摘要
【目的】分析电子射野影像系统（EPID）在鼻咽癌放射治疗中的临床应用价值。【方法】选取适形放疗的鼻咽癌患者30例，每拍一次电子射野影像片（EPI），拍摄正位片（机架角为0°）和侧位片（机架角为90°）共计2张。拍摄正、侧位片时射野面积一般取10cm×10cm，机器跳数为3～4MU。将射野片和计划系统中的数字重建射野（DRR）图像片进行误差比较。【结果】三个方向的偏差和国内的文献相比，没有很大的差别。表明医用直线加速器的质量保证都在国家标准范围内，使用热塑面膜固定技术产生的偏差大约是2～3mm。【结论】建议每次鼻咽部肿瘤放射治疗前，于EPID下进行实时摆位纠正误差。这样可以进一步降低摆位的系统误差和随机误差，提高摆位精度，减小CTV到计划靶区的外扩边界，提高放射治疗增益比。
[ Objective]To analyze the clinical effect of electronic portal imaging device （EPID） in radiotherapy of nasopharyngeal carcinoma （NPC）. [Methods]Thirty NPC patients receiving conformal radiation therapy （CRT） were enrolled in the study. Electronic portal imaging was performed for twice before each treatment at the position AP （gantry angle 0°） and LT （gantry angle 90°） , respectively. The field size was 10 cm × 10cm, and the monitor unit was 3-4MU. The set-up errors were analyzed by comparing the films of digitally reconstructed radiographs （DRR） with EPID. [Results] The errors in three dimensions were likely to the results of many other researches which indicated that the quality assurance of our accelerator was within the national standards. The error caused by thermoplastic immobilization was 2- 3 mm. [Conclusion] Position errors should be corrected at actual time under EPID before each radiotherapy of NPC to reduce the errors of system and random, improve the set-up precision, reduce the margin from CTV to PTV, and increase the ratio of therapeutic enhancement.
出处
《医学临床研究》
CAS
2008年第7期1239-1241,共3页
Journal of Clinical Research
