利用拐点重定义FFF射束半影及射野尺寸的方法研究  

Study on FFF Beam Penumbra and Filed Size Re-definition Method Based on Inflection Point

作　　者：秦建军[1] 夏林云[1] 王昊 赵飞 QIN Jian-jun;XIA Lin-yun;WANG Hao;ZHAO Fei(Jiangyin People's Hospital,Jiangyin,Jiangsu,214400,China;Dongfang Hepatobiliary Surgery Hospital,Shanghai,200438,China;China Nuclear Ankerui(Tianjin)Medical Science Co.LTD.,Tianjin,300300,China)

机构地区：[1]江苏省江阴市人民医院,江苏江阴214400 [2]海军军医大学第三附属医院,东方肝胆外科医院,上海200438 [3]中核安科锐(天津)医疗科技有限责任公司,天津300300

出　　处：《中国血液流变学杂志》2022年第2期319-323,共5页Chinese Journal of Hemorheology

摘　　要：目的探讨临床使用的未均整射束(flatten-filter-free,FFF)半影及射野尺寸的重新定义方法,为临床放疗物理质控与评估提供参考。方法分析临床常用的FFF射野(标称射野10 mm、20 mm、25 mm、40 mm、60 mm)离轴剂量比曲线,并确定曲线中拐点位置。根据拐点建立新的半影及射野尺寸定义体系,并与传统定义方法得到的结果进行对比。结果5个FFF射野各离轴比曲线上确定的拐点位置较固定;利用拐点法确定的半影分别为(2.40~2.82)mm、(2.51~3.01)mm、(2.64~3.43)mm、(2.41~3.51)mm、(3.31~6.06)mm,比传统定义的半影区小(P=0.0000、P=0.0002、P=0.0003、P=0.0000、P=0.0013),且能更准确反映射野边缘的变化范围;拐点法确定的5个射野尺寸分别为(10.20±0.01)mm、(20.60±0.01)mm、(25.51±0.01)mm、(41.49±0.00)mm、(61.51±0.01)mm,比传统定义的射野尺寸稍大(P=0.0000、P=0.0000、P=0.0003、P=0.0000、P=0.0006),且更能准确表达原射线的射野范围。结论利用离轴比曲线拐点的方法定义半影及射野尺寸的方法相比传统方法更适用于FFF射束。Objective To evaluate the new method of defining penumbra and field size for FFF beam,and provide new reference for radiation physics evaluation and QA procedure.Methods Inflection points were analyzed in FFF beam(nominal field size:10 mm,20 mm,25 mm,40 mm,60 mm)Off-Center-Ratio profiles,and were set as reference points for penumbra and field size re-definition system.Results were compared with value calculated by previous method.Results The inflection points position determined in 5 FFF beam fields had good consistency.IP based penumbra values were(2.40-2.82)mm,(2.51-3.01)mm,(2.64-3.43)mm,(2.41-3.51)mm,(3.31-6.06)mm,which were smaller and better represented field edge regions compared to traditional-based method(P=0.0000,P=0.0002,P=0.0003,P=0.0000,P=0.0013).IP based field sizes were(10.20±0.01)mm,(20.60±0.01)mm,(25.51±0.01)mm,(41.49±0.00)mm,(61.51±0.01)mm,and larger compared with traditional-based method(P=0.0000,P=0.0000,P=0.0003,P=0.0000,P=0.0006),which reflected the collimated primary beam fields.Conclusion It is a better way to define FFF beam penumbra and field size based on inflection points in OCR profile.

关 键 词：FFF射束 离轴比 拐点 半影 射野尺寸 

分 类 号：R815.6[医药卫生—放射医学]