Objective To explore the apllication of GT-MRI fusion images in deterning the target region in intensity-modulated radiation therapy (IMRT) for prostate cancer. Methods All the patients underwent pelvic CT and MRI scans. All of the collected images were automatically matched and then were sent to the treatment planning system for image fusion. The target region, and the rectum and bladder were delineated based on the CT and CT-MRI fusion images. Two kinds of IMRT planning were designed. The volume of target region and the irradiated volume of the rectum and bladder were compared between the two approaches. Results The mean CTV on CT and CT-MRI fusion images was 75.13 cm3 and 56.67 cm3, respectively (t= 2.522, P= 0.024). Conclusions The mean CTV on CT-MRI fusion imagea is smaller than that on CT images. IMRT based on CT-MRI fusion images for determing the target region can obviously reduce the irradiated volume of the rectum receiving high dose of irradiation.%目的:探讨CT-MRI 融合图像在前列腺癌调强放疗靶区勾画中的应用及对正常组织受照剂量的影响.方法:对25 例前列腺癌患者先后进行CT 和MRI 图像采集.将采集到的图像自动配准后图像融合.分别在CT 和CT-MRI 融合图像上勾画靶区和直肠、膀胱等危及器官,再对其分别做调强放疗计划,比较两种计划中靶区体积、直肠和膀胱受照体积差异.结果:CT 和CT-MRI 融合图像上勾画的靶区体积分别为75.13、56.67 cm3(t ＝ 2.522,P ＝ 0.024).结论:CT-MRI 融合图像上勾画的靶区体积比CT 图像上小,用CT-MRI 融合图像勾画靶区制定调强放疗计划比单纯用CT 图像可明显减少受较高剂量照射的直肠体积.
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