J. Duan; Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi, China
Purpose/Objective(s): The present research aims to examine the dosimetric advantages associated with a cutting-edge radiotherapy platform, which integrates linear accelerator (Linac) and a non-invasive stereotactic radiosurgery instrument, incorporating both X-ray and ?-ray modalities. Primary focus of this investigation is to assess the efficacy of platform in treatment of prostate cancer. Materials/
Methods: A retrospective study was conducted involving ten patients who underwent radiotherapy for prostate cancer. Each patient underwent three different treatment plans: Linac plan, X-ray and ?-ray Combined plan, and escalated-dose combined plan. In the Linac and combined plan, the prescribed dose to the planning target volume (PTV) was 50Gy, with an additional radiation dose boost to the planning gross tumor volume (PGTV) of 20Gy. In the escalated-dose combined plan, the prescribed dose for the PTV was 50Gy and PGTV was boost to 30Gy. The Linac plan utilized the traditional accelerators treatment planning system (TPS), while the combined and escalated-dose combined plan used the RT PRO TPS. For combined and escalated-dose combined plan, PGTV received radiotherapy using ?-rays, and X rays was utilized to optimize the PTV based on a cutting-edge radiotherapy platform. For escalated-dose combined plan, the radiation dose to the PGTV was increased while ensuring that the doses to critical organs remained within clinically tolerable limits. Comparisons and analyses of the dosimetric data were conducted among the three treatment plans, focusing on the ability to increase the target dose while reducing the dose to organs at risk (OAR). Results: All plans met the clinical requirements. Regarding the target volumes, both the combined and the escalated-dose combined plan exhibit a noteworthy increase in the mean dose (Dmean) for the primary gross tumor volume (PGTV) compared to Linac plans (77.05 ± 0.9 vs. 71.21 ± 0.18, p < 0.001; 89.75 ± 1.26 vs. 71.21 ± 0.18, p < 0.001). However, the Dmean for the planning target volume (PTV) remains comparable (54.88 ± 2.05 vs. 54.77 ± 1.80, p = 0.59; 56.62 ± 3.1 vs. 54.77 ± 1.80, p = 0.04). In terms of organ at risk (OAR) doses, the combined plans demonstrate relatively lower or comparable values when compared to the Linac plans. In detail, bladder V45 (40.6 ± 19.9 vs. 46 ± 17.8, p = 0.01; 41.4 ± 20 vs. 46 ± 17.8, p = 0.01); rectum V45 (32.18 ± 15.84 vs. 52.35 ± 24.8, p = 0.053; 37.57 ± 18.61 vs. 52.35 ± 24.8, p = 0.110); intestine V45 (39.18 ± 13.28 vs. 51.57 ± 19.74, p = 0.02; 39.43 ± 13.48 vs. 51.57 ± 19.74, p = 0.02); left femoral head V30 (3.25 ± 3.36 vs. 6.77 ± 6.06, p = 0.07, 3.58 ± 3.56 vs. 6.77 ± 6.06, p = 0.08); and right femoral head V30 (2.02 ± 1.96 vs. 6.29 ± 4.53, p = 0.04, 2.35 ± 2.36 vs. 6.29 ± 4.53, p = 0.06). Conclusion: This novel multimodal radiotherapy technique harnesses the physical characteristics of X-rays and ?-rays to provide evidence of the viability of increasing the irradiation does to the gross tumor volume for prostate cancer therapy, while simultaneously reducing the radiation dose to some OARs.
