radiation protection surgical drapes

Use of Disposable Radiation-absorbing Surgical Drapes Results in Significant Dose Reduction During EVAR Procedures

RADPAD Radiation Protection shields have been tested in many clinical studies to prove their efficacy in reducing radiation exposure, including the study below.

Throughout 36 endovascular aneurysm repair (EVAR) procedures, dose measurements were taken to evaluate the reduction RADPAD shielding provided. Results showed that scatter radiation was significantly lower at the interventionalists hands and chest as well as the theatre nurse’s chest.

RADPAD shielding will protect you and your team from up to 95% of scatter radiation presented in your OR. Protect yourself and your team.

 


Editor’s Choice – Use of Disposable Radiation-absorbing Surgical Drapes Results in Significant Dose Reduction During EVAR Procedures

  • C. Kloeze
  • E.G. Klompenhouwer
  • P.J.M. Brands
  • M.R.H.M. van Sambeek
  • P.W.M. Cuypers
  • J.A.W. Teijink

 

Objectives

Because of the increasing number of interventional endovascular procedures with fluoroscopy and the corresponding high annual dose for interventionalists, additional dose-protecting measures are desirable. The purpose of this study was to evaluate the effect of disposable radiation-absorbing surgical drapes in reducing scatter radiation exposure for interventionalists and supporting staff during an endovascular aneurysm repair (EVAR) procedure.

 

Materials

This was a randomized control trial in which 36 EVAR procedures were randomized between execution with and without disposable radiation-absorbing surgical drapes (Radpad: Worldwide Innovations & Technologies, Inc., Kansas City, US, type 5511A). Dosimetric measurements were performed on the interventionalist (hand and chest) and theatre nurse (chest) with and without the use of the drapes to obtain the dose reduction and effect on the annual dose caused by the drapes.

 

Results

Use of disposable radiation-absorbing surgical drapes resulted in dose reductions of 49%, 55%, and 48%, respectively, measured on the hand and chest of the interventionalist and the chest of the theatre nurse.

 

Conclusions

The use of disposable radiation-absorbing surgical drapes significantly reduces scatter radiation exposure for both the interventionalist and the supporting staff during EVAR procedures.

 

What this paper adds:
Because of the increasing number of endovascular procedures with fluoroscopy, the corresponding high annual dose for interventionalists, and the European directive (ICRP 2011) requiring a lower annual radiation dose to the eye lens, additional dose-protecting measures are desirable for all operating staff during endovascular aneurysm repair (EVAR). The effect of disposable radiation-absorbing surgical drapes has never been studied before in a randomized controlled setting during endovascular procedures for AAA repair. This study evaluates the effect of these drapes on the annual dose to the interventionalist and supporting staff.

 

Introduction

In the last two decades endovascular aortic repair (EVAR) has become the preferred treatment of abdominal aortic aneurysm in patients suitable for EVAR.

Despite precautions like a lead apron and thyroid shield, this increasing use of EVAR and other endovascular interventions results in considerable fluoroscopic exposure of the intervening physician.

Low-energy scattered radiation scatters in all directions from the patient during fluoroscopy. This scatter radiation is the main source of exposure for medical staff during fluoroscopic procedures. Chronic exposure to low-dose radiation confers a small risk of stochastic effects, including malignant disease, skin damage, or eye problems.Recently the International Commission on Radiological Protection (ICRP) reported that the equivalent dose limit for the lens of the eye should be reduced from 150 to 20 mSv per year, averaged over a 5-year period, with no year’s dose exceeding 50 mSv.

This reduction in eye dose limit and the applicable ALARA (as low as reasonably achievable) principle demands additional dose-protecting measures for operating staff performing EVAR procedures, especially in a non-dedicated endosuite, where no additional dose-protecting measures, like lead flaps or shields, are available.

In cardiac interventions, it is shown that the use of sterile disposable radiation-absorbing surgical drapes reduces the radiation exposure of the medical staff, from 23% to 80%.

The aim of this study is to evaluate the effect of these drapes in reducing scatter radiation exposure for endovascular surgeons and supporting medical staff during EVAR procedures.

 

Materials and Methods

From June 2012 to October 2012, 36 consecutive EVAR procedures were randomly assigned to be performed with or without the use of radiation-absorbing surgical drapes (Radpad; Worldwide Innovations & Technologies Inc., Kansas City, MO; US type 5511A), henceforth referred to as “drape”. All patients with an indication for infrarenal endovascular aortic aneurysm repair with a bifurcated stent graft were included. The procedures were carried out by three vascular surgeons with extensive experience in performing EVAR procedures; no randomization of operators was performed. During the procedures, standard radiation protective measures were used for the interventionalist and supporting staff, including a lead apron and thyroid shield. The study was approved by the local ethics committee.

 

Positioning of the interventionalist and theatre nurse during the EVAR procedures was standardized: the primary operator (interventionalist) stood on the right side of the patient near the pelvis, and the secondary operator stood on the opposite side of the operating table. The theatre nurse stood beside the secondary operator (Fig. 1). Both the interventionalist and the theatre nurse wore dosimeters for dosimetric measurements.

 

Figure thumbnail gr1
Figure 1 – Schematic overview of the position of the drapes, medical staff, and C-arm during the endovascular aneurysm procedure. 1 = interventionalist; 2 = assisting interventionalist; 3 = theatre nurse.

The drapes are the only commercially available, sterile, disposable, lead-free surgical drapes. They have a uniform thickness of a few millimeters and contain bismuth and barium. The dose-reducing function is comparable to 0.4–0.8 mm lead (Pb) depending on the kilovoltage used to make the image (90–60 kV). In the “drape” group two drapes were used. These sterile drapes were interposed between the patient and interventionalist, outside the radiation field, and positioned above the normal sterile surgical drape after the femoral operative site had been prepared. Positioning of the drapes is shown in Figs. 1 and 2.

 

Figure thumbnail gr2
Figure 2 – Position of the Radpad (type 5511A) during an endovascular aneurysm procedure (top view).

 

All procedures were performed in a non-dedicated endosuite, where no additional dose-protecting measures, like lead flaps or shields, were available. A mobile angiographic C-arm was used (Axiom Artis U; Siemens, Munich, Germany) for fluoroscopic imaging. Both the milliAmpere (mA), which is the quantity of produced radiation, and the peak kilovoltage (kVp), which is a quantity of the beam penetrability, were kept in a range between 2.1–2.5 mA and 60–90 kVp for all procedures. The image intensifier was positioned above the abdomen of the patient. Scatter radiation was measured on the left chest of the interventionalist and the theatre nurse using a calibrated electrical personal dosimeter (EPD, DoseAware system, Philips Medical Systems, Eindhoven, The Netherlands). Scatter radiation was measured on the base of the left ring finger of the primary operator with a calibrated ring dosimeter (Nuclear Research and consultancy Group, Arnhem, The Netherlands).

 

For each procedure the start and end time of the procedure, the total fluoroscopy time(s), the dose area product (DAP) (cGycm2), and dose (μSv) were registered. Since start and end times of the procedures were registered, the dose could be determined after the procedure by selecting the time frame in which the procedure was performed using special software (DoseManager, Philips Medical Systems, Eindhoven, The Netherlands). Since the path length difference for the scattered radiation to chest and eye is just a few centimeters, it can be assumed that the measured dose on the chest is comparable to the dose on the eye lens. The ring dosimeter was sent monthly to the Nuclear Research and consultancy Group for evaluation.

 

By dividing the measured dose by the DAP value of each procedure, compensation for the inequalities due to different interventionalist, fluoroscopic times, and body mass index (BMI) of the patients was performed. Second, the mean dose reduction per procedure due to the use of the drapes was calculated.

 

Data are presented as mean (range), mean ± SD, and percentages. A skewness test was performed to investigate whether data were normally distributed. A Student t-test was performed to determine whether dosimetric measurements with the use of the drapes were significantly different from those without the drapes. A value of p ≤.05 was considered statistically significant. The analyses were performed using SPSS (Version 15.0, IBW Company, Chicago, IL, USA). The annual doses for both the interventionalist and the theatre nurse were calculated by multiplying the mean dose per procedure by the number of procedures performed annually per surgeon. It was assumed that each interventionalist and supporting staff members were present during 80 EVAR procedures annually. Since all medical staff wear a lead apron and thyroid shield during the procedure, the measured dose on the chest can be reduced fivefold to obtain the actual dose received.

 

Results

All data were successfully collected during the 36 EVAR procedures. An overview of the procedural data is given in Table 1. Dosimetric data are normally distributed. The mean DAP was 9548 cGycm2 and 8638 cGycm2 in the control group and “drape” cohort respectively (p = .613).
Table 1 – Procedural data.
Control group Drape cohort p
Number of procedures 18 18
                                              Operator
 A 9 4
 B 7 10
 C 2 4
Fluoroscopy time (s) 841 (208–1089) 669 (515–1385)
DAP (cGycm2) 9458 (1497–16510) 8638 (2896–22991) 0.613
Dose per procedure in front of apron chest operator (μSv) 167.7 ± 134.1 73.0 ± 50.9 0.008a
Dose/DAP per procedure chest operator (mSv/Gycm2) 0.023 0.011 0.023a
Dose per procedure on hand operator (μSv) 470.3 ± 222.4 236.8 ± 193.1 0.002a
Dose/DAP per procedure hand operator (mSv/Gycm2) 0.050 0.025 0.000a
Dose per procedure in front of apron chest theatre nurse (μSv) 41.9 ± 74.8 21.4 ± 33.3 0.29
Dose/DAP per procedure chest theatre nurse (mSv/Gycm2) 0.006 0.003 0.086
Data are expressed as number or mean (range) and mean ± SD.
a Significant difference between control group and drape cohort.

 

During a single EVAR procedure, the mean dose measured on the chest of the interventionalist was 167.7 μSv in the control group compared with 73.0 μSv (p = .008) in the drape group. The mean dose measured on the hand of the interventionalist was reduced from 470.3 μSv to 236.8 μSv (p = .002) with the use of a drape. A dose reduction due to the use of the drapes was found at the chest of theatre nurse as well (42.3 μSv to 21.4 μSv); however, this difference did not reach significance (p = .29) (Table 1, Fig. 3).

 

Figure thumbnail gr3

Figure 3 – Overview mean dose (μSv) on chest and hand of the operator and chest of theatre nurse during an endovascular aneurysm procedure with (Drape group) and without (Control group) the use of the drapes.

 

This results in a decrease in the annual dose on the chest of the interventionalist from 13.4 mSv to 5.8 mSv (55%); the annual dose on the hand of the interventionalist from 37.6 mSv to 18.9 mSv (49%); and the annual dose on the chest of the theatre nurse from 3.4 to 1.7 mSv (48%). Since it can be assumed that the dose measured in front of the lead apron on the chest is representative for the dose on the eye lens, the eye lens dose of the interventionalist will reduce from 13.4 mSv to 5.8 mSv, which corresponds to a dose reduction of 55%.

 

Discussion

This randomized trial in humans shows that the use of a sterile lead-free disposable drape is feasible during EVAR procedures and significantly reduces the radiation exposure of the intervening endovascular surgeons. The Radpad drape is simple to position and does not interfere with the EVAR procedure. There were no safety issues, prolonged fluoroscopy times or complications associated with the use of the drape. The protective lead-free drape we used in the study has been tested before in phantoms showing a radiation exposure reduction varying from 14% up to 94%, depending on the amount of radiation-absorbing material used in the drape, distance, and position of the measurements and additional protection measures.

In humans the drape has been tested during percutaneous coronary angiography, complex coronary interventions, pectoral device implantation, electrophysiology procedures, and cardiac resynchronization therapy all showing a significant reduction in radiation exposure. The drape had not previously been tested during abdominal procedures like EVAR.

The risk of radiation-induced lens opacities among interventional cardiology and radiology workers is higher than suspected, and the lowest cataractogenic dose in humans seems to be substantially less than previously thought.

 

In 2011 the ICRP statement prescribed new restrictions, reducing the annual eye dose limit from 150 to 20 mSv. The number of endovascular procedures performed by endovascular surgeons has increased significantly in recent years. As a result of this increase, the endovascular surgeon is cumulatively exposed to radiation and is in danger of exceeding the new limitations for eye lens dose. Our study shows that a sterile lead-free disposable drape can reduce the chest and eye lens dose to the operator by 55%.

 

The measured dose reduction on the chest of the theatre nurse was not significant. This can be explained by the large standard deviation in the received dose of the theatre nurse during an EVAR procedure. Since the nurse is handing over the instruments during the procedure, the angle of the dosimeter to the source of radiation (the patient) may vary considerably per procedure. This is not the case for the primary operator, since the operator is standing in the same position or angle to the patient most of the time.

 

Since we were interested in the dose reduction caused by the use of a sterile lead-free disposable drape during an average infrarenal EVAR procedure in our hospital, we included all EVAR procedures in the period June 2012 to October 2012. Because of variation in complexity of the EVAR procedures, an expected large standard deviation in used fluoroscopic time and DAP values was found. Further, three different operators performed the 36 procedures. To correct or compensate for this variability all measured doses were divided by the DAP value of the procedure. This results in an objective percentage of the mean dose reduction due to the use of these drapes.

 

This is a single center, randomized study with three experienced operators involved. We think that the results are representative for many other centers performing EVAR procedures in a non-dedicated endosuite without additional radiation protection measures like a lead acrylic radiation protective shield in the ceiling or lower body protective lead panels mounted on the operating table. When EVAR procedures are performed in a dedicated endosuite, with the above-mentioned additional radiation protection, the dose-reducing effect of the drapes is expected to be lower because of the dose-reducing effect of the shield and/or panels.

 

An alternative for the use of scatter radiation protective drapes is the use of protective eyewear to reduce the eye dose, since they are reusable and less expensive. However, these glasses could cause discomfort and a drape protects not only the eyes, but the whole upper body of the operator. For example, we also found a reduction in hand dose of 49%. The drape not only protects the operator but also the other supporting staff; a mean dose reduction for the theatre nurse of 48% was achieved.

 

Therefore, because of the ALARA principle, we prefer the use of the scatter radiation protective drapes.

 

Each hospital has to weigh the amount of dose reduction with the costs of the drapes and consider other possible dose-protecting measures like lead glasses, lead panels, and lead shields. The dose-reducing effect of all these measures depends strongly on the set up in the operating room, that is the position of the medical staff relative to the patient (and scatter radiation) and angulations of the C-arm. A drawback of the lead-free drapes is the fact that they are disposable, and therefore for each procedure additional costs are made (approximately 75 euros per drape).

 

Our study has certain limitations. First, operators were not blinded with respect to the presence of a protective drape since no sham drape was used in procedures in the control group. However, it is unlikely that this circumstance will influence the results of this study.

 

Further, in this study, only patients with an infrarenal aortic repair were included. More complex and lengthier procedures like fenestrated/branched EVAR procedures were excluded. Since the position of the medical staff relative to the source of radiation is the same during standard and complex EVAR procedures, we can assume that the relative reduction in doses to the interventionalist and theatre nurse is approximately equal.

 

Conclusion

Endovascular interventionalists are more frequently exposed to radiation due to the increase in EVAR and other endovascular procedures which employ fluoroscopy. This study showed that the use of disposable, radiation-absorbing drapes significantly reduces scatter radiation exposure for the interventionalist, resulting in a lower risk of the stochastic effects of radiation. We also showed that staff during EVAR procedures are additionally protected by the use of these drapes. In adherence to the ALARA principle and the knowledge of the stricter ICRP guidelines, utilization of these drapes during EVAR procedures is recommended when performed in a non-dedicated endosuite.

 

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