Tamil Nadu Medical Services Corporation Ltd, 417, Pantheon Road, Egmore, Chennai, Tamil Nadu, 600008, India.
Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India.
Asian Pac J Cancer Prev. 2023 Jul 1;24(7):2455-2463. doi: 10.31557/APJCP.2023.24.7.2455.
To propose an expression relating the number and volume of targets with the prescription dose in determining normal brain volume receiving 12 Gy dose (V12) for five to ten brain metastases treated in linear accelerator-based stereotactic radiosurgery (SRS) planning. To determine the volume of tumor that can be treated within the brain tolerance dose, for different SRS prescription doses.
Single-isocenter multiple-target (SIMT) SRS plans were devised for spherical targets that are modeled to simulate 47 tumor scenarios with varying tumor sizes and locations within the brain. Volumetric modulated arc therapy (VMAT) plans were devised using a 5-mm-leaf-width multi-leaf collimator (MLC) with high conformity and dose gradient in the Eclipse treatment planning system for the 21 Gy prescription dose with a 6FFF photon beam. The prescription dose was rescaled to 20 Gy, 18 Gy, 15 Gy and 12Gy to determine the brain V12 volume for a total of 235 SRS plans.
Linear correlation was observed between the number, volume and prescription dose of the tumor. The expression relating these parameters was constructed to predict the normal brain V12 volume. The maximum tumor volume that can be treated using SIMT SRS with a 5-mm MLC for 5 to 10 number of targets and for a prescription dose of 21 Gy, 20 Gy, 18 Gy and 15 Gy is determined.
Using the expression obtained, V12 volume can be calculated using the number of tumors and the total volume of tumors from the pre-planning MRI data. The prescription dose and the SRS fractionation size can be determined before radiotherapy treatment planning.
提出一个与目标数量和体积与处方剂量相关的表达式，用于确定在基于直线加速器的立体定向放射外科（SRS）计划中治疗 5 至 10 个脑转移瘤时，正常脑体积接受 12 Gy 剂量（V12）的情况。确定在脑耐受剂量内可以治疗的肿瘤体积，用于不同的 SRS 处方剂量。
为模拟不同大小和位置的肿瘤的 47 种肿瘤情况，设计了单等中心多靶（SIMT）SRS 计划。使用具有高度适形性和剂量梯度的 5-mm 叶片宽度多叶准直器（MLC），在 Eclipse 治疗计划系统中为 21 Gy 处方剂量设计了容积调制弧形治疗（VMAT）计划，使用 6FFF 光子束。将处方剂量缩放到 20 Gy、18 Gy、15 Gy 和 12 Gy，以确定总共 235 个 SRS 计划的脑 V12 体积。
观察到肿瘤的数量、体积和处方剂量之间存在线性相关性。构建了这些参数之间的关系式，以预测正常脑 V12 体积。确定了使用 5-mm MLC 的 SIMT SRS 治疗 5 至 10 个目标和 21 Gy、20 Gy、18 Gy 和 15 Gy 处方剂量时，可以治疗的最大肿瘤体积。
使用获得的表达式，可以根据预规划 MRI 数据中的肿瘤数量和肿瘤总体积计算 V12 体积。可以在放射治疗计划之前确定处方剂量和 SRS 分割大小。
