OCCUPATIONAL DOSES FOR THE FIRST AND SECOND OPERATORS IN LEBANESE INTERVENTIONAL CARDIOLOGY SUITES

OCCUPATIONAL DOSES FOR THE FIRST AND SECOND OPERATORS IN LEBANESE INTERVENTIONAL CARDIOLOGY SUITES Abstract The study monitored occupational dose for 12 interventional cardiologists (first operators) and 10 technicians (second operators), from 10 different Lebanese hospitals performing coronary angiography and precutaneous coronary interventions exclusively on adult patients. Each individual wore dosemeters under and over the lead apron at chest and collar level, respectively, on the wrist and next to the left eye. The total follow-up period for each first/second operator varied between two to six bimonthly monitoring periods. For the first operator, the mean (range) effective, hand and eye lens doses were of 6 (1–41), 112 (10–356) and 15 (5–47) μSv/procedure, respectively. These were of 2.3 (0.1–8), 16 (2–109) and 7 (2–14) μSv/procedure for the second operator. Extrapolated annual eye lens doses revealed that both first and second operators may exceed 3/10th of the annual eye lens dose permissible limit thus supporting the need for dedicated eye lens monitoring. INTRODUCTION Interventional cardiologists have among the highest radiation exposure levels of all health professionals owing to the prolonged use of fluoroscopy and to the position of medical staff near the patient (source of scattered radiation) during such interventions(1). Additionally, increased frequency of lens opacities was identified in recent studies on interventional cardiologists when compared to a control group if radiation protection tools are not properly and routinely used(2–5). In 2012, the International Commission on Radiological Protection (ICRP)(6) has set the threshold for radiation-induced eye cataracts to be 0.5 Gy for both acute and fractioned exposures. Consequently, they recommended a reduction of the occupational dose limit for the eye lens from 150 mSv to 20 mSv per year, averaged over defined periods of 5 y, with no single year exceeding 50 mSv. In addition, the new EU BSS(7) states that those exposed workers who are liable to receive an effective dose > 6 mSv per year or an equivalent dose > 6 mSv per year for the lens of the eye or > 150 mSv per year for skin and extremities, belong to the category A. The EU BSS also states that category A workers must be systematically monitored, whereas for category B, the monitoring must be at least sufficient to demonstrate that such workers are correctly classified in that category. Over the past years, several studies dealt with the assessment of radiation doses received by interventional radiology staff. Reported results from the ORAMED (Optimization of Radiation protection for MEDical staff) project, performed in clinic, provided data on the exposure levels for eye and extremities received by the main operators(8–10). While other studies reported only eye lens doses for the first (interventional cardiologist) and second (technicians) operators(11, 12). In addition, the dose reduction afforded by the lead glasses and ceiling shield was tested using phantoms(13–15) or simulations(16–18). However, such data correspond to static situations. Yet, the most realistic results will obviously be obtained from measurements performed on operators in clinical practice. In Lebanon, the Lebanese Atomic Energy Commission-Individual Monitoring Services Laboratory (LAEC-IMSL) is responsible for monitoring occupational radiation exposure. Approximately, 400 healthcare professionals working in interventional cardiology (IC) suites are monitored. Interventional cardiologists are required to wear a whole body dosemeter (WBD) under the lead apron at chest level as well as an extremity dosemeter which should be worn on the left hand’s wrist. Meanwhile, second operators are only monitored for their whole body exposure. The permissible limits for the effective dose is 20 mSv per year, averaged over a period of 5 y, without exceeding 50 mSv in any year and 500 mSv per year for the dose equivalent to the skin following ICRP 103(19). The monitoring period is 2 months for all workers regardless of their level of exposure to ionising radiation. So far, eye lens monitoring is not yet a legal requirement and thus routine monitoring of eye lens doses is not performed within the LAEC-IMSL. In the present work, co-ordinated measurements were organised in 10 different Lebanese IC suites with 12 cardiologists and 10 technicians who volunteered to wear dosemeters for several monitoring periods. The study aims to: (a) investigate the magnitude of potential occupational exposure of effective dose, extremity Hp(0.07) and eye lens Hp(3) doses among different health professionals performing coronary angiography (CA) and/or percutaneous coronary interventions (PCI), (b) suggest a categorisation of workers and investigate the incorporation of eye lens monitoring into the service, (c) correlate eye lens and Hp(10) measurements to investigate if eye exposure could be estimated from whole body dosimetry, (d) investigate the efficacy of the lead glasses in reducing the eye lens dose for first and second operators and (e) propose practical recommendations to reduce the operator’s exposure. MATERIALS AND METHODS The study included 12 interventional cardiologists (first operators) and 10 technicians (second operators) selected from 10 Lebanese hospitals based on their commitment to wear the set of dosemeters throughout 2–6 bimonthly monitoring periods. Measurements were performed from June 2016 until September 2017. Selected procedures For the first operator, the procedures monitored were CA and PCI examinations performed on adult’s patients exclusively. Only two operators (#6 and #7 in Table 1) performed few numbers (21 out of 248 procedures and 10 out of 139 procedures, respectively) of lower limb arteriography procedures in addition to CAs and PCIs. While for the second operators, they were mainly involved in adult’s CA, PCI, and in lower frequency, pacemaker and defibrillator implantation and vascular procedures. Table 1. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different interventional cardiologists (first operators) and facilities FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO, first operator; SD, standard deviation. Table 1. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different interventional cardiologists (first operators) and facilities FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO, first operator; SD, standard deviation. For each examination, information on the use of protective equipment (lead apron and thyroid shield, lead glasses, caps, ceiling mounted shields and table-suspended drapes) and position of (a) the first or second operator with respect to the X-ray tube, (b) the flat panel detector (FPD) with respect to the patient and (c) the monitor screen with respect to the operator during the examination were recorded. In addition, in order to correlate staff with patient doses, online dose indicators like dose-area product (DAP), cumulative dose at reference point (CD), fluoroscopy time (FT) and number of frames (NoF) were also collected for every single procedure performed by each first and second operator during the entire 2-month monitoring period. It should be noted that no information on the DAP metres’ calibrations were obtained from the different institutes participating in this study but all of them are regularly tested according to the manufacturer quality assurance protocol and performance requirements and the systems were adjusted whenever needed. For this study, one dosemeter was worn under and one over the lead apron at left chest and collar level, respectively, and one dosemeter at the wrist level of the left hand. Additionally, to monitor the dose to the lens of the eye, one dosemeter was attached to the left lateral side of the lead glasses (when lead glasses were used) for the first (#1, #2, #3, #4, #6 and #12 in Table 3) and second (#1, #5, #7, #8 and #10 in Table 4) operators, or directly beside the left eye for the first (#5, #7, #8, #9, #10 and #11 in Table 3) and second operators (#2, #3, #4, #6 and #9 in Table 4). Hence, when lead glasses were worn, the measurements were performed outside the glasses thus overestimating the eye lens doses. It should be noted that not all the 10 institutions were represented by the 12 first and 10 second operators. Tables 1 and 2 present the number of monitoring periods in addition to the number of procedures, the mean patient online dose indicators (i.e. FT, CD, DAP and NoF) together with their spread for both CA and PCI for each of the first and second operators respectively from each facility. Table 2. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different technicians (second operators) and facilities SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO, second operator; SD, standard deviation. Table 2. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different technicians (second operators) and facilities SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO, second operator; SD, standard deviation. Dosimetric techniques and dose measurements The personal dose equivalent at 10 mm depth Hp(10) was used for the measurements under and over the lead apron using WBD: Harshaw 8814 two element cards with LiF:Mg,Ti detectors (Thermofisher Scientific, Oakwood Village, USA) with a lower limit of detection (LLD) of 0.05 mSv. For calibration purpose, WBD were irradiated on a PMMA phantom using a Cs-137 radiation source according to ISO 4037-Part 1(20) at the Secondary Standard Dosimetry Laboratory (SSDL) of the Greek Atomic Energy Commission. While, the EXTRAD dosemeter (Thermofisher Scientific, Oakwood Village, USA), with a LLD equal to 0.1 mSv, was used for extremity and eye lens dose measurements. The operational quantity used to monitor the dose equivalent to the skin at 0.07 mm depth Hp(0.07) was used for the measurements of hand doses. EXTRAD dosemeters were calibrated in term of Hp(0.07) on a pillar phantom using a Cs-137 radiation source at the SSDL-Greek Atomic Energy Commission. In addition, the operational quantity Hp(3) (dose equivalent at 3 mm depth) was used to control the dose to the eye lens. For this purpose, EXTRAD dosemeters were calibrated in term of Hp(3) on a cylindrical head phantom (20 × 20 cm) with a reference radiation quality RQR6(21) at the SSDL-Belgium Nuclear Research Center (SCK-CEN). It should be noted that Behrens et al.(22) justified the use of Hp(0.07) dosemeters to monitor the eye lens dose due to photon radiation. For a single measurement, relative uncertainties, estimated within the range 60–125 kVp normally employed in interventional practices, were in the order of 13(23) and 15% (at a coverage factor k = 1) for Harshaw 8814 and EXTRAD detectors respectively, taking into account the following components: calibration errors, linearity, energy and angular dependences, homogeneity, fading and reader stability. All dosemeters were provided through the normal exchange process performed within the LAEC and evaluated at LAEC-IMSL. The LAEC-IMSL is accredited since 2015 to comply with the general requirements of ISO/IEC 17 025 (2005)(24). The measured doses were corrected for background radiation from additional dosemeters issued to each of the 10 IC suites with no readings were recorded below the LLD mainly because of the length of the monitoring period. Although the requirements from ISO 15 382(2015)(25) concerning the position of the eye lens dosemeters were followed, the measurements of eye lens doses still include a large uncertainty because of the well-known practical difficulties in positioning the dosemeter relative to the eye itself. The effective dose (E) was estimated using the data collected from the WBD worn under (Hu) and over (Ho) the lead apron using the formula: E = Hu + 0.05 ∗ Ho(26). This equation considers the dose contributions to the protected (under the lead apron and the thyroid shield) and unprotected parts of the body (head and extremities). Estimation of the annual doses The estimation of annual effective, hand and eye lens doses is also reported in this study. The yearly workload performed by each first and second operator was estimated from the logbook of each hospital for the last calendar year (2016). Assuming that the collected procedures were representative of all the procedures that an operator performs per year, extrapolated effective, hand and eye lens doses values per procedure to annual doses were estimated to check if the annual limits might be exceeded and if the 3/10th might be reached. This was performed by multiplying the mean effective, hand and eye lens dose per procedure with the yearly workload of each first and second operator. Correlation between Hp(3) and Hp(10) To check if the doses to the lens of the eye could be linked to the doses measured at the level of the neck over the lead apron (Ho), Hp(3) values were presented as a function of Ho. To test the fitting quality, the coefficient of determination (R2) was used. Linear fits were performed using the software package Statistica version 7.0. In practice, the correlation was considered poor when R2 ranged from 0.3 to 0.5. For values of R2 between 0.5 and 0.7, the correlation was estimated to be good and between 0.7 and 1.0, the correlation was estimated to be excellent. Protection efficacy of lead glasses Two models of lead glasses were used with frontal lenses lead equivalent thickness of 0.75 mm. One model had a flat frontal lenses and additional 0.5 mm side shield, this was the preferred model worn by first operators, while the other model had wrap-around style, with no-side shield, and was mostly worn by second operators. In order to evaluate the effectiveness of lead glasses in reducing the dose to the eyes, an additional dosemeter was attached to the internal left lateral side of the glasses for four first (#1, #3, #4 and #6 in Table 3) and three second operators (#1, #5 and #10 in Table 4) for three monitoring periods. The dose reduction factor was evaluated by dividing the eye lens dose from the dosemeter attached at the external left lateral side by that from the dosemeter attached on the internal left lateral side of the glasses. Table 3. Extrapolated annual doses and the use of lead glasses for different interventional cardiologists (first operators) included in this study. FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  OLLSG, outside left lateral side of the glasses; ILLSG,inside left lateral side of the glasses. Table 3. Extrapolated annual doses and the use of lead glasses for different interventional cardiologists (first operators) included in this study. FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  OLLSG, outside left lateral side of the glasses; ILLSG,inside left lateral side of the glasses. Table 4. Extrapolated annual doses and the use of lead glasses for different technicians (second operators) included in this study. SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  OLLSG, outside left lateral side of the glasses; ILLSG, inside left lateral side of the glasses. Table 4. Extrapolated annual doses and the use of lead glasses for different technicians (second operators) included in this study. SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  OLLSG, outside left lateral side of the glasses; ILLSG, inside left lateral side of the glasses. RESULTS Effective, hand and eye lens doses per procedure The data were collected from 10 different Lebanese hospitals and covered almost 5300 procedures. Occupational doses were assessed for 12 cardiologists (first operator) and 10 technologists (second operator). In order to have an idea of the level of exposure per procedure and to compare the results reported within this study with those performed in the literature, Figure 1 shows the mean values, interquartile (Q1, Q2 and Q3), ranges and spread of the effective, hand and eye lens doses per procedure for the first and second operators. The mean eye lens dose measured on the internal left lateral side of the glasses were 5.1 ± 2.3 μSv/procedure and 4.5 ± 1.2 μSv/procedure for the first and the second operator respectively. Figure 1. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator per procedure. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Figure 1. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator per procedure. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. For the first operators, the highest effective dose was found in hospital G with an average of 27 μSv/procedure. While the highest eye and hand doses were found in hospitals B and D, respectively, with an average of 38 and 225 μSv/procedure, respectively. However, for the second operators, 7, 20 and 80 μSv/procedure were the highest mean effective, eye and hand doses, respectively, and were found in Hospital I. For example, the mean together with the spread of eye lens dose per procedure of the cardiologists (respectively technicians) #1, #4 and #6 (respectively #1, #2 and #10) were 11.8 ± 5, 38 ± 7 and 5.8 ± 0.8 μSv/procedure (respectively, 11.6 ± 2.4, 2.5 ± 0.4 and 6 ± 1.8 μSv/procedure). Effective, hand and eye lens doses normalised to DAP All measured values were also normalised, for each monitoring period, to the individual cumulative DAP values. Results are presented in Figure 2 for the first and second operators, respectively. Indeed, DAP provides a good patient dose quantity, because it gives a measure of the total radiation emitted, which is linked to the amount of scatter to which operators are exposed. In addition, this quantity allows adjustment of radiation used, which is one of the most significant factors determining staff doses, but does not take account of variation related to the technique and position taken up by the operator(27). However, for a given procedure type, normalised dose distributions still exhibit large relative standard deviations since it is well known that staff doses and DAP hardly correlate, particularly for CA and PCI examinations which involve notably several different angulations(10, 28). The average eye lens doses measured on the internal left side of the glasses for the first and the second operators were 0.17 ± 0.09 μSv/Gy.cm2 and 0.13 ± 0.1 μSv/Gy.cm2, respectively. Figure 2. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator normalised to the total DAP for each monitoring period. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Figure 2. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator normalised to the total DAP for each monitoring period. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Extrapolated annual effective, hand and eye lens doses Tables 3 and 4 present the annual extrapolated doses together with the use of lead glasses for each of the first and second operators, respectively. The total number of procedures was estimated from the logbook of each hospital based on each operator workload during 2016. The extrapolated annual eye lens doses, measured at the internal left lateral side of the glasses for a sub-sample of the first (six operators) and second (five operators) operators, are presented as well. Additionally, for operator #1 (respectively operator #2) from Table 3, the extrapolated annual effective, hand and eye lens doses were 32, 50 and 10% (respectively, 64, 62 and 27%) higher than the accumulated annual doses measured during the six monitoring periods. Actually, the mean effective, hand and eye lens doses for those two operators (3, 49 and 11 μSv/procedure, respectively) were lower than those shown in Figure 1 for the 12 first operators. Correlation of Hp(3) and Ho and eye lens dose reduction To provide an estimation of the eye lens dose when alternative methods are used, such as the use of a WBD, Figure 3 shows the correlation between Hp(3) measured on the outside left lateral side of the lead glasses and Hp(10) measured on the left collar level over the lead apron (Ho) for both FO and SO. A good overall correlation of the two measured operational quantities was found, resulting in a correction factor of a = 0.31 (R2 = 0.82). Furthermore, the dose reduction factor provided by lead glasses reduced the doses on average by a factor 2.8 and 2.1 for the first and second operators, respectively. Figure 3. View largeDownload slide Correlation of Hp(3) measured outside the left lateral side of the lead glasses and Hp(10) measured at the left collar level over the lead apron for both FO and SO. Figure 3. View largeDownload slide Correlation of Hp(3) measured outside the left lateral side of the lead glasses and Hp(10) measured at the left collar level over the lead apron for both FO and SO. DISCUSSION AND RECOMMENDATIONS The extrapolated yearly doses for the first and the second operator, respectively, show low effective doses especially for the second operator. In fact, the 3/10th of the dose limit is neither reached by the first or the second operator. Although the doses are relatively low, one cannot exclude that accidentally higher doses are encountered especially when workload or complexity of procedures increases, thus monitoring cannot be excluded. Also, extrapolated hand doses are low with none of the first or second operators reaching 3/10th of the dose limit. However, bad practices among the first operators were observed by the authors (e.g. placing the hands directly in the X-ray beam). This could lead to higher doses than those presented in this study. Additionally, the dosemeter worn on the wrist (like those used in this study) may underestimate the maximum dose to an area of skin on the hand by a factor of 3(27) for the first operator. The hand doses to the second operator are found to be lower than those from the first operator due to the large distance from the X-ray tube and from the irradiated area. Therefore, extremity monitoring is needed especially for the first operator. For the annual extrapolated eye lens dose, none of the first or second operators surpassed the present annual eye lens dose limit of 20 mSv per year, not even when measuring the doses outside the lead glasses. However, 30% of the first and 20% of the second operators exceed the 6 mSv when the doses were measured at the outer left lateral side of the glasses or directly near the left eye. None of the eye lens dose values measured on the internal left lateral side of the lead glasses exceeded 6 mSv for the first operators. For the second operators, the dose measured inside the glasses still exceeded 6 mSv for one technician with the highest workload (out of three monitored using lead glasses). Hence, dedicated eye lens monitoring should be performed for the first and second operators and not estimated from workplace monitoring or WBD. Table 5 presents the comparison of the mean effective, hand and eye lens doses per procedure and the normalised doses to DAP for the first and the second operators with the results of similar studies performed for the same type of procedures mentioned here. Table 5. Comparison of the published data effective, eye lens and hand doses per procedure and normalised to respective DAP for CA and PCI examinations for the positions first and second operators.     E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)      E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)  Table 5. Comparison of the published data effective, eye lens and hand doses per procedure and normalised to respective DAP for CA and PCI examinations for the positions first and second operators.     E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)      E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)  The effective, extremities and eye lens doses from this study are comparable with those presented in the literature(9, 11, 29–33). Yet, variability of the measurements performed within this multi-centre study and those from the literature is noticed. This can be attributed to many factors such as: (a) the use of personal and collective protective equipment, (b) skill and experience of the physicians, (c) practice and technique applied, (d) tube configuration (above or below the table), (e) access route (e.g. femoral or radial) and (f) calibration procedures and dosimetric quantities used. The relatively low exposure of the eye lens in this study can be explained by the fact that most procedures used radial access (90%) and in this situation a better positioning of the ceiling shield is possible. In fact, when the operator is closer to the X-ray beam (radial access), it is easier to correctly position the shield(9). In addition, the FPD can play an important role in giving an extra shielding for the eyes when the radial access is used. Those factors can explain as well the dose differences among the different operators and/or the different hospitals included in this study. The large observed spread of doses, within the study, for the same operator could be attributed to the complexity of the procedure even when performing the same type of intervention (e.g. CA or PCI). Also, other factors like the inconsistency in the position of the operator/head from one procedure to another, the different access routes, projections, collimations and magnifications used to perform each procedure could affect the measured doses from one monitoring period to another. The use of dosemeters worn on other parts of the body such as the thyroid collar outside the lead apron could be a valuable tool for the estimation of the eye lens dose for investigative reasons or for retrospective calculations. The eye lens dose could be estimated by roughly 1/3 of the dose measured at the left collar level over the lead apron where direct monitoring of the eye lens in terms of Hp(3) is not available. This ratio is lower than those reported by other studies (between 0.44 and 1.86)(34). In addition, the variability of the ratio is extremely dependent on practice and wearing positions. Therefore, this method is associated with large uncertainty and great caution is needed if the measured dose levels are close to the dose limits owing to the difference in personal habits, the exact place of the above apron dosemeters and the protection measures taken(34). By measuring eye exposure for some operators inside and outside the lead glasses, information was obtained on the dose reduction factor from the lead glasses. This dose reduction was found to be on average 2.8 and 2.1 for the first and second operators, respectively. It should be mentioned that this is an estimation because measuring on the eye lens itself is not possible. Furthermore, although, the dose reduction factor reported in this study (2.8 for first operators) is similar to that found by Principi et al.(17) (2–3 depending on the glasses’ type), it is lower than those reported by other works (between 8 and 10)(34). Also, the wrap-around lead glasses style did not reduce the doses efficiently as those reported in the literature(16). The position of the dosemeter and the left anterior oblique projections used in clinical practice can explain these differences. Finally, this estimation is based on small sample of operators (4 first and 3 second operators) and might not be valid in general. Observations, performed by the author in the clinics, revealed bad practices in a representative sample of the Lebanese IC suites. Firstly, about 25 and 50% of the first and the second operators, respectively, were not wearing leaded glasses. In addition, as already mentioned before, different models of glasses were used among which 50% had no lateral shields. Consequently, lead glasses with lateral shields should be supplied for a better radiation protection scheme(18). Secondly, although present in all the examinations included in the study, the use and positioning of ceiling shields markedly varied between operators even at the same medical centre: a fixed position close to the operator was held during 90% of the procedures. In addition, operators were changing their position in some procedures; hence they were not well covered by the shields. The effect of the shields is implicitly incorporated in the doses reported within this study and it was not possible to investigate its efficiency in clinical practice. Still, its effectiveness in reducing the doses is highlighted by different studies performed in clinic(8), on phantom(15) or through simulation(16). Those authors stated that a reduction factor varying between 1.5 and 5.7 is granted by the ceiling shield. For instance, ceiling shields can reduce the dose to the brain tissue from 74 up to 94%. Moreover, a combination of leaded glasses and a ceiling shield can reduce the dose to the head, both eyes and also protect very efficiently the upper part and hands of the operator as well as other people present in the operating room (technicians–nurses). Thus, the use of ceiling shield should be systematic in all the Lebanese IC suites. Thirdly, the monitor screens were frontward (0°) from the operator for 100% of the procedures performed within this study. Some authors(16–17) found, based on Monte-Carlo simulations, that a rotation of the head of 30° or 45° away from the tube can reduce the eye lens dose by approximately 50%. Consequently, the monitors screen should be located to the right of the operators in the Lebanese IC suites. Finally, FPD were, in the majority of the procedures at 20 cm or more from the patient depending on the tube projection used. As reported by Koukorava et al.(16), the FPD should be placed as close as possible to the patient, especially when PA and small angled oblique projections are used. This will reduce operator’s exposure to scattered radiation. Moreover, the preferential use of right anterior oblique projections where additional shield is occasionally provided by the FPD, positioned at the left side of the operator, can reduced the scattered radiation reaching the left eye(18). Thus, the distance between the FPD and the patient should be decrease in the Lebanese IC during the interventions. STUDY LIMITATION The study is subjected to many limitations. Firstly, the selection of the first and second operators was not done randomly and was based on the commitment of the operators to wear the set of dosemeters throughout the monitoring period, which could have biased the results. Secondly, the univariate analysis performed within the study is based on the average bimonthly registered dose and do not take into account the number of monitoring periods collected for each of the first/second operators included in the study. Finally, the 2-month monitoring period might be too long for IC operators owing to the exposure situation (e.g. dose level) and should be reduced to 1 month monitoring period. CONCLUSIONS A large dose data set was collected at the level of chest and collar, respectively, wrist and left eye of 12 interventional cardiologists and 10 technicians working at 10 major Lebanese hospitals. For the first and second operators, large range and variability of the doses were observed among the centres owing mainly to the practice and technique applied in each centre by each operator. Effective doses were relatively low with a mean values of 6 (range, 0.8–41) and 2.3 (range, 0.1–8) μSv/procedure for the first and second operators, respectively. This further demonstrates that whole body dose would not be the limiting exposure index if a lead apron is worn; which is very common and easy to achieve. Similarly, hand doses were relatively low with a mean values of 112 (range, 10–356) μSv/procedure for the sample of first operators included in this study also showing that extremity doses will not be the limiting factor if good practices are in place (e.g. the hands should be kept out of the beam). Meanwhile, for the eye lens dose, the highest measured doses of the first and second operators were around 47 and 14 μSv/procedure (1.06 and 0.33 μSv/Gy.cm2, respectively). Although the ceiling shield was used in all procedures performed within this study, the extrapolated annual left eye doses revealed that 30% of the first and 20% of the second operators may exceed the 6 mSv limit. Thus, dedicated eye lens monitoring is needed for both first and second operators. Doses to the lens of the left eyes were reduced by about 1/3 when lead glasses with lateral shield were used. Measurements hence proved that eye lens dose would be the limiting exposure index for both primary and secondary operators who do not wear eye protection. Also, eye lens dose could still remain an issue even for those wearing lead glasses due to the origin of scattered radiation reaching the eyes which actually in the large majority come from unprotected parts of the head further justifying the need for systematic monitoring. FUNDING This work was supported by the National Council for Scientific Research in Lebanon and Saint Joseph University. REFERENCES 1 Vano, E., Gonzalez, L., Guibelalde, E., Fernandez, J. M. and Ten, J. I. Radiation exposure to medical staff in interventional and cardiac radiology. Br. J. Radiol.  71, 954– 960 ( 1998). Google Scholar CrossRef Search ADS PubMed  2 Ciraj-Bejlac, O., Rehani, M. M., Slim, K. H., Liew, H. B., Vano, E. and Kleiman, N. J. 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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

OCCUPATIONAL DOSES FOR THE FIRST AND SECOND OPERATORS IN LEBANESE INTERVENTIONAL CARDIOLOGY SUITES

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com
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0144-8420
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1742-3406
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10.1093/rpd/ncy085
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Abstract

Abstract The study monitored occupational dose for 12 interventional cardiologists (first operators) and 10 technicians (second operators), from 10 different Lebanese hospitals performing coronary angiography and precutaneous coronary interventions exclusively on adult patients. Each individual wore dosemeters under and over the lead apron at chest and collar level, respectively, on the wrist and next to the left eye. The total follow-up period for each first/second operator varied between two to six bimonthly monitoring periods. For the first operator, the mean (range) effective, hand and eye lens doses were of 6 (1–41), 112 (10–356) and 15 (5–47) μSv/procedure, respectively. These were of 2.3 (0.1–8), 16 (2–109) and 7 (2–14) μSv/procedure for the second operator. Extrapolated annual eye lens doses revealed that both first and second operators may exceed 3/10th of the annual eye lens dose permissible limit thus supporting the need for dedicated eye lens monitoring. INTRODUCTION Interventional cardiologists have among the highest radiation exposure levels of all health professionals owing to the prolonged use of fluoroscopy and to the position of medical staff near the patient (source of scattered radiation) during such interventions(1). Additionally, increased frequency of lens opacities was identified in recent studies on interventional cardiologists when compared to a control group if radiation protection tools are not properly and routinely used(2–5). In 2012, the International Commission on Radiological Protection (ICRP)(6) has set the threshold for radiation-induced eye cataracts to be 0.5 Gy for both acute and fractioned exposures. Consequently, they recommended a reduction of the occupational dose limit for the eye lens from 150 mSv to 20 mSv per year, averaged over defined periods of 5 y, with no single year exceeding 50 mSv. In addition, the new EU BSS(7) states that those exposed workers who are liable to receive an effective dose > 6 mSv per year or an equivalent dose > 6 mSv per year for the lens of the eye or > 150 mSv per year for skin and extremities, belong to the category A. The EU BSS also states that category A workers must be systematically monitored, whereas for category B, the monitoring must be at least sufficient to demonstrate that such workers are correctly classified in that category. Over the past years, several studies dealt with the assessment of radiation doses received by interventional radiology staff. Reported results from the ORAMED (Optimization of Radiation protection for MEDical staff) project, performed in clinic, provided data on the exposure levels for eye and extremities received by the main operators(8–10). While other studies reported only eye lens doses for the first (interventional cardiologist) and second (technicians) operators(11, 12). In addition, the dose reduction afforded by the lead glasses and ceiling shield was tested using phantoms(13–15) or simulations(16–18). However, such data correspond to static situations. Yet, the most realistic results will obviously be obtained from measurements performed on operators in clinical practice. In Lebanon, the Lebanese Atomic Energy Commission-Individual Monitoring Services Laboratory (LAEC-IMSL) is responsible for monitoring occupational radiation exposure. Approximately, 400 healthcare professionals working in interventional cardiology (IC) suites are monitored. Interventional cardiologists are required to wear a whole body dosemeter (WBD) under the lead apron at chest level as well as an extremity dosemeter which should be worn on the left hand’s wrist. Meanwhile, second operators are only monitored for their whole body exposure. The permissible limits for the effective dose is 20 mSv per year, averaged over a period of 5 y, without exceeding 50 mSv in any year and 500 mSv per year for the dose equivalent to the skin following ICRP 103(19). The monitoring period is 2 months for all workers regardless of their level of exposure to ionising radiation. So far, eye lens monitoring is not yet a legal requirement and thus routine monitoring of eye lens doses is not performed within the LAEC-IMSL. In the present work, co-ordinated measurements were organised in 10 different Lebanese IC suites with 12 cardiologists and 10 technicians who volunteered to wear dosemeters for several monitoring periods. The study aims to: (a) investigate the magnitude of potential occupational exposure of effective dose, extremity Hp(0.07) and eye lens Hp(3) doses among different health professionals performing coronary angiography (CA) and/or percutaneous coronary interventions (PCI), (b) suggest a categorisation of workers and investigate the incorporation of eye lens monitoring into the service, (c) correlate eye lens and Hp(10) measurements to investigate if eye exposure could be estimated from whole body dosimetry, (d) investigate the efficacy of the lead glasses in reducing the eye lens dose for first and second operators and (e) propose practical recommendations to reduce the operator’s exposure. MATERIALS AND METHODS The study included 12 interventional cardiologists (first operators) and 10 technicians (second operators) selected from 10 Lebanese hospitals based on their commitment to wear the set of dosemeters throughout 2–6 bimonthly monitoring periods. Measurements were performed from June 2016 until September 2017. Selected procedures For the first operator, the procedures monitored were CA and PCI examinations performed on adult’s patients exclusively. Only two operators (#6 and #7 in Table 1) performed few numbers (21 out of 248 procedures and 10 out of 139 procedures, respectively) of lower limb arteriography procedures in addition to CAs and PCIs. While for the second operators, they were mainly involved in adult’s CA, PCI, and in lower frequency, pacemaker and defibrillator implantation and vascular procedures. Table 1. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different interventional cardiologists (first operators) and facilities FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO, first operator; SD, standard deviation. Table 1. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different interventional cardiologists (first operators) and facilities FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  A  6  389  CA  4 (3)  281 (205)  18 (14)  380 (158)  PTCA  18 (9)  840 (737)  57 (50)  624 (274)  2  A  6  417  CA  6 (19)  280 (216)  22 (17)  330 (138)  PTCA  15 (9)  1106 (683)  71 (44)  641 (217)  3  A  4  347  CA  4 (3)  218 (230)  15 (15)  296 (159)  PTCA  9 (5)  557 (502)  36 (31)  542 (228)  4  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  5  B  3  49  CA  4 (3)  527 (278)  30 (15)  313 (124)  PTCA  17 (5)  1810 (915)  100 (47)  819 (250)  6  C  4  248  CA  3 (3)  356 (265)  23 (18)  541 (273)  PTCA  13 (8)  1104 (667)  69 (43)  865 (376)  7  D  3  139  CA  3 (4)  640 (578)  50 (47)  543 (290)  PTCA  14 (10)  2405(1955)  181 (144)  1331 (567)  8  E  3  37  CA  3 (2)  795 (461)  59 (35)  504 (161)  PTCA  13 (8)  2274 (1379)  149 (87)  788 (221)  9  E  3  92  CA  5 (4)  897 (539)  65 (43)  480 (159)  PTCA  11 (7)  2414 (1493)  160 (113)  816 (319)  10  F  3  31  CA  3 (2)  854 (468)  61 (38)  548 (228)  PTCA  12 (5)  2549 (865)  146 (54)  928 (350)  11  G  4  55  CA  3 (7)  538 (434)  47 (36)  412 (210)  PTCA  11 (6)  2333(1497)  221 (145)  1081 (286)  12  H  2  133  CA  3 (3)  233 (155)  20 (20)  537 (216)  PTCA  17 (6)  1423 (954)  97 (75)  1054 (501)  FO, first operator; SD, standard deviation. For each examination, information on the use of protective equipment (lead apron and thyroid shield, lead glasses, caps, ceiling mounted shields and table-suspended drapes) and position of (a) the first or second operator with respect to the X-ray tube, (b) the flat panel detector (FPD) with respect to the patient and (c) the monitor screen with respect to the operator during the examination were recorded. In addition, in order to correlate staff with patient doses, online dose indicators like dose-area product (DAP), cumulative dose at reference point (CD), fluoroscopy time (FT) and number of frames (NoF) were also collected for every single procedure performed by each first and second operator during the entire 2-month monitoring period. It should be noted that no information on the DAP metres’ calibrations were obtained from the different institutes participating in this study but all of them are regularly tested according to the manufacturer quality assurance protocol and performance requirements and the systems were adjusted whenever needed. For this study, one dosemeter was worn under and one over the lead apron at left chest and collar level, respectively, and one dosemeter at the wrist level of the left hand. Additionally, to monitor the dose to the lens of the eye, one dosemeter was attached to the left lateral side of the lead glasses (when lead glasses were used) for the first (#1, #2, #3, #4, #6 and #12 in Table 3) and second (#1, #5, #7, #8 and #10 in Table 4) operators, or directly beside the left eye for the first (#5, #7, #8, #9, #10 and #11 in Table 3) and second operators (#2, #3, #4, #6 and #9 in Table 4). Hence, when lead glasses were worn, the measurements were performed outside the glasses thus overestimating the eye lens doses. It should be noted that not all the 10 institutions were represented by the 12 first and 10 second operators. Tables 1 and 2 present the number of monitoring periods in addition to the number of procedures, the mean patient online dose indicators (i.e. FT, CD, DAP and NoF) together with their spread for both CA and PCI for each of the first and second operators respectively from each facility. Table 2. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different technicians (second operators) and facilities SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO, second operator; SD, standard deviation. Table 2. Number of monitoring periods with the workload, mean patient online dose indicators together with the spread of the data for different technicians (second operators) and facilities SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO  Facility  # of monitoring period  # of procedure  Type of procedure  Mean FT (SD) (min)  Mean CD (SD) (mGy)  Mean DAP (SD) (Gy.cm2)  Mean NoF (SD)  1  B  4  385  CA  2 (2)  275 (202)  17 (13)  219 (105)  PTCA  18 (13)  1982 (2004)  106 (107)  606 (610)  2  C  3  347  CA  4 (3)  462 (366)  31 (25)  645 (327)  PTCA  14 (8)  1182 (704)  74 (42)  1092 (575)  3  D  4  146  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  4  D  4  151  CA  4 (4)  682 (620)  53 (48)  455 (353)  PTCA  14 (10)  2446 (1800)  185 (133)  1082 (717)  5  E  2  145  CA  4 (4)  855 (526)  62 (40)  492 (191)  PTCA  12 (7)  2730 (1744)  174 (115)  1060 (754)  6  G  3  117  CA  3 (4)  736 (466)  63 (40)  513 (170)  PTCA  12 (11)  2263 (2085)  199 (181)  888 (441)  7  H  2  242  CA  4 (4)  260 (224)  22 (26)  556 (303)  PTCA  17 (10)  1266 (940)  68 (61)  946 (495)  8  H  2  207  CA  4 (4)  261 (232)  22 (26)  563 (306)  PTCA  17 (11)  1254 (977)  68 (63)  909 (471)  9  I  3  282  CA  3 (3)  516 (384)  35 (28)  547 (513)  PTCA  14 (9)  2069 (1442)  136 (91)  985 (582)  10  J  5  945  CA  4 (3)  262 (187)  16 (13)  264 (111)  PTCA  10 (7)  685 (640)  35 (26)  455 (240)  SO, second operator; SD, standard deviation. Dosimetric techniques and dose measurements The personal dose equivalent at 10 mm depth Hp(10) was used for the measurements under and over the lead apron using WBD: Harshaw 8814 two element cards with LiF:Mg,Ti detectors (Thermofisher Scientific, Oakwood Village, USA) with a lower limit of detection (LLD) of 0.05 mSv. For calibration purpose, WBD were irradiated on a PMMA phantom using a Cs-137 radiation source according to ISO 4037-Part 1(20) at the Secondary Standard Dosimetry Laboratory (SSDL) of the Greek Atomic Energy Commission. While, the EXTRAD dosemeter (Thermofisher Scientific, Oakwood Village, USA), with a LLD equal to 0.1 mSv, was used for extremity and eye lens dose measurements. The operational quantity used to monitor the dose equivalent to the skin at 0.07 mm depth Hp(0.07) was used for the measurements of hand doses. EXTRAD dosemeters were calibrated in term of Hp(0.07) on a pillar phantom using a Cs-137 radiation source at the SSDL-Greek Atomic Energy Commission. In addition, the operational quantity Hp(3) (dose equivalent at 3 mm depth) was used to control the dose to the eye lens. For this purpose, EXTRAD dosemeters were calibrated in term of Hp(3) on a cylindrical head phantom (20 × 20 cm) with a reference radiation quality RQR6(21) at the SSDL-Belgium Nuclear Research Center (SCK-CEN). It should be noted that Behrens et al.(22) justified the use of Hp(0.07) dosemeters to monitor the eye lens dose due to photon radiation. For a single measurement, relative uncertainties, estimated within the range 60–125 kVp normally employed in interventional practices, were in the order of 13(23) and 15% (at a coverage factor k = 1) for Harshaw 8814 and EXTRAD detectors respectively, taking into account the following components: calibration errors, linearity, energy and angular dependences, homogeneity, fading and reader stability. All dosemeters were provided through the normal exchange process performed within the LAEC and evaluated at LAEC-IMSL. The LAEC-IMSL is accredited since 2015 to comply with the general requirements of ISO/IEC 17 025 (2005)(24). The measured doses were corrected for background radiation from additional dosemeters issued to each of the 10 IC suites with no readings were recorded below the LLD mainly because of the length of the monitoring period. Although the requirements from ISO 15 382(2015)(25) concerning the position of the eye lens dosemeters were followed, the measurements of eye lens doses still include a large uncertainty because of the well-known practical difficulties in positioning the dosemeter relative to the eye itself. The effective dose (E) was estimated using the data collected from the WBD worn under (Hu) and over (Ho) the lead apron using the formula: E = Hu + 0.05 ∗ Ho(26). This equation considers the dose contributions to the protected (under the lead apron and the thyroid shield) and unprotected parts of the body (head and extremities). Estimation of the annual doses The estimation of annual effective, hand and eye lens doses is also reported in this study. The yearly workload performed by each first and second operator was estimated from the logbook of each hospital for the last calendar year (2016). Assuming that the collected procedures were representative of all the procedures that an operator performs per year, extrapolated effective, hand and eye lens doses values per procedure to annual doses were estimated to check if the annual limits might be exceeded and if the 3/10th might be reached. This was performed by multiplying the mean effective, hand and eye lens dose per procedure with the yearly workload of each first and second operator. Correlation between Hp(3) and Hp(10) To check if the doses to the lens of the eye could be linked to the doses measured at the level of the neck over the lead apron (Ho), Hp(3) values were presented as a function of Ho. To test the fitting quality, the coefficient of determination (R2) was used. Linear fits were performed using the software package Statistica version 7.0. In practice, the correlation was considered poor when R2 ranged from 0.3 to 0.5. For values of R2 between 0.5 and 0.7, the correlation was estimated to be good and between 0.7 and 1.0, the correlation was estimated to be excellent. Protection efficacy of lead glasses Two models of lead glasses were used with frontal lenses lead equivalent thickness of 0.75 mm. One model had a flat frontal lenses and additional 0.5 mm side shield, this was the preferred model worn by first operators, while the other model had wrap-around style, with no-side shield, and was mostly worn by second operators. In order to evaluate the effectiveness of lead glasses in reducing the dose to the eyes, an additional dosemeter was attached to the internal left lateral side of the glasses for four first (#1, #3, #4 and #6 in Table 3) and three second operators (#1, #5 and #10 in Table 4) for three monitoring periods. The dose reduction factor was evaluated by dividing the eye lens dose from the dosemeter attached at the external left lateral side by that from the dosemeter attached on the internal left lateral side of the glasses. Table 3. Extrapolated annual doses and the use of lead glasses for different interventional cardiologists (first operators) included in this study. FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  OLLSG, outside left lateral side of the glasses; ILLSG,inside left lateral side of the glasses. Table 3. Extrapolated annual doses and the use of lead glasses for different interventional cardiologists (first operators) included in this study. FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  FO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  462  2.8  51.7  6.9  2.4  2 (Yes)  468  2.8  52.4  7  2.4  3 (Yes)  564  3.4  63.2  8.5  2.9  4 (Yes)  576  3.5  64.5  8.6  2.9  5 (No)  126  0.8  14.1  1.9  NA  6 (Yes)  396  2.4  44.4  5.9  2.0  7 (No)  306  1.8  34.3  4.6  NA  8 (No)  90  0.5  10.1  1.4  NA  9 (No)  157  0.9  17.6  2.4  NA  10 (No)  60  0.4  6.7  0.9  NA  11 (No)  84  0.5  9.4  1.3  NA  12 (Yes)  396  2.4  44.4  5.9  2  OLLSG, outside left lateral side of the glasses; ILLSG,inside left lateral side of the glasses. Table 4. Extrapolated annual doses and the use of lead glasses for different technicians (second operators) included in this study. SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  OLLSG, outside left lateral side of the glasses; ILLSG, inside left lateral side of the glasses. Table 4. Extrapolated annual doses and the use of lead glasses for different technicians (second operators) included in this study. SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  SO # (use of lead glasses)  # of procedures  Annual E (mSv)  Annual Hp(0.07) (mSv)  Annual Hp(3) OLLSG (mSv)  Annual Hp(3) ILLSG (mSv)  1 (Yes)  576  1.3  9.2  3.8  2.6  2 (No)  920  2.1  14.7  6.1  NA  3 (No)  220  0.5  3.5  1.5  NA  4 (No)  250  0.6  4  1.7  NA  5 (Yes)  456  1  7.3  3.0  2.1  6 (No)  240  0.6  3.8  1.6  NA  7 (Yes)  755  1.7  12.1  5  3.4  8 (Yes)  650  1.5  10.4  4.3  2.9  9 (No)  600  1.4  9.6  4  NA  10 (Yes)  1350  3.1  21.6  8.9  6.1  OLLSG, outside left lateral side of the glasses; ILLSG, inside left lateral side of the glasses. RESULTS Effective, hand and eye lens doses per procedure The data were collected from 10 different Lebanese hospitals and covered almost 5300 procedures. Occupational doses were assessed for 12 cardiologists (first operator) and 10 technologists (second operator). In order to have an idea of the level of exposure per procedure and to compare the results reported within this study with those performed in the literature, Figure 1 shows the mean values, interquartile (Q1, Q2 and Q3), ranges and spread of the effective, hand and eye lens doses per procedure for the first and second operators. The mean eye lens dose measured on the internal left lateral side of the glasses were 5.1 ± 2.3 μSv/procedure and 4.5 ± 1.2 μSv/procedure for the first and the second operator respectively. Figure 1. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator per procedure. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Figure 1. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator per procedure. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. For the first operators, the highest effective dose was found in hospital G with an average of 27 μSv/procedure. While the highest eye and hand doses were found in hospitals B and D, respectively, with an average of 38 and 225 μSv/procedure, respectively. However, for the second operators, 7, 20 and 80 μSv/procedure were the highest mean effective, eye and hand doses, respectively, and were found in Hospital I. For example, the mean together with the spread of eye lens dose per procedure of the cardiologists (respectively technicians) #1, #4 and #6 (respectively #1, #2 and #10) were 11.8 ± 5, 38 ± 7 and 5.8 ± 0.8 μSv/procedure (respectively, 11.6 ± 2.4, 2.5 ± 0.4 and 6 ± 1.8 μSv/procedure). Effective, hand and eye lens doses normalised to DAP All measured values were also normalised, for each monitoring period, to the individual cumulative DAP values. Results are presented in Figure 2 for the first and second operators, respectively. Indeed, DAP provides a good patient dose quantity, because it gives a measure of the total radiation emitted, which is linked to the amount of scatter to which operators are exposed. In addition, this quantity allows adjustment of radiation used, which is one of the most significant factors determining staff doses, but does not take account of variation related to the technique and position taken up by the operator(27). However, for a given procedure type, normalised dose distributions still exhibit large relative standard deviations since it is well known that staff doses and DAP hardly correlate, particularly for CA and PCI examinations which involve notably several different angulations(10, 28). The average eye lens doses measured on the internal left side of the glasses for the first and the second operators were 0.17 ± 0.09 μSv/Gy.cm2 and 0.13 ± 0.1 μSv/Gy.cm2, respectively. Figure 2. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator normalised to the total DAP for each monitoring period. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Figure 2. View largeDownload slide E, Hp(0.07) and Hp(3) for the first (grey box) and second (white box) operator normalised to the total DAP for each monitoring period. Figure shows the first quartile, median, third quartile, mean (dashed line) values together with the outliers. Extrapolated annual effective, hand and eye lens doses Tables 3 and 4 present the annual extrapolated doses together with the use of lead glasses for each of the first and second operators, respectively. The total number of procedures was estimated from the logbook of each hospital based on each operator workload during 2016. The extrapolated annual eye lens doses, measured at the internal left lateral side of the glasses for a sub-sample of the first (six operators) and second (five operators) operators, are presented as well. Additionally, for operator #1 (respectively operator #2) from Table 3, the extrapolated annual effective, hand and eye lens doses were 32, 50 and 10% (respectively, 64, 62 and 27%) higher than the accumulated annual doses measured during the six monitoring periods. Actually, the mean effective, hand and eye lens doses for those two operators (3, 49 and 11 μSv/procedure, respectively) were lower than those shown in Figure 1 for the 12 first operators. Correlation of Hp(3) and Ho and eye lens dose reduction To provide an estimation of the eye lens dose when alternative methods are used, such as the use of a WBD, Figure 3 shows the correlation between Hp(3) measured on the outside left lateral side of the lead glasses and Hp(10) measured on the left collar level over the lead apron (Ho) for both FO and SO. A good overall correlation of the two measured operational quantities was found, resulting in a correction factor of a = 0.31 (R2 = 0.82). Furthermore, the dose reduction factor provided by lead glasses reduced the doses on average by a factor 2.8 and 2.1 for the first and second operators, respectively. Figure 3. View largeDownload slide Correlation of Hp(3) measured outside the left lateral side of the lead glasses and Hp(10) measured at the left collar level over the lead apron for both FO and SO. Figure 3. View largeDownload slide Correlation of Hp(3) measured outside the left lateral side of the lead glasses and Hp(10) measured at the left collar level over the lead apron for both FO and SO. DISCUSSION AND RECOMMENDATIONS The extrapolated yearly doses for the first and the second operator, respectively, show low effective doses especially for the second operator. In fact, the 3/10th of the dose limit is neither reached by the first or the second operator. Although the doses are relatively low, one cannot exclude that accidentally higher doses are encountered especially when workload or complexity of procedures increases, thus monitoring cannot be excluded. Also, extrapolated hand doses are low with none of the first or second operators reaching 3/10th of the dose limit. However, bad practices among the first operators were observed by the authors (e.g. placing the hands directly in the X-ray beam). This could lead to higher doses than those presented in this study. Additionally, the dosemeter worn on the wrist (like those used in this study) may underestimate the maximum dose to an area of skin on the hand by a factor of 3(27) for the first operator. The hand doses to the second operator are found to be lower than those from the first operator due to the large distance from the X-ray tube and from the irradiated area. Therefore, extremity monitoring is needed especially for the first operator. For the annual extrapolated eye lens dose, none of the first or second operators surpassed the present annual eye lens dose limit of 20 mSv per year, not even when measuring the doses outside the lead glasses. However, 30% of the first and 20% of the second operators exceed the 6 mSv when the doses were measured at the outer left lateral side of the glasses or directly near the left eye. None of the eye lens dose values measured on the internal left lateral side of the lead glasses exceeded 6 mSv for the first operators. For the second operators, the dose measured inside the glasses still exceeded 6 mSv for one technician with the highest workload (out of three monitored using lead glasses). Hence, dedicated eye lens monitoring should be performed for the first and second operators and not estimated from workplace monitoring or WBD. Table 5 presents the comparison of the mean effective, hand and eye lens doses per procedure and the normalised doses to DAP for the first and the second operators with the results of similar studies performed for the same type of procedures mentioned here. Table 5. Comparison of the published data effective, eye lens and hand doses per procedure and normalised to respective DAP for CA and PCI examinations for the positions first and second operators.     E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)      E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)  Table 5. Comparison of the published data effective, eye lens and hand doses per procedure and normalised to respective DAP for CA and PCI examinations for the positions first and second operators.     E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)      E (μSv/procedure)  E/DAP (μSv/Gy.cm2)  Hp(0.07) (μSv/procedure)  Hp(0.07)/DAP (μSv/Gy.cm2)  Hp(3) (μSv/procedure)  Hp(3)/DAP (μSv/Gy.cm2)  This work  FO  6 ± 7 (1–41)  0.13 ± 0.11 (0.01–0.48)  112 ± 92 (10–356)  1.91 ± 1.33 (0.2–5.4)  15 ± 11 (5–47)  0.45 ± 0.24 (0.11–1.06)  SO  2.3 ± 2 (0.1–8)  0.03 ± 0.02 (0–0.10)  16 ± 24 (2–109)  0.25 ± 0.29 (0.1–1.39)  7 ± 3.6 (2–14)  0.16 ± 0.1 (0.1–0.33)  Donadille et al.(9)  FO      163 ± 239 (8–1775)  3.4  52 ± 77 (4–820)  1  Antic et al.(11)  FO          121 ± 84 (5–370)  0.94 ± 0.61 (0.2–3.6)  SO          33 ± 26 (4.4–138)  0.33 ± 0.26 (0.1–1.9)  Martin(29)  FO  0.2–19    175 (8–514)  2.5 (0.43–9)  66 (5–439)    Ingwersen et al.(30)  FO  0.5 ± 0.9    66.2 ± 122.2    6.4 ± 10.5    Efstathopoulos et al.(31)  FO      493 ± 1289 (20–3684)  11.7  13 ± 25 (0–61)  1.37  Bor et al.(32)  FO  12.4 (1.2–30.2)  0.14 (0.02–0.42)  216 (53–425)  1.87 (0.5–4.37)  72 (32–107)  0.86 (0.5–1.3)  Lie et al.(33)  FO  5.5 (1.5–12.4)  0.08 (0.03–0.14)      44 (10–223)  0.6 (0.2–2.6)  The effective, extremities and eye lens doses from this study are comparable with those presented in the literature(9, 11, 29–33). Yet, variability of the measurements performed within this multi-centre study and those from the literature is noticed. This can be attributed to many factors such as: (a) the use of personal and collective protective equipment, (b) skill and experience of the physicians, (c) practice and technique applied, (d) tube configuration (above or below the table), (e) access route (e.g. femoral or radial) and (f) calibration procedures and dosimetric quantities used. The relatively low exposure of the eye lens in this study can be explained by the fact that most procedures used radial access (90%) and in this situation a better positioning of the ceiling shield is possible. In fact, when the operator is closer to the X-ray beam (radial access), it is easier to correctly position the shield(9). In addition, the FPD can play an important role in giving an extra shielding for the eyes when the radial access is used. Those factors can explain as well the dose differences among the different operators and/or the different hospitals included in this study. The large observed spread of doses, within the study, for the same operator could be attributed to the complexity of the procedure even when performing the same type of intervention (e.g. CA or PCI). Also, other factors like the inconsistency in the position of the operator/head from one procedure to another, the different access routes, projections, collimations and magnifications used to perform each procedure could affect the measured doses from one monitoring period to another. The use of dosemeters worn on other parts of the body such as the thyroid collar outside the lead apron could be a valuable tool for the estimation of the eye lens dose for investigative reasons or for retrospective calculations. The eye lens dose could be estimated by roughly 1/3 of the dose measured at the left collar level over the lead apron where direct monitoring of the eye lens in terms of Hp(3) is not available. This ratio is lower than those reported by other studies (between 0.44 and 1.86)(34). In addition, the variability of the ratio is extremely dependent on practice and wearing positions. Therefore, this method is associated with large uncertainty and great caution is needed if the measured dose levels are close to the dose limits owing to the difference in personal habits, the exact place of the above apron dosemeters and the protection measures taken(34). By measuring eye exposure for some operators inside and outside the lead glasses, information was obtained on the dose reduction factor from the lead glasses. This dose reduction was found to be on average 2.8 and 2.1 for the first and second operators, respectively. It should be mentioned that this is an estimation because measuring on the eye lens itself is not possible. Furthermore, although, the dose reduction factor reported in this study (2.8 for first operators) is similar to that found by Principi et al.(17) (2–3 depending on the glasses’ type), it is lower than those reported by other works (between 8 and 10)(34). Also, the wrap-around lead glasses style did not reduce the doses efficiently as those reported in the literature(16). The position of the dosemeter and the left anterior oblique projections used in clinical practice can explain these differences. Finally, this estimation is based on small sample of operators (4 first and 3 second operators) and might not be valid in general. Observations, performed by the author in the clinics, revealed bad practices in a representative sample of the Lebanese IC suites. Firstly, about 25 and 50% of the first and the second operators, respectively, were not wearing leaded glasses. In addition, as already mentioned before, different models of glasses were used among which 50% had no lateral shields. Consequently, lead glasses with lateral shields should be supplied for a better radiation protection scheme(18). Secondly, although present in all the examinations included in the study, the use and positioning of ceiling shields markedly varied between operators even at the same medical centre: a fixed position close to the operator was held during 90% of the procedures. In addition, operators were changing their position in some procedures; hence they were not well covered by the shields. The effect of the shields is implicitly incorporated in the doses reported within this study and it was not possible to investigate its efficiency in clinical practice. Still, its effectiveness in reducing the doses is highlighted by different studies performed in clinic(8), on phantom(15) or through simulation(16). Those authors stated that a reduction factor varying between 1.5 and 5.7 is granted by the ceiling shield. For instance, ceiling shields can reduce the dose to the brain tissue from 74 up to 94%. Moreover, a combination of leaded glasses and a ceiling shield can reduce the dose to the head, both eyes and also protect very efficiently the upper part and hands of the operator as well as other people present in the operating room (technicians–nurses). Thus, the use of ceiling shield should be systematic in all the Lebanese IC suites. Thirdly, the monitor screens were frontward (0°) from the operator for 100% of the procedures performed within this study. Some authors(16–17) found, based on Monte-Carlo simulations, that a rotation of the head of 30° or 45° away from the tube can reduce the eye lens dose by approximately 50%. Consequently, the monitors screen should be located to the right of the operators in the Lebanese IC suites. Finally, FPD were, in the majority of the procedures at 20 cm or more from the patient depending on the tube projection used. As reported by Koukorava et al.(16), the FPD should be placed as close as possible to the patient, especially when PA and small angled oblique projections are used. This will reduce operator’s exposure to scattered radiation. Moreover, the preferential use of right anterior oblique projections where additional shield is occasionally provided by the FPD, positioned at the left side of the operator, can reduced the scattered radiation reaching the left eye(18). Thus, the distance between the FPD and the patient should be decrease in the Lebanese IC during the interventions. STUDY LIMITATION The study is subjected to many limitations. Firstly, the selection of the first and second operators was not done randomly and was based on the commitment of the operators to wear the set of dosemeters throughout the monitoring period, which could have biased the results. Secondly, the univariate analysis performed within the study is based on the average bimonthly registered dose and do not take into account the number of monitoring periods collected for each of the first/second operators included in the study. Finally, the 2-month monitoring period might be too long for IC operators owing to the exposure situation (e.g. dose level) and should be reduced to 1 month monitoring period. CONCLUSIONS A large dose data set was collected at the level of chest and collar, respectively, wrist and left eye of 12 interventional cardiologists and 10 technicians working at 10 major Lebanese hospitals. For the first and second operators, large range and variability of the doses were observed among the centres owing mainly to the practice and technique applied in each centre by each operator. Effective doses were relatively low with a mean values of 6 (range, 0.8–41) and 2.3 (range, 0.1–8) μSv/procedure for the first and second operators, respectively. This further demonstrates that whole body dose would not be the limiting exposure index if a lead apron is worn; which is very common and easy to achieve. Similarly, hand doses were relatively low with a mean values of 112 (range, 10–356) μSv/procedure for the sample of first operators included in this study also showing that extremity doses will not be the limiting factor if good practices are in place (e.g. the hands should be kept out of the beam). Meanwhile, for the eye lens dose, the highest measured doses of the first and second operators were around 47 and 14 μSv/procedure (1.06 and 0.33 μSv/Gy.cm2, respectively). Although the ceiling shield was used in all procedures performed within this study, the extrapolated annual left eye doses revealed that 30% of the first and 20% of the second operators may exceed the 6 mSv limit. Thus, dedicated eye lens monitoring is needed for both first and second operators. 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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)

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Radiation Protection DosimetryOxford University Press

Published: May 23, 2018

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