PET-CT在三维适形放射治疗晚期胰腺癌中的应用

目的：评价PET-CT在三维适形放射治疗晚期胰腺癌中靶区勾画的价值及放疗后评价疗效的意义。方法：对13例晚期胰腺癌患者,采用PET-CT检查并定位,分别勾画出大体肿瘤体积CT-GTV和PET-CT-GTV,并分别制定出三维适形放射治疗的GTV进行比较。放疗后3个月行PET-CT复查。结果：13例患者的PET-CT-GTV和CT-GTV均不同,其中5例患者PET-CT-GTV较CT-GTV平均减少10.9cm3（25.7%）。CT-GTV平均42.4 cm3,PET-CT-GTV平均为31.5cm3（P=0.0045）;8例患者的PET-CT-GTV较CT-GTV增加45.3%（27.4 cm3）,CT-GTV平均为60.4 cm3,PET-CT-GTV平均为87.8 cm3（P=0.0000）。治疗后3个月PET-CT复查示：7例胰腺病灶较前明显缩小,局部FDG代谢明显减低或消失。其余6例病灶略缩小,FDG不同程度减低。治疗后的SUVmax变化范围为1.6-6.0,SUVmean变化范围为1.4-2.2。结论：采用PET-CT融合图像能够更好地提高靶区确定的精度及不确定性,最大限度减少不同勾画者之间的差异性。治疗前后局部病灶代谢活性的不同程度改变,对评价放疗疗效具有一定的指导意义。

Application of positron emission tomography CT for three-dimensional conformal radiotherapy in advanced pancreatic cancer

Objective：To evaluate the value of PET/CT on gross tumor volume delineation and three-dimensional conformal radiotherapy for patients with locally advanced panreatic cancer and to observe the curative effects.Methods：In 13 patients with locally advanced pancreatic cancer,were scanned with both 18F-FDG PET/CT and enhanced CT,GTV was delineated based on both CT image and PET-CT fusion image（CT-GTV and PET-CT-GTV） and the GTV from each imaging technique（designated CT-GTV and PET-CT-GTV） was compared with three-dimensional conformal treatment planning and reviewed PET-CT for three months after radiation.Results：The paired CT-GTV and PET-CT-GTV values for each patient were 25.7%（10.9cm3） with a median CT-GTV of 42.4 cm3 and a median PET-CT-GTV different from each other.5 of 13 patients＇ GTV was reduced an average of 31.5 cm3（P=0.0045）;8 of 13 patients＇ GTV increased by 45.3%（27.4cm3） with a median CT-GTV of 60.4 cm3 and a median PET-CT-GTV of 87.8cm3（P=0.0000）.The lower values obtained for PET-CT-GTV were due to the ability of PET-CT to differentiate cancer induced normal tissue from gross tumor,reducing the target volume and sparing more of the surrounding normal tissue.This factor alone displays the superiority of 3DCRT using PET-CT.7 of 13 was reduced in tumor size and FDG-PET uptake was markedly reduced,the rest was changed small after three months of the treatment.Range of SUVmax and SUVmean change was 1.6-6.0 and 1.4-2.2,respectively after treatment.Conclusion：The incorporation of PET-CT fused image with gross tumor delineation improves the accuracy and uncertainty of 3DCRT for advanced pancreatic cancer patients,and reduce variability for different physicians,metabolic activity of the tumor changes in different degrees for pretherapy and posttherapy,FDG-PET-CT aids in analysis of the effectiveness of radiotherapy.