Giakoumettis Georgios, Gkantaifi Areti, Giakoumettis Dimitrios, Papanastasiou Emmanouil, Plataniotis Georgios, Misailidou Despoina, Kouskouras Konstantinos, Bamidis Panagiotis D, Siountas Anastasios
Medical Physics and Digital Innovation Laboratory, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, GRC.
Radiation Oncology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, GRC.
Cureus. 2024 Jun 25;16(6):e63137. doi: 10.7759/cureus.63137. eCollection 2024 Jun.
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.
海马体作为脑部放疗中的危险器官，对其进行保护可能有助于保护患者的生活质量。预防性颅脑照射（PCI）传统上用于小细胞肺癌（SCLC）患者，因为它能提高生存率。本研究旨在通过使用三种不同的治疗机器，找出成功进行PCI并同时保护海马体的相关参数。为此，使用三台直线加速器（LINAC；医科达Infinity、Synergy和Axesse；医科达有限公司，瑞典斯德哥尔摩）的三个半弧，针对45例SCLC患者生成治疗计划，这些直线加速器具有不同的辐射野尺寸和多叶准直器（MLC）叶片厚度特征。处方剂量为25 Gy，分10次照射。根据放射治疗肿瘤学组0933的剂量限制计算海马体的阈值。三台LINAC的计划和治疗系统模板相同。计划评估基于95%等剂量线的剂量学靶区覆盖情况、计划的最大剂量、适形指数（CI）、计划调制程度（MOD）以及患者特定的质量保证（QA）通过率。Infinity的平均靶区覆盖率最高（97.3%），其次是Axesse（96.6%）和Synergy（95.5%）。Synergy的平均最大剂量更高（27.5 Gy），其次是Infinity（27.0 Gy）和Axesse（26.9 Gy）。Axesse计划的CI最高（0.93），其次是Infinity（0.91）和Synergy（0.88）。与Infinity（3.07）和Axesse（3.69）相比，Synergy的计划MOD较低（2.88）。最后，如该治疗单元的射野尺寸所预期的那样，所有Infinity计划、除一个之外的所有Synergy计划以及17/45的Axesse计划中的患者特定QA均成功。基于总体性能，使用具有最大射野开口和最薄MLC叶片的LINAC可获得靶区覆盖、海马体保护和计划可交付性的最有利组合。
