MRI/CT融合图像与CT图像勾画海马区在HP-WBRT中TOMO适宜参数的研究

Research on Appropriate Parameters of TOMO in HP-WBRT for MRI/CT Fusion Image and CT Image Delineation of the Hippocampal Region

目的探索MRI/CT融合图像与CT图像在勾画海马区时,螺旋断层放射治疗技术(Tomotherapy,TOMO)应用于海马保护性全脑放射治疗的适宜参数。方法选取2017年1月至2022年12月间在陕西省肿瘤医院实施海马保护性全脑放射治疗的66例患者数据为研究对象,其中36例患者海马区使用MRI/CT融合图像进行勾画,30例患者使用CT图像进行勾画。通过调整不同的调制因子(Modulation Factor,MF)、射野宽度(Field Width,FW)和螺距(Pitch)参数,采用不同的参数组合,评估治疗计划的靶区覆盖率和危及器官剂量,以探索适用于TOMO的合适参数。结果基于MRI/CT融合图像勾画的海马区体积(HPL、HPR两侧)显著大于基于CT图像勾画的海马区体积(P<0.001)。使用MRI/CT融合图像勾画海马区时,TOMO的最佳MF取值为2.7,使用CT图像勾画时最佳取值则为2.5;两者的FW最佳值均为2.5 cm;MRI/CT融合图像的Pitch最佳值为0.287,CT的Pitch取值为0.287和0.430时均符合要求。结论通过比较MRI/CT融合图像和CT图像勾画海马区时的不同参数方案,得出适用于海马保护性全脑放射治疗的TOMO适宜参数,可为优化放疗方案,提高海马保护性全脑放射治疗的准确性和安全性提供参考。

Objective To explore the appropriate parameters for the application of spiral tomotherapy(TOMO)in hippocampal protective whole brain radiotherapy in mapping the hippocampus between MRI/CT fusion images and CT images.Methods Data from 66 patients who underwent HP-WBRT at Shaanxi Provincial Cancer Hospital from January 2017 to December 2022 were collected as research objects.Among them,36 patients had hippocampal delineation based on MRI/CT fusion images,while 30 patients had delineation based on CT images.Different parameter combinations were adjusted,including modulation factor(MF),field width(FW),and pitch(Pitch),to evaluate the target coverage and organ at risk coverage of treatment plans to explore the suitable parameters for TOMO.Results The volume of the hippocampal region delineated based on MRI/CT fusion images(HPL,HPR on both sides)was significantly larger than that delineated based on CT images(P<0.001).The optimal MF for TOMO was 2.7 when using MRI/CT fusion images for hippocampal delineation,and 2.5 when using CT images.The optimal FW for both approaches was 2.5 cm.The optimal Pitch for MRI/CT fusion images was 0.287,while for CT images,both 0.287 and 0.430 met the requirements.Conclusion By comparing different parameter schemes of MRI/CT fusion images and CT mapping of hippocampus,the appropriate parameters of TOMO for hippocampal protective whole brain radiotherapy are obtained,which can provide references for optimizing radiotherapy schemes and improve the accuracy and safety of hippocampal protective whole brain radiotherapy.