A GPU-Based Track-Repeating Algorithm for Dose Calculation for Photon Radiotherapy

An essential ingredient in radiotherapy is the calculation of the dose to be delivered to the patient. Analytical algorithms are commonly used for such a task, however their accuracy is not always satisfactory. Monte Carlo techniques provide higher accuracy, but they often require large computational times. Track-repeating algorithms, for example the Fast Dose Calculator, have shown promise for achieving the accuracy of the Monte Carlo approach for proton radiotherapy dose calculations, while considerably reducing the calculation time. We report on the implementation of the Fast Dose Calculator for photon dose calculations on a GPU architecture. As in the proton case, this implementation reproduces the full Monte Carlo dose calculations within 2%, while achieving a statistical uncertainty of 2% in less than one minute utilizing one single GPU card.