Feasibility of three-dimensional dose verification using Octavius 1600SRS(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2022年第11期
- Page:
- 1321-1328
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Feasibility of three-dimensional dose verification using Octavius 1600SRS
- Author(s):
- ZHOU Yang1; LIU Yimei2; TAN Yuhong3; ZHANG Jun2; CHEN Meining2; DENG Xiaowu2; PENG Yinglin2
- 1.Tumor Radiotherapy Center, Zhuzhou Hospital Affiliated to Xiangya School of Medicine, Central South University, Zhuzhou 412000, China 2. Department of Radiation Oncology, Sun Yat-sen University Cancer Center/State Key Laboratory of Oncology in South China/Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China 3. Department of Medical Equipment, the First Dongguan Affiliated Hospital of Guangdong Medical University, Dongguan 523000, China
- Keywords:
- Keywords: three-dimensional dose verification system Octavius 1600SRS stereotactic body radiation therapy dose verification Gamma passing rate
- PACS:
- R318；R811
- DOI:
- DOI:10.3969/j.issn.1005-202X.2022.11.001
- Abstract:
- Abstract: Objective To carry out performance test on PTW Octavius 1600SRS before clinical application through phantom experiment, and to evaluate the feasibility of dose verification for stereotactic body radiation therapy (SBRT) plan using PTW Octavius 1600SRS. Methods Seven spherical target areas, including a central target area (PTV0) with a diameter of 3.0 cm, 2 target areas with a diameter of 1.0 cm, 2 target areas with a diameter of 1.5 cm and 2 target areas with a diameter of 2.0 cm, were delineated in the CT image of the phantom in PTW Octavius 1600SRS. The distance from the center point of each target area to the center point of PTV0 was from 3 to 6 cm. With the central point of PTV0 as the planning center, the SBRT plan (Plan0) was designed in the treatment planning system, and its prescribed dose was 8 Gy×3 F. The experiment simulated and set the MLC position deviations (1, 2, 3 mm), the plan isocenter point (ISO) position deviations (1, 2, 3 mm) and the gantry rotation deviations (0.5°, 1.0°, 2.0°) for Plan0, and the corresponding deviation plans were generated. The 1600SRS verification system was used to measure the original plan and the deviation plans, and compare the difference of Gamma passing rate and target area coverage between the planned dose and the measured dose for evaluating the sensitivity of the system to radiotherapy dose deviation. In addition, pre-treatment dose verification using PTW Octavius 1600SRS was carried out in 6 cases of clinical SBRT plans, and then the results were compared with EPID verification results for evaluating its performance in clinical plan verification. Results The 1600SRS verification system was very sensitive to MLC position deviation. When a 1 mm deviation occurred in MLC, the gamma passing rate and the coverage rate of each target area were decreased significantly, and with the increase of MLC position deviation, the decrease was more obvious. When a 3 mm deviation occurred in MLC, the gamma passing rate decreased from 99.6% to 92.8% (3 mm/3%), and from 98.0% to 81.7% (2 mm/3%) and the coverage rates of 7 target areas (V98%) was decreased by (58.8±6.8)% on average. The 1600SRS was also sensitive to gantry rotation deviation and ISO translation error. When there was a 2° deviation in gantry rotation or a 3 mm deviation in ISO, the gamma passing rate (2 mm/2%) was decreased from 95.1% to 89.5% or 86.2%, respectively. The average gamma passing rate (2 mm/3%) in 6 cases of clinical SBRT plans was (95.5±1.5)%. Conclusion Octavius 1600SRS can detect MLC position deviation, gantry rotation deviation and ISO position deviation in SBRT plan sensitively, and can be used in pre-treatment dose verification for SBRT plan.
Last Update: 2022-11-25