A GPU implementation of a track-repeating algorithm for proton radiotherapy dose calculations

An essential component in proton radiotherapy is the algorithm to calculate the radiation dose to be delivered to the patient. The most common dose algorithms are fast but they are approximate analytical approaches. However their level of accuracy is not always satisfactory, especially for heterogeneous anatomic areas, like the thorax. Monte Carlo techniques provide superior accuracy, however, they often require large computation resources, which render them impractical for routine clinical use. Track-repeating algorithms, for example the Fast Dose Calculator, have shown promise for achieving the accuracy of Monte Carlo simulations for proton radiotherapy dose calculations in a fraction of the computation time. We report on the implementation of the Fast Dose Calculator for proton radiotherapy on a card equipped with graphics processor units (GPU) rather than a central processing unit architecture. This implementation reproduces the full Monte Carlo and CPU-based track-repeating dose calculations within 2%, while achieving a statistical uncertainty of 2% in less than one minute utilizing one single GPU card, which should allow real-time accurate dose calculations

Comparison of the clonogenic survival of A549 non-small cell lung adenocarcinoma cells after irradiation with low-dose-rate beta particles and high-dose-rate X-rays

Purpose: Lung cancer is the leading cause of cancer-related death. Among the new modalities to treat cancer, internal radiotherapy seems to be very promising. However, the achievable dose-rate is two orders of magnitude lower than the one used in conventional external radiotherapy, and data has to be collected to evaluate the cell response to highlight the potential effectiveness of low-dose-rate beta particles irradiation. This work investigates the phosphorus beta irradiation ( P) dose response on the clonogenicity of human A549 non-small cell lung adenocarcinoma cells and compares it to high-dose-rate X-irradiations results. Materials and methods: Cell survival was evaluated by a colony forming assay eight days after low-dose-rate P beta irradiations (0.8 Gy/h) and high-dose-rate X-ray irradiations (0.855 Gy/min). Results: Survival curves were obtained for both types of irradiations, and showed hyper-radiosensitivity at very low doses. Radiosensitivity parameters were obtained by using the linear-quadratic and induced-repair models. Conclusions: Comparison with high-dose-rate X-rays shows a similar surviving fraction, confirming the effectiveness of beta particles for tumor sterilization. © 2012 Informa UK, Ltd

Equilibrium core design methods for molten salt breeder reactor based on two-cell model

Two unit-cell-based core design methods are presented for a molten salt breeder reactor (MSBR) equilibrium core with online reprocessing and refueling: a single-cell method and a two-cell method. The single-cell method adopts a representative single unit cell which has the same fuel-to-moderator volume ratio as the average value of an MSBR core which actually consists of two zones with different ratios. The two-cell method uses two representative unit cells, one for each zone, with each zone having the appropriate fuel-to-moderator ratio. It is demonstrated that the two-cell-based method is able to catch the neutron physics of spectral interaction of the two zones with different neutron energy spectra, whereas the single-cell method cannot accurately predict the breeding ratio nor the resonance escape probability of the MSBR core. A new code system was established using MCNP6/PYTHON script language for modeling of the online reprocessing of molten fuel, and the depletion and online refueling of the MSBR core.close0