自制体部固定装置在SBRT放疗中的应用分析

The analysis of clinical application of home-made immobilization device in SBRT

目的 应用千伏级CBCT评价自制体部固定装置在肺部SBRT中的固定效果.方法 选取SBRT肺肿瘤患者10例（中央型、周围型各5例）,通过数据分析得到每次SBRT前后骨性配准和软组织配准的平均摆位误差.采用单因素方差分析两种型别分次间骨性配准后摆位误差差别.结果 中央型和周围型患者分次间骨性配准摆位误差在横断面左右、前后、上下方向不同（P=0.001）,分别为（0.01 ±0.32）、（-0.08 ±0.38）、（0.14±0.36） cm和（-0.23 ±0.39）、（-0.13±0.52）、（0.21±0.33） cm,上下方向误差最大（P=0.003）,左右方向误差最小（P=0.001）.总平均误差分别为（0.09±0.33）、（-0.10±0.44）、（0.17±0.35） cm,效果优于其他常见固定方式.利用骨性配准分次内摆位误差为（0.00±0.00） cm.软组织配准的结果也类似.结论 自制体部固定装置可降低SBRT中肺肿瘤运动范围,提高摆位精度.

Abstract： Objective To evaluate the effect of home-made immobilization device with KV-CBCT in lung-SBRT and investigate its clinical use value.Methods Choosing 10 lung tumor patients （half centre type tumor;half peripheral type） random analysis the interfractional and intrafractional setup errors in the SBRT process by this fixed device with KV-CBCT.The concrete method is using Varian＇s KV-CBCT scans the patients before and after the SBRT each time,then make the registration between the reconstructed 3 d image and the planned CT image （both based on bone landmark）,we then obtain the average setup errors in LR,AP and SI directions.Simultaneously,this research make contrastive analysis of setup errors among this fixed device and other fixed devices such as vacuum pad,phantom in body IMRT.All data make one-factor analysis of variance by SSPS 17.0.Results All the setup errors data was gaussian distribution,the centre type interfraction was at （0.01 ±0.32） cm （LR）,（-0.08 ±0.38） cm （AP）,（0.14 ±0.36） cm （SI） of the cross section,peripheral type interfraction was at （0.01 ± 0.32） cm （LR）,（-0.08 ± 0.38） cm （AP）,（0.14 ± 0.36） cm （SI） of the cross section （P =0.001）.We found out that the average of lung tumor＇s setup error at all three directions have no significant difference-the largest was the AP directions （P =0.003）,the second was the SI direction （P =0.003） and the smallest was the LR direction （P =0.001）.The central type has no significant difference at three directions.Compare to the other fixed device,the average setup errors of our device are （0.09 ± 0.33） cm （LR）,（-0.10 ± 0.44） cm （SI）,（0.17 ±0.35） cm （AP） better than the report at present paper.As the interfraction setup error was small enough by using this fixed device while it has beyond the system algorithm,the registration software of system shows （0.0 ± 0.0 cm）.Conclusions The range of lung tumor motion can be cut down obviously and enhance each placement accuracy,repeatability,on SBRT with home-made immobilization device.