HT加速器参数调整对射线质及横截面剂量分布影响  

Influence of changing the parameters on energy and profiles of helical tomotherapy

作　　者：肖斌 岳麒[2] 张莉 王志伟[2] 杨秀美[2] 谷丹[2] 段继梅[2] 张勇[2] 

机构地区：[1]大理大学第一附属医院肿瘤科,671000 [2]昆明医科大学第一附属医院肿瘤放疗科,650032

出　　处：《中华放射肿瘤学杂志》2017年第9期1072-1076,共5页Chinese Journal of Radiation Oncology

基　　金：国家自然科学基金（81560462）;云南省自然科学基金面上项目（2016FB150）

摘　　要：研究HT机器参数电子枪电流IC、电子枪电压IV和磁控管脉冲PFN的改变对射线质（D20/D10）及射野横截面剂量分布（Profile）的影响规律,以提高对剂量稳定性的QC。方法 改变IC 、IV 和PFN值,采用电离室和TomoDose分别测出各情况下的射线质和Profile,对射线质数据进行Pearson法相关分析,对Profile数据进行比较分析。结果 对于射线质：IV和PFN与射线质均无相关性（P〉0.05）,IC与射线质有强相关性（P=0.007）且随IC增大能量比降低。对于x方向上的Profile：（1）主射野区域（-200~200 mm）,随IC增大Profile肩区明显呈规律性上升;IV从6.42 V增大到6.54 V时Profile无变化,IV=6.60 V时Profile肩区上升到最高点,之后Profile随IV增大而下降;随PFN增大Profile肩区明显呈规律性下降;（2）半影区（±200 mm以外的区域）,IC、 IV和PFN对Profile都无影响。对于y方向上的Profile：（1）主射野区域（-20~20 mm）,IC取5.40和5.46 V时在离轴距〈16 mm区域内Profile才可见上升趋势,但整体上Profile肩区随IC增大而上升;IV和PFN对Profile无影响;（2）半影区（±20 mm以外区域）,Profile随IV增大规律性下降,IC和PFN对Profile无影响。3个参数在主射野区域对Profile影响显著程度大小依次为IC、PFN和IV,半影区对Profile有影响的只有IV。结论 调节射线质时应以IC值为主,PFN作为辅助进行微调;调节Profile时主射野区域应以调节IC为主、IV为辅,半影区的调节只涉及到y方向 Profile,应调节IV。研究结果对射线质和Profile的QC具有指导性作用,能减少QC的盲目性,节省时间。Objective To investigate the impact of injection current （IC）, injection voltage （IV）, and pulse forming network （PFN） on energy （depth ratio D20/D10） and profiles of helical tomotherapy, and to improve the quality control for the stability of beam characteristics. Methods The energy and profiles were measured by ion chamber and TomoDose at different values of IC, IV, and PFN, the relationship between the energy and various parameters was evaluated by Pearson correlation analysis, and the changes in profiles were evaluated by comparative analysis. Results The energy had no correlation with IV and PFN values （P〉0.05）, but had a strong correlation with IC value （P=0.007）, which showed a downward trend with the increase in IC. For the profiles in the x direction：（1） in the main beam region （-200 to 200 mm）, the shoulder area of the profiles increased regularly with the increase in IC. There were no significant changes for the profiles when the IV values ranged from 6.42 V to 6.54 V, and the shoulder area of the profiles reached the highest point with IV=6.60 V, then decreased with further increase in IV. The shoulder area of the profiles decreased regularly with the increase in PFN.（2） In the penumbral region （±200 mm outside）, all the three parameters had no effect on the profiles. For the profiles in the y direction：（1） in the main beam region （-20 to 20 mm）, the profiles showed an upward trend in the area with an off-axis distance less than 16 mm when IC values were 5.40 V and 5.46 V, and showed an upward trend in the area with an off-axis distance less than 16 mm. But on the whole, the shoulder area of the profiles increased with the increase in IC, and was not affected by IV and PFN.（2） In the penumbral region （±20 mm outside）, the profiles decreased regularly with the increase in IV, and was not affected by IC and PFN. IC had the highest influence on the profiles in the main beam region, followed by PFN and IV. Only IV had impact on the profiles i

关 键 词：螺旋断层治疗 射线质 剂量分布 半导体探测器 

分 类 号：R730.55[医药卫生—肿瘤]