Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA.
Med Phys. 2012 Jan;39(1):237-45. doi: 10.1118/1.3668059.
To describe biological-based optimization and Monte Carlo (MC) dose calculation-based treatment planning for volumetric modulated arc therapy (VMAT) delivery of stereotactic body radiation therapy (SBRT) in lung, liver, and prostate patients.
Optimization strategies and VMAT planning parameters using a biological-based optimization MC planning system were analyzed for 24 SBRT patients. Patients received a median dose of 45 Gy [range, 34-54 Gy] for lung tumors in 1-5 fxs and a median dose of 52 Gy [range, 48-60 Gy] for liver tumors in 3-6 fxs. Prostate patients received a fractional dose of 10 Gy in 5 fxs. Biological-cost functions were used for plan optimization, and its dosimetric quality was evaluated using the conformity index (CI), the conformation number (CN), the ratio of the volume receiving 50% of the prescription dose over the planning target volume (Rx/PTV50). The quality and efficiency of the delivery were assessed according to measured quality assurance (QA) passing rates and delivery times. For each disease site, one patient was replanned using physical cost function and compared to the corresponding biological plan.
Median CI, CN, and Rx/PTV50 for all 24 patients were 1.13 (1.02-1.28), 0.79 (0.70-0.88), and 5.3 (3.1-10.8), respectively. The median delivery rate for all patients was 410 MU/min with a maximum possible rate of 480 MU/min (85%). Median QA passing rate was 96.7%, and it did not significantly vary with the tumor site.
VMAT delivery of SBRT plans optimized using biological-motivated cost-functions result in highly conformal dose distributions. Plans offer shorter treatment-time benefits and provide efficient dose delivery without compromising the plan conformity for tumors in the prostate, lung, and liver, thereby improving patient comfort and clinical throughput. The short delivery times minimize the risk of patient setup and intrafraction motion errors often associated with long SBRT treatment delivery times.
描述基于生物学的优化和蒙特卡罗（MC）剂量计算的立体定向体部放射治疗（SBRT）容积调强弧形治疗（VMAT）的治疗计划，包括肺、肝和前列腺患者。
使用基于生物学的优化 MC 计划系统，对 24 例 SBRT 患者的优化策略和 VMAT 计划参数进行了分析。肺肿瘤患者接受中位数为 45 Gy[范围 34-54 Gy]的 1-5 次分割治疗，肝肿瘤患者接受中位数为 52 Gy[范围 48-60 Gy]的 3-6 次分割治疗，前列腺患者接受 5 次分割治疗，每次 10 Gy。采用生物成本函数进行计划优化，并通过适形指数（CI）、适形指数（CN）、接受处方剂量 50%的计划靶区体积与 Rx/PTV50 的比值来评估其剂量学质量。根据测量质量保证（QA）通过率和输送时间评估输送的质量和效率。对于每个疾病部位，我们用物理成本函数对一位患者进行了重新规划，并与相应的生物计划进行了比较。
所有 24 例患者的中位 CI、CN 和 Rx/PTV50 分别为 1.13（1.02-1.28）、0.79（0.70-0.88）和 5.3（3.1-10.8）。所有患者的中位输送率为 410 MU/min，最大可能输送率为 480 MU/min（85%）。中位 QA 通过率为 96.7%，与肿瘤部位无显著差异。
使用基于生物学的优化成本函数优化的 SBRT 计划的 VMAT 输送可产生高度适形的剂量分布。这些计划提供了更短的治疗时间优势，并提供了高效的剂量输送，同时不会影响前列腺、肺和肝脏肿瘤的计划适形性，从而提高了患者的舒适度和临床效率。短的输送时间最大限度地减少了患者摆位和分次内运动误差的风险，这些误差通常与 SBRT 治疗的长输送时间有关。
