PDF(Pubmed)
Abstract：
Hippocampus protection, as an organ at risk in brain radiotherapy, might protect patients\' quality of life. Prophylactic cranial irradiation (PCI) has been used traditionally in small cell lung cancer (SCLC) patients as it increases survival. This study aimed to discover the contributing parameters for a successful PCI with simultaneous protection of the hippocampus by using three different treatment machines. For this purpose, treatment plans were generated for 45 SCLC patients using three half-arcs in three linear accelerators (LINACs; Elekta Infinity, Synergy, and Axesse; Elekta Ltd, Stockholm, Sweden) with different radiation field sizes and multileaf collimator (MLC) leaf thickness characteristics. The prescribed dose was 25 Gy in 10 fractions. Thresholds for the hippocampus were calculated based on the Radiation Therapy Oncology Group 0933 dose constraints. The planning and treatment system templates were common to all three LINACs. Plan evaluation was based on the dosimetric target coverage by the 95% isodose, the maximum dose of the plan, the conformity index (CI), the degree of plan modulation (MOD), and the patient-specific quality assurance (QA) pass rate. The mean target coverage was highest for Infinity (97.3%), followed by Axesse (96.6%) and Synergy (95.5%). The mean maximum dose was higher for Synergy (27.5 Gy), followed by Infinity (27.0 Gy) and Axesse (26.9 Gy). Axesse plans had the highest CI (0.93), followed by Infinity (0.91) and Synergy (0.88). Plan MOD was lower for Synergy (2.88) compared with Infinity (3.07) and Axesse (3.69). Finally, patient-specific QA was successful in all Infinity plans, in all but one Synergy plan, and in 17/45 Axesse plans, as was expected from the field size in that treatment unit. Based on overall performance, the most favorable combination of target coverage, hippocampus sparing, and plan deliverability was obtained with the LINAC, which has the largest field opening and thinnest MLC leaves.
摘要：
海马保护,作为脑部放射治疗的危险器官，可以保护患者的生活质量。传统上，预防性颅骨照射（PCI）已用于小细胞肺癌（SCLC）患者，因为它可以提高生存率。这项研究旨在通过使用三种不同的治疗机来发现成功的PCI并同时保护海马体的贡献参数。为此,使用三个线性加速器中的三个半弧为45名SCLC患者生成了治疗计划(LINAC；ElektaInfinity，Synergy,和Axesse；Elekta有限公司，斯德哥尔摩,瑞典）具有不同的辐射场尺寸和多叶准直器（MLC）叶片厚度特征。处方剂量为25Gy，分为10个部分。基于放射疗法肿瘤学组0933剂量约束计算海马体的阈值。计划和治疗系统模板对所有三个LINAC都是通用的。计划评估基于95%等剂量的剂量学目标覆盖率，计划的最大剂量,合格指数(CI)，计划调制程度(MOD)，和患者特定质量保证(QA)合格率。Infinity的平均目标覆盖率最高(97.3%)，其次是Axesse（96.6%）和Synergy（95.5%）。Synergy的平均最大剂量较高（27.5Gy），其次是Infinity（27.0Gy）和Axesse（26.9Gy）。Axesse计划的最高CI(0.93)，其次是Infinity（0.91）和Synergy（0.88）。与Infinity（3.07）和Axesse（3.69）相比，Synergy（2.88）的计划MOD较低。最后,患者特定的QA在所有Infinity计划中都是成功的，除了一个协同计划，在17/45Axesse计划中，正如从该处理单元的现场大小所预期的那样。基于整体性能，目标覆盖率的最有利组合，海马体保留，用LINAC获得了计划的可交付性，具有最大的田间开口和最薄的MLC叶子。
