Author: Lei Fu, Eric Gressen, Yingcui Jia, Shari Rudoler, Yevgeniy Vinogradskiy, Qianyi Xu 👨🔬
Affiliation: Thomas Jefferson University 🌍
Purpose: InTempo imaging in the Accuray CyberKnife System improves the ability to track/correct target motion during treatment. However, no studies have provided information on the impact of InTempo Imaging on treatment plan quality. This retrospective study aims to evaluate and compare CyberKnife radiation plans with and without InTempo Imaging in prostate stereotactic body radiotherapy (SBRT).
Methods: This study included seven consecutive prostate SBRT patients from Oct. 2023 through July 2024, with a prescription of 36.25Gy in 5 fractions to the prostate planning treatment volume (PTV) plus a simultaneously integrated boost dose of 40Gy to the Prostate clinical target volume. Four of the 7 prostate patients were also treated with an additional 44Gy simultaneously to the boosted prostatic nodule. To evaluate the impact of InTempo imaging on plan quality, the clinically treated plans were replanned with the same optimization parameters and machine settings except for the path set. To evaluate both plans equivalently, the study plan was prescribed with the same PTV coverage as the originally approved treatment plan. Mean and standard deviation, plotting of the dose metrics, and Mann-Whitney U test were performed to compare different dose metrics with and without InTempo planning.
Results: Our results showed that the plans with Prostate, Prostate_InTempo, Prostate_InTempo_Short path sets had no statistical differences in dose metrics; for example, Prostate V40Gy(%) was (89.4 ± 6.5), (90.3 ± 4.3), (90.6 ± 4.9) for Prostate, Prostate_InTempo, Prostate_InTempo_Short, respectively. Prostate path set statistically demonstrated lower means in total MU and number of imaging beams compared to Prostate_InTempo. Reduced_Prostate_InTempo had the worst plan quality in dosimetry compared to the Prostate path set. Two study plans with Reduced_Prostate_InTempo could not be created due to too few nodes in the optimization.
Conclusion: Reduced_Prostate_InTempo should be avoided in prostate patient SBRT treatment planning, whereas other paths exhibited no significant dosimetry difference.