ABSTRACT

This study aimed to investigate the effect of the number of control points (CPs) on the plan quality, plan delivery efficiency, and gamma passing rate (GPR) of intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Twenty patients with NPC were selected. With all other optimization conditions unchanged, only the number of CPs in each field was changed and optimized to formulate four groups of IMRT plans (CP10, CP15, CP20, and CP25) for each case. An IMRT factor (IF) was used to evaluate the plan complexity, and the plan quality index (PQI) was employed to measure the plan quality. The MatriXX was used to measure each plan, and the plan delivery time (PDT) was recorded. The CP20 group had the lowest PQI (20.2%), while the CP10 group had the highest PQI (51.4%). The monitor unit (MU) values and PDTs gradually increased as the number of control points increased, while the MUs/segment significantly decreased. A negative correlation was observed between GPR and IF at the three commonly used criteria (R² = 0.39, 0.39, and 0.41, respectively). Considering the IMRT plan quality and the efficiency and accuracy of plan delivery, 20 CPs per field should be used in the IMRT planning for NPC.

摘要

本研究旨在探讨控制点（CP）数量对鼻咽癌（NPC）调强放疗（IMRT）的计划质量、计划实施效率和伽马通过率（GPR）的影响。选择了 20 名 NPC 患者。在其他所有优化条件不变的情况下，仅改变和优化每个领域的CP数量，为每种情况制定四组IMRT计划（CP10、CP15、CP20和CP25）。使用IMRT因子（IF）来评估计划复杂度，并使用计划质量指数（PQI）来衡量计划质量。MatriXX 用于测量每个计划，并记录计划交付时间（PDT）。CP20 组的 PQI 最低（20.2%），而 CP10 组的 PQI 最高（51.4%）。随着控制点数量的增加，监测单元 (MU) 值和 PDT 逐渐增加，而 MU/segment 显着减少。在三个常用标准（R²  = 0.39、0.39 和 0.41，分别）。考虑到 IMRT 计划质量和计划交付的效率和准确性，NPC 的 IMRT 计划中应使用每个字段 20 个 CP。