Curtis Lee Anderson MD, PhD, Presenter: Nothing to Disclose

Matthew J. Bassignani MD, Abstract Co-Author: Radiology Advisory Board, Nuance Communications, Inc

Amy S. Burns MD, Abstract Co-Author: Nothing to Disclose

Noah Schenkman MD, Abstract Co-Author: Stockholder, Intuitive Surgical, Inc

To investigate the effective radiation dose to the patients during percutaneous cryoablation of renal tumors and identify factors which may affect the dose.

CT-guided percutaneous cryoablation (CT-PCA) of renal tumors was performed by a single operator on a GE LightSpeed Pro 16 slice computed tomography (CT) scanner with fluoroscopy capability. Radiation exposure was calculated for all patients that CT-PCA of renal masses between 1/2007 and 2/2008. A total of 15 procedures were included in this study. Dose line products were retrieved from CT scanner calculations during the fluoroscopy and spiral scanning portions of the procedure. Effective doses were calculated using tissue weighing factors. Pearson correlation calculations were performed to evaluate for change in patient doses over time with increased operator experience, BMI and number of cryoprobes placed.

The total mean effective dose from the procedures was 19.4 +/- 7.4 mSv. The mean effective dose from the CT fluoroscopy portion was 7.7 +/- 6.5 mSv and the spiral CT portion of the procedure was 11.8 +/- 6.1 mSv. There was a statistically significant negative correlation between both the total effective dose as well as the CT fluoroscopy related dose and the date of the procedure (p ~ 0.03 and 0.01 respectively). There was no significant correlation between the date of the procedure and the effective dose contribution from the spiral CT portion of the procedure (p ~ 0.5). Additionally, there was no statistically significant correlation with BMI and effective radiation dose. Level of complexity (i.e., number of cryoprobes placed) did not show correlation to total or fluoroscopy related effective dose.

CT-PCA is an exciting, minimally invasive therapy for renal tumors which has shown good therapeutic outcomes while largely sparing renal parenchyma and function. Our series demonstrates a moderate effective radiation dose approximately equal to 3-4 abdominal CT scans. In addition, our study demonstrates that this dose significantly declines with increased operator experience. In particular, there is significant reduction in the effective dose contribution from the CT fluoroscopy portion of the exam with increased operator experience.

CT-PCA is an increasingly utilized therapy for renal tumors. Radiation dose to the patient is moderate and can be mitigated with increased operator experience.

Anderson, C, Bassignani, M, Burns, A, Schenkman, N, Radiation Dose during Percutaneous CT-guided Cryoablation of Renal Tumors.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8012285.html