两种自动配准方式对食管癌放疗危及器官受照剂量的影响

Dosimetric effects of two automatic registration methods on organs at risk in esophageal cancer radiotherapy

摘要:

目的 以手动配准作为参照，探讨骨性配准、软组织灰度配准对食管癌容积调强放疗危及器官受照剂量的影响。方法 选取2024年5月—2025年1月徐州市中心医院行根治性放疗的76例食管癌患者，放疗前均经胃镜病理确诊。使用锥形束CT（CBCT）系统采集患者治疗前10次的摆位验证图像，采用骨性配准、软组织灰度配准和手动配准，得到3组摆位误差，利用该误差值分别计算出每个患者的计划靶区外扩边界，重新制作容积调强放疗计划。以手动配准作为对比参照，通过剂量-体积直方图来比较不同配准方式下危及器官（肺、心脏、脊髓）的受照剂量。结果 与骨性配准、灰度配准相比较，手动配准的左右方向、腹背方向、头脚方向的摆位误差较小（P <0.05）。3种配准方式肺V5、肺V20、肺V30、肺D_mean、心脏V30、心脏V40、心脏D_mean危及器官的受照剂量比较，差异均有统计学意义（P <0.05），3种配准方式脊髓D_max危及器官的受照剂量比较，差异无统计学意义（P >0.05）。结论 采用适宜的配准方式，对千伏级CBCT图像引导食管癌放疗的摆位工作具有临床参考意义。结合实际操作，建议骨性配准结合手动调整的配准模式作为首选的配准方法。优化配准精度，对于提高放疗的安全性和疗效至关重要。

Abstract:

Objective To compare the effects of automatic bony registration and soft-tissue gray-value registration on organs-at-risk doses in volumetric modulated arc therapy (VMAT) for esophageal cancer, with manual registration as a reference.Methods Senventy-six patients with esophageal cancer who underwent radical radiotherapy at Xuzhou Central Hospital from May 2024 to January 2025 were selected, and all patients were pathologically confirmed by gastroscopy before radiotherapy. The cone beam computed tomography (CBCT) system was used to acquire pre-treatment verification images of the first 10 positions for each patient. The acquired images were then registered using bony alignment, soft-tissue gray-value alignment, and manual alignment, yielding three sets of positioning errors. The obtained error values were utilized to calculate the expansion margins of the planning target volume (PTV) for each patient, after which a new VMAT plan was generated. Manual alignment was used as the reference for comparison, and the dose-volume histograms were employed to compare the doses to the lungs, heart, and spinal cord under different alignment methods.Results The absolute positioning errors obtained through manual registration in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were lower compared with the bony registration and soft-tissue gray-value registration (P < 0.05). Statistically significant differences were observed among the three registration methods for lung (V5, V20, V30, D_mean) and heart (V30, V40, D_mean) doses (P < 0.05), whereas spinal cord D_max did not differ significantly (P > 0.05).Conclusions Using an appropriate registration method has important clinical implications for kV-CBCT-guided patient setup in esophageal cancer radiotherapy. Based on practical considerations, a bony registration combined with manual adjustment is recommended as the preferred registration strategy. Optimizing registration accuracy is crucial for enhancing both the safety and efficacy of radiotherapy.