CT模拟在适形调强放射治疗中的应用研究

Study on application of CT simulator to intensity modulated radiation therapy

目的将CT模拟应用适形调强放射治疗,在临床应用中探索与之相关的一系列更简便和更好的方法,为以后的调强放射治疗提供指南。方法64例肿瘤患者,其中头颈部肿瘤患者42人,胸部肿瘤患者15人,腹部和盆腔肿瘤患者7人。针对不同的患者采取不同的体位固定技术,做CT\MRI扫描,采用两种标记法标记坐标系并比较了两种方法特点,然后做三维重建、图像融合、射野布置,并对靶中心做了验证。结果CT模拟可以大大提高治疗位置的精确度,更好地避开和保护重要器官,使其受到较低的剂量,而靶区受到高适形剂量。内标记方法的位置精读和CT扫描的层厚无关,而外标记法的位置精读与扫描层厚相关。头颈部肿瘤靶点偏差小于3mm,胸部肿瘤、腹部和盆腔肿瘤,靶点偏差均小于5mm。结论CT模拟定位是适形调强放射治疗必不可少的工具,但还需更好的解决体位的固定和器官运动等问题;内外标记同时采用的方法,是一种安全、准确的方法,图像融合智能化还需要加强;三维适形的布野原则对调强放疗的布野有指导意义;采用X光模拟机验证靶中心也是一种方便可靠的方法。

[Objective] CT simulator was applied to intensity modulated radiated radiation therapy (IMRT) and a series of convenient and better methods were explored in the clinic application to guide the IMRT afterwards. [Method] Sixty-four patients with tumor were involved in the study including 42 patients with head and neck tumor, 15 patients with baenosome tumor and 7 patients with abdomen and pelvic tumor. The patients fixed with different immobility technology scanned in CT and (or) MRI were marked to record the coordinate system by two methods. Then, three dimension reconstruction, image fusion and field by two methods. Then, three dimension reconstruction, image fusion and field layout were implemented respectively and the target points were verified in the end. [Result] Location precision can be remarked enhanced with CT simulation which can avoid and protect the important organs from high radiation dose while taget volume received high conformity radiation dose. The precise of internal marked method did not related to the CT layer thickness while that of external marked method related to the CT layer thickness the deviation of the tumor target point was no more than 3 mm, 5 mm in head and neck tumor and in the baenosome tumor, abdomen tumor and pelvic turmor, respectively. [Conclusion] CT simulator is indispensable tools but there are some issue to be resolved such as the body immobilization and organ movement etc. Internal marked method combined with external marked method proved to be a secure and precise method. The intelligence of image still need to improve. The principle of the field layout in 3DCRT can guide the that of IMRT. The verification of target point by X ray simulator is a convenient and credit method.