Modeling and validation on Monte Carlo of a vertebral metastases treatment on phantom by kyphoplasty and intraoperative RT (KYPHO-IORT)

Abstract

For many cancer patients who develop spinal metastases in the natural course of the disease, percutaneous kyphoplasty is a valuable treatment option. Using IORT with INTRABEAM® during kyphoplasty, metastases can be sterilized and the vertebra stabilized at the same time. This solution results in reduced patient discomfort and also restores mobility, thereby improving the quality of life of the patient. The aim of our study is to model the INTRABEAM® system with applicator ”needle” dedicated to the application of kypho-IORT and verify and validate the doses actually received for such treatment. A first step is to calibrate the model with the applicator needle with simple simulations in a water tank. In a second step, a simulation of clinical treatment is performed on an anthropomorphic phantom RANDO and dose measurements are collected from thermoluminescent detectors placed on the skin and inside the phantom around the X-ray source. Finally, dose calculations are performed on the platform Monte Carlo GATE by integrating CT images of the phantom with the applicator integrated in the phantom. The validation is performed by comparing simulations and experimental measurements on the phantom. The first simulation results show a good fit with the experimental measurements and confirm with personalized study on CT images of the phantom. The mean relative deviation between experimental measurements and calculated doses is 1% (Min: 0.2% High: 7.5%) with a maximum uncertainty of 0.3% in GATE. This model has been validated for the breast and can be considered validated for vertebral metastases. However, it is necessary to confirm this study on patients taking into account tissue heterogeneities.