Li Miaomiao, Cui Yongbin, Lin Xinjun, Yan Yuanyuan, Liu Qianyu, Nie Mingming, Ye Wenzhen Gong, Huang Yong, Chen Jinhu, Yin Yong
Shandong University Cancer Center, Shandong University, Jinan, Shandong, China.
Department of Medical Imaging, Shandong Medical College, Jinan, Shandong, China.
Front Oncol. 2025 Apr 23;15:1591139. doi: 10.3389/fonc.2025.1591139. eCollection 2025.
To investigate the feasibility of proton therapy planning using stopping power ratio (SPR) maps directly generated from spectral CT raw data, and to perform a comparative evaluation of dose calculation uncertainties between SPR maps derived from conventional CT Hounsfield Unit (HU) conversion and direct spectral CT SPR generation.
A retrospective analysis was conducted on 30 patients with mid-thoracic esophageal squamous cell carcinoma (ESCC) who underwent pre-treatment spectral CT imaging. Target volumes and organs at risk (OARs) were delineated on contrast-enhanced CT images and subsequently registered to both non-contrast CT and SPR maps. Three treatment plans were generated: Intensity-modulated radiotherapy (IMRT) plan based on conventional CT, Intensity-modulated proton therapy (IMPT) plan using HU-SPR conversion, IMPT plan utilizing direct SPR maps (IMPT-SPR) from spectral CT. Dose-volume parameters for target volumes and OARs (lungs, heart, spinal cord) were systematically analyzed. Comparative dosimetric analyses were performed among the three plans and between paired groups.
All plans met clinical radiotherapy requirements. For OARs (lungs, heart), IMPT plans demonstrated significantly lower dose-volume parameters compared to IMRT, except for maximum dose (Dmax). Between the two IMPT approaches, no statistically significant differences were observed in dose-volume parameters (>0.05), except for the gradient index which was significantly higher in the HU-converted IMPT plan (<0.05). No significant differences were detected in heart, lung and spinal cord dosimetric parameters between IMPT approaches.
IMPT demonstrated superior OAR sparing compared to IMRT. For mid thoracic ESCC patients under proton therapy, dose calculations based on CT-HU conversion was showed comparable dosimetric impact to DECT-derived SPR in terms of target coverage and OAR protection. These findings support the clinical feasibility of conventional CT-based proton therapy planning and dose calculation.
探讨使用直接从光谱CT原始数据生成的阻止本领比（SPR）图进行质子治疗计划的可行性，并对传统CT亨氏单位（HU）转换得到的SPR图与直接光谱CT生成的SPR图之间的剂量计算不确定性进行比较评估。
对30例接受治疗前光谱CT成像的中胸段食管鳞状细胞癌（ESCC）患者进行回顾性分析。在增强CT图像上勾画靶区体积和危及器官（OARs），随后将其配准到非增强CT和SPR图上。生成三个治疗计划：基于传统CT的调强放疗（IMRT）计划、使用HU-SPR转换的调强质子治疗（IMPT）计划、利用光谱CT直接SPR图的IMPT计划（IMPT-SPR）。系统分析靶区体积和OARs（肺、心脏、脊髓）的剂量体积参数。对三个计划之间以及配对组之间进行比较剂量学分析。
所有计划均满足临床放疗要求。对于OARs（肺、心脏），IMPT计划的剂量体积参数与IMRT相比显著更低，但最大剂量（Dmax）除外。在两种IMPT方法之间，除了梯度指数在HU转换的IMPT计划中显著更高（<0.05）外，剂量体积参数未观察到统计学显著差异（>0.05）。IMPT方法之间在心脏、肺和脊髓剂量学参数上未检测到显著差异。
与IMRT相比，IMPT在保护OARs方面表现更优。对于接受质子治疗的中胸段ESCC患者，基于CT-HU转换的剂量计算在靶区覆盖和OARs保护方面显示出与双能CT衍生的SPR相当的剂量学影响。这些发现支持基于传统CT的质子治疗计划和剂量计算的临床可行性。
