直肠癌术后调强放疗和三维适形放疗剂量学比较研究

目的比较研究直肠癌术后调强放疗（IMRT）和三维适形放疗（3DCRT）时靶区及其周围危及器官受照剂量的差异。方法随机选择6例直肠癌术后患者，进行CT扫描、靶区和危及器官的勾画，用三维治疗计划系统进行3DCRT和IMRT计划设计，并对结果进行比较分析。结果IMRT计划PTV的均匀性（1．09±0．02）和适形度（0．81±0．08）均优于3DCRT计划（1．17±0．01，0．66±0．05），差异具有统计学意义（P〈0．05）。IMRT与3DCRT相比，在50Gy的高剂量区，膀胱的V50下降了10％，小肠的V50下降了4％，差异具有统计学意义（P〈0．05），而左、右股骨头的差异无统计学意义。结论在直肠癌术后放疗中，IMRT技术较3DCRT技术有剂量学方面的优越性。

Dosimetric study of intensity-modulated radiotherapy and 3-dimensional eonformal radiotherapy for postoperative rectal cancer

Objective To compare the dosimetric difference of the planning target volume (PTV) and the organs at risk (OAR) for postoperative patients with rectal cancer on 3-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRD). Methods Six postoperative patients with rectal cancer were chosen randomly. They were marked by CT scan and the PIV and OAR were contoured. The treatment plans were designed into 3DCRT and IMRT by TPS. Finally, the dose distribution was compared. Results IMRT plans showed a significant superior uniformity (1.09±0.02) and conformity (0.81±0.08) over 3DCRT for PTV (1.17±0.01, 0.66±0.05)(P <0.05). IMRT as compared with 3DCRT, the percentage volume of bladder and small intestine which received 50 Gy was reduced by 10% and 4% (P <0.05). But the differences of the femoral head (left & right) have no statistical significance. Conclusion In postoperative radiotherapy for rectal cancer, IMRT have more dosimetric advantages than 3DCRT.