AN ANALYSIS OF OPERATING PHYSICIAN AND PATIENT RADIATION EXPOSURE DURING RADIAL CORONARY ANGIOPLASTIES

AN ANALYSIS OF OPERATING PHYSICIAN AND PATIENT RADIATION EXPOSURE DURING RADIAL CORONARY... Abstract The objective of this study was to evaluate radiation exposure levels in conjunction with operator dose implemented, patient vascular characteristics, and other technical angiographic parameters. In total, 756 radial coronary angioplasties were evaluated in a major metropolitan general hospital in Tabriz, Iran. The classification of coronary lesions was based on the ACC/AHA system. One interventional cardiologist performed all of the procedures using a single angiography unit. The mean kerma-area product and mean cumulative dose for all cases was 5081 μGy m2 and 814.44 mGy, respectively. Average times of 26.16 and 9.1 min were recorded for the overall procedure and fluoroscopy, respectively. A strong correlation was demonstrated between types of lesions, number of stents and vessels treated in relation to physician radiation exposure. It was determined that operator radiation exposure levels for percutaneous coronary interventions lesions (complex) were higher than that of simple and moderate lesions. In addition, operator radiation exposure levels increased with the treatment of more coronary vessels and implementation of additional stents. INTRODUCTION Studies have demonstrated the contribution of multiple factors to operating physician and patient radiation exposure during coronary angiographies (CA). Such factors can be divided into patient-related and operator-related parameters, radiation shielding methods, and technical factors operating the angiography unit(1–6). Despite technological advancements within such operating units along with the implementation of new safety protocols(7–9), both patients and operators expose themselves to a high level of radiation during coronary procedures(10). Potential visual and neurologic impairments were noted for the operators while patients exposed themselves to potential skin damage(11–13). With the rise in generalized vascular complexity (such as chronic total occlusion (CTO)) and consequently the number of operating physicians, our team raised a level of concern and hypothesized a rise in operating physician radiation exposure with increasing case complexity(14, 15). Although many studies have focused on characteristics affecting levels of patient radiation exposure(16–20), limited studies have focused on factors specifically affecting operating physician radiation exposure levels(2, 3, 5), motivating our team to study and evaluate this topic in greater detail. METHODS AND MATERIALS Demographic, clinical and procedural data from 756 patients who underwent percutaneous coronary interventions (PCI) following CA were collected and analysed from August 2012 to March 2017. Exclusion criteria included primary and left main PCI, post coronary artery bypass graft angiography, peripheral arterial disease, patients with a negative Allen test, valvular heart disease, diagnostic coronary angiography, emergency cases, unsuccessful cannulation, coronary artery engagement, wide dissection and arterial perforation. An ethics committee from the medical school approved the study, and all patients signed informed consent forms prior to the procedures. Each procedure was performed using the Siemens angiography system (Model Axiom Artis dfc, Munich, Germany). Implemented variables included a pulse rate of 15 pulses per second (PPS), a frame rate of 15 frames per second (FPS), and a fluoroscopy magnification of 25 cm and acquisition of 20 cm. The height of tabletop was ~60 cm from x-ray tube and the approximate distance between radial approach and operator was 40 cm. A dosimetric quality control kit (PTW, Freiburg, Germany) was used to evaluate machine output. Considering the radiation protection rule of As Low As Reasonably Achievable (ALARA), the operator was protected by both structural shields (ceiling-suspended lead shield and a pivotal lead shield, 0.5 mm lead equivalent, MAVIG, Munich, Germany) and a two-piece apron with lead glasses and thyroid protection. Radiation exposure levels were measured using an integrated ionization chamber (Diametor, PTW, freiburg, Germany). The dosimeter (Smart Rad; Model: EV-1, Type GM-Tube, Enviro Korea Co., Ltd) was attached to left side of the operator’s chest at the level of the neck. All the dosimeters were calibrated by Iranian organization of atomic energy. All cases were performed using a right-sided radial approach. Procedure time was defined as the time from local anaesthetic injection to removal of the guiding catheter. In order to prevent radial artery spasm and occlusion, 5000 units of heparin was administrated in the artery. The specific contrast media used in the study was Omnipaque 350 mg/ml; the injection was manually performed. Lesion classification criteria were based on American Heart Association and American College of Cardiology (AHA & ACC). ANALYSIS OF DATA Descriptive statistical methods were implemented, and means, standard deviations, numbers and percentages were obtained. Additionally, the Mann Whitney U test, multi-factor ANOVA, and chi-squared test were performed using the SPSS ver.17 software. Since some variables were not normally distributed, the comparisons between variables were made by the Kruskal Wallis test. A statistical significance of p ≤ 0.05 was used. RESULTS Patient demographic and clinical characteristics were recorded in Table 1. The mean patient BMI was 27 kg/m2, 72.9% of all patients were male, with mean age of 60 years, and 51% of the patients had stable chronic angina. The average number of angioplasty cases and the number of inserted stents was 1.5 and 1.7, respectively. Also, complex, moderate and simple lesions accounted for 21, 54 and 25%, respectively. Table 1. Quantitative analysis of baseline demographic, clinical and angiography data. Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Values are shown mean ± SD, N (%). ACS, acute coronary syndrome; CSA, chronic stable angina; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery. Table 1. Quantitative analysis of baseline demographic, clinical and angiography data. Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Values are shown mean ± SD, N (%). ACS, acute coronary syndrome; CSA, chronic stable angina; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery. Table 2 shows the level of patient and operator radiation exposure in relation to the type of lesion. A mean operator radiation exposure of 52.5 μSv was estimated and the mean KAP and cumulative dose of patients were 5081 μGy m2 and 814 mGy, respectively. Using the bivariate Spearman method, correlations between clinical status and operator radiation exposure; number of treated vessels and operator radiation exposure; and the number of stents and operator radiation exposure were investigated (Figure 1). There was a significant positive correlation between the operator radiation dose and the lesion type (p < 0.001, r = 0.594). Additionally, a positive correlation was noted in terms of number of stents included and clinical status with physician radiation exposure levels. Also a direct correlation was observed between the number of vessels and operator radiation exposure (p < 0.001, r = 0.295). However, no correlation was found between patients’ BMI and operator radiation doses (Figure 2A). On the other hand, a significant positive correlation was noted between patients’ BMI and patient radiation exposure, p < 0.001 (Figure 2B). Table 2. Analysis of lesion type in relation to patient and operator radiation exposure. Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 KAP, kerma area product. aSimple lesions; bmoderate lesions; ccomplex lesions. Table 2. Analysis of lesion type in relation to patient and operator radiation exposure. Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 KAP, kerma area product. aSimple lesions; bmoderate lesions; ccomplex lesions. Figure 1. View largeDownload slide Linear correlation between operator dose and number of vessel treated (A) and number of stents (B). Figure 1. View largeDownload slide Linear correlation between operator dose and number of vessel treated (A) and number of stents (B). Figure 2. View largeDownload slide Results of correlation tests between body mass index (BMI) of patients and operator exposure (A) and correlation between patients’ BMI and patients’ radiation exposure (B). Figure 2. View largeDownload slide Results of correlation tests between body mass index (BMI) of patients and operator exposure (A) and correlation between patients’ BMI and patients’ radiation exposure (B). Significant differences were noted in terms of radiation dose exposure and time including air kerma area product (KAP), air kerma and fluoroscopy time between the three complexity groups (Table 2). Additionally, the procedural duration time for type C lesions was almost 18 min longer than the group treated for type A lesions. Table 3 shows the results of linear regression analysis of confounding factors that affected the operator radiation dose. It is seen that there is no correlation between operator dose and patients’ BMI as well as number of vessels. But for other factors such as fluoroscopy time, patient dose, complexity of procedure, it was found a direct correlation with operator dose. Table 3. Linear regression analysis of confounding factors that affected operator radiation dose. Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Dependent variable: operator dose. BMI, body mass index. aStatistically significant difference. Table 3. Linear regression analysis of confounding factors that affected operator radiation dose. Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Dependent variable: operator dose. BMI, body mass index. aStatistically significant difference. Figure 3 demonstrates an increase in operator radiation exposure for every additional vessel treated or stented. More specifically, it was determined that increasing the number of stents or vessels treated from 1 to 3 increased operator radiation exposure by a factor of 2.7 and 1.2, respectively (bivariate correlation analysis). Mean operator radiation exposure levels during CA+PTCA for type A, B and C lesions were 25.81 ± 5.33, 44.97 ± 20.03 and 91.55 ± 52.33 μSv, respectively, which indicates higher radiation exposure from type C lesions when compared with both type A and type B lesions (p < 0.001). Figure 3. View largeDownload slide Relation of operator exposure dose to number of vessels (A), number of stenting (B) and lesion type (C). Figure 3. View largeDownload slide Relation of operator exposure dose to number of vessels (A), number of stenting (B) and lesion type (C). A multi-factor linear regression model showed that with an increase in fluoroscopy time, patient radiation exposure levels significantly increased. Additionally, increasing the number of stents from 1 to 3 increased operator radiation exposure levels by 9 μSv, while a change in case complexity from simple to complex increased operator radiation exposure by a factor of 2.1. DISCUSSION It was determined that operating physician radiation exposure levels were significantly affected by the number of stents implemented along with coronary lesion complexity. The results revealed a positive correlation between the number of stents and treated vessels with operator radiation exposure levels, further emphasizing a rise in radiation exposure with an increase in overall case complexity. Several studies elaborated on clinical and technical factors influencing operator radiation exposure(16, 18, 21, 22); however, only one of these studies specifically addressed the effect of stenting strategies on operator radiation exposure levels(23). Additionally, several studies found correlations between body surface areas and procedure type with both patient and operator radiation exposure doses(24, 25). Shah et al.(26) elaborated on higher risks associated with radiation exposure for both patients and operating physicians operating on higher BMI patients, while our results demonstrated only a direct relationship between patients’ BMI and patient radiation exposure and it was not seen between patients’ BMI and operator dose. However, the study completed by Shah et al.(26) only evaluated patients undergoing CA and not angioplasties. Additionally, the study only collected patient radiation exposure data, and then simply speculated a concern for increased operating radiation exposure for physicians with no specific supporting radiation data. Although both patients and physicians were exposed to radiation, both sample groups were exposed through different physical mechanisms, which can potentially account for the differences in radiation exposure between patients and physicians when compared to increases in patient BMI. Patients were exposed to both primary and secondary radiation; however, operating physician radiation exposure was a consequence of deflection and scatter off of the patient(27). Studies have also evaluated procedure complexity on patient radiation exposure(21, 22). Bernardi et al. studied anatomical and technical procedural factors influencing fluoroscopy and cine fluoroscopy times, with cases evaluated through multi-regression analysis by three levels of complexity, simple, intermediate and complex. Their study proposed that complex-lesion procedures require 2.5 times more fluoroscopy time when compared with simple-level lesions (19.83 min compared with 7.85 min), paralleling the results of our study(21). According to our results, the extent of radiation exposure to the patients in simple, moderate and complex lesions during coronary angioplasties was ~2.12 (31.02 vs. 65.8 Gy cm2), 1.88 (49.36 vs. 93 Gy cm2) and 1.63 (70.77 vs.116 Gy cm2) times respectively lower than those reported in Bernardi et al.'s study. This variation in results could be attributed to the differences in levels of expertise among the operators performing the procedures. Furthermore, the result of our study indicated 71 and 132% decrease in air-kerma factor compared to the Fetterly et al. and Suzuki et al.s' studies. This different could be resulted from lower patients’ BMI in our study (29.7 vs. 27 kg/m2). It should be mentioned that there was a direct correlation between patients’ BMI and patients’ radiation exposure in our study as reported in the previous investigations. With recent advancements in coronary angiography systems along with strides in surgical dexterity and training, treatment of more complex cases such as CTO has risen, resulting in better control of stable angina, dyspnoea and resistant arrhythmia. However, with this rise in surgical and technical proficiency comes the risk for elongated procedure and fluoroscopy time(28–31). In another study, Suzuki et al.(13), evaluated dermatological injuries due to CTO angioplasty procedures demonstrating that treatment of complex lesions exposed patients to higher levels of radiation by a factor of 2.6 when compared to simple lesions, paralleling a similar trend found by Fetterly et al.(13, 16). In terms of radiation measurement, it was demonstrated that kerma-area product (KAP) is a stronger predictor for hazardous patient radiation dose exposure when compared to air-kerma(32). While our study implemented evaluation using KAP, Suzuki et al. only evaluated patient radiation exposure using air-kerma. Reports also indicated that more complex lesions such as MVD-PCI including multiple lesions within one segment, single lesion within multi segments, as well as high tortuosity, bifurcation or CTO-PCI, expose patients to higher radiation doses(16, 18). However, these studies only specified patient radiation exposure levels with little attention to operator radiation exposure(33). In terms of radiation exposure time and lesion complexity, it was determined that operating physician radiation exposure time for group C was almost 2.5 times higher than group A and 1.5 times greater than group B, indicating a rise in physician radiation exposure with a rise in case complexity. Although cases were ordered and evaluated in terms of generalized case complexity, it is important to note that the number of stents implemented for each complexity level was non-standardized. Several coronary cases even required no stenting; in some cases only pre-dilatation and post dilatation were sufficient. Additionally, several segments may have required the implementation of multiple stents, further hindering standardization and significantly affecting the radiation time and exposure. With this in mind, future studies may wish to find a better way to standardize such cases by controlling for the specific number of stents implemented within each level of complexity of the lesion. CONCLUSION Our results indicated a significant increase in operator radiation exposure with rise in lesion complexity, the number of stents implemented, and number of coronary vessels involved. However, our team determined that lesion type or complexity had the most significant effect on operator radiation exposure levels. Although there are a myriad of studies evaluating radiation exposure of either patients or operating physicians from such coronary interventions, more studies are needed to compare radiation exposure between operating physicians and patients, potentially opening the doors to additional studies on the physics behind radiation absorption, deflection and scatter. 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Comparison of the patient radiation exposure during coronary angiography and angioplasty procedures using trans-radial and trans-femoral access . J. Cardiovasc. Thorac. Res. 8 ( 2 ), 77 – 82 ( 2016 ) doi:10.15171/jcvtr.2016.15 . Google Scholar CrossRef Search ADS PubMed 33 Kuipers , G. , Velders , X. L. and Piek , J. J. Exposure of cardiologists from interventional procedures . Radiat. Prot. Dosim. 140 ( 3 ), 259 – 265 ( 2010 ) doi:10.1093/rpd/ncq113 . Google Scholar CrossRef Search ADS © 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/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Radiation Protection Dosimetry Oxford University Press

AN ANALYSIS OF OPERATING PHYSICIAN AND PATIENT RADIATION EXPOSURE DURING RADIAL CORONARY ANGIOPLASTIES

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Abstract

Abstract The objective of this study was to evaluate radiation exposure levels in conjunction with operator dose implemented, patient vascular characteristics, and other technical angiographic parameters. In total, 756 radial coronary angioplasties were evaluated in a major metropolitan general hospital in Tabriz, Iran. The classification of coronary lesions was based on the ACC/AHA system. One interventional cardiologist performed all of the procedures using a single angiography unit. The mean kerma-area product and mean cumulative dose for all cases was 5081 μGy m2 and 814.44 mGy, respectively. Average times of 26.16 and 9.1 min were recorded for the overall procedure and fluoroscopy, respectively. A strong correlation was demonstrated between types of lesions, number of stents and vessels treated in relation to physician radiation exposure. It was determined that operator radiation exposure levels for percutaneous coronary interventions lesions (complex) were higher than that of simple and moderate lesions. In addition, operator radiation exposure levels increased with the treatment of more coronary vessels and implementation of additional stents. INTRODUCTION Studies have demonstrated the contribution of multiple factors to operating physician and patient radiation exposure during coronary angiographies (CA). Such factors can be divided into patient-related and operator-related parameters, radiation shielding methods, and technical factors operating the angiography unit(1–6). Despite technological advancements within such operating units along with the implementation of new safety protocols(7–9), both patients and operators expose themselves to a high level of radiation during coronary procedures(10). Potential visual and neurologic impairments were noted for the operators while patients exposed themselves to potential skin damage(11–13). With the rise in generalized vascular complexity (such as chronic total occlusion (CTO)) and consequently the number of operating physicians, our team raised a level of concern and hypothesized a rise in operating physician radiation exposure with increasing case complexity(14, 15). Although many studies have focused on characteristics affecting levels of patient radiation exposure(16–20), limited studies have focused on factors specifically affecting operating physician radiation exposure levels(2, 3, 5), motivating our team to study and evaluate this topic in greater detail. METHODS AND MATERIALS Demographic, clinical and procedural data from 756 patients who underwent percutaneous coronary interventions (PCI) following CA were collected and analysed from August 2012 to March 2017. Exclusion criteria included primary and left main PCI, post coronary artery bypass graft angiography, peripheral arterial disease, patients with a negative Allen test, valvular heart disease, diagnostic coronary angiography, emergency cases, unsuccessful cannulation, coronary artery engagement, wide dissection and arterial perforation. An ethics committee from the medical school approved the study, and all patients signed informed consent forms prior to the procedures. Each procedure was performed using the Siemens angiography system (Model Axiom Artis dfc, Munich, Germany). Implemented variables included a pulse rate of 15 pulses per second (PPS), a frame rate of 15 frames per second (FPS), and a fluoroscopy magnification of 25 cm and acquisition of 20 cm. The height of tabletop was ~60 cm from x-ray tube and the approximate distance between radial approach and operator was 40 cm. A dosimetric quality control kit (PTW, Freiburg, Germany) was used to evaluate machine output. Considering the radiation protection rule of As Low As Reasonably Achievable (ALARA), the operator was protected by both structural shields (ceiling-suspended lead shield and a pivotal lead shield, 0.5 mm lead equivalent, MAVIG, Munich, Germany) and a two-piece apron with lead glasses and thyroid protection. Radiation exposure levels were measured using an integrated ionization chamber (Diametor, PTW, freiburg, Germany). The dosimeter (Smart Rad; Model: EV-1, Type GM-Tube, Enviro Korea Co., Ltd) was attached to left side of the operator’s chest at the level of the neck. All the dosimeters were calibrated by Iranian organization of atomic energy. All cases were performed using a right-sided radial approach. Procedure time was defined as the time from local anaesthetic injection to removal of the guiding catheter. In order to prevent radial artery spasm and occlusion, 5000 units of heparin was administrated in the artery. The specific contrast media used in the study was Omnipaque 350 mg/ml; the injection was manually performed. Lesion classification criteria were based on American Heart Association and American College of Cardiology (AHA & ACC). ANALYSIS OF DATA Descriptive statistical methods were implemented, and means, standard deviations, numbers and percentages were obtained. Additionally, the Mann Whitney U test, multi-factor ANOVA, and chi-squared test were performed using the SPSS ver.17 software. Since some variables were not normally distributed, the comparisons between variables were made by the Kruskal Wallis test. A statistical significance of p ≤ 0.05 was used. RESULTS Patient demographic and clinical characteristics were recorded in Table 1. The mean patient BMI was 27 kg/m2, 72.9% of all patients were male, with mean age of 60 years, and 51% of the patients had stable chronic angina. The average number of angioplasty cases and the number of inserted stents was 1.5 and 1.7, respectively. Also, complex, moderate and simple lesions accounted for 21, 54 and 25%, respectively. Table 1. Quantitative analysis of baseline demographic, clinical and angiography data. Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Values are shown mean ± SD, N (%). ACS, acute coronary syndrome; CSA, chronic stable angina; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery. Table 1. Quantitative analysis of baseline demographic, clinical and angiography data. Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Age (year) 59.89 ± 10.33 Sex  Male 551 (72.9)  Female 205 (27.1) BMI (kg/m2) 27.25 ± 3.86 Clinical status  ACS 373 (49.3)  CSA 383 (50.7) Target vessels treated  LAD 285 (37.7)  LCX 229 (30.3)  RCA 242 (32) Number vessel treated  One vessel 398 (52.6)  Two vessels 328 (43.4)  Three vessels 30 (4) Number of stenting  1 stent 252 (33.3)  2 stents 473 (62.6)  3 ≥ stents 31 (4.1) Type of lesion  A 160 (21.2)  B 408 (54)  C 188 (24.9) Values are shown mean ± SD, N (%). ACS, acute coronary syndrome; CSA, chronic stable angina; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery. Table 2 shows the level of patient and operator radiation exposure in relation to the type of lesion. A mean operator radiation exposure of 52.5 μSv was estimated and the mean KAP and cumulative dose of patients were 5081 μGy m2 and 814 mGy, respectively. Using the bivariate Spearman method, correlations between clinical status and operator radiation exposure; number of treated vessels and operator radiation exposure; and the number of stents and operator radiation exposure were investigated (Figure 1). There was a significant positive correlation between the operator radiation dose and the lesion type (p < 0.001, r = 0.594). Additionally, a positive correlation was noted in terms of number of stents included and clinical status with physician radiation exposure levels. Also a direct correlation was observed between the number of vessels and operator radiation exposure (p < 0.001, r = 0.295). However, no correlation was found between patients’ BMI and operator radiation doses (Figure 2A). On the other hand, a significant positive correlation was noted between patients’ BMI and patient radiation exposure, p < 0.001 (Figure 2B). Table 2. Analysis of lesion type in relation to patient and operator radiation exposure. Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 KAP, kerma area product. aSimple lesions; bmoderate lesions; ccomplex lesions. Table 2. Analysis of lesion type in relation to patient and operator radiation exposure. Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 Type of lesion p-Value Aa mean(min − max) Bb mean(min − max) Cc mean(min − max) Operator dose (μsv) 25.81 (15.76–59.75) 44.97 (20.52–215.6) 91.55 (21.41–333.2) <0.001 KAP (μGy.m2) 3102.69 (1305.3–18 760) 4936.69 (1253.9–19 452) 7077.96 (1521.8–19 452) <0.001 Air-kerma (mGy) 457.53 (186–2110) 795.02 (185.9–2879) 1160.35 (185–2650) <0.001 Fluoroscopy time (min) 5.29 (2.6–14) 9.03 (3–42.3) 12.81 (4–37.05) <0.001 Procedural time (min) 15.55 (5–38) 26.7 (6–89) 34.02 (6–69) <0.001 KAP, kerma area product. aSimple lesions; bmoderate lesions; ccomplex lesions. Figure 1. View largeDownload slide Linear correlation between operator dose and number of vessel treated (A) and number of stents (B). Figure 1. View largeDownload slide Linear correlation between operator dose and number of vessel treated (A) and number of stents (B). Figure 2. View largeDownload slide Results of correlation tests between body mass index (BMI) of patients and operator exposure (A) and correlation between patients’ BMI and patients’ radiation exposure (B). Figure 2. View largeDownload slide Results of correlation tests between body mass index (BMI) of patients and operator exposure (A) and correlation between patients’ BMI and patients’ radiation exposure (B). Significant differences were noted in terms of radiation dose exposure and time including air kerma area product (KAP), air kerma and fluoroscopy time between the three complexity groups (Table 2). Additionally, the procedural duration time for type C lesions was almost 18 min longer than the group treated for type A lesions. Table 3 shows the results of linear regression analysis of confounding factors that affected the operator radiation dose. It is seen that there is no correlation between operator dose and patients’ BMI as well as number of vessels. But for other factors such as fluoroscopy time, patient dose, complexity of procedure, it was found a direct correlation with operator dose. Table 3. Linear regression analysis of confounding factors that affected operator radiation dose. Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Dependent variable: operator dose. BMI, body mass index. aStatistically significant difference. Table 3. Linear regression analysis of confounding factors that affected operator radiation dose. Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Model Unstandardized coefficients Standardized coefficients t p-Value B SE Beta (Constant) −19.806 9.030 −2.193 0.029 BMI(kg m−2) −0.028 0.275 −0.003 −0.101 0.919 Clinical status −4.403 2.084 −0.058 −2.112 0.035a Type of lesion 21.080 1.986 0.374 10.614 0.000a Number of stent 9.326 2.479 0.131 3.762 0.000a Number of vessel 0.605 2.225 0.009 0.272 0.786 Air-kerma (mGy) 0.016 0.003 0.213 5.436 0.000a Fluoroscopy time (min) 0.790 0.278 0.112 2.837 0.005a Dependent variable: operator dose. BMI, body mass index. aStatistically significant difference. Figure 3 demonstrates an increase in operator radiation exposure for every additional vessel treated or stented. More specifically, it was determined that increasing the number of stents or vessels treated from 1 to 3 increased operator radiation exposure by a factor of 2.7 and 1.2, respectively (bivariate correlation analysis). Mean operator radiation exposure levels during CA+PTCA for type A, B and C lesions were 25.81 ± 5.33, 44.97 ± 20.03 and 91.55 ± 52.33 μSv, respectively, which indicates higher radiation exposure from type C lesions when compared with both type A and type B lesions (p < 0.001). Figure 3. View largeDownload slide Relation of operator exposure dose to number of vessels (A), number of stenting (B) and lesion type (C). Figure 3. View largeDownload slide Relation of operator exposure dose to number of vessels (A), number of stenting (B) and lesion type (C). A multi-factor linear regression model showed that with an increase in fluoroscopy time, patient radiation exposure levels significantly increased. Additionally, increasing the number of stents from 1 to 3 increased operator radiation exposure levels by 9 μSv, while a change in case complexity from simple to complex increased operator radiation exposure by a factor of 2.1. DISCUSSION It was determined that operating physician radiation exposure levels were significantly affected by the number of stents implemented along with coronary lesion complexity. The results revealed a positive correlation between the number of stents and treated vessels with operator radiation exposure levels, further emphasizing a rise in radiation exposure with an increase in overall case complexity. Several studies elaborated on clinical and technical factors influencing operator radiation exposure(16, 18, 21, 22); however, only one of these studies specifically addressed the effect of stenting strategies on operator radiation exposure levels(23). Additionally, several studies found correlations between body surface areas and procedure type with both patient and operator radiation exposure doses(24, 25). Shah et al.(26) elaborated on higher risks associated with radiation exposure for both patients and operating physicians operating on higher BMI patients, while our results demonstrated only a direct relationship between patients’ BMI and patient radiation exposure and it was not seen between patients’ BMI and operator dose. However, the study completed by Shah et al.(26) only evaluated patients undergoing CA and not angioplasties. Additionally, the study only collected patient radiation exposure data, and then simply speculated a concern for increased operating radiation exposure for physicians with no specific supporting radiation data. Although both patients and physicians were exposed to radiation, both sample groups were exposed through different physical mechanisms, which can potentially account for the differences in radiation exposure between patients and physicians when compared to increases in patient BMI. Patients were exposed to both primary and secondary radiation; however, operating physician radiation exposure was a consequence of deflection and scatter off of the patient(27). Studies have also evaluated procedure complexity on patient radiation exposure(21, 22). Bernardi et al. studied anatomical and technical procedural factors influencing fluoroscopy and cine fluoroscopy times, with cases evaluated through multi-regression analysis by three levels of complexity, simple, intermediate and complex. Their study proposed that complex-lesion procedures require 2.5 times more fluoroscopy time when compared with simple-level lesions (19.83 min compared with 7.85 min), paralleling the results of our study(21). According to our results, the extent of radiation exposure to the patients in simple, moderate and complex lesions during coronary angioplasties was ~2.12 (31.02 vs. 65.8 Gy cm2), 1.88 (49.36 vs. 93 Gy cm2) and 1.63 (70.77 vs.116 Gy cm2) times respectively lower than those reported in Bernardi et al.'s study. This variation in results could be attributed to the differences in levels of expertise among the operators performing the procedures. Furthermore, the result of our study indicated 71 and 132% decrease in air-kerma factor compared to the Fetterly et al. and Suzuki et al.s' studies. This different could be resulted from lower patients’ BMI in our study (29.7 vs. 27 kg/m2). It should be mentioned that there was a direct correlation between patients’ BMI and patients’ radiation exposure in our study as reported in the previous investigations. With recent advancements in coronary angiography systems along with strides in surgical dexterity and training, treatment of more complex cases such as CTO has risen, resulting in better control of stable angina, dyspnoea and resistant arrhythmia. However, with this rise in surgical and technical proficiency comes the risk for elongated procedure and fluoroscopy time(28–31). In another study, Suzuki et al.(13), evaluated dermatological injuries due to CTO angioplasty procedures demonstrating that treatment of complex lesions exposed patients to higher levels of radiation by a factor of 2.6 when compared to simple lesions, paralleling a similar trend found by Fetterly et al.(13, 16). In terms of radiation measurement, it was demonstrated that kerma-area product (KAP) is a stronger predictor for hazardous patient radiation dose exposure when compared to air-kerma(32). While our study implemented evaluation using KAP, Suzuki et al. only evaluated patient radiation exposure using air-kerma. Reports also indicated that more complex lesions such as MVD-PCI including multiple lesions within one segment, single lesion within multi segments, as well as high tortuosity, bifurcation or CTO-PCI, expose patients to higher radiation doses(16, 18). However, these studies only specified patient radiation exposure levels with little attention to operator radiation exposure(33). In terms of radiation exposure time and lesion complexity, it was determined that operating physician radiation exposure time for group C was almost 2.5 times higher than group A and 1.5 times greater than group B, indicating a rise in physician radiation exposure with a rise in case complexity. Although cases were ordered and evaluated in terms of generalized case complexity, it is important to note that the number of stents implemented for each complexity level was non-standardized. Several coronary cases even required no stenting; in some cases only pre-dilatation and post dilatation were sufficient. Additionally, several segments may have required the implementation of multiple stents, further hindering standardization and significantly affecting the radiation time and exposure. With this in mind, future studies may wish to find a better way to standardize such cases by controlling for the specific number of stents implemented within each level of complexity of the lesion. CONCLUSION Our results indicated a significant increase in operator radiation exposure with rise in lesion complexity, the number of stents implemented, and number of coronary vessels involved. However, our team determined that lesion type or complexity had the most significant effect on operator radiation exposure levels. Although there are a myriad of studies evaluating radiation exposure of either patients or operating physicians from such coronary interventions, more studies are needed to compare radiation exposure between operating physicians and patients, potentially opening the doors to additional studies on the physics behind radiation absorption, deflection and scatter. 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Radiation Protection DosimetryOxford University Press

Published: Mar 23, 2018

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