Optimization of the Temporal Pattern of Applied Radiation Dose: Implication for the Treatment of Prostate Cancer

摘要

Our previous modeling study demonstrated that the temporal pattern of applied dose during a single fraction of radiation can impact cell survival, especially in situations with low a/b and large dose/fx and fraction length (Tf). Two different arrangements of the same set of radiation fields were applied to low and high a/b cell lines at a high dose/fx and long Tf; a low a/b line was subjected to the same experiment at a low dose/fx, then a short Tf. Comparison of cell survival between both field arrangements agreed with the modeling study: statistically significant differences for the low a/b lines at high dose/fx and long Tf but not in any other case. To analyze temporal effects in vitro in a realistic treatment environment, a specialized phantom was characterized. Thermoluminescence dosimeters and film showed good agreement with dose predicted by a clinical treatment planning algorithm. A separate experiment showed good cellular response agreement with the phantom versus traditional experimental setups. These results show that the phantom is a useful tool to assess integration of temporal optimization into prostate cancer treatment planning, as these temporal optimization techniques could prove an important element in enhancing the efficacy of prostate cancer radiation therapy.