ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL PROCEDURES

ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL... ABSTRACT The present work reports data of the radiation exposure to the patient in various diagnostic and therapeutic interventional radiological (IR) procedures. The study includes 260 diagnostic and 195 therapeutic exposure data in 455 IR procedures. All the IR procedures were performed on a biplane angiographic machine in a tertiary care hospital. The radiation exposure was estimated from dose–area product (DAP), fluoroscopy time (FT), number of fluoroscopic runs, number of images and cumulative dose (CD) value recorded during the procedure. The data reported in the present study show significant variability in DAP values in diagnostic and therapeutic IR procedures. In diagnostic procedures, the minimum median DAP value is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and maximum DAP value is 108.8 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. For therapeutic procedures, the median value of DAP ranges from 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min to 267.23 Gy cm2 for coiling of cerebral aneurysm with mean FT of 60.52 min. The DAP value for each procedure was also correlated with FT, number of fluoroscopic runs, number of images and CD. The reported DAP values in this study are within the range of earlier published results which suggest that our finding provides at least approximate applicability to other hospitals. The third quartile DAP values of the procedures having significant number of patient data (n ≥ 10) serves as provisional reference values for the optimization of procedure protocols. INTRODUCTION Interventional radiology (IR) is a medical sub-specialty which aids in the image-guided diagnosis and treatment of disease through minimally invasive techniques. The IR procedure can avoid all the major complications associated with open surgeries. The majority of vascular IR procedures require negotiating and manipulating a catheter under fluoroscopy guidance to evaluate the patient pathology and to guide the treatment processes.(1) The fluoroscopic exposure may result in significant radiation burden to the patient during such angiographic procedures. In contrast to diagnostic radiography, where radiation exposure to patient’s skin is of the order of μGy to mGy, exposure in IR procedures usually range from hundreds of mGy and may go up to several Gy in some cases.(2, 3) The use of extensive radiation exposure in fluoroscopy guided IR procedures may lead to high probability of stochastic effects along with high chances of deterministic injuries to the patients. Many studies have reported and investigated radiation induced skin injuries after IR procedures and threshold doses required to manifest these injuries in the exposed individuals.(4–7) However, some patient may show severe reaction at relatively lower dose levels compared to others, due to biological variations.(8) Depending on the clinical intent, the fluoroscopy guided IR procedures can be divided into diagnostic and therapeutic. Each of the procedure has different level of radiation risk associated with it.(9) The therapeutic procedure is supposed to be more complex than diagnostic procedure as it may require longer fluoroscopy time and more number of fluoroscopic frames.(10) For same IR procedure large variability in patient’s dose has been reported in the literature. Major causes of these variation are attributed to variable and long FT, number of images acquired, type of procedure, complexity involved, patient body size, age and performance of angiographic equipment and expertise of the interventionist.(11–18) Radiation dose in IR procedure could be measured using direct and indirect methods.(19–43) The direct method mostly involves the use of thermoluminescence dosemeters (TLD’s) or films attached on the patient skin during the procedure to measure maximum skin dose(19–26). The direct measurement is desirable but not always feasible, as use of TLD or film is laborious task and it is difficult to evaluate maximum skin dose accurately with these dosimeters, due to restricted measurement points available with them. In IR procedure, it is impossible to know beforehand the exact location of region where the maximum dose will occur, that may lead to underestimation of the maximum skin dose.(22, 25) An alternative to direct measurement is to estimate radiation dose from measured DAP value with the help of ionization chamber attached in the collimator assembly of the angiography system.(27–29) Precise estimation of skin dose using DAP requires assumption of beam orientation and exposure factors employed during the procedure. The DAP value has been reported to correlate reasonably well with skin dose and radiation risk.(27, 30, 31) In addition, DAP meter can be used during the procedure without any interference in the procedure, making it a convenient method for dose monitoring in IR procedure.(33) The International Commission on Radiation Protection (ICRP) has proposed the concept of diagnostic reference level (DRL) for optimization of medical exposure in diagnostic procedure.(44–46) The concept of reference level (RL) has become a valuable and well accepted tool for dose optimization and comparison of radiation dose.(1, 34, 47, 48) The RL is evaluated from third-quartile value of radiation dose parameter. In IR procedure, RL can be set for DAP, FT and the number of images acquired during the procedure. A single measured DAP reading may not provide information on dose optimization status in the facility but comparing the local mean DAP or third quartile DAP with available DRL, can be used to access radiation optimization practice in the facility.(24) Till date, there is no specific report published for setting RL’s in IR procedures in India. The aim of the present study is to estimate the radiation exposure to the patients from DAP value in various diagnostic and therapeutic IR procedures. The third quartile DAP value is proposed as provisional local RL for the procedure having sufficient number of database (n ≥ 10). MATERIALS AND METHODS The radiation exposure to the patients in IR procedures was estimated from angiographic database of 455 procedures on adult patients for a period of 1 year. The angiographic database includes 260 (112 females, 148 males; median age: 42 years, range: 18–75 years) diagnostic and 195 (82 females, 113 males; median age: 40.5 years, range: 18–80 years) therapeutic IR procedures listed in the flow chart shown in Figure 1. All the procedures were performed on a biplane angiographic units (Allura Xper FD 20/10: M/s Philips Medical Systems, Germany) installed at Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India. The angiographic unit is equipped with two amorphous silicon flat panel detectors (FPD) with CsI scintillator in A and B planes. The size (diagonal length) of A and B plane detectors are 48 and 25 cm, respectively. The zoom fields of plane A detector are 30, 26, 22, 19, 16, 13.5 and 11 cm and of plane B detector are 25, 20 and 15 cm. The angiographic unit is equipped with integrated DAP meters (KermaX® plus TinO, IBA dosimetry, Germany, GmbH) in both arms of x-ray tube housing. DAP meters were calibrated in situ from measurement of air kerma and beam area with a 75 cm3 shadow free ionization chamber (UnidosE dosimeter PTW, Freiburg, Germany) after taking into account of attenuation and scatter contribution from patient’s table. The angiographic unit used in the study met the quality assurance (QA) criterion as specified by relevant national regulations.(49) Figure 1. View largeDownload slide Information about types of diagnostic and therapeutic IR procedures investigated. Figure 1. View largeDownload slide Information about types of diagnostic and therapeutic IR procedures investigated. The angiography unit operates in three user selectable dose rate mode—low, normal and high with fluoroscopic pulse rate of 15 pulses/s. The procedures were mostly performed in normal mode of fluoroscopy. The measured dose rates of the angiographic system on the surface of solid water phantom taking into account of attenuation and scatter contribution from couch for each mode of operation is listed in Table 1. The present study is retrospective in nature and conducted under QA category. As, this study does not involve any additional radiation exposure to the patients, therefore approval from research ethics board was not required. Information on type of examination, gender, age, DAP, number of images acquired, FT and number of fluoroscopic runs employed during the procedures was gathered for data collection. The data were further classified into diagnostic and therapeutic categories depending on the intent of the procedure. Table 1. Dose rates measured in solid water phantom for the biplane x-ray tubes used in the study. Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Table 1. Dose rates measured in solid water phantom for the biplane x-ray tubes used in the study. Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 RESULT AND DISCUSSION The information about number of exposure, age range, number of runs, number of images, FT (mean and median), DAP (range, mean, median and third quartile) and CD value for the IR procedure is listed in Table 2. The reported data show large variability in DAP values for all the diagnostic and therapeutic IR procedures included in the study. It is clear from Table 2, for diagnostic procedures minimum value of median DAP is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and the maximum value of median DAP is 108.80 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. On the other hand, for therapeutic IR procedures minimum median DAP is 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min and the maximum value of median DAP is 267.23 Gy cm2 for coiling of aneurysm with mean FT of 60.52 min. For all other IR procedures, the median DAP lies between the quoted above minimum and maximum values. The correlation of DAP with (i) FT, (ii) number of runs, (iii) number of images and (iv) CD in cerebral and lower limb angiography is shown in Figure 2. Likewise, Figure 3 shows the correlation of DAP with these parameters in coiling of cerebral aneurysm and intra-arterial thrombolysis procedures. To assess DAP linearity with above mentioned parameters; Pearson’s correlation test was performed for all the procedures. A P < 0.0001 was considered statistically significant. In cerebral angiography, a moderate correlation (r = 0.554, R2 = 0.307) was noticed between DAP and FT, DAP and fluoroscopic runs (r = 0.657, R2 = 0.431) and a weaker correlation (r = 0.437, R2 = 0.110) is observed between DAP and the number of images. However, we observed a strong correlation (r = 0.771, R2 = 0.594) between DAP and number fluoroscopy runs, a moderate correlation (r = 0.605, R2 = 0.366) between DAP and FT and a weak correlation (r = 0 .329, R2 = 0.108) between DAP and number of images in coiling of cerebral aneurysm. A strong correlation (r ≥ 0.734, R2 ≥ 0.567) has been noticed between DAP and CD for all diagnostic and therapeutic procedures. We also observed a moderate correlation between DAP and FT for all the IR procedures, which signifies use of different dose rate modes and different magnification factors during the procedure. Same observation have been noticed by Fletcher et al.(16) for the correlation between patient dose and FT and concluded that FT is unlikely to correlate well with dose. Table 2. Parameters recorded during diagnostic and therapeutic IR procedures in present study. Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Table 2. Parameters recorded during diagnostic and therapeutic IR procedures in present study. Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Figure 2. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in case of cerebral angiography and lower limb angiography. Figure 2. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in case of cerebral angiography and lower limb angiography. Figure 3. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in coiling of cerebral aneurysm and cerebral AVM embolization. Figure 3. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in coiling of cerebral aneurysm and cerebral AVM embolization. The comparison of our data with earlier reported values in literature is also summarized in Table 3. Table 3 shows that our data is within the range of earlier reported values.(8–10, 14, 17, 28, 34–43) The mean DAP value for cerebral angiography (103 Gy cm2) in present study is lower than that reported by Brambilla et al.(39) (158 Gy cm2) and Chun et al.(28)(136.6 Gy cm2), but comparable with mean DAP values reported by Iha et al.(37)(106.2 Gy cm2) and Aroua et al.(34) (121 Gy cm2). The mean number of images acquired by us is comparable to reported studies, but Aroua et al.(34) has reported more than double number of images acquired for cerebral angiography. In lower limb angiography, our mean DAP (13.35 Gy cm2) is considerably lower than the DAP value reported by Pitton et al.(35) (36.5 Gy cm2), Vano et al.(9) (66.63 Gy cm2), Ruiz-Cruces et al.(17)(30 Gy cm2) and Ruiz-Cruces et al.(36) (58.17 Gy cm2). For abdomen angiography, Ruiz-Cruces et al.(17) have reported mean and third quartile DAP of 61 and 92 Gy cm2. However, we reported mean DAP of 125.84 Gy cm2 with third quartile value of 147 Gy cm2 for 168 number of images. In case of upper limb angiography, our mean and third quartile DAP values are 9.73 Gy cm2 and 13.11 Gy cm2 for 68 number of images which is lower than the values reported by Williams.(38) and McParland.(10) Table 3. Comparison of DAP (mean, median and third quartile), mean FT, mean CD and number of images with earlier published values. Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Table 3. Comparison of DAP (mean, median and third quartile), mean FT, mean CD and number of images with earlier published values. Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — For cerebral AVM embolization, our mean DAP value of 211.06 Gy cm2 is considerably lower than that reported by Miller et al.(8) (339.76 Gy cm2), comparable to the value reported by Kemerink et al.(40) (226 Gy cm2) but considerably more than the value reported by McParland.(10) (105 Gy cm2). Our mean DAP value of 314.69 Gy cm2 for coiling of cerebral aneurysm is comparable with the value reported by Miller et al.(8) (319.9 Gy cm2) and Aroua et al.(34) (335 Gy cm2). However, our DAP value for this procedure is more than that reported by Ihn et al.(37) (218.8 Gy cm2) and Chun et al.(28)(226 Gy cm2) but less than the value reported by D’Ecroleet al.(14) (382.2 Gy cm2). For bronchial artery embolization (BAE), Miller et al.(8) has reported mean DAP of 139.43 Gy cm2 with mean FT of 34.7 min in sample size of 27 patients, whereas, our mean DAP value is 133.2 Gy cm2, with mean FT of 38.87 min in sample size of 19 patients. The average number of images acquired in our study for BAE has been found to be double than the number of images reported by Miller et al.(8) For Intra-arterial thrombolysis, our study reported mean DAP value of 201.62 Gy cm2 with mean FT of 35.53 min for sample size of eight patients is comparable with the value reported by Miller et al.(8) (198.24 Gy cm2) with mean FT of 42.9 min for nine patients. For lower limb angioplasty, Ruiz-Cruces et al.(36) has reported mean and third quartile DAP values of 81.41 and 120.49 Gy cm2 with mean FT of 15.2 min. However, we have reported mean and third quartile DAP value of 31.92 and 48.12 Gy cm2 with mean FT of 31.52 min. Table 3 reveals significant differences between our third quartile DAP value, mean FT and number of images acquired relative to the previous study for the similar procedures. These variations could be attributed to difference in the definition of the type of examination, the technique used by the various centers, number of images acquired and angiographic equipment used for the procedure. The variation could also be attributed to the fact that nowadays a wider variety of IR procedures with varying complexity are being performed than reported in previous studies, resulting in longer FT and large number of images being acquired, so radiation dose may be higher. Struelens et al.(20) suggested that a large dose variation is caused by a difference in the number of frames, number of projections and exposure parameters selected for the procedures. Moreover, the variation could also be related to complexity of the procedures as well as lack of experience of the operator. Aroua et al.(34) has noticed large variability in the DAP, FT and number of images acquired during cerebral angiography procedure performed by experienced radiologists. They suggested that the high dose in these procedures is due to the complexity of the procedure rather than lack of experience of the operator. However, Mini et al.(15) and Neofotistouet al.(47) observed that lack of experience of young radiologist in training is a major reason for dose variability. These studies concluded that, first year training fellows would use longer fluoroscopy time than experienced operator during the procedure and attributed high dose variability in teaching hospital to training and skills of the operator. Figure 4 shows histograms for DAP values in cerebral angiography (226 procedures) and coiling of cerebral aneurysm (54 procedures). Distribution of DAP in both type of procedure is asymmetrically skewed with a main peak and a long tail. The nature of these histograms is similar to what is expected for IR procedures, irrespective of its being a diagnostic or a therapeutic procedure. We expect that the variability of DAP in a same type of procedure is unavoidable due to different degree of complexity involved as well as on experience of operator. It is expected that every interventionist should be looking for the ways to reduce unnecessary radiation exposure to the patient form the procedures performed by them and try to evolve the ways to limit the long tail as observed in Figure 4, by opting for dose optimization protocols in the facility. Figure 4. View largeDownload slide Histograms of DAP values for (A) cerebral angiography and (B) coiling of cerebral aneurysm. Figure 4. View largeDownload slide Histograms of DAP values for (A) cerebral angiography and (B) coiling of cerebral aneurysm. In addition to this, it is also expected that higher DAP will result from the older equipment, due to degradation of image intensifier and to maintain same image quality it is necessary to increase radiation exposure with old intensifiers. Over the last decade, there is a significant development in the detectors used for imaging and angiography x-ray tube technology. The IR equipments are now equipped with a FPD and pulsed fluoroscopy. Prasana et al.(50) found that use of FPD technology had resulted in increased CD as compared to the procedures performed using image intensifier technology and concluded that the advantage of FPD over image intensifier is only in terms of their less susceptibility to image quality degradation over time. Mini et al.(15) reported that use of pulsed fluoroscopy in angiography systems will reduce the dose to 10% for the same FT and provide better image quality with less radiation doses during digital angiography. We have noticed that the reporting of radiation doses in IR procedure has some unresolved difficulties. As, there is no broad consensus on appropriate dosimetric quantities for radiation dose assessment, due to use of different dose metrics in the published studies, comparison of radiation doses at different centers become difficult. CONCLUSION The present study reports the data on radiation exposure to the patients during diagnostic and therapeutic IR procedures. Our results exhibit significant variability in DAP values for the same procedures as compared to the earlier reported data in literature. We have proposed local RL for some diagnostic and therapeutic IR procedures where significant patient data (n ≥ 10) is available. These RL values can be taken as QA parameter in the institute for dose optimization in these procedures. It is expected that each institute should take initiative to establish the nominal radiation dose for the commonly performed procedures in their facility, identify the procedures that may result in higher dose that may lead to skin reactions and evolve methods to reduce radiation dose from such procedures. Adequate and proper training of operator is must in interventional procedures for effective treatment and optimization of radiation exposure from these procedures. Furthermore, frequent and regular quality-control checks on angiographic equipments should be performed along with proper use of these equipments. ACKNOWLEDGEMENTS The authors of the study wish to thank Mr Amitabh Sinha, Sr Tech of the department of radiodiagnosis for his kind support in data collection. We express special thanks to Mrs. Ashima Rana for critically reading the manuscript for grammatical and presentable language. One of the authors would like to thank the I.K. 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For Permissions, please email: journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Radiation Protection Dosimetry Oxford University Press

ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL PROCEDURES

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Abstract

ABSTRACT The present work reports data of the radiation exposure to the patient in various diagnostic and therapeutic interventional radiological (IR) procedures. The study includes 260 diagnostic and 195 therapeutic exposure data in 455 IR procedures. All the IR procedures were performed on a biplane angiographic machine in a tertiary care hospital. The radiation exposure was estimated from dose–area product (DAP), fluoroscopy time (FT), number of fluoroscopic runs, number of images and cumulative dose (CD) value recorded during the procedure. The data reported in the present study show significant variability in DAP values in diagnostic and therapeutic IR procedures. In diagnostic procedures, the minimum median DAP value is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and maximum DAP value is 108.8 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. For therapeutic procedures, the median value of DAP ranges from 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min to 267.23 Gy cm2 for coiling of cerebral aneurysm with mean FT of 60.52 min. The DAP value for each procedure was also correlated with FT, number of fluoroscopic runs, number of images and CD. The reported DAP values in this study are within the range of earlier published results which suggest that our finding provides at least approximate applicability to other hospitals. The third quartile DAP values of the procedures having significant number of patient data (n ≥ 10) serves as provisional reference values for the optimization of procedure protocols. INTRODUCTION Interventional radiology (IR) is a medical sub-specialty which aids in the image-guided diagnosis and treatment of disease through minimally invasive techniques. The IR procedure can avoid all the major complications associated with open surgeries. The majority of vascular IR procedures require negotiating and manipulating a catheter under fluoroscopy guidance to evaluate the patient pathology and to guide the treatment processes.(1) The fluoroscopic exposure may result in significant radiation burden to the patient during such angiographic procedures. In contrast to diagnostic radiography, where radiation exposure to patient’s skin is of the order of μGy to mGy, exposure in IR procedures usually range from hundreds of mGy and may go up to several Gy in some cases.(2, 3) The use of extensive radiation exposure in fluoroscopy guided IR procedures may lead to high probability of stochastic effects along with high chances of deterministic injuries to the patients. Many studies have reported and investigated radiation induced skin injuries after IR procedures and threshold doses required to manifest these injuries in the exposed individuals.(4–7) However, some patient may show severe reaction at relatively lower dose levels compared to others, due to biological variations.(8) Depending on the clinical intent, the fluoroscopy guided IR procedures can be divided into diagnostic and therapeutic. Each of the procedure has different level of radiation risk associated with it.(9) The therapeutic procedure is supposed to be more complex than diagnostic procedure as it may require longer fluoroscopy time and more number of fluoroscopic frames.(10) For same IR procedure large variability in patient’s dose has been reported in the literature. Major causes of these variation are attributed to variable and long FT, number of images acquired, type of procedure, complexity involved, patient body size, age and performance of angiographic equipment and expertise of the interventionist.(11–18) Radiation dose in IR procedure could be measured using direct and indirect methods.(19–43) The direct method mostly involves the use of thermoluminescence dosemeters (TLD’s) or films attached on the patient skin during the procedure to measure maximum skin dose(19–26). The direct measurement is desirable but not always feasible, as use of TLD or film is laborious task and it is difficult to evaluate maximum skin dose accurately with these dosimeters, due to restricted measurement points available with them. In IR procedure, it is impossible to know beforehand the exact location of region where the maximum dose will occur, that may lead to underestimation of the maximum skin dose.(22, 25) An alternative to direct measurement is to estimate radiation dose from measured DAP value with the help of ionization chamber attached in the collimator assembly of the angiography system.(27–29) Precise estimation of skin dose using DAP requires assumption of beam orientation and exposure factors employed during the procedure. The DAP value has been reported to correlate reasonably well with skin dose and radiation risk.(27, 30, 31) In addition, DAP meter can be used during the procedure without any interference in the procedure, making it a convenient method for dose monitoring in IR procedure.(33) The International Commission on Radiation Protection (ICRP) has proposed the concept of diagnostic reference level (DRL) for optimization of medical exposure in diagnostic procedure.(44–46) The concept of reference level (RL) has become a valuable and well accepted tool for dose optimization and comparison of radiation dose.(1, 34, 47, 48) The RL is evaluated from third-quartile value of radiation dose parameter. In IR procedure, RL can be set for DAP, FT and the number of images acquired during the procedure. A single measured DAP reading may not provide information on dose optimization status in the facility but comparing the local mean DAP or third quartile DAP with available DRL, can be used to access radiation optimization practice in the facility.(24) Till date, there is no specific report published for setting RL’s in IR procedures in India. The aim of the present study is to estimate the radiation exposure to the patients from DAP value in various diagnostic and therapeutic IR procedures. The third quartile DAP value is proposed as provisional local RL for the procedure having sufficient number of database (n ≥ 10). MATERIALS AND METHODS The radiation exposure to the patients in IR procedures was estimated from angiographic database of 455 procedures on adult patients for a period of 1 year. The angiographic database includes 260 (112 females, 148 males; median age: 42 years, range: 18–75 years) diagnostic and 195 (82 females, 113 males; median age: 40.5 years, range: 18–80 years) therapeutic IR procedures listed in the flow chart shown in Figure 1. All the procedures were performed on a biplane angiographic units (Allura Xper FD 20/10: M/s Philips Medical Systems, Germany) installed at Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India. The angiographic unit is equipped with two amorphous silicon flat panel detectors (FPD) with CsI scintillator in A and B planes. The size (diagonal length) of A and B plane detectors are 48 and 25 cm, respectively. The zoom fields of plane A detector are 30, 26, 22, 19, 16, 13.5 and 11 cm and of plane B detector are 25, 20 and 15 cm. The angiographic unit is equipped with integrated DAP meters (KermaX® plus TinO, IBA dosimetry, Germany, GmbH) in both arms of x-ray tube housing. DAP meters were calibrated in situ from measurement of air kerma and beam area with a 75 cm3 shadow free ionization chamber (UnidosE dosimeter PTW, Freiburg, Germany) after taking into account of attenuation and scatter contribution from patient’s table. The angiographic unit used in the study met the quality assurance (QA) criterion as specified by relevant national regulations.(49) Figure 1. View largeDownload slide Information about types of diagnostic and therapeutic IR procedures investigated. Figure 1. View largeDownload slide Information about types of diagnostic and therapeutic IR procedures investigated. The angiography unit operates in three user selectable dose rate mode—low, normal and high with fluoroscopic pulse rate of 15 pulses/s. The procedures were mostly performed in normal mode of fluoroscopy. The measured dose rates of the angiographic system on the surface of solid water phantom taking into account of attenuation and scatter contribution from couch for each mode of operation is listed in Table 1. The present study is retrospective in nature and conducted under QA category. As, this study does not involve any additional radiation exposure to the patients, therefore approval from research ethics board was not required. Information on type of examination, gender, age, DAP, number of images acquired, FT and number of fluoroscopic runs employed during the procedures was gathered for data collection. The data were further classified into diagnostic and therapeutic categories depending on the intent of the procedure. Table 1. Dose rates measured in solid water phantom for the biplane x-ray tubes used in the study. Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Table 1. Dose rates measured in solid water phantom for the biplane x-ray tubes used in the study. Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 Position of x-ray tubes Doses rate (mGy/min) Low dose mode Medium dose mode High dose mode Under couch 4.2 32.64 59.46 Lateral 8.48 37.07 87.7 RESULT AND DISCUSSION The information about number of exposure, age range, number of runs, number of images, FT (mean and median), DAP (range, mean, median and third quartile) and CD value for the IR procedure is listed in Table 2. The reported data show large variability in DAP values for all the diagnostic and therapeutic IR procedures included in the study. It is clear from Table 2, for diagnostic procedures minimum value of median DAP is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and the maximum value of median DAP is 108.80 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. On the other hand, for therapeutic IR procedures minimum median DAP is 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min and the maximum value of median DAP is 267.23 Gy cm2 for coiling of aneurysm with mean FT of 60.52 min. For all other IR procedures, the median DAP lies between the quoted above minimum and maximum values. The correlation of DAP with (i) FT, (ii) number of runs, (iii) number of images and (iv) CD in cerebral and lower limb angiography is shown in Figure 2. Likewise, Figure 3 shows the correlation of DAP with these parameters in coiling of cerebral aneurysm and intra-arterial thrombolysis procedures. To assess DAP linearity with above mentioned parameters; Pearson’s correlation test was performed for all the procedures. A P < 0.0001 was considered statistically significant. In cerebral angiography, a moderate correlation (r = 0.554, R2 = 0.307) was noticed between DAP and FT, DAP and fluoroscopic runs (r = 0.657, R2 = 0.431) and a weaker correlation (r = 0.437, R2 = 0.110) is observed between DAP and the number of images. However, we observed a strong correlation (r = 0.771, R2 = 0.594) between DAP and number fluoroscopy runs, a moderate correlation (r = 0.605, R2 = 0.366) between DAP and FT and a weak correlation (r = 0 .329, R2 = 0.108) between DAP and number of images in coiling of cerebral aneurysm. A strong correlation (r ≥ 0.734, R2 ≥ 0.567) has been noticed between DAP and CD for all diagnostic and therapeutic procedures. We also observed a moderate correlation between DAP and FT for all the IR procedures, which signifies use of different dose rate modes and different magnification factors during the procedure. Same observation have been noticed by Fletcher et al.(16) for the correlation between patient dose and FT and concluded that FT is unlikely to correlate well with dose. Table 2. Parameters recorded during diagnostic and therapeutic IR procedures in present study. Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Table 2. Parameters recorded during diagnostic and therapeutic IR procedures in present study. Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Examination No. of exposure (M,F) Median age in years (range) Avg. no. of runs (range) Avg. no. of images (range) Median FT in min. (range) Mean FT ± Std. dev. (min) DAP range (Gy cm2) Mean DAP ± Std. dev. (Gy cm2) Median DAP (Gy cm2 Third quartile DAP (Gy cm2) CD Avg. ± Std. dev. (mGy) Diagnostic  Cerebral angiography 226 (130,96) 43.5 (18–70) 10.4 (2–31) 382.7 (47–1664) 10.9 (2.1–64.2) 13.37 ± 9.24 12.47–428.6 103.07 ± 53.32 94.62 121.97 564.41 ± 360.10  Abdomen angiography 8 (3,5) 46 (24–58) 13.4 (5–23) 168 (67–339) 15.40 (5.9–47.6) 19.57 ± 13.28 36.83–279.96 125.84 ± 81.55 107.91 146.68 359.78 ± 161.17  Inferior vena cava graphy 10 (4,6) 29.5 (24–49) 5.3 (2–10) 123.5 (29–264) 12.05 (5.8–18.7) 12.55 ± 4.00 30.32–147.29 96.45 ± 39.97 108.80 119.29 496.55 ± 229.9  Lower limb angiography 9 (7,2) 26 (19–70) 6.67 (1–11) 81.6 (7–204) 4.2 (1.7–13) 6.24 ± 4.40 2.92–28.25 13.35 ± 8.43 10.14 20.42 39.60 ± 20.77  Upper limb angiography 7 (4,3) 54 (19–66) 4.7 (3–6) 68 (28–99) 1.8 (0.7–5.4) 2.7 ± 1.73 5.68–15.17 9.73 ± 4.07 8.93 13.11 28.68 ± 14.30 Therapeutic  Cerebral AVM   embolization 7 (6,1) 37 (22–55) 20.28 (9–30) 1214.4 (150–2308) 28.7 (8.4–61.5) 31.1 ± 19.82 92.19–362.51 211.06 ± 112.9 216.17 288.54 1578.69 ± 588.81  Bronchial artery   embolization 19 (14,5) 47 (18–73) 19.6 (6–35) 583 (79–2114) 30.6 (6–123.2) 38.87 ± 27.60 14.68–304.25 133.2 ± 86.96 127.38 196.52 627.11 ± 583.28  Coiling of cerebral   aneurysm 54 (25,29) 50 (27–70) 28.2 (15–52) 1726 (620–3885) 53.4 (19.73–146.4) 60.52 ± 27.24 139.36–801.98 314.69 ± 146.90 267.23 370.78 3403.24 ± 1820.75  Intra-arterial thrmbolysis 8 (5,3) 67 (26–79) 16.3 (6–30) 816 (130–2408) 25.45 (9.9–96.1) 35.53 ± 27.87 62.89–335.55 201.62 ± 102.33 184.88 284.55 1160.12 ± 741.40  Intra-arterial Nimodipine   injection 15 (9,6) 45 (22–65) 8.13 (2–18) 182.3 (40–663) 9.1 (2.6–50.3) 12.08 ± 11.83 27.24–381.56 96.99 ± 86.62 82.37 107.14 503.82 ± 444.86  JNA embolization 6 (6,0) 21 (19–42) 13.67 (7–18) 750.3 (294–2059) 26.1 (20.3–30.5) 25.75 ± 4.16 74.99–184.63 129.30 ± 37.22 130.02 143.37 806.28 ± 296.28  Lower limb angioplasty 11 (9,2) 52 (23–70) 25.1 (10–63) 985.5 (135–3206) 29.2 (5.8–78.6) 31.52 ± 23.49 4.38–114.12 31.92 ± 35.31 15.45 48.12 309.5 ± 502  Renal artery embolization 21 (18,3) 45 (26–80) 16 (5–53) 378 (51–1808) 17.5 (6.5–57) 21.55 ± 14.19 36.17–530.13 161.22 ± 111.42 130.08 197.54 677.59 ± 545.65 Uterine artery embolization 16 (0,16) 27 (22–40) 18.2 (5–32) 421 (60–1008) 23.8 (5.4–53.1) 23 ± 10.96 35.41–369.43 192.96 ± 99.89 175.21 257.33 667.93 ± 418.79 Spinal artery embolization 7 (7,0) 40 (24–49) 16.5 (3–29) 451.8 (52–1160) 20.8 (8.3–34.6) 20.98 ± 8.49 74.47–369 183.88 ± 114 138.39 245.58 1679.5 ± 2253 Sclerotherapy 31 (14,17) 22 (18–71) 2.75 (1–5) 153 (11–667) 0.5 (0.1–2) 0.65 ± 0.44 0.17–45.35 5.25 ± 8.56 2.43 5.86 28.46 ± 33.26 Figure 2. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in case of cerebral angiography and lower limb angiography. Figure 2. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in case of cerebral angiography and lower limb angiography. Figure 3. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in coiling of cerebral aneurysm and cerebral AVM embolization. Figure 3. View largeDownload slide Correlation between (i) DAP and FT, (ii) DAP and number of runs, (iii) DAP and number of images and (iv) DAP and CD in coiling of cerebral aneurysm and cerebral AVM embolization. The comparison of our data with earlier reported values in literature is also summarized in Table 3. Table 3 shows that our data is within the range of earlier reported values.(8–10, 14, 17, 28, 34–43) The mean DAP value for cerebral angiography (103 Gy cm2) in present study is lower than that reported by Brambilla et al.(39) (158 Gy cm2) and Chun et al.(28)(136.6 Gy cm2), but comparable with mean DAP values reported by Iha et al.(37)(106.2 Gy cm2) and Aroua et al.(34) (121 Gy cm2). The mean number of images acquired by us is comparable to reported studies, but Aroua et al.(34) has reported more than double number of images acquired for cerebral angiography. In lower limb angiography, our mean DAP (13.35 Gy cm2) is considerably lower than the DAP value reported by Pitton et al.(35) (36.5 Gy cm2), Vano et al.(9) (66.63 Gy cm2), Ruiz-Cruces et al.(17)(30 Gy cm2) and Ruiz-Cruces et al.(36) (58.17 Gy cm2). For abdomen angiography, Ruiz-Cruces et al.(17) have reported mean and third quartile DAP of 61 and 92 Gy cm2. However, we reported mean DAP of 125.84 Gy cm2 with third quartile value of 147 Gy cm2 for 168 number of images. In case of upper limb angiography, our mean and third quartile DAP values are 9.73 Gy cm2 and 13.11 Gy cm2 for 68 number of images which is lower than the values reported by Williams.(38) and McParland.(10) Table 3. Comparison of DAP (mean, median and third quartile), mean FT, mean CD and number of images with earlier published values. Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Table 3. Comparison of DAP (mean, median and third quartile), mean FT, mean CD and number of images with earlier published values. Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — Procedure Study Sample size Mean DAP (Gy cm2) Median DAP (Gy cm2) Third quartile DAP (Gy cm2) Mean FT (min) Mean CD (mGy) No of images Cerebral angiography This study 226 103 94.62 122 13.37 564 383 Brambilla et al.(39) 188 158 — 198 13.7 — — Chun et al.(28) 439 136.6 — 154.2 12.6 — 251 Iha et al.(37) 490 106.2 89.4 144 9.8 — 242 Aroua et al.(34) 91 121 — 125 12.6 — 679 Abdomen angiography This study 8 125.84 107.91 147 19.57 359.78 168 Ruiz-Cruces et al.(17) 16 61 33 92 — — — McParland(10) 21 118 102 133 8.0 Lower limb angiography This study 9 13.35 10.14 20.42 6.24 39.60 82 Pitton et al.(35) 53 36.5 29.6 46.4 3.4 — 216 Vano et al.(9) 40 66.63 51.75 87.89 — — — Ruiz-Cruces et al.(17) 35 30 27 36 — — — Ruiz-Cruces et al.(36) — 58.17 51.84 71.14 5.58 — — Upper limb angiography This study 7 9.73 8.93 13.11 2.7 28.68 68 Vano et al.(9) 15 8.71 7.67 11.08 — — — Williams(38) 26 22.9 14.7 37.4 — — — McParland(10) 7 27.3 20.2 — 4.6 — — Cerebral AVM embolization This study 7 211.06 216.17 288.54 31.1 1578 1214 Miller et al.(8) 177 339.76 — — 92.5 3791 1037 Miller et al.(42) — — — 550 135 — 1500 Kemerink et al.(40) 31 226 185 — 35 — 267 McParland(10) 5 105 85.4 — 34.1 — — Bronchial artery embolization This study 19 133.2 127.38 196.52 38.87 627.11 583 Miller et al.(8) 27 139.43 — — 34.7 1123 284 Miller et al.(42) — — — 240 50 — 450 Coiling of cerebral aneurysm This study 54 314.69 267.23 370.78 60.52 3403.24 1726 Ihn et al.(37) 371 218.8 179 271 51.5 3365.7 443.5 Miller et al.(8) 356 319.9 — — 87.1 — 1053 Aroua et al.(34) 52 335 — 440 36.5 — 760 D’Ecrole et al.(14) 72 382.2 351.91 487 37.2 — 574 Chun et al.(28) 111 226 — 272.8 52.9 — 241 Intra-arterial thrombolysis This study 8 201.62 184.88 284.55 35.53 1160.12 816 Miller et al.(8) 9 198.24 — — 42.9 2369 563 Lower limb angioplasty This study 11 31.92 15.45 48.12 31.52 309.50 986 Ruiz-Cruces et al.(36) — 81.41 92.96 120.49 15.2 — — Renal artery embolization This study 21 161.22 130.08 197.54 21.55 677.59 378 McParland(10) 6 85.5 61.2 — 14.0 — — Sclerotherapy This study 31 5.25 2.43 5.86 0.65 28.46 153 Lie et al.(43) 39 20.12 — — — 0.3 — For cerebral AVM embolization, our mean DAP value of 211.06 Gy cm2 is considerably lower than that reported by Miller et al.(8) (339.76 Gy cm2), comparable to the value reported by Kemerink et al.(40) (226 Gy cm2) but considerably more than the value reported by McParland.(10) (105 Gy cm2). Our mean DAP value of 314.69 Gy cm2 for coiling of cerebral aneurysm is comparable with the value reported by Miller et al.(8) (319.9 Gy cm2) and Aroua et al.(34) (335 Gy cm2). However, our DAP value for this procedure is more than that reported by Ihn et al.(37) (218.8 Gy cm2) and Chun et al.(28)(226 Gy cm2) but less than the value reported by D’Ecroleet al.(14) (382.2 Gy cm2). For bronchial artery embolization (BAE), Miller et al.(8) has reported mean DAP of 139.43 Gy cm2 with mean FT of 34.7 min in sample size of 27 patients, whereas, our mean DAP value is 133.2 Gy cm2, with mean FT of 38.87 min in sample size of 19 patients. The average number of images acquired in our study for BAE has been found to be double than the number of images reported by Miller et al.(8) For Intra-arterial thrombolysis, our study reported mean DAP value of 201.62 Gy cm2 with mean FT of 35.53 min for sample size of eight patients is comparable with the value reported by Miller et al.(8) (198.24 Gy cm2) with mean FT of 42.9 min for nine patients. For lower limb angioplasty, Ruiz-Cruces et al.(36) has reported mean and third quartile DAP values of 81.41 and 120.49 Gy cm2 with mean FT of 15.2 min. However, we have reported mean and third quartile DAP value of 31.92 and 48.12 Gy cm2 with mean FT of 31.52 min. Table 3 reveals significant differences between our third quartile DAP value, mean FT and number of images acquired relative to the previous study for the similar procedures. These variations could be attributed to difference in the definition of the type of examination, the technique used by the various centers, number of images acquired and angiographic equipment used for the procedure. The variation could also be attributed to the fact that nowadays a wider variety of IR procedures with varying complexity are being performed than reported in previous studies, resulting in longer FT and large number of images being acquired, so radiation dose may be higher. Struelens et al.(20) suggested that a large dose variation is caused by a difference in the number of frames, number of projections and exposure parameters selected for the procedures. Moreover, the variation could also be related to complexity of the procedures as well as lack of experience of the operator. Aroua et al.(34) has noticed large variability in the DAP, FT and number of images acquired during cerebral angiography procedure performed by experienced radiologists. They suggested that the high dose in these procedures is due to the complexity of the procedure rather than lack of experience of the operator. However, Mini et al.(15) and Neofotistouet al.(47) observed that lack of experience of young radiologist in training is a major reason for dose variability. These studies concluded that, first year training fellows would use longer fluoroscopy time than experienced operator during the procedure and attributed high dose variability in teaching hospital to training and skills of the operator. Figure 4 shows histograms for DAP values in cerebral angiography (226 procedures) and coiling of cerebral aneurysm (54 procedures). Distribution of DAP in both type of procedure is asymmetrically skewed with a main peak and a long tail. The nature of these histograms is similar to what is expected for IR procedures, irrespective of its being a diagnostic or a therapeutic procedure. We expect that the variability of DAP in a same type of procedure is unavoidable due to different degree of complexity involved as well as on experience of operator. It is expected that every interventionist should be looking for the ways to reduce unnecessary radiation exposure to the patient form the procedures performed by them and try to evolve the ways to limit the long tail as observed in Figure 4, by opting for dose optimization protocols in the facility. Figure 4. View largeDownload slide Histograms of DAP values for (A) cerebral angiography and (B) coiling of cerebral aneurysm. Figure 4. View largeDownload slide Histograms of DAP values for (A) cerebral angiography and (B) coiling of cerebral aneurysm. In addition to this, it is also expected that higher DAP will result from the older equipment, due to degradation of image intensifier and to maintain same image quality it is necessary to increase radiation exposure with old intensifiers. Over the last decade, there is a significant development in the detectors used for imaging and angiography x-ray tube technology. The IR equipments are now equipped with a FPD and pulsed fluoroscopy. Prasana et al.(50) found that use of FPD technology had resulted in increased CD as compared to the procedures performed using image intensifier technology and concluded that the advantage of FPD over image intensifier is only in terms of their less susceptibility to image quality degradation over time. Mini et al.(15) reported that use of pulsed fluoroscopy in angiography systems will reduce the dose to 10% for the same FT and provide better image quality with less radiation doses during digital angiography. We have noticed that the reporting of radiation doses in IR procedure has some unresolved difficulties. As, there is no broad consensus on appropriate dosimetric quantities for radiation dose assessment, due to use of different dose metrics in the published studies, comparison of radiation doses at different centers become difficult. CONCLUSION The present study reports the data on radiation exposure to the patients during diagnostic and therapeutic IR procedures. Our results exhibit significant variability in DAP values for the same procedures as compared to the earlier reported data in literature. We have proposed local RL for some diagnostic and therapeutic IR procedures where significant patient data (n ≥ 10) is available. These RL values can be taken as QA parameter in the institute for dose optimization in these procedures. It is expected that each institute should take initiative to establish the nominal radiation dose for the commonly performed procedures in their facility, identify the procedures that may result in higher dose that may lead to skin reactions and evolve methods to reduce radiation dose from such procedures. Adequate and proper training of operator is must in interventional procedures for effective treatment and optimization of radiation exposure from these procedures. Furthermore, frequent and regular quality-control checks on angiographic equipments should be performed along with proper use of these equipments. ACKNOWLEDGEMENTS The authors of the study wish to thank Mr Amitabh Sinha, Sr Tech of the department of radiodiagnosis for his kind support in data collection. We express special thanks to Mrs. Ashima Rana for critically reading the manuscript for grammatical and presentable language. One of the authors would like to thank the I.K. 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Journal

Radiation Protection DosimetryOxford University Press

Published: Feb 16, 2018

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