The analysis of clinical application of home-made immobilization device in SBRT / 中华放射肿瘤学杂志

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.