摘要
目的：探讨鼻咽癌的合理照射体位及设野的剂量分布特点，比较几种体位固定方法的摆位重复性和位移情况。方法：利用 TPS探讨常规和改进体位下设野的合理性和剂量分布特点；将 120例鼻咽癌随机均分成砂袋组、面罩组、泡沫塑枕组和等距离照射（ SSD）组，利用模拟机模拟定位和治疗过程 ,并分别摄取头颅侧位片，测量各照片间中心点的移动距离。结果：改进体位和设野与常规设野比较靶区中心剂量差别不大，但明显提高了茎突后、后组筛窦和眶尖等靶区边缘的剂量，降低了脑干中、脊髓、口腔和下颌角区的剂量；各组间摆位重复性的差别无统计学意义，放疗过程中发生位移的例数 SSD组和砂袋组明显多于其它两组。结论：改进体位有利于合理布野，避免射野间的重叠，配合低熔点铅挡块技术，能使靶区剂量分布更均匀； SSD照射和砂袋固定法不宜继续使用，泡沫塑枕值得临床推广，面罩在改进后可继续使用。
Objective： The current study was designed to seek the reasonable irradiation posture for nasopharyngeal carcinoma and analyze the dose distribution between modified posture and routine posture and the duplicability and reliability of immobilization. Methods： Treatment planning system(TPS) was used to seek the reasonable posture and dose distribution of radiation fields between routine irradiation posture and modified irradiation posture;120 patients were randomly assigned into 4 groups： cotton- pillow and sand- bag group, plastic mask group, foam- plastic- pillow group and source skin distance irradiation group (SSD group). Every patient was taken lateral radiographs of the skull under the simulator simulating the course of the setting of position and treatment. The moving distance of center in radiographs was measured. Results： There was little difference of radiation dose on the central target area between the improved field planning and routine treatment planning, but the former increased radiation dose significantly on the edge of the target area and reduced dose of brain stem, spinal cord, oral cavity and angled of the mandible. The repetition of these posture had no significant difference. Immobilization reliability was worse in the posture with SSD, cotton- pillow and sand- bag group. Conclusion： The modified posture benefits improving of reasonable irradiation field and avoiding overlap of various fields. Addition with the technique of low- melting- point lead block will result in dose distribution of the target more equally. The posture with SSD, cotton- pillow and sandbag should not be further used. The method with foam- plastic- pillow is worthy to recommendation for clinical application. Immobilization method with plastic mask can be used clinically after improvement.
出处
《癌症》
SCIE
CAS
CSCD
北大核心
2000年第11期1058-1060,共3页
Chinese Journal of Cancer
关键词
鼻咽肿瘤
放射治疗
体位
设野
体位固定
Nasopharyngeal neoplasms； Radiotherapy； Radiation fields； Position； Postural immobilization
