Old and new applications for IORT
A simulation based dosimetric study for a Kypho-IORT treatment using Intrabeam™
Abstract
Background and objective: For many cancer patients who develop vertebral metastases in the natural course of the disease, percutaneous kyphoplasty is a valuable treatment option. By using intraoperative radiotherapy (IORT) with the INTRABEAM™ system during kyphoplasty™, metastases may be sterilized and vertebra stabilized together. This solution results in the reduction of patient discomfort and also restores mobility, which improves the patient quality of life. The aim of our study is to perform a dosimetric evaluation of a Kypho-IORT treatment using the needle applicator to control and validate the doses actually received for such treatment.
Method: A simulation of a 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 made on the GATE Monte Carlo (MC) platform by integrating computed tomography (CT) images of the phantom with the applicator in place. The validation was performed by comparing simulations and experimental measurements on the phantom.
Result: The simulation results show a good fit with the experimental measurements. The average relative differences between experimental measurements and calculated dose rates was lower than 1.5% (Min: 0.2%, Max: 7.5%) and a maximum uncertainty of 0.3% in GATE.
Conclusions: This model which has been previously validated in breast cancer can be now considered to be validated for vertebral metastases. The next step will be the validation of the described approach for use in patient dosimetry which should facilitate accounting for the impact of local tissue heterogeneities.
Method: A simulation of a 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 made on the GATE Monte Carlo (MC) platform by integrating computed tomography (CT) images of the phantom with the applicator in place. The validation was performed by comparing simulations and experimental measurements on the phantom.
Result: The simulation results show a good fit with the experimental measurements. The average relative differences between experimental measurements and calculated dose rates was lower than 1.5% (Min: 0.2%, Max: 7.5%) and a maximum uncertainty of 0.3% in GATE.
Conclusions: This model which has been previously validated in breast cancer can be now considered to be validated for vertebral metastases. The next step will be the validation of the described approach for use in patient dosimetry which should facilitate accounting for the impact of local tissue heterogeneities.
