Purpose/Objectives-We have created an automated process utilizing real-time tracking data to evaluate adequacy of PTV margins in prostate cancer, allowing for a process of adaptive radiotherapy with minimal physician workload. We present an analysis of PTV adequacy and a proposed adaptive process.Materials/Methods-Tracking data was analyzed for 15 patients who underwent SMLC IMRT with uniform 5mm PTV margins for prostate cancer utilizing the Calypso® Localization System. Additional plans were generated with 0 and 3 mm margins. A custom software application utilizing the planned dose distribution and structure location from CT simulation was developed to evaluate the dosimetric impact to the target due to motion. The dose delivered to the prostate was calculated for the initial 3, 5, and 10 fractions, and for the entire treatment. Treatment was accepted as adequate if minimum delivered prostate dose (D min ) was at least 98% of the planned D min . Conclusions-Our adaptive process successfully utilized real-time tracking data to predict the need for PTV modifications, without the added burden of physician contouring and image analysis. Our methods are applicable to other utilizations of real-time tracking, including hypofractionated treatment.
Results-For
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