Matsumoto Kenji, Monzen Hajime, Kubo Kazuki, Otsuka Masakazu, Nambu Hidekazu, Nishimura Yasumasa
Department of Radiology Service, Kindai University Hospital, Osakasayama, JPN.
Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka, JPN.
Cureus. 2023 Mar 21;15(3):e36493. doi: 10.7759/cureus.36493. eCollection 2023 Mar.
This study aims to determine the feasibility of using a new O-ring linear accelerator (Halcyon, Varian Medical Systems, CA, USA) to perform treatment planning using volumetric modulated arc therapy (VMAT) for craniospinal irradiation (CSI). A 20-year-old male patient with leukemia was selected. The planning target volume (PTV) was contoured to include the entire contents of the brain and spinal canal. The PTV margin was 10 mm applied to the clinical target volume (CTV). VMAT (RapidArc, Varian Medical Systems, CA, USA) planning was performed using four isocenter with five arcs, two full rotation arcs to cover the brain and upper part of the spinal cord, and one full rotation arc for the lower part of the spinal cord. The plan was created using the auto-feathering photon optimizer calculation of the planning system. The conformity index (CI) and heterogeneity index (HI) as well as dose-volume histograms of organs at risk (OAR) were evaluated. The patient position of ±3.0 mm in the craniocaudal direction was moved in to simulate the effect of treatment inaccuracy. The total treatment time was also measured. The CI and HI were 1.09 and 8.44, respectively. The mean dose (PTV) was 105.5%, and the mean dose (OARs) was lower than the planning dose constraints. Simulations with a patient position shift of ±3.0 mm resulted in an error of less than ±10.0% of the planned dose to the spinal cord. The total treatment time was within 15 minutes. VMAT planning for CSI with Halcyon achieved high conformality, uniform dose distribution, low dose to the surrounding normal tissues, and reduced treatment time.
本研究旨在确定使用新型O型环直线加速器（Halcyon，瓦里安医疗系统公司，美国加利福尼亚州）通过容积调强弧形治疗（VMAT）进行全脑全脊髓照射（CSI）治疗计划的可行性。选取一名20岁的白血病男性患者。勾勒出计划靶区（PTV）以包括脑和脊髓管的全部内容物。PTV边界为在临床靶区（CTV）上施加10毫米。使用四个等中心和五条弧进行VMAT（RapidArc，瓦里安医疗系统公司，美国加利福尼亚州）计划，两条全旋转弧覆盖脑和脊髓上部，一条全旋转弧用于脊髓下部。该计划使用计划系统的自动羽化光子优化器计算创建。评估了适形指数（CI）和异质性指数（HI）以及危及器官（OAR）的剂量体积直方图。在头脚方向上移动±3.0毫米的患者体位以模拟治疗不准确的影响。还测量了总治疗时间。CI和HI分别为1.09和8.44。平均剂量（PTV）为105.5%，平均剂量（OARs）低于计划剂量限制。患者体位偏移±3.0毫米的模拟导致脊髓计划剂量的误差小于±10.0%。总治疗时间在15分钟内。使用Halcyon进行CSI的VMAT计划实现了高适形性、均匀的剂量分布、对周围正常组织的低剂量以及缩短的治疗时间。
