Tze Min Wah MBChB, FRCR, Abstract Co-Author: Consultant, Galil Medical Ltd

Michael Min Gallagher, Presenter: Nothing to Disclose

Christopher Min Hounslow, Abstract Co-Author: Nothing to Disclose

Gareth Richard Iball MSC, BSC, Abstract Co-Author: Nothing to Disclose

The aim of this study was to evaluate the CT radiation dose in CT guided cryoablation (CRYO) of renal tumors in a single large teaching institution and to assess the percentage reduction of radiation dose with and without a dose reduction technique in our intra-procedural CT CRYO treatment protocol. 

From 2008 to 2014, a total of 97 patients underwent CT guided CRYO of renal tumors and were included in this retrospective evaluation of their CT radiation dose during treatment. Amongst them were 56 patients (61 procedures; mean age, 65; 37 males and 29 females) without CT dose reduction technique and 41 patients (43 procedures; mean age, 73; 27 males and 14 females) with CT dose reduction technique. The group without CT dose reduction technique were scanned with the same parameters throughout whilst those with the dose reduction technique had sequential reduction of mAs during scanning until the interventional radiologist deemed the increased image noise had compromised the diagnostic quality of the images.  

The average DLP with and without CT dose reduction technique was 6044 (+/- SD 2676) mGy-cm and 3354 (+/- SD 1308) mGy-cm. Thus the average DLP was 43.7% lower in the dose reduced group when compared to the non-dose reduced group (p<0.0001) (Figure 1). The total CTDIvol was used to estimate the patient skin dose; in the non-reduced group the maximum "skin dose" was 1.1Gy, vs. 0.38Gy in the dose reduced group. However, there was no significant difference between the number of cryoprobes used, number of CT examination runs or total exam time between the two groups. 

The use of a sequential mAs dose reduction strategy in our CT CRYO treatment protocol has produced significant dose reduction for patients undergoing treatment of their renal tumors. In our clinical practice, we would now advocate the use of this dose reduction strategy at all times as long as the image quality remains sufficient for the clinical purpose of the examination.  

It is important to use the dose reduction strategy during CT CRYO treatment of renal tumors as the radiation burden can be reduced significantly by the simple sequential mAs dose reduction approach.

Wah, T, Gallagher, M, Hounslow, C, Iball, G, A Retrospective Evaluation of CT Radiation Dose in CT Guided Cryoablation of Renal Tumors: With and without Radiation Dose Reduction Technique  .  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045477.html