双模外标志用于脑肿瘤放疗图像配准的可行性研究

Feasibility of Dual-mode External Marker as Images Registration for Brain Tumor Radiotherapy

目的探讨自制CT-MRI双模外标志用于脑肿瘤放疗图像配准的可行性。方法选取在T1WI上信号强度为最高的Gd-DTPA稀释液与碘海醇按不同比例配成混合液,测量不同比例混合液在MR各成像序列的信号强度及CT值;将符合双模成像标准的混合液密封于细塑料管中制成外标志,作体模检测,并应用于临床。选取脑肿瘤患者15例,按放疗计划要求行CT、MR扫描。数据传至Varian工作站作Match points配准。结果在T1WI上信号强度为最高的Gd-DTPA稀释液浓度为1.61 mg/ml;该稀释液与碘海醇按6:1混合符合双模外标志成像要求;经临床应用,配准平均误差为(1.35±0.22)mm。结论将浓度为1.61 mg/ml的Gd-DTPA稀释液与碘海醇按6:1混合密封于细塑料管中,制成双模外标志,固定在定位热塑面罩的模拟校准线上,可作为脑肿瘤放疗图像配准的外标志。

Objective To investigate the feasibility of CT-MRI dual-mode external marker as images registration for brain tumor radiotherapy. Methods The Gd-DTPA diluents with maximum value of the signal intensity in T1WI was mixed with different proportions of iohexol. The signal intensity of T1WI, T2WI and FLAIR in MR and CT value were measured. The intermixture with a right proportion was sealed in a thin plastic pipe as the dual-mode external marker and applied in clinic.Its feasibility was evaluated by QA phantom test.Fifteen patients with brain tumor underwent CT and MR scanning according to radiotherapy planning requirements.The data was transmitted to Varian workstation for Match points registration.Results The diluted concentration of 1.61 mg/ml had the maximum value of the signal intensity in T1WI.The intermixture of Gd-DTPA diluents and iohexol by 6:1 was chosen as CT-MRI dual-mode external marker.The mean error was(1.35±0.22) mm in images registration.Conclusion The intermixture, Gd-DTPA dilution with concentration of 1.61mg/ml and iohexol by 6:1 might be chosen as the dual-mode external marker of images registration for brain tumor radiotherapy.