Abstract:
Objective To analyze the feasibility, advantages, and disadvantages of background dose optimization method in sequential radiotherapy planning for prostate cancer.
Methods Ten patients with prostate cancer treated were selected, and the first course plan (PTV 50.4 Gy/28 fractions) was designed on the Monaco planning system.Then, the second course plan (GTV 16 Gy/8 fractions) was designed according to the conventional method and the background dose optimization method (Bias Dose), respectively.The doses of target and organs at risk, monitor unit and deliver time were compared and analyzed.
Results The target dose of two plan design methods met clinical requirements.In GTV and PTV, the D98, Dmean, and D2 doses in the Bias group were lower than those in the Normal group (P < 0.01), and there was a statistically significant difference in TC dose of PTV (P < 0.01).In terms of HI, the Bias group in the GTV target area showed a disadvantage, while the Bias group in the PTV target area showed better uniformity than the Normal group (P < 0.05 and P < 0.01).The CI of the Bias group was higher than that of the Normal group in all target areas (P < 0.01).There was no statistically significant difference in machine hop count and execution time between the Bias group and the Normal group (P>0.05).Regarding small intestine Dmean, left and right femur Dmean, and rectal V50 dose indicators, the Bias group was significantly lower than the Normal group (P < 0.05 to P < 0.01).
Conclusions Bias Dose method is feasible in sequential radiotherapy of prostate cancer.Bias dose plan should be used in clinical application to obtain better clinical plan.