# A Closer Look at Radiation Exposure During Percutaneous Cryoablation for T1 Renal Tumors

## TL;DR

This study finds that kidney tumor cryoablation exposes patients to 26 mSv of radiation, which is lower than the radiation from follow-up scans.

## Contribution

The study quantifies radiation exposure during cryoablation and identifies factors that influence it.

## Key findings

- The median radiation dose during cryoablation was 26 mSv.
- Follow-up CT scans expose patients to 105-158 mSv of radiation.
- Higher BMI, more needles, and additional procedures increase radiation exposure.

## Abstract

Radiation Exposure During Kidney Tumor Cryoablation Percutaneous cryoablation (PCA) is a minimally invasive treatment for renal tumors, offering an alternative to surgical removal. However, this CT-guided procedure exposes patients to radiation, and little is known about the magnitude of this. This study analyzed 164 PCA procedures performed on kidney cancer patients between 2014 and 2024. The radiation exposure of each procedure was measured and was compared to the estimated radiation exposure acquired during follow-up after treatment. The key findings showed that the median radiation dose during PCA was 26 mSv (millisieverts), which is relatively modest. To put this in perspective, patients typically receive much more radiation from the multiple CT scans required for long-term monitoring after treatment - between 105-158 mSv depending on which urological guidelines are followed. Several factors increased radiation exposure during the procedure, such as patients with higher body mass index, procedures requiring more needles, and cases requiring hydro- or aero-dissection all resulted in higher radiation doses. Our study concludes that while PCA does involve radiation exposure, the amount is reasonable compared to the ongoing surveillance scans. The procedure remains a viable treatment option for small kidney tumors, with radiation risk being manageable and predictable based on patient and procedural factors.

Introduction: Percutaneous cryoablation (PCA) can be a valid alternative to partial nephrectomy for patients with cT1a renal tumors. A potential disadvantage of PCA is radiation exposure for patients, though the exact significance of this is unknown. This study aims to uncover the degree of radiation exposure during PCA and what factors are of influence. Methods: This is a retrospective analysis of a prospectively maintained database of patients who underwent CT-guided PCA for cT1 renal cell carcinoma (RCC) between January 2014 and September 2024. The median effective dose (mSV) of PCA was calculated and compared to the expected cumulative radiation exposure during follow-up. Multivariate linear regression was performed to identify factors predictive of higher radiation exposure (mSV). Results: A total of 164 PCAs were performed, with radiation data available for 133 cases. Mean age was 65 (±11) years and the mean tumor diameter was 28 (±9.6) mm. Median effective dose of the CA procedures was 26 mSV (IQR 18–37). The estimated cumulative effective dose of follow-up CT scans according to 2016 and 2024 European Association of Urology guidelines was 158 (IQR 117–213) and 105 mSV (IQR 78–142), respectively. Multivariate linear regression analysis identified BMI (OR 1.723, p < 0.001), the number of needles used (OR 4.060, p < 0.001), and the necessity for additional procedures (OR 8.056, p < 0.001) as significant predictors of a higher effective dose. Conclusions: We found a median effective dose of 26 mSV for PCA, which is relatively low compared to the cumulative radiation exposure associated with CT scans during follow-up of patients post-ablation according to the guidelines. Furthermore, increased BMI, a higher number of required needles and the execution of additional procedures are all associated with a higher effective dose.