase of the FDD, to compensate for the increased thickness in overweight and obese patients, while maintaining a constant FSD. However, this change may be difficult to be practically achieved for patients positioned in the supine or prone position, and taking into account the known influences of some factors, such as the tissue size, shape and composition, the reduction in the patient dose cannot be achieved in all cases. There may also be some ramifications on the image quality, which however were not reflected within the framework of this study. Table 3. KAP values obtained for normal, overweight and obese patients, for all examinations studied. Examination KAP (Gycm2) Normal Overweight Obese Chest PA  Mean 0.07 0.11 0.18  Median 0.06 0.10 0.18  Range 0.02–0.21 0.04–0.23 0.08–0.29 Chest LAT  Mean 0.31 0.53 0.92  Median 0.26 0.47 0.74  Range 0.07–0.91 0.18–1.19 0.27–2.06 Abdomen AP  Mean 0.92 1.86 3.97  Median 0.75 1.76 3.92  Range 0.13–3.52 0.25–4.34 2.94–4.70 Lumbar Spine AP  Mean 0.78 1.74 3.83  Median 0.74 1.73 3.38  Range 0.25–1.76 0.59–2.77 2.04–9.66 Lumbar Spine LAT  Mean 1.20 2.25 4.48  Median 1.17 2.16 3.83  Range 0.33–2.98 1.25–3.24 2.67–12.35 Pelvis AP  Mean 1.03 1.78 3.03  Median 0.97 1.58 2.35  Range 0.42–2.61 0.51–5.57 1.38–11.73 KUB AP  Mean 0.88 1.92 5.80  Median 0.69 1.88 4.81  Range 0.25–2.28 0.73–4.32 3.69–12.57 Examination KAP (Gycm2) Normal Overweight Obese Chest PA  Mean 0.07 0.11 0.18  Median 0.06 0.10 0.18  Range 0.02–0.21 0.04–0.23 0.08–0.29 Chest LAT  Mean 0.31 0.53 0.92  Median 0.26 0.47 0.74  Range 0.07–0.91 0.18–1.19 0.27–2.06 Abdomen AP  Mean 0.92 1.86 3.97  Median 0.75 1.76 3.92  Range 0.13–3.52 0.25–4.34 2.94–4.70 Lumbar Spine AP  Mean 0.78 1.74 3.83  Median 0.74 1.73 3.38  Range 0.25–1.76 0.59–2.77 2.04–9.66 Lumbar Spine LAT  Mean 1.20 2.25 4.48  Median 1.17 2.16 3.83  Range 0.33–2.98 1.25–3.24 2.67–12.35 Pelvis AP  Mean 1.03 1.78 3.03  Median 0.97 1.58 2.35  Range 0.42–2.61 0.51–5.57 1.38–11.73 KUB AP  Mean 0.88 1.92 5.80  Median 0.69 1.88 4.81  Range 0.25–2.28 0.73–4.32 3.69–12.57 Table 3. KAP values obtained for normal, overweight and obese patients, for all examinations studied. Examination KAP (Gycm2) Normal Overweight Obese Chest PA  Mean 0.07 0.11 0.18  Median 0.06 0.10 0.18  Range 0.02–0.21 0.04–0.23 0.08–0.29 Chest LAT  Mean 0.31 0.53 0.92  Median 0.26 0.47 0.74  Range 0.07–0.91 0.18–1.19 0.27–2.06 Abdomen AP  Mean 0.92 1.86 3.97  Median 0.75 1.76 3.92  Range 0.13–3.52 0.25–4.34 2.94–4.70 Lumbar Spine AP  Mean 0.78 1.74 3.83  Median 0.74 1.73 3.38  Range 0.25–1.76 0.59–2.77 2.04–9.66 Lumbar Spine LAT  Mean 1.20 2.25 4.48  Median 1.17 2.16 3.83  Range 0.33–2.98 1.25–3.24 2.67–12.35 Pelvis AP  Mean 1.03 1.78 3.03  Median 0.97 1.58 2.35  Range 0.42–2.61 0.51–5.57 1.38–11.73 KUB AP  Mean 0.88 1.92 5.80  Median 0.69 1.88 4.81  Range 0.25–2.28 0.73–4.32 3.69–12.57 Examination KAP (Gycm2) Normal Overweight Obese Chest PA  Mean 0.07 0.11 0.18  Median 0.06 0.10 0.18  Range 0.02–0.21 0.04–0.23 0.08–0.29 Chest LAT  Mean 0.31 0.53 0.92  Median 0.26 0.47 0.74  Range 0.07–0.91 0.18–1.19 0.27–2.06 Abdomen AP  Mean 0.92 1.86 3.97  Median 0.75 1.76 3.92  Range 0.13–3.52 0.25–4.34 2.94–4.70 Lumbar Spine AP  Mean 0.78 1.74 3.83  Median 0.74 1.73 3.38  Range 0.25–1.76 0.59–2.77 2.04–9.66 Lumbar Spine LAT  Mean 1.20 2.25 4.48  Median 1.17 2.16 3.83  Range 0.33–2.98 1.25–3.24 2.67–12.35 Pelvis AP  Mean 1.03 1.78 3.03  Median 0.97 1.58 2.35  Range 0.42–2.61 0.51–5.57 1.38–11.73 KUB AP  Mean 0.88 1.92 5.80  Median 0.69 1.88 4.81  Range 0.25–2.28 0.73–4.32 3.69–12.57 Table 4. ESAK values obtained for normal, overweight and obese patients, for all examinations studied. Examination ESAK (mGy) Normal Overweight Obese Chest PA  Mean 0.09 0.15 0.23  Median 0.08 0.14 0.24  Range 0.05–0.34 0.07–0.35 0.11–0.37 Chest LAT  Mean 0.53 0.92 1.55  Median 0.43 0.86 1.23  Range 0.11–1.53 0.28–2.13 0.44–3.41 Abdomen AP  Mean 1.42 2.90 6.19  Median 1.14 2.29 6.37  Range 0.24–5.20 0.30–7.31 4.43–7.41 Lumbar Spine AP  Mean 2.94 6.17 12.90  Median 2.64 6.07 11.75  Range 1.08–5.94 1.94–12.19 4.83–34.06 Lumbar Spine LAT  Mean 3.73 7.01 14.75  Median 3.69 6.26 11.17  Range 0.90–12.07 3.65–20.24 5.63–78.42 Pelvis AP  Mean 1.84 3.34 6.18  Median 1.77 2.94 4.43  Range 0.68–4.89 1.06–11.04 2.66–25.52 KUB AP  Mean 1.72 3.76 12.97  Median 1.24 3.40 10.98  Range 0.43–4.32 1.32–9.40 6.95–33.73 Examination ESAK (mGy) Normal Overweight Obese Chest PA  Mean 0.09 0.15 0.23  Median 0.08 0.14 0.24  Range 0.05–0.34 0.07–0.35 0.11–0.37 Chest LAT  Mean 0.53 0.92 1.55  Median 0.43 0.86 1.23  Range 0.11–1.53 0.28–2.13 0.44–3.41 Abdomen AP  Mean 1.42 2.90 6.19  Median 1.14 2.29 6.37  Range 0.24–5.20 0.30–7.31 4.43–7.41 Lumbar Spine AP  Mean 2.94 6.17 12.90  Median 2.64 6.07 11.75  Range 1.08–5.94 1.94–12.19 4.83–34.06 Lumbar Spine LAT  Mean 3.73 7.01 14.75  Median 3.69 6.26 11.17  Range 0.90–12.07 3.65–20.24 5.63–78.42 Pelvis AP  Mean 1.84 3.34 6.18  Median 1.77 2.94 4.43  Range 0.68–4.89 1.06–11.04 2.66–25.52 KUB AP  Mean 1.72 3.76 12.97  Median 1.24 3.40 10.98  Range 0.43–4.32 1.32–9.40 6.95–33.73 Table 4. ESAK values obtained for normal, overweight and obese patients, for all examinations studied. Examination ESAK (mGy) Normal Overweight Obese Chest PA  Mean 0.09 0.15 0.23  Median 0.08 0.14 0.24  Range 0.05–0.34 0.07–0.35 0.11–0.37 Chest LAT  Mean 0.53 0.92 1.55  Median 0.43 0.86 1.23  Range 0.11–1.53 0.28–2.13 0.44–3.41 Abdomen AP  Mean 1.42 2.90 6.19  Median 1.14 2.29 6.37  Range 0.24–5.20 0.30–7.31 4.43–7.41 Lumbar Spine AP  Mean 2.94 6.17 12.90  Median 2.64 6.07 11.75  Range 1.08–5.94 1.94–12.19 4.83–34.06 Lumbar Spine LAT  Mean 3.73 7.01 14.75  Median 3.69 6.26 11.17  Range 0.90–12.07 3.65–20.24 5.63–78.42 Pelvis AP  Mean 1.84 3.34 6.18  Median 1.77 2.94 4.43  Range 0.68–4.89 1.06–11.04 2.66–25.52 KUB AP  Mean 1.72 3.76 12.97  Median 1.24 3.40 10.98  Range 0.43–4.32 1.32–9.40 6.95–33.73 Examination ESAK (mGy) Normal Overweight Obese Chest PA  Mean 0.09 0.15 0.23  Median 0.08 0.14 0.24  Range 0.05–0.34 0.07–0.35 0.11–0.37 Chest LAT  Mean 0.53 0.92 1.55  Median 0.43 0.86 1.23  Range 0.11–1.53 0.28–2.13 0.44–3.41 Abdomen AP  Mean 1.42 2.90 6.19  Median 1.14 2.29 6.37  Range 0.24–5.20 0.30–7.31 4.43–7.41 Lumbar Spine AP  Mean 2.94 6.17 12.90  Median 2.64 6.07 11.75  Range 1.08–5.94 1.94–12.19 4.83–34.06 Lumbar Spine LAT  Mean 3.73 7.01 14.75  Median 3.69 6.26 11.17  Range 0.90–12.07 3.65–20.24 5.63–78.42 Pelvis AP  Mean 1.84 3.34 6.18  Median 1.77 2.94 4.43  Range 0.68–4.89 1.06–11.04 2.66–25.52 KUB AP  Mean 1.72 3.76 12.97  Median 1.24 3.40 10.98  Range 0.43–4.32 1.32–9.40 6.95–33.73 The maximum/minimum ratio of ESAK values for normal patients were 7.2 for pelvis, 10.0 for KUB, 21.7 for abdomen, 6.8 for chest PA, 13.9 for chest LAT, 5.5 for lumbar AP and 13.4 lumbar LAT radiographs. For overweight patients were 10.4 for pelvis, 7.1 for KUB, 24.4 for abdomen, 5.0 for chest PA, 7.6 for chest LAT, 6.3 for lumbar AP and 5.5 for lumbar LAT radiographs, while for obese patients were 9.6 for pelvis, 4.9 for KUB, 1.7 for abdomen, 3.4 for chest PA, 7.8 for chest LAT, 7.1 for lumbar AP and 13.9 for lumbar LAT radiographs. These findings show that operational conditions were not fully optimised and reductions of the patients’ dose would be possible for all patient groups. Generally, the higher the maximum/minimum ratios of the ESAK values are, the higher the potential for dose reductions will be. However, the corresponding image quality should always taken into consideration during the optimisation process, since a very low dose may compromise the diagnostic quality of the images. If the total sample of patients is taken into consideration the corresponding maximum/minimum ratios of ESAK values were 37.5 for pelvis, 78.4 for KUB, 30.9 for abdomen, 7.4 for chest PA, 31.0 for chest LAT, 31.5 for lumbar AP and 87.1 for lumbar LAT radiographs. The above range factors imply that within the same X-ray room wide variations of patient dose may occur that could be partly related to differences in patients’ size, but could not be accounted for by this parameter alone. The spread of ESAK values is mainly attributed to the spread of tube load values, choice of FDD and collimation(14, 26). Patient dose can also be affected by the design and performance of the X-ray generator(25), insufficient filtration of the X-ray beam and manual setting of the exposure parameters. In the UK hospitals within which exposure settings are manually controlled, insufficient adjustment of radiography technique to individual patient body mass was observed, resulting in variations of patient the doses up to a factor of 10(37). Also, insufficient total filtration of X-ray beam results in higher patient exposure. By applying better filtration of the X-ray beams, it is possible to achieve a dose reduction, while maintaining diagnostic information(20). In Figures 1 and 2, the KAP and ESAK values are presented as a function of BMI, along with the equations describing the relationship between them, for all examinations studied. However, these equations should be implemented with caution for patient dose estimation, especially for radiographs acquired under different clinical conditions, to avoid overestimation or underestimation, in view of the fact that a number of factors affect patients’ dose. The range of variation for the ESAK and KAP values of the obese patients is larger compared to the corresponding range for the normal and overweight patients. This is mainly attributed to the smaller number of the obese patients compared to normal and overweight patients for each examination (Table 1) and to the larger variation of the tube load values for obese patients (Table 2). A larger number of patients and possibly the decrease in the variation of the exposure geometry and the operational parameters used by the radiographers will reduce the uncertainty. The re-audit of the radiographic room at a later stage, following some additional guidance to the radiographers, regarding the homogenisation of the exposure techniques for these patients, could contribute towards this direction. A strong positive correlation was found between KAP and BMI values for chest PA (Spearman Rho test, rs = 0.7727, p < 0.001), chest LAT (Spearman Rho test, rs = 0.6676, p < 0.001), abdomen AP (Spearman Rho test, rs = 0.7671, p < 0.001) and pelvis AP (Spearman Rho test, rs = 0.7164, p < 0.001) radiographs, while a very strong positive correlation was found for lumbar spine AP (Spearman Rho test, rs = 0.8557, p < 0.001), lumbar spine LAT (Spearman Rho test, rs = 0.9003, p < 0.001) and KUB AP (Spearman Rho test, rs = 0.8704, p < 0.001) radiographs. Regarding the ESAK values, a strong positive correlation was found for chest PA (Spearman Rho test, rs = 0.7702, p < 0.001), chest LAT (Spearman Rho test, rs = 0.6364, p < 0.001), abdomen AP (Spearman Rho test, rs = 0.7408, p < 0.001) and pelvis AP (Spearman Rho test, rs = 0.7138, p < 0.001) radiographs, while a very strong positive correlation was found for lumbar spine AP (Spearman Rho test, rs = 0.8257, p < 0.001), lumbar spine LAT (Spearman Rho test, rs = 0.8249, p < 0.001) and KUB AP (Spearman Rho test, rs = 0.8617, p < 0.001) radiographs. The small number of patients and the increased variation of the dose values, especially for chest LAT examinations, could be considered as the main factors which made the correlation coefficient low. The re-audit of the radiographic room at a later stage could also provide additional data, to improve the correlation between KAP and ESAK values with BMI. The dosimetric data reported could be considered sufficient and could be used as a baseline in other X-ray departments to compare their local performance, within the framework of optimisation of radiation protection during radiographic examinations. In a similar study with the same radiography system, the average least squared R2 correlation coefficient of ESAK values with BMI for chest PA examinations was approximately the same with this study (R2 = 0.471 vs R2 = 0.529)(18). Gfirtner et al.(18) reported a clear increase of ESAK values with BMI for chest radiography, as well as that the rate of increase is greater for the lower kV technique than for the higher kV techniques. Thus, treating subgroups of patients in terms of BMI provides a clearer view of the applicability of doses involved. Figure 1. Open in new tabDownload slide KAP values as a function of BMI, along with the fitting equations, for all examinations studied. Figure 1. Open in new tabDownload slide KAP values as a function of BMI, along with the fitting equations, for all examinations studied. Figure 2. Open in new tabDownload slide ESAK values as a function of BMI, along with the fitting equations, for all examinations studied. Figure 2. Open in new tabDownload slide ESAK values as a function of BMI, along with the fitting equations, for all examinations studied. The fat distribution is different for the torso of male and female patients: apple shape for males and pear shape for females(38). Based on this fact, it would be expected that chest examinations do not show different correlation of the dose values with BMI, while the abdominal examinations for female patients would show stronger correlation compared to male patients. However, this hypothesis was not supported by the data reported in this study. Specifically, the chest PA examinations for female patients showed stronger correlation with BMI for both ESAK and KAP values (Spearman Rho test, rs = 0.814, p < 0.001; Spearman Rho test, rs = 0.810, p < 0.001), compared to male patients (Spearman Rho test, rs = 0.693, p < 0.001; Spearman Rho test, rs = 0.698, p < 0.001). This is mainly attributed to the presence of the female breast tissue inside the X-ray field. The abdominal examinations for female patients do not show different correlation with BMI for both ESAK and KAP values (Spearman Rho test, rs = 0.709, p < 0.001; Spearman Rho test, rs = 0.741, p < 0.001), compared to male patients (Spearman Rho test, rs = 0.782, p < 0.001; Spearman Rho test, rs = 0.799, p < 0.001). In overweight and obese patients, the attenuation of the X-ray beam by the increased body fat results in reduced contrast resolution and increased noise in the radiographs, as well as to increased exposure times associated with a greater risk to have motion artefacts(39, 40). In these cases, image quality can be improved by manually selecting the exposure parameters (tube voltage, tube load)(9). However, this results in dose increase and therefore careful monitoring and adherence to the ALARA principle is needed for these patient groups. In digital radiographic equipment, the AEC controls the dose received by the detector and ideally terminates the exposure at a level corresponding to the optimum image quality(10). In the case that this is not achieved, the maximum value of exposure before it is terminated is 600 mAs or 6 s(41). The radiation scattered in the body is influenced by the field of view and the thickness of the patient and degrades the subject contrast, since scatter photons reaching the detector carry no anatomic information(42). Tight collimation of the X-ray beam to the anatomical region of interest reduces scatter and improves image quality(36). Another way to reduce scatter in obese patients is the usage of an antiscatter grid with a high grid ratio (8:1 or 10:1)(43). Furthermore, the digital systems provide the ability to use post-processing algorithms, such as window level and width, zoom, etc., to improve image quality(6). Although the usage of digital techniques may increase the patient dose, the implementation of dose management programs, specific training of radiographers and frequent patient dose audits can improve radiographic practice, while maintaining or optimising patient doses(7, 19). The LDRLs in terms of KAP and ESAK values for normal, overweight and obese patients, for all examinations studied are presented in Table 5. Regarding the KAP, the LDRLs for overweight patients increased 63% for chest PA, 77% for chest LAT, 91% for abdomen AP, 114% for lumbar spine AP, 84% for lumbar spine LAT, 96% for KUB AP and 73% for pelvis AP radiographs compared to normal patients, while for obese patients the increase values were 163%, 182%, 280%, 309%, 240%, 374% and 166%, respectively. As far as the ESAK values are concerned, the LDRLs for overweight patients increased 55% for chest PA, 64% for chest LAT, 101% for abdomen AP, 105% for lumbar spine AP, 79% for lumbar spine LAT, 100% for KUB AP and 79% for pelvis AP radiographs compared to normal patients, while for obese patients the increase values were 155%, 146%, 290%, 302%, 210%, 432% and 202%, respectively. The LDRL values estimated for each patient group (normal, overweight, obese) could be used as a basis in our institution to evaluate the local practice and equipment performance by comparing them with mean KAP or ESAK values and effectively to reduce patient dose without degradation of the image quality. Generally, the DRLs are defined for a standard-sized patient of 70 kg and those that are over 90 kg or under 50 kg are excluded. This standardisation needs to be adjusted to take into account the patients’ body habitus based on BMI. The typical reference dose levels cannot be applied for dose optimisation either for overweight or obese patients. For an institution that encounters such patients, it is necessary the imaging protocols and the LDRLs to be updated(10). In this study, the mean ESAK values for normal and overweight patients were lower than the national DRLs (NDRLs)(30), for all examinations studied. For obese patients, the mean ESAK values were 34.3% and 7.8% lower than NDRLs for chest PA and lumbar spine LAT radiographs, respectively, and 14.8% higher for chest LAT, 84.3% for lumbar spine AP, 3.0% for pelvis AP and 99.5% for KUB radiographs. Table 5. LDRLs obtained for normal, overweight and obese patients, for all examinations studied. Examination LDRLs KAP (Gycm2) ESAK (mGy) Chest PA  Normal 0.08 0.11  Overweight 0.13 0.17  Obese 0.21 0.28 Chest LAT  Normal 0.39 0.74  Overweight 0.69 1.21  Obese 1.10 1.82 Abdomen AP  Normal 1.23 1.86  Overweight 2.35 3.74  Obese 4.68 7.26 Lumbar Spine AP  Normal 0.98 3.76  Overweight 2.10 7.70  Obese 4.01 15.10 Lumbar Spine LAT  Normal 1.41 4.47  Overweight 2.59 7.99  Obese 4.80 13.86 Pelvis AP  Normal 1.23 2.28  Overweight 2.13 4.07  Obese 3.27 6.89 KUB AP  Normal 1.27 2.52  Overweight 2.49 5.03  Obese 6.02 13.40 Examination LDRLs KAP (Gycm2) ESAK (mGy) Chest PA  Normal 0.08 0.11  Overweight 0.13 0.17  Obese 0.21 0.28 Chest LAT  Normal 0.39 0.74  Overweight 0.69 1.21  Obese 1.10 1.82 Abdomen AP  Normal 1.23 1.86  Overweight 2.35 3.74  Obese 4.68 7.26 Lumbar Spine AP  Normal 0.98 3.76  Overweight 2.10 7.70  Obese 4.01 15.10 Lumbar Spine LAT  Normal 1.41 4.47  Overweight 2.59 7.99  Obese 4.80 13.86 Pelvis AP  Normal 1.23 2.28  Overweight 2.13 4.07  Obese 3.27 6.89 KUB AP  Normal 1.27 2.52  Overweight 2.49 5.03  Obese 6.02 13.40 Table 5. LDRLs obtained for normal, overweight and obese patients, for all examinations studied. Examination LDRLs KAP (Gycm2) ESAK (mGy) Chest PA  Normal 0.08 0.11  Overweight 0.13 0.17  Obese 0.21 0.28 Chest LAT  Normal 0.39 0.74  Overweight 0.69 1.21  Obese 1.10 1.82 Abdomen AP  Normal 1.23 1.86  Overweight 2.35 3.74  Obese 4.68 7.26 Lumbar Spine AP  Normal 0.98 3.76  Overweight 2.10 7.70  Obese 4.01 15.10 Lumbar Spine LAT  Normal 1.41 4.47  Overweight 2.59 7.99  Obese 4.80 13.86 Pelvis AP  Normal 1.23 2.28  Overweight 2.13 4.07  Obese 3.27 6.89 KUB AP  Normal 1.27 2.52  Overweight 2.49 5.03  Obese 6.02 13.40 Examination LDRLs KAP (Gycm2) ESAK (mGy) Chest PA  Normal 0.08 0.11  Overweight 0.13 0.17  Obese 0.21 0.28 Chest LAT  Normal 0.39 0.74  Overweight 0.69 1.21  Obese 1.10 1.82 Abdomen AP  Normal 1.23 1.86  Overweight 2.35 3.74  Obese 4.68 7.26 Lumbar Spine AP  Normal 0.98 3.76  Overweight 2.10 7.70  Obese 4.01 15.10 Lumbar Spine LAT  Normal 1.41 4.47  Overweight 2.59 7.99  Obese 4.80 13.86 Pelvis AP  Normal 1.23 2.28  Overweight 2.13 4.07  Obese 3.27 6.89 KUB AP  Normal 1.27 2.52  Overweight 2.49 5.03  Obese 6.02 13.40 The mean, median and the range of ED values for normal, overweight and obese patients are presented in Table 6. At this point, it should be noted that the conversion coefficients used for the determination of the ED from KAP measurements do not take into account the body size, since they are derived from Monte Carlo simulations, utilising standard-sized computational human phantoms(12). Thus, the ED values reported for overweight and obese patients could be significantly different, if body size-dependent conversion coefficients are used. There was a statistically significant increase in overweight (Mann–Whitney test, p < 0.00001) and obese patients (Mann–Whitney test, p < 0.00001) compared to normal patients, for all examinations studied. The median ED values for overweight patients increased 89% for chest PA, 54% for chest LAT, 146% for abdomen AP, 138% for lumbar spine AP, 82% for lumbar spine LAT, 183% for KUB AP and 57% for pelvis AP radiographs compared to normal patients. For obese patients, the corresponding increase values were 222%, 156%, 446%, 363%, 218%, 625% and 136%, respectively. Table 6. ED values obtained for normal, overweight and obese patients, for all examinations studied. Examination ED (mSv) Normal Overweight Obese Chest PA  Mean 0.010 0.018 0.028  Median 0.009 0.017 0.029  Range 0.004–0.034 0.006–0.037 0.013–0.046 Chest LAT  Mean 0.045 0.07 0.12  Median 0.039 0.06 0.10  Range 0.015–0.118 0.02–0.15 0.04–0.27 Abdomen AP  Mean 0.17 0.34 0.72  Median 0.13 0.32 0.71  Range 0.02–0.63 0.05–0.78 0.53–0.85 Lumbar Spine AP  Mean 0.17 0.38 0.84  Median 0.16 0.38 0.74  Range 0.05–0.39 0.13–0.61 0.45–2.13 Lumbar Spine LAT  Mean 0.11 0.21 0.41  Median 0.11 0.20 0.35  Range 0.03–0.27 0.12–0.30 0.25–1.14 Pelvis AP  Mean 0.14 0.25 0.42  Median 0.14 0.22 0.33  Range 0.06–0.37 0.07–0.78 0.19–1.64 KUB AP  Mean 0.16 0.35 1.04  Median 0.12 0.34 0.87  Range 0.04–0.41 0.13–0.78 0.66–2.26 Examination ED (mSv) Normal Overweight Obese Chest PA  Mean 0.010 0.018 0.028  Median 0.009 0.017 0.029  Range 0.004–0.034 0.006–0.037 0.013–0.046 Chest LAT  Mean 0.045 0.07 0.12  Median 0.039 0.06 0.10  Range 0.015–0.118 0.02–0.15 0.04–0.27 Abdomen AP  Mean 0.17 0.34 0.72  Median 0.13 0.32 0.71  Range 0.02–0.63 0.05–0.78 0.53–0.85 Lumbar Spine AP  Mean 0.17 0.38 0.84  Median 0.16 0.38 0.74  Range 0.05–0.39 0.13–0.61 0.45–2.13 Lumbar Spine LAT  Mean 0.11 0.21 0.41  Median 0.11 0.20 0.35  Range 0.03–0.27 0.12–0.30 0.25–1.14 Pelvis AP  Mean 0.14 0.25 0.42  Median 0.14 0.22 0.33  Range 0.06–0.37 0.07–0.78 0.19–1.64 KUB AP  Mean 0.16 0.35 1.04  Median 0.12 0.34 0.87  Range 0.04–0.41 0.13–0.78 0.66–2.26 Table 6. ED values obtained for normal, overweight and obese patients, for all examinations studied. Examination ED (mSv) Normal Overweight Obese Chest PA  Mean 0.010 0.018 0.028  Median 0.009 0.017 0.029  Range 0.004–0.034 0.006–0.037 0.013–0.046 Chest LAT  Mean 0.045 0.07 0.12  Median 0.039 0.06 0.10  Range 0.015–0.118 0.02–0.15 0.04–0.27 Abdomen AP  Mean 0.17 0.34 0.72  Median 0.13 0.32 0.71  Range 0.02–0.63 0.05–0.78 0.53–0.85 Lumbar Spine AP  Mean 0.17 0.38 0.84  Median 0.16 0.38 0.74  Range 0.05–0.39 0.13–0.61 0.45–2.13 Lumbar Spine LAT  Mean 0.11 0.21 0.41  Median 0.11 0.20 0.35  Range 0.03–0.27 0.12–0.30 0.25–1.14 Pelvis AP  Mean 0.14 0.25 0.42  Median 0.14 0.22 0.33  Range 0.06–0.37 0.07–0.78 0.19–1.64 KUB AP  Mean 0.16 0.35 1.04  Median 0.12 0.34 0.87  Range 0.04–0.41 0.13–0.78 0.66–2.26 Examination ED (mSv) Normal Overweight Obese Chest PA  Mean 0.010 0.018 0.028  Median 0.009 0.017 0.029  Range 0.004–0.034 0.006–0.037 0.013–0.046 Chest LAT  Mean 0.045 0.07 0.12  Median 0.039 0.06 0.10  Range 0.015–0.118 0.02–0.15 0.04–0.27 Abdomen AP  Mean 0.17 0.34 0.72  Median 0.13 0.32 0.71  Range 0.02–0.63 0.05–0.78 0.53–0.85 Lumbar Spine AP  Mean 0.17 0.38 0.84  Median 0.16 0.38 0.74  Range 0.05–0.39 0.13–0.61 0.45–2.13 Lumbar Spine LAT  Mean 0.11 0.21 0.41  Median 0.11 0.20 0.35  Range 0.03–0.27 0.12–0.30 0.25–1.14 Pelvis AP  Mean 0.14 0.25 0.42  Median 0.14 0.22 0.33  Range 0.06–0.37 0.07–0.78 0.19–1.64 KUB AP  Mean 0.16 0.35 1.04  Median 0.12 0.34 0.87  Range 0.04–0.41 0.13–0.78 0.66–2.26 Yanch et al. reported that for a moderate overweight patient the ED will be 1.4–7 mSv for abdomen AP, lumbar spine AP and pelvis AP, and 0.04–0.11 mSv for chest PA examinations, depending on the different distributions of the fat in the body. For very overweight patients the corresponding ED values were 2.1–16.8 mSv and 0.04–0.35 mSv, respectively(11). The distribution of the fat may change with respect to the patients’ positioning (supine or standing), but only the thickness of the fat on the exit side of the body that intercepts with the X-ray beam affect the patients’ ED. Thus, for some patients, in the supine position the abdomen, lumbar spine and pelvis examinations results in lower ED than that with the patient in the standing position, since in this case a percentage of the patients’ fat tissue may shift to lateral positions. Therefore, to limit the increase of ED for overweight and obese patients, it is of critical importance to consider patient orientation (AP or PA projection). An additional option is to increase the beam energy, but this also results in a reduced image contrast. Pascoal et al.(21) reported that the overall effects of tube voltage on image quality and ED for chest radiography are dependent on patient size and that a single value of tube voltage cannot be considered optimum for imaging all the patients. The lower kV techniques can be implemented to smaller patients where there is possibility to optimise patient dose and image quality, while higher kV techniques can be applied for thicker patients(24) in an attempt to balance between radiation risk and image quality within the limits of the technical capabilities. Other studies have also shown that the radiation dose received by the organs of different body sizes decreases with increasing BMI(22, 23). Generally, to optimise radiographic examinations it is necessary to know the factors affecting the image quality and radiation dose received by the patient, so that the appropriate options can be selected, given the clinical conditions(3, 6). The radiography system should be periodically evaluated within the framework of a QC program by a medical physicist, to ensure its dosimetric and imaging performance. It is essential the radiographers to have adequate training in radiation protection issues and awareness in dose reduction techniques, to avoid unnecessary exposures to patients(3). The establishment of DRLs is an important step towards optimisation, as it provides the ability for comparison with the institutional doses(5, 29). The appropriate technical and exposure factors (tube voltage, tube load, field size, filtration, FDD, grid ratio, AEC sensors selection, etc.) for each type of examination should be selected according to the patient’s anatomical characteristics. Οptimisation can also be achieved utilising phantom-based studies or Monte Carlo simulation techniques(27, 28, 33, 43). The major limitations of this study were the inclusion of data from one hospital, one radiography system and the limited number of radiographers. Even though the reported dose values correspond to the AEC settings of the specific radiography system, they could be used as a baseline for the comparison with the corresponding dose values obtained in other institutions, utilising either the same or different radiography systems. This is an important step towards evaluation of the local performance of an X-ray room or an institution and thus could contribute towards the establishment of a radiation protection culture. While this BMI-dependent approach could contribute towards patients’ dose optimisation, future work should focus on considering body size-dependent conversion coefficients for the calculation of the ED, an extended BMI range and/or different imaging protocols (filtration, exposure parameters, etc.), to obtain a BMI-dependent dose curve for each examination, as well as to establish DRLs for the different groups of patients. CONCLUSION It seems that dose monitoring with respect to the patients’ BMI is an important topic towards optimisation of diagnostic radiography. The results of the statistical analysis showed a statistically significant increase of the radiation dose received by overweight and obese patients compared to normal patients. The imaging protocols need to be properly adjusted to reduce the dose received by the overweight or obese patients, while maintaining a clinically acceptable image quality. Establishing DRLs as a function of BMI can be considered as an additional step towards optimisation of imaging technique and patients’ radiation protection. Obviously, further efforts are needed, in order to establish radiation protection culture in a radiography department. ACKNOWLEDGEMENTS We would like to thank all the radiographers for their assistance and cooperation, during data collection. REFERENCES 1 United Nations Scientific Committee on the Effects of Atomic Radiation . Sources and effects of ionizing radiation. UNSCEAR 2008 Report to the General Assembly with Scientific Annexes (United Nations, New York) ( 2010 ). 2 International Commission on Radiological Protection . The 2007 recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37(2–4), ( 2007 ). 3 International Atomic Energy Agency . Be informed About the Safe Use of Ionizing Radiation in Medicine. Information to Help Health Professionals Achieve Safer Use of Radiation in Medicine for the Benefit of Patients. Available on https://rpop.iaea.org/RPOP/RPoP/Content/index.htm. 4 Council Directive 2013/59/Euratom of 5 December 2013 laying down basic safety standards for protection against the dangers arising from exposure to ionizing radiation, and repealing directives 89/618/ Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom . Off. J. Eur. Commun. L13 , 1 ( 2014 ). WorldCat 5 International Commission on Radiological Protection . Managing patient dose in digital radiology. ICRP Publication 93. Ann. ICRP 34(1), ( 2004 ). 6 Uffmann , M. and Schaefer-Prokop , C. Digital radiography: the balance between image quality and required radiation dose . Eur. J. Radiol. 72 , 202 – 208 ( 2009 ). Google Scholar Crossref Search ADS PubMed WorldCat 7 Vano , E. , Fernandez , J. M. , Ten , J. I. , Prieto , C. , Gonzalez , L. , Rodriguez , R. and de las Heras , H. Transition from screen-film to digital radiography: evolution of patient radiation doses at projection radiography . Radiology 243 , 461 – 466 ( 2007 ). Google Scholar Crossref Search ADS PubMed WorldCat 8 Doyle , P. and Martin , C. J. Calibrating automatic exposure control devices for digital radiography . Phys. Med. Biol. 51 , 5475 – 5485 ( 2006 ). Google Scholar Crossref Search ADS PubMed WorldCat 9 Uppot , R. N. Impact of obesity on radiology . Radiol. Clin. North Am. 45 , 231 – 246 ( 2007 ). Google Scholar Crossref Search ADS PubMed WorldCat 10 Buckley , O. , Ward , E. , Ryan , A. , Colin , W. , Snow , A. and Torreggiani , W. C. European obesity and the radiology department. What can we do to help? Eur. Radiol. 19 , 298 – 309 ( 2009 ). Google Scholar Crossref Search ADS PubMed WorldCat 11 Yanch , J. C. , Behrman , R. H. , Hendricks , M. J. and McCall , J. H. Increased radiation dose to overweight and obese patients from radiographic examinations . Radiology 252 , 128 – 139 ( 2009 ). Google Scholar Crossref Search ADS PubMed WorldCat 12 Wall , B. F. , Haylock , R. , Jansen , J. T. M. , Hillier , M. C. , Hart , D. and Shrimpton , P. C. Radiation risks from medical X-ray examinations as a function of the age and sex of the patient. Report HPA-CRCE 028 (Chilton, UK: Health Protection Agency) ( 2011 ). 13 Roch , P. and Aubert , B. French diagnostic reference levels in diagnostic radiology, computed tomography and nuclear medicine: 2004–2008 review . Radiat. Prot. Dosim. 154 , 52 – 75 ( 2013 ). Google Scholar Crossref Search ADS WorldCat 14 Miliatovic , A. , Ciraj-Bjelac , O. , Ivanovic , S. , Jovanovic , S. and Spasic-Jokic , V. Patient dose measurements in diagnostic radiology procedures in Montenegro . Radiat. Prot. Dosim. 149 , 454 – 463 ( 2012 ). Google Scholar Crossref Search ADS WorldCat 15 Inal , T. and Atac , G. Dose audit for patients undergoing two common radiography examinations with digital radiology systems . Diagn. Interv. Radiol. 20 , 100 – 104 ( 2014 ). Google Scholar PubMed WorldCat 16 Blanco , S. et al. . Determination of diagnostic reference levels in general radiography in Latin America . Radiat. Prot. Dosim. 156 , 303 – 309 ( 2013 ). Google Scholar Crossref Search ADS WorldCat 17 Brennan , P. C. and Nash , M. Increasing FFD: an effective dose-reducing tool for lateral lumbar spine investigations . Radiography 4 , 251 – 259 ( 1998 ). Google Scholar Crossref Search ADS WorldCat 18 Gfirtner , H. , Kaplanis , P. A. , Moores , B. M. , Schneider , P. and Vassileva , J. A study in Europe of patient dosimetry in diagnostic radiology: protocol development and findings . Radiat. Prot. Dosim. 139 , 380 – 387 ( 2010 ). Google Scholar Crossref Search ADS WorldCat 19 Aldrich , J. E. , Duran , E. , Dunlop , P. and Mayo , J. R. Optimization of dose and image quality for computed radiography and digital radiography . J. Digit. Imaging 19 , 126 – 131 ( 2006 ). Google Scholar Crossref Search ADS PubMed WorldCat 20 Ekpo , E. U. , Hoban , A. C. and McEntee , M. F. Optimisation of direct digital chest radiography using Cu filtration . Radiography 20 , 346 – 350 ( 2014 ). Google Scholar Crossref Search ADS WorldCat 21 Pascoal , A. , Patel , R. , Lawinski , C. P. and Tabakov , S. Optimization of tube voltage and dose for digital chest radiography—a study addressing patient size. In: Proceedings of UK Radiological Congress, Birmingham, 6–8 June 2005, p. 2 ( 2005 ). 22 Tung , C. J. , Lee , C. J. , Tsai , H. Y. , Tsai , S. F. and Chen , I. J. Body size-dependent patient effective dose for diagnostic radiography . Radiat. Meas. 13 , 1008 – 1011 ( 2008 ). Google Scholar Crossref Search ADS WorldCat 23 Kim , H. , Park , M. , Park , S. , Jeong , H. , Kim , J. and Kim , Y. Estimation of organ absorbed doses and effective dose based on body mass index in digital radiography . Radiat. Prot. Dosim. 153 , 92 – 99 ( 2013 ). Google Scholar Crossref Search ADS WorldCat 24 Tsai , H. Y. , Yang , C. H. , Huang , K. M. , Li , M. J. and Tung , C. J. Analyses of patient dose and image quality for chest digital radiography . Radiat. Meas. 45 , 722 – 725 ( 2010 ). Google Scholar Crossref Search ADS WorldCat 25 Fernandez , J. M. , Ordiales , J. M. , Guibelalde , E. , Prieto , C. and Vano , E. Physical image quality comparison of four types of digital detector for chest radiology . Radiat. Prot. Dosim. 129 , 140 – 143 ( 2008 ). Google Scholar Crossref Search ADS WorldCat 26 Ofori , E. K. , Antwi , W. K. , Arthur , L. and Duah , H. Comparison of patient radiation dose from chest and lumbar spine x-ray examinations in 10 hospitals in Ghana . Radiat. Prot. Dosim. 149 , 424 – 430 ( 2012 ). Google Scholar Crossref Search ADS WorldCat 27 Tapiovaara , M. and Siiskonen , Τ. PCXMC-A Monte Carlo program for calculating patient doses in medical X-ray examinations. Report STUK-A231 (Helsinki: Finnish Centre for Radiation and Nuclear Safety (STUK)) ( 2008 ). 28 Kramer , R. , Khoury , H. J. and Vieira , J. W. CALDose_X-a software tool for the assessment of organ and tissue absorbed doses, effective dose and cancer risks in diagnostic radiology . Phys. Med. Biol. 53 , 6437 – 6459 ( 2008 ). Google Scholar Crossref Search ADS PubMed WorldCat 29 International Commission on Radiological Protection . Diagnostic reference levels in medical imaging. ICRP Publication 135. Ann. ICRP 46( 1 ), ( 2017 ). 30 National Diagnostic Reference Levels (NDRL) for Common X-Ray Examinations and Interventional Cardiology Procedures. Available on http://eeae.gr/en/index.php?fvar=html/files/_dea_radiology. Accessed May 27, 2018 . 31 World Health Organization . BMI Classification. Available on http://apps.who.int/bmi/index.jsp?introPage=intro_3.html. Accessed May 27, 2018 . 32 International Commission on Radiation Units and Measurements . Patient dosimetry for x rays used in medical imaging. ICRU report 74 (Bethesda, MD: International Commission on Radiation Units and Measurements) ( 2005 ). 33 International Atomic Energy Agency . Dosimetry in diagnostic radiology: an international code of practice. IAEA technical reports series 457 (IAEA: Vienna) ( 2007 ). 34 American Association Physicists in Medicine . Quality control in diagnostic radiology. AAPM report No 74 (Medical Physics Publishing: USA) ( 2002 ). 35 Carmichael , J. H. E. , Maccia , C. , Moores , B. M. , Oestmann , J. W. , Sshibilla , H. , Teunen , D. , Van Tiggelen , R. and Wall , B. European Guidelines on quality criteria for diagnostic radiology images. EUR 16260 EN (Luxemburg, Office for Official Publications of the European Communities) ( 1996 ). 36 Parry , R. A. , Sharon , A. G. and Benjamin , R. A. Typical patient dose in diagnostic radiology: the AAPM/RSNA physics tutorials for residents . Radiographics 19 , 1289 – 1302 ( 1999 ). Google Scholar Crossref Search ADS PubMed WorldCat 37 Institute of Physical Sciences in Medicine . National Radiological Protection Board and College of Radiographers. National protocol for patient dose measurements in diagnostic radiology. NRPB ( 1992 ). 38 Fu , J. , Hofker , M. and Wijmenga , C. Apple or pear: size and shape matter . Cell Metab. 21 , 507 – 508 ( 2015 ). Google Scholar Crossref Search ADS PubMed WorldCat 39 Fetterly , K. A. and Schueler , B. A. Experimental evaluation of fiber-interspaced antiscatter grids for large patient imaging with digital x-ray systems . Phys. Med. Biol. 52 , 4863 – 4880 ( 2007 ). Google Scholar Crossref Search ADS PubMed WorldCat 40 Modica , M. F. , Kanal , K. M. and Gunn , M. L. The obese emergency patient: Imaging challenges and solutions . Radiographics 31 , 811 – 823 ( 2011 ). Google Scholar Crossref Search ADS PubMed WorldCat 41 European Commission . Criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installation. Radiation Protection No. 91 ( 1997 ). 42 Bushberg , J. T. X-ray interactions . Radiographics 18 , 457 – 468 ( 1998 ). Google Scholar Crossref Search ADS PubMed WorldCat 43 Rill , L. N. , Brateman , L. and Arreola , M. Evaluating radiographic parameters for mobile chest computed radiography: phantoms, image quality and effective dose . Med. Phys. 30 , 2727 – 2735 ( 2003 ). Google Scholar Crossref Search ADS PubMed WorldCat © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - PATIENT DOSE IN DIGITAL RADIOGRAPHY UTILISING BMI CLASSIFICATION
JF - Radiation Protection Dosimetry
DO - 10.1093/rpd/ncy194
DA - 2019-08-01
UR - https://www.deepdyve.com/lp/oxford-university-press/patient-dose-in-digital-radiography-utilising-bmi-classification-Ola2yeSU3q
SP - 155
VL - 184
IS - 2
DP - DeepDyve
ER -