Reduction of Operator Radiation Dose by a Pelvic Lead Shield During Cardiac Catheterization by Radial Access

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provided by Elsevier - Publisher Connector JACC: CARDIOVASCULAR INTERVENTIONS VOL. 5, NO. 4, 2012 © 2012 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION ISSN 1936-8798/$36.00 PUBLISHED BY ELSEVIER INC. DOI: 10.1016/j.jcin.2011.12.013

Comparison With Femoral Access

Helmut W. Lange, MD,* Heiner von Boetticher, PHD† Bremen, Germany

Objectives This study sought to determine the efﬁcacy of patient pelvic lead shielding for the reduction of operator radiation exposure during cardiac catheterization via the radial access in comparison with the femoral access.

Background Cardiac catheterization via the radial access is associated with signiﬁcantly increased radiation dose to the patient and the operator. Improvements in radiation protection are needed to minimize this drawback. Pelvic lead shielding has the potential to reduce operator radiation dose.

Methods We randomly assigned 210 patients undergoing elective coronary angiography by the same operator to a radial and femoral access with and without pelvic lead shielding of the patient. Operator radiation dose was measured by a radiation dosimeter attached to the outside breast pocket of the lead apron.

Results For radial access, operator dose decreased from 20.9 Ϯ 13.8 ␮Sv to 9.0 Ϯ 5.4 ␮Sv, p Ͻ 0.0001 with pelvic lead shielding. For femoral access, it decreased from 15.3 Ϯ 10.4 ␮Sv to 2.9 Ϯ 2.7 ␮Sv, p Ͻ 0.0001. Pelvic lead shielding signiﬁcantly decreased the dose-area product–normalized operator dose (operator dose divided by the dose-area product) by the same amount for radial and femoral access (0.94 Ϯ 0.28 to 0.39 Ϯ 0.19 ␮Sv ϫ GyϪ1 ϫ cmϪ2 and 0.70 Ϯ 0.26 to 0.16 Ϯ 0.13 ␮Sv ϫ GyϪ1 ϫ cmϪ2, respectively).

Conclusions Pelvic lead shielding is highly effective in reducing operator radiation exposure for radial as well as femoral procedures. However, despite its use, radial access remains associated with a higher operator radiation dose. (J Am Coll Cardiol Intv 2012;5:445–9) © 2012 by the American College of Cardiology Foundation

From the *Kardiologisch-Angiologische Praxis Herzzentrum Bremen, Bremen, Germany; and the †Institute for Radiology and Academy for Radiation Protection, Klinikum Links der Weser, Bremen, Germany. Both authors have reported that they have no relationships relevant to the contents of this paper to disclose. Manuscript received September 14, 2011; revised manuscript received December 13, 2011, accepted December 22, 2011. 446 Lange and von Boetticher JACC: CARDIOVASCULAR INTERVENTIONS, VOL. 5, NO. 4, 2012 Reduction of Radiation Dose by Pelvic Lead Shield APRIL 2012:445–9

Radial access is gaining increasing acceptance in catheter- catheters were used initially in radial cases, a Judkins left 4.0 ization laboratories because of its lower vascular complica- in femoral cases. tion rate, less patient discomfort, and lower cost (1–5). Radiation protection. Attention was given in all cases to Higher operator radiation exposure has been recognized as cone in as much as possible. An overhead-suspended lead a drawback contributing to the skepticism held by many acrylic shield with a patient contour cutout (0.5-mm lead interventional cardiologists against the transradial route equivalent; MAVIG, Munich, Germany) was pulled down (6–9). Despite the efficacy of conventional lead aprons in to the patient’s abdomen. An undertable pivotal leaded side blocking nearly 95% of scatter radiation to the body, shield (0.5-mm lead equivalent) was mounted to the side of radiation-induced neoplasms of the unprotected brain, na- the table. The 17.8-cm upper shield flap was folded down sophanryngeal tract, and upper extremities remain a concern in all cases. An additional table-to-floor flap (0.5-mm for high-volume operators (10–12). Additional measures to lead equivalent) extended 30 cm along the table. The reduce operator radiation during radial procedures have pelvic lead shield used was a custom-made lead blanket been proposed, such as a tubing extension allowing for (0.5-mm lead equivalent; MAVIG; list price currently greater distance between the x-ray tube and the operator, $1,500) measuring 70 ϫ 90 cm extending from the patient’s and a special radiation protection board (13,14). Pelvic lead diaphragm to the knees. The upper portion is shaped shielding of the patient has been reported to reduce operator diagonally to permit caudal projections. There are 1 or 2 radiation exposure during femoral access cardiac catheter- 15 ϫ 15-cm cutouts for the femoral puncture sites (Fig. 1). ization, but its effect for radial access has not been investi- Radiation measurements. An electronic Geiger Muller ra- gated (15). In this study, we evaluated the efficacy of a pelvic diation dosimeter (R. A. Stephen 6000, Centronic, Croy- lead shield for transradial cardiac catheterization and com- den, United Kingdom) was used to measure operator pared it with the femoral access. radiation exposure. It was attached to the breast pocket on the outside of the lead apron. The dosimeter has an energy response Ϯ20% between 35 keV and 1.0 MeV and a dose Methods range displayed from 0 to 9,999 mSv in steps of 0.0001 mSv ϭ 0.1 ␮Sv. The operator radiation dose was recorded Study design. Patients sched- at the beginning and the end of each procedure. The patient Abbreviation uled for elective, outpatient cor- radiation dose, expressed as dose-area product (DAP) and Acronym onary angiography with an inter- (Gy·cm2), and the fluoroscopy time were recorded for each ventional cardiologist (H.W.L.), case. To account for low-energy scatter radiation below 35 dose-area product ؍ DAP who has extensive experience in keV and other dosimetric effects, the Stephen 6000 dosim- radial access procedures, were eter was calibrated with a verified ionization chamber asked to participate in the study. After informed consent dosimeter (EG&G Berthold TOL/F, Berthold Technolo- was obtained, the catheterization procedures were randomly allocated by time period to a femoral or radial approach with or without the pelvic lead shield in place. After completion of the procedure, only cases fulfilling the following criteria were included in the study: the procedure was uncomplicated, and the right radial or right femoral artery could be accessed without difficulties; aortic valve stenosis or bypass grafts were not present; and aortography was not performed. If coronary intervention was performed immediately after the diagnostic procedure, fluoroscopy time and radiation measurements were recorded before the intervention was started. Cardiac catheterization. Procedures were performed on a digital single-plane cineangiography unit (Integris, Philips Medical Systems, Best, the Netherlands) with an undertable x-ray tube. In general, 17.8-cm magnification and a film speed of 12.5 frames/s was used except for selected views. Figure 1. Pelvic Lead Shield Protecting the Operator From Scatter For radial procedures, the patient’s right arm was placed on Radiation an arm board with the wrist extended. All cases were done Scatter source is the triangle between the ceiling-mounted lead acrylic ϫ from the right arm. Radial access was accomplished by shield and the undertable pivotal side shield. A 15 15-cm cutout enables access to the groin. The position of the right wrist is slightly closer to the puncture with a 20-gauge needle and insertion of a 5-F x-ray tube than the groin. hydrophilic sheath. Judkins left 3.5, right 4.0, and pigtail JACC: CARDIOVASCULAR INTERVENTIONS, VOL. 5, NO. 4, 2012 Lange and von Boetticher 447 APRIL 2012:445–9 Reduction of Radiation Dose by Pelvic Lead Shield

Table 1. Patient Characteristics

Radial Standard Radial Pelvic Shield Femoral Standard Femoral Pelvic Shield p Value (53 ؍ n) (50 ؍ p Value (n (56 ؍ n) (51 ؍ n)

Female 14 (27) 15 (27) 0.938 20 (40) 14 (26) 0.143 Age, yrs 63 Ϯ 9.3 64.1 Ϯ 9.9 0.958 64.9 Ϯ 11.5 66.2 Ϯ 10.4 0.639 Body surface area, m2 1.9 Ϯ 0.2 2.0 Ϯ 0.2 0.435 1.9 Ϯ 0.2 1.9 Ϯ 0.2 0.748 Left ventriculogram 16 (31) 16 (29) 0.752 14 (28) 13 (25) 0.125

Values are n (%) and mean Ϯ SD.

gies, Bad Wildbad, Germany), which has a reliable energy standard protection or those with the pelvic shield (Table 2). response between 10 keV and 7 MeV. Calibration measure- Operator radiation dose with standard protection was 20.9 Ϯ 13.8 ments using an Alderson Rando phantom (Radiology Sup- ␮Sv in the radial group and 15.3 Ϯ 10.4 ␮Sv in the femoral group port Devices, Long Beach, California) at a height of 130 cm (p Ͻ 0.001). Pelvic lead shielding decreased operator exposure to during fluoroscopy revealed that the Stephen 6000 dosim- 9.0 Ϯ 5.4 ␮Sv (p Ͻ 0.0001) in the radial group and to 2.9 Ϯ 2.7 eter underestimated the ambient dose equivalent at tissue ␮Sv (p Ͻ 0.0001) in the femoral group. The absolute depth of 10 mm, that is, H*(10), by a factor of 1.7. reduction in DAP-normalized operator dose (operator dose Data analysis. All data are expressed as mean Ϯ standard in ␮Sv divided by DAP in Gy ϫ cm2) was the same (0.55 deviation. Comparisons between groups were done with the and 0.54) (Fig. 2) for radial and femoral cases (from 0.94 Ϯ Ϫ Ϫ Mann-Whitney U-test and the chi-square test. A p value 0.28 to 0.39 Ϯ 0.19 ␮Sv ϫ Gy 1 ϫ cm 2 and 0.70 Ϯ 0.26 to Ϫ Ϫ Ͻ0.05 was considered significant. To take into account 0.16 Ϯ 0.13 ␮Sv ϫ Gy 1 ϫ cm 2, respectively). differences in patient radiation dose between radial and We used the SAS procedure General Linear Model (SAS femoral cases, the DAP-normalized operator dose (operator Institute, Cary, North Carolina) to analyze the influence of dose divided by the DAP) was calculated. shield (yes, no), route of access (radial, femoral), and the interaction term shield ϫ access on operator radiation dose Results and DAP-normalized operator radiation, respectively. In both models, we observed a significant influence of shield Of 305 cases scheduled for cardiac catheterization, 210 and route of access, whereas the interaction term shield ϫ (69%) fulfilled the inclusion criteria. One hundred seven access was not significant (p ϭ 0.82 and p ϭ 0.91 for cases were done from a radial access, 51 without and 56 with operator radiation dose and DAP-normalized operator ra- pelvic lead shielding; 103 cases were done from a femoral diation dose, respectively). access, 50 without and 53 with pelvic lead shielding. Analysis of patient characteristics revealed no differences Discussion in age, sex, body surface area, and the prevalence of cases in whom a left ventriculogram was done in addition to coro- Transradial cardiac catheterization is well known to be nary angiography (Table 1). associated with an increase in radiation dose to the patient Fluoroscopy time was higher for the 107 radial cases than and the operator, even for highly experienced cardiologists for the 103 femoral cases: 2.7 Ϯ 1.4 min for radial versus 2.1 Ϯ 1.1 and despite the use of optimal strategies to reduce radiation min for femoral cases (p Ͻ 0.001). Fluoroscopy times were exposure (6–9). The degree of increase in radiation with similar when the same access was used. Patient radiation radial access varies between operators, suggesting different dose (DAP) was not different when comparing all radial and all measures to protect against radiation exposure (7,8). Ϫ Ϫ femoral cases (23.2 Ϯ 13.7 vs. 21.9 Ϯ 13.7 ␮Sv ϫ Gy 1 ϫ cm 2; Factors responsible for the increased radiation are proce- p ϭ 0.51), and there were no differences between the groups with dure related and operator related: first, technical challenges

Table 2. Fluoroscopy Time and Radiation Measurements

Radial Standard Radial Pelvic Shield Femoral Standard Femoral Pelvic Shield p Value (53 ؍ n) (50 ؍ p Value (n (56 ؍ n) (51 ؍ n)

Fluoroscopy time, min 2.7 Ϯ 1.5 2.7 Ϯ 1.2 0.866 2.3 Ϯ 1.2 1.9 Ϯ 1.0 0.047 DAP*, Gy ϫ cm2 22.5 Ϯ 13.8 23.8 Ϯ 13.6 0.508 23.6 Ϯ 16.0 20.3 Ϯ 12.8 0.323 Operator radiation dose†, ␮Sv 20.9 Ϯ 13.8 9.0 Ϯ 5.4 Ͻ0.0001 15.3 Ϯ 10.4 2.9 Ϯ 2.7 Ͻ0.0001 DAP-normalized operator radiation dose, 0.94 Ϯ 0.28 0.39 Ϯ 0.19 Ͻ0.0001 0.70 Ϯ 0.26 0.16 Ϯ 0.13 Ͻ0.0001 ␮Sv ϫ GyϪ1 ϫ cmϪ2

Values are mean Ϯ SD. *Dose-area product (DAP); †ambient dose equivalent H*(10), where 10 indicates a depth of 10 mm. 448 Lange and von Boetticher JACC: CARDIOVASCULAR INTERVENTIONS, VOL. 5, NO. 4, 2012 Reduction of Radiation Dose by Pelvic Lead Shield APRIL 2012:445–9

leaded shield on the patient’s arm rest. It was found to 1 reduce radiation dose for diagnostic radial cases from 19 to ␮ 0.9 0.94 Standard protection 12 Sv (14). Comparisons of the efficacy of radiation 0.8 Pelvic lead shield protection devices between studies are difficult since dosim- eters used in their study may have a different dose response. 0.7 0.7 Based on the data provided, we estimate that the transradial 0.6 protection board and the pelvic lead shield have similar 0.5 efficacy. 0.4 For the assessment of the relative efficacy of an added 0.39 0.3 radiation protection device, the DAP-normalized operator ␮ 0.2 dose, defined as the dose ( Sv) received by the operator with each Gy·cm2 applied to the patient, has been advocated 0.1 0.16 OPERATOR DOSE / DAP [µSv/(Gy cm²)] and was applied in our study (16). We found that the 0 absolute reduction by the use of pelvic lead shielding was RADIAL FEMORAL similar for radial and femoral access (0.55 and 0.54 ␮Sv ϫ Ϫ1 ϫ Ϫ2 Figure 2. Effect of a Pelvic Lead Shield During Cardiac Catheterization Gy cm , respectively). Thus, pelvic lead shielding is equally effective for the femoral approach, reducing the The dose-area product (DAP)-normalized radiation dose of the operator ␮ ϫ Ϫ1 ϫ Ϫ2 (␮Sv·ϫ GyϪ1 ϫ cmϪ2) by radial access (left) and femoral access (right). radiation dose to as little as 0.16 Sv Gy cm . The amount of reduction is similar for both routes. However, when comparing radial and femoral access routes with optimal radiation protection by pelvic lead shielding, a radial-access operator still received a markedly higher DAP- Ϫ Ϫ in maneuvering the catheters into the coronary ostia lead to normalized dose (0.39 Ϯ 0.19 ␮Sv ϫ Gy 1 ϫ cm 2) than more fluoroscopy time, which will diminish with increasing a femoral-access operator. However, this radiation exposure expertise of the operator (9). In our study, fluoroscopy time was less than that received by a femoral operator without the Ϫ was only slightly longer (2.7 vs. 2.1 min; p Ͻ 0.001) without benefit of pelvic lead protection (0.70 Ϯ 0.26 ␮Sv ϫ Gy 1 ϫ Ϫ increasing the DAP to a statistically significant degree. The cm 2). Looking at our results from a different perspective, increase in fluoroscopy time and DAP due to the transradial we can conclude that the use of pelvic shielding enables the route is less for percutaneous coronary intervention com- operator to perform 4 times more femoral cases and more pared with diagnostic angiography since catheter position- than twice as many radial cases with the same radiation ing claims a much smaller portion of the total procedure exposure. (6,7). A recent study in 5,954 cases estimated the overall Because the use of pelvic lead shielding is associated with increase in patient radiation exposure due to the radial very little inconvenience to the patient, the operator, or the approach at 23% (8). Second and most important for the laboratory personnel, it has been readily accepted in our need of improved radiation protection, the closer position of institution by femoral operators as well. The lead cover has the operator relative to the x-ray tube is inherent to the a Velcro fastener that allows for easy removal with the sterile radial procedure. We have previously reported that the draping of the patient intact when tortuous iliac arteries operator dose was doubled for diagnostic procedures and need to be visualized or abdominal aortography needs to be 50% higher for interventions (6). performed. For percutaneous coronary intervention of Exploratory measurements in our laboratory (data on file) chronic total occlusions, pelvic lead covers with 2 custom- showed profound amounts of scatter radiation from the made holes for bilateral femoral access are routinely used in pelvic bones emerging from the angle between the ceiling- our institution. mounted transparent lead shield positioned at a 90° angle to Although pelvic lead shielding is highly effective in the table and the undertable pivotal side shield (Fig. 1), reducing radiation, it cannot close the “radiation gap” for which can be nearly abolished by a shield covering the the operator between radial and femoral access. We believe patient’s pelvis and thighs. Our study proves that the pelvic that further reductions in radiation exposure for radial lead shield is a highly effective protection device reducing operators are possible and should be aimed for, such as a radiation dose from 20.9 to 9.0 ␮Sv for radial coronary combination of the pelvic lead shield and the protection angiography. Two previous studies investigated additional board. These measures may eventually eliminate the differ- ways to improve radiation protection for radial access ence in operator radiation exposure associated with the catheterization. A 10-mm tube extension of the coronary radial approach, which still exists today. catheter failed to reduce operator dose significantly (13). Study limitations. We only included highly selected proce- The “transradial radiation-protection board,” developed by dures, that is, elective uncomplicated diagnostic coronary Hildick-Smith, addresses the same radiation leak of scatter angiograms by the same experienced operator. We choose radiation by mounting a 20-cm-high vertical plane of a this study design to be able to analyze uniform and highly JACC: CARDIOVASCULAR INTERVENTIONS, VOL. 5, NO. 4, 2012 Lange and von Boetticher 449 APRIL 2012:445–9 Reduction of Radiation Dose by Pelvic Lead Shield

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