4D-CT与MR-T2图像在肝癌精准放疗中的临床研究

Clinical study of 4D-CT and MR-T2 images in accurate radiotherapy of liver cancer

目的探讨四维计算机断层扫描(4D-CT)与T2加权像扫描(MR-T2)图像在肝癌精准放疗中的临床效果。方法选择2020年1月至2021年3月就诊于齐齐哈尔医学院附属第三医院的48例肝癌患者,均接受4D-CT与MR-T2扫描,利用MIM软件实施图像配准,手动在所获图像上勾画肿瘤靶区(GTV),并通过形变配准技术将MR-T2图像中勾画的GTV形变至4D-CT各时相图像中。4D-CT各时相图像上GTV的形变配准前后分别融合为IGTV、IGTVDR,分别形变至4D-CT0时相图像上,外扩获得ITV、ITVDR,取PTV作内靶区,设计放疗计划实施治疗。比较形变配准前后IGTV体积、PTV体积、PTV剂量学与肝脏剂量学评价指标。结果形变配准后IGTV体积高于形变配准前[(421.05±82.57)cm^(3) vs.(383.94±62.65)cm^(3)],PTV体积低于形变配准前[(530.86±141.60)cm^(3) vs.(626.80±194.15)cm^(3)],差异有统计学意义(P<0.05);形变配准前后PTV剂量学评价指标比较,差异无统计学意义(P>0.05);形变配准后平均剂量(Dmean)和肝脏V5、V10、V20、V30、V40受量较形变配准前低,差异有统计学意义(P<0.05)。结论4D-CT与MR-T2图像相结合获得的IGTV可更准确反映肝癌靶区范围、运动轨迹,提高靶区勾画精确度,降低正常肝脏受照剂量。

Objective To explore the clinical effect of four-dimensional computed tomography(4D-CT)and T2 weighted imaging(MR-T2)in accurate radiotherapy of liver cancer.Methods A total of 48 patients with liver cancer who visited the Third Affiliated Hospital of Qiqihar Medical University from January 2020 to March 2021 were scanned by 4D-CT and MR-T2.The MIM software was used for image registration,and the gross tumor volume(GTV)was manually sketched on the acquired images.The GTV sketched in MR-T2 images was transformed into 4D-CT images by deformable registration technology.GTV on 4D-CT images was fused into IGTV and IGTVDR before and after deformable registration,and deformed to 4D-CT0 images respectively.ITV and ITVDR were obtained by expansion.PTV was taken as the internal target area,and radiotherapy plan was designed to implement treatment.The IGTV volume,PTV volume,PTV dosimetry and liver dosimetry were compared before and after deformable registration.Results After deformable registration,the volume of IGTV was higher than that before deformable registration([421.05±82.57]cm^(3) vs.[383.94±62.65]cm^(3)),and the volume of PTV was lower than that before deformable registration([530.86±141.60]cm^(3) vs.[626.80±194.15]cm^(3)),with statistically significant differences(P<0.05).There was no significant difference in PTV dosimetry evaluation indexes before and after deformable registration(P>0.05).The mean dose(Dmean)and liver V5,V10,V20,V30 and V40 after deformable registration were lower than those before deformable registration,and the difference was statistically significant(P<0.05).Conclusion IGTV obtained by combining 4D-CT and MR-T2 images can more accurately reflect the target area and motion trajectory of liver cancer,improve the accuracy of target area delineation and reduce the irradiation dose of normal liver.