ORIGINAL CONTRIBUTIONS

Electrophysiology: A Novel Radiation Protection Drape Reduces Radiation Exposure during Fluroscopy-Guided Electrophysiology Proc

Joseph J. Germano, MD, Gina Day, MD, David Gregorious, MD, Venkataraman Natarajan, MD, Todd Cohen, MD
Joseph J. Germano, MD, Gina Day, MD, David Gregorious, MD, Venkataraman Natarajan, MD, Todd Cohen, MD
Over the past 15 years, there has been an exponential increase in the number of procedures performed in the electrophysiology (EP) laboratory. These procedures can be technically difficult with relatively long fluoroscopy times and high radiation dose exposure to patients, operators and laboratory staff.1,2 During fluoroscopic imaging, diagnostic information is carried in the primary beam. These high intensity X-rays are the chief hazard to the patient. Lower energy scattered radiation deviates in all directions from the patient. Despite typical precautions (i.e., hanging a lead shield between the patient and the operator), long-term radiation exposure may result in stochastic and deterministic effects. Stochastic effects (malignancy in those exposed and inherited defects in later generations) have no particular threshold dose. Deterministic effects (skin erythema, sterility and cataracts) occur at a particular threshold, above which, the probability of observing these effects increases rapidly.1–3 The purpose of this study was to test the hypothesis that a disposable radiation protection drape could help minimize radiation exposure as low as reasonably achievable (ALARA principle) to the operator and staff.4,5 Methods A sterile, disposable, lead-free surgical drape of uniform thickness containing radiation protection materials (primarily bismuth) was used during fluoroscopic EP procedures in addition to standard lead shield protection. The RADPAD® drape (Worldwide Innovations & Technologies, Inc., Overland Park, Kansas) is commercially available and has been employed in a series of patient studies. The RADPAD was positioned slightly lateral to the incision site for pectoral device implants (Figure 1A) and superior to femoral venous line insertion sites (Figure 1B) making contact with a standard transparent leaded acrylic shield suspended from the ceiling. This shield was positioned between the image intensifier and the operator during EP studies and catheter ablations but not used during device implants due to technical issues. A target number of EP procedures, including standard EP studies, radiofrequency catheter ablations, permanent pacemaker implantations and implantable cardioverter-defibrillator (ICD) implantations, were performed. Dosimetric measurements were obtained with and without the RADPAD in place. A fixed angiographic C-arm with a 9-inch image intensifier (Phillips Medical Systems, Andover, Massachusetts), calibrated pursuant to New York State Department of Health regulations, was used. The image intensifier was positioned close to the chest and scatter radiation levels were measured in milliroentgen (mR)/hour using a Panoramic Victoreen Model 470A survey meter (Victoreen Instrument Company; Cleveland, Ohio). The survey meter was placed approximately 14 inches away from the isocenter of the x-ray beam at the examiner’s left hand and left elbow during femoral and pectoral approaches. Each patient served as an internal control with measurements taken for each procedure with and without the RADPAD. All patient studies were performed using the same X-ray equipment. The milliampere (mA), the quantity of radiation produced, and the kilovolt (kVp), the beam penetrability, used in each study was in the range of 2.0–2.8 mA and 75–100 kVp, respectively. Standard shielding equipment, including a lead apron, thyroid shield and protective lenses were used in all cases.3,6,7 A Student’s paired t-test was performed to determine whether dosimetric measurements with the radiation protection drape were significantly different than those without the drape. For each patient, data were recorded as a range in mR/hr. Subsequently, mean mR/hour and standard error of the mean for each measurement were calculated. A p-value Results Table 2 shows the detailed results of the study. Radiation dosimetry was obtained in 20 consecutive patient studies which included: 7 EP studies, 6 pacemakers, 5 radiofrequency ablations and 2 ICDs. The mean age was 63 ± 4 years; 55% of patients were women. The average fluoroscopy time was 2.5 ± 0.4 minutes. Mean dosimetric measurements without the protective drape at the hand and elbow were 141.38 ± 24.67 mR/hour and 78.78 ± 7.95 mR/hour, respectively (Figure 2). The dosage was reduced with the radiation protective device to 48.63 ± 9.02 mR/hour at the hand and to 34.50 ± 4.18 mR/hour at the elbow. A mean reduction of 63% in radiation exposure was observed at the level of the examiner’s hand (p Discussion Electrophysiologists continue to perform more complex EP procedures (such as atrial fibrillation ablations and biventricular devices). These procedures are associated with longer fluoroscopy times and therefore greater cumulative scatter radiation to the operator and staff. While the acute radiation exposure per case is not significant enough to be a major concern, the cumulative risk associated with a lifetime of exposure could become significant.2,4,8,9 The use of lead aprons, thyroid protection, lead eyeglasses, overcouch and undercouch lead shielding and ceiling shields all help to reduce patient and operator exposure.10 Since 1986, pulsed progressive fluoroscopy, a progressively scanned X-ray video system, has been employed in many interventional laboratories showing reductions in radiation entrance exposure rates by 32% to 53% to operators and staff.11 Other modalities such as high-output pulsation, grid-switching tubes, extra beam filtration and digital imaging have all been utilized in continuing attempts to improve image quality and reduce radiation dose.12 Further measures, such as nonfluoroscopic catheter visualization used in conjunction with traditional fluoroscopy has shown significant reductions in radiation dose.2 In addition to these modalities, we employed a sterile disposable lead-free drape and convincingly demonstrated, in each patient, a significant decrease in scatter radiation to the operator. Since the operator is closest to the image intensifier and has the highest radiation exposure during a particular case, the interposition of the drape between the operator and the patient can reduce scatter radiation by approximately 50%. These results were similar to other data using the RADPAD which showed a 29% reduction at the left wrist during fluoroscopic procedures.13 The effect of this drape was more impressive in patients undergoing device implants than femoral-based procedures. During implants, a ceiling-suspended lead shield was impossible to employ due to the surgical nature of the procedure and proximity of the operator to the incision site. Reduction in radiation exposure for these cases was in excess of 70% with use of the RADPAD. In addition to all the modern complex advances in fluoroscopy and shielding, a simple disposable radiation drape (RADPAD) can further help to reduce operator exposure during all types of EP procedures. During this series and the subsequent 100 cases of RADPAD use at our institution, there have been no patient complications from the drape and no logistical inconveniences to the operator. Conclusion In areas of interventional cardiology utilizing fluoroscopy, medical staff have been noted to receive radiation exposures that approach or exceed recommended dose limits. The addition of a radiation protection drape such as the RADPAD during cases will reduce the amount of radiation exposure to operators placing them at lower risk for deterministic and stochastic effects of radiation. The most logical application appears to be longer and more complex cases and in high volume EP laboratories; however, using the ALARA principle, the utilization of this device in all interventional fluoroscopic procedures may be warranted.
References
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