肺癌调强放疗计划的设计

Intensity-modulated radiotherapy plan for lung cancer

目的:三维适形放射治疗是目前肺癌放射治疗的标准方法,研究怎样优化计划才能设计符合治疗要求的IMRT放疗计划。方法:随机选择1例肺癌患者,进行CT扫描、靶区和危及器官的勾画,用放射治疗计划系统进行IMRT计划设计,对计划进行优化直到找到最优解或满足临床医生所设定的条件,优化过程中通过改变照射野数目、射野角度、调强参数和各目标函数等多次实验达到临床医生能接受的标准。结果:在保证靶区剂量的同时,能很好地控制肺V20,大大降低了病人治疗后患放射性肺炎的几率,而且能保证脊髓、心脏等重要器官未超过耐受剂量。结论:该计划是一个能被临床医生所接受的计划。IMRT放疗技术主要是通过提高肿瘤靶区的适形度以增加照射剂量,同时减少正常组织照射体积和剂量,增加肿瘤控制而不增加正常组织照射量的方式来提高肺癌放疗增益比。

Objective To make the intensity-modulated radiotherapy （IMRT） plan be more suitable for the requirements of treatment, by the optimization plan of three dimensional conformal radiotherapy, the standard method for lung cancer radiotherapy at present. Methods One patient with lung cancer was selected to undergo CT scan, and delineate target volume and organs at risk （OAR） in planning target volume （PTV）. The IMRT plans, designed by treatment planning system （TPS）, was optimized until the optimal solutions or conditions were found or the solutions and conditions satisfied clinical doctors. Plan was optimized by changing the number of the radiation field, beam angle, intensity-modulated parameters and objective functions for many times to reach the standard which clinical doctors can accept. Results The plan ensured the target dose, and at the same time achieved a good control of the whole lung V20, greatly reducing the risk of contracting radioactive pneumonia for patients after the treatment, and guaranteeing that the doses on spinal cord, heart and other vital organs were not more than the tolerance dose. Conclusions The plan can be accepted by clinical physicians. The dose for thoracic tumor radiotherapy is also constrained by the various complications developed by radiation damage, such as esophageal and cardiovascular radioactivity injury and radiation myelopathy. IMRT increases the exposure dose mainly by developing the conformity of PTV in the meantime, improves the gain ratio of lung cancer radiotherapy by reducing the radiation exposure volume and dose to normal tissue and strengthening the tumor control without increasing the exposure dose on normal tissue.