CAJ | 학술논문

目的制定鼻咽癌调强放疗计划时,通过控制直线加速器二级准直器的位置及角度以达到更好地限制头颈部危及器官的受照剂量.方法应用Eclipse计划系统针对10例鼻咽癌患者分别制定T1、T2模式调强放疗计划.T1模式采用0°、52°、106°、160°、212°、258°、308°方向射野,二级准直器位置及角度不做限制,设置优化参数进行剂量运算.T2模式保持射野方向和优化参数与T1相同,根据每个计划实际情况适当修正射野二级准直器位置和角度,然后进行剂量运算.通过剂量体积直方图比较两种模式下计划的计划靶体积和危及器官剂量分布.结果 T1、T2模式调强放疗计划的计划靶体积均满足剂量要求,适形指数分别为0.82、0.83(t=-0.25,P=0.815).危及器官中晶状体、眼球、视神经和角膜的最大剂量分别降低28.7%(t=4.80,P=0.000)、2.7%(t=2.99,P=0.021)、1. 4%(t=1.05,P=0.032)和30.5%(t=2.99,P=0.020),腮腺平均受量和V35增加0.6%和9.9%(t=-2.82,P=0.043;t=-2.05,P=0.038).结论与T1模式相比,适当控制二级准直器的位置和角度能更好减少散射线及漏射线对眼球特别是晶状体的影响,但会略增加腮腺受量.
목적 제정비인암조강방료계화시,통과공제직선가속기이급준직기적위치급각도이체도경호지한제두경부위급기관적수조제량.방법 응용Eclipse계화계통침대10례비인암환자분별제정T1、T2모식조강방료계화.T1모식채용0°、52°、106°、160°、212°、258°、308°방향사야,이급준직기위치급각도불주한제,설치우화삼수진행제량운산.T2모식보지사야방향화우화삼수여T1상동,근거매개계화실제정황괄당수정사야이급준직기위치화각도,연후진행제량운산.통과제량체적직방도비교량충모식하계화적계화파체적화위급기관제량분포.결과 T1、T2모식조강방료계화적계화파체적균만족제량요구,괄형지수분별위0.82、0.83(t=-0.25,P=0.815).위급기관중정상체、안구、시신경화각막적최대제량분별강저28.7%(t=4.80,P=0.000)、2.7%(t=2.99,P=0.021)、1. 4%(t=1.05,P=0.032)화30.5%(t=2.99,P=0.020),시선평균수량화V35증가0.6%화9.9%(t=-2.82,P=0.043;t=-2.05,P=0.038).결론 여T1모식상비,괄당공제이급준직기적위치화각도능경호감소산사선급루사선대안구특별시정상체적영향,단회략증가시선수량.
Objective To study the efficacy of using multileaf collimators with different position and different degree in the treatment of nasopharyngeal carcinoma (NPC) using intensity-modulated radiotherapy techniques. Methods Ten patients with NPC were administered and analyzed. The penumbra characteristics, dose of target, and radiation conformal indexes (CI) of mode T1 and mode T2 were measured and compared using dose volume histogram generated by Varian Eclipse three-dimensional planning computer system. Mode T1 :The angles of seven coplanar beams were 0°, 52°, 106°, 160°, 212°, 258°and 308°,respectively. There were no restriction on the position and degree of multileaf collimators. Parameters were set and optimized. Mode T2 :The beam angles and the parameters were as same as mode T1. According to the actual situations, the position and the degree of the multileaf collimators were changed. Then thedose optimization was performed. Results Target dose coverage in both mode T1 and T2 could be clinically accepted, and the CI were 0. 82 and 0. 83(t = -0. 25, P =0. 815). The maximum dose reductions in the lens, eyes, optic nerves and corneas were 28. 7% (t = 4. 80, P = 0. 000), 2. 7% (t = 2. 99, P = 0. 021),1.4%(t= 1.05,P=0.032), and 30.5% (t=2.99,P=0. 020), respectively. However, the mean dose and V35 of the parotid were increased by 0. 6% (t = - 2. 82, P = 0. 043) and 9.9% (t = - 2. 05, P =0. 038). Conclusions Opimization of multileaf collimators can reduce the scattering and leaking rays. Compared with mode T1 ,controlling the position and degree of multileaf collimators could reduce the radiation dose to the eyes and optic-nerves, especially to the lens.