自制定位装置对喉癌CT-MRI图像放疗靶区勾画影响

目的 使用自制定位装置对喉癌患者进行CT-MRI图像融合的探索,分析图像融合的精度和融合后靶区勾画的变化。方法 选择10例喉癌患者使用自制定位装置固定体位进行CT、MRI图像采集,应用互信息+手动融合法将图像融合,通过测量两幅图像内、外标记点位置偏差和GTV交叠度(P_CT-MRI)来评价图像融合精度。依据CT、MRI、CT-MRI图像勾画GTV的V_CT、V_MRI、V_CT-MRI,计算V_CT和V_MRI重叠部分的体积V_CT-MRI,单因素方差分析差异性。结果 3个外标记点x、y、z轴向上平均位置偏差分别为(0.996±0.222)、(1.146±0.291)、(1.368±0.298) mm (P=0.000);内部解剖标志点平均位置偏差分别为(0.476±0.151)、(0.561±0.083)、(0.724±0.125) mm (P=0.000);V_CT、V_MRI、V_CT-MRI分别为(26.355±7.876)、(33.556±7.407) cm³、(19.875±8.588) cm³(P=0.000);P_CT-MRI为(73.7±9.8)%。结论 应用自制定位装置可提高CT、MRI图像采集时的体位一致性;CT-MRI图像可提供更多的信息增加靶区定义精确性。

Application of a self-made positioning device in laryngeal CT-MRI image fusion

Objective To investigate the application of a self-made positioning device in CT-MRI image fusion in patients with laryngeal tumor,as well as the precision of image fusion and the changes in target volume delineation after fusion.Methods A total of 10 patients with laryngeal cancer were enrolled,and a self-made positioning device was used to collect CT and MRI images in a fixed position.These images were fused by mutual information combined with manual fusion.The precision of image fusion was assessed by the positional deviation of internal and external markers and degree of gross tumor volume (GTV) overlap (PCT-MRI) between CT and MRI images.GTV was contoured based on CT images (VCr),MRI images (VMRI),and fused images (VCT+MRI).The overlapped volume of VCT and VMRI(VCT-MRI) Was calculated,and the target volume was analyzed and compared.Results The positional deviations of three external markers in the three directions were 0.996±0.222 mm,1.146±0.291 mm,and 1.368±0.298 mm (P=0.000),respectively,while those of the internal markers were 0.476±0.151 mm,0.561±0.083 mm,and 0.724± 0.125 mm (P=0.000),respectively.VCT,VMRI,VCT+MRI,and VCT-MRI were 26.355±7.876 cm3,33.556± 7.407 cm3,40.036±7.627 cm3,19.875±8.588 cm3(P=0.000),respectively.PCT-MRI was 73.7％±9.8％.Conclusions The self-made positioning device can improve the consistency of position during the collection of CT and MRI images,and fused CT-MRI images can provide more information and improve the precision of target volume delineation.