Wang Xuetao, Zhang Bailin, He Qiang, Kong Yilin, Dai Zhenhui, Meng Haoyu, Huang Fangjun, Zhang Shengfeng, Zhu Yuanhu, Tan Xiang, Zhen Xin
Radiation Oncology Department, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
School of Biomedical Engineering, Southern Medical University, Guangzhou, China.
Front Oncol. 2021 Apr 16;11:657208. doi: 10.3389/fonc.2021.657208. eCollection 2021.
This retrospective study aimed to evaluate the dosimetric effects of a rectal insertion of on rectal protection using deformable dose accumulation and machine learning-based discriminative modelling.
Sixty-two patients with cervical cancer enrolled in a clinical trial, who received a injection of 20 g into their rectum for rectal protection high-dose rate brachytherapy (HDR-BT, 6 Gy/f), were studied. The cumulative equivalent 2-Gy fractional rectal surface dose was deformably summed using an in-house-developed topography-preserved point-matching deformable image registration method. The cumulative three-dimensional (3D) dose was flattened and mapped to a two-dimensional (2D) plane to obtain the rectal surface dose map (RSDM). For analysis, the rectal dose (RD) was further subdivided as follows: whole, anterior, and posterior 3D-RD and 2D-RSDM. The dose-volume parameters (DVPs) were extracted from the 3D-RD, while the dose geometric parameters (DGPs) and textures were extracted from the 2D-RSDM. These features were fed into 192 classification models (built with 8 classifiers and 24 feature selection methods) for discriminating the dose distributions between pre- and pro-.
The rectal insertion of dialated the rectum in the ambilateral direction, with the rectal column increased from pre- 15 cm to post- 18 cm ( < 0.001). The characteristics of DGPs accounted for the largest portions of the top-ranked features. The top-ranked dosimetric features extracted from the posterior rectum were more reliable indicators of the dosimetric effects/changes introduced by the rectal insertion of . A significant dosimetric impact was found on the dose-volume parameters D-D extracted on the posterior rectal wall.
The rectal insertion of incurs significant dosimetric changes on the posterior rectal wall. Whether this effect is eventually translated into clinical gains requires further long-term follow-up and more clinical data for confirmation.
本回顾性研究旨在利用可变形剂量累积和基于机器学习的判别模型评估直肠插入[具体物质未提及]对直肠保护的剂量学影响。
研究了62例参加一项临床试验的宫颈癌患者，这些患者在高剂量率近距离放疗（HDR - BT，6 Gy/次）时接受了向直肠内注射20 g[具体物质未提及]以保护直肠。使用自行开发的保留地形的点匹配可变形图像配准方法对累积等效2 - Gy分次直肠表面剂量进行可变形求和。将累积三维（3D）剂量进行扁平化处理并映射到二维（2D）平面以获得直肠表面剂量图（RSDM）。为进行分析，直肠剂量（RD）进一步细分为：整体、前部和后部3D - RD以及2D - RSDM。从3D - RD中提取剂量体积参数（DVPs），同时从2D - RSDM中提取剂量几何参数（DGPs）和纹理。将这些特征输入192个分类模型（由8个分类器和24种特征选择方法构建），以区分术前和术后的剂量分布。
直肠插入[具体物质未提及]使直肠在双侧方向扩张，直肠柱长度从术前的15 cm增加到术后的18 cm（P < 0.001）。DGPs的特征在排名靠前的特征中占比最大。从直肠后部提取的排名靠前的剂量学特征是直肠插入[具体物质未提及]所引入的剂量学效应/变化的更可靠指标。在直肠后壁提取的剂量体积参数D - D上发现了显著的剂量学影响。
直肠插入[具体物质未提及]会对直肠后壁产生显著的剂量学变化。这种效应最终是否转化为临床获益需要进一步的长期随访和更多临床数据来证实。
