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Thursday, October 25, 2018

Operator Dose Reduction during Transjugular Liver Biopsy Using a Radiation-Attenuating Drape: A Prospective, Randomized Study


Summary


Radiation protection is a critical consideration for routine as well as complex interventional radiology procedures. The authors in this study utilized disposable, heavy metal, lead-free, radiation-absorbing surgical drapes laid over the patient during transjugular liver biopsies (TJLB). The primary outcome was operator dose equivalent (ODE), measured in microSieverts (uSv). This was measured by personal dosimeters worn at the chest level outside of lead aprons. ODE was then compared between the protective drapes and standard non-protective drapes. The authors point out several similar studies comparing dose reduction with protective drapes during nephrostomy tube placements, femoral access procedures, and coronary artery interventions. This is the only known study comparing standard and protective drapes during TJLB. A total of 60 patients were included in the statistical analysis. There were no differences in mean kerma-area product (KAP), fluoroscopy time, or number of exposures between the two groups. Ultimately, mean radiation dose incident on the operator was decreased by 56% when using radiation absorbing drapes (37 uSv versus 84 uSv, p < 0.0001). Additionally, ODE corrected for KAP was reduced in the protective drape arm (p < 0.0001). The authors have shown that using radiation-absorbing drapes during TJLB reduces operator scatter radiation as measured by a chest-level personal dosimeter.



Figure 1. Drape positioning. A square split drape was positioned around the jugular access sheath. A rectangular drape was then applied to the patient’s shoulder and body wall, partially overlapping the square drape at the access site.



Figure 4. Operator exposure data per KAP. PD = protective drape; SD = standard drape.

Commentary


While continued investigation into methods of radiation dose reduction is absolutely warranted and valuable, an element of diminishing returns should not be overlooked. Most commonly in these types of studies the method of measurement is a dosimeter worn outside of conventional lead apron shielding. While this is appropriate for modeling and comparing across studies it would be difficult to extrapolate true dose reduction given that the dosimeter is outside of the lead apron. It is important to remember that typical 0.5 mm lead apron shielding provides a significant 90% reduction in equivalent dose. Therefore the actual reduction in dose to the operator in this study is presumably much lower than 56%. That said the authors report that the cost of protective drapes for each case was $60. This is a small price to pay for radiation protection and peace of mind. Additionally, over an entire career, consistent utilization of protective drapes would certainly provide a benefit. However, consistent use of protective drapes would come with consistent costs which can add up if used for a large percentage of procedures. Ultimately, this would necessitate a departmental discussion which will vary between institutions and practices based on ideology and finances.

Click here for abstract

Ryan Kohlbrenner, MD, Evan D. Lehrman, MD, Andrew G. Taylor, MD, PhD, Maureen P. Kohi, MD, Nicholas Fidelman, MD, Vishal Kumar, MD, Miles Conrad, MD, K. Pallav Kolli, MD. Operator Dose Reduction during Transjugular Liver Biopsy Using a Radiation-Attenuating Drape: A Prospective, Randomized Study. J Vasc Interv Radiol 2018; 29: 1248-1253.

Cane Hoffman, MD, PGY-5
Department of Radiology
Wake Forest Baptist Medical Center
@WakeForest_IR

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