Fast dose analysis of movement effects during treatments with scanned proton and carbon-ion beams

Charged particle therapy delivered using scanned pencil beams shows the potential to produce better dose conformity than conventional radiotherapy, although the dose distributions are more sensitive to anatomical changes and patient motion. Therefore, the introduction of engines to monitor the dose as it is being delivered is highly desirable, in order to enhance the development of adaptive treatment techniques in hadrontherapy. A tool for fast dose distributions analysis is presented, which integrates on GPU a Fast Forward Planning, a Fast Image Deformation algorithm, a fast computation of Gamma-Index and Dose-Volume Histogram. The tool is being interfaced with the Dose Delivery System and the Optical Tracking System of a synchrotron-based facility to investigate the feasibility to quantify, spill by spill, the effects of organ movements on dose distributions during treatment deliveries with protons and carbon-ions. The dose calculation and comparison times for a patient treated with protons on a 61.3 cm3 planning target volume, a CT matrix of 512x512x125 voxels, and a computation matrix of 170x170x125 voxels are within 1 s per spill. In terms of accuracy, the absolute dose differences compared with benchmarked Treatment Planning System results are negligible (<10-4 Gy).