The Analysis of Clinical Application of the Homemade Prone Immobilization Device

Objective:To analysis the influence of in-house prone immobilization device for intestine dose,setup error and patient's comfort.Methods: 24 cases with rectum cancer treated by radiotherapy were randomly divided into reserch guoup with 12cases and matched group with the other 12cases.The reserch guoup was used in-house prone immobilization device with thermoplastic mask.The matched group was used conventional Carbon fiber floor prone immobilization device with thermoplastic mask.The location image was delivered into TPS by DICOM.The CRT plan was designed with BOX technique and target dose was 1.8 Gy/f ×25 fractions.The delivered doses of intestines are retrieved with DVH,0°and 90°DRR images was transmitted into iViewGT.The set-up images were obtained by EPID and the set-up errors in x 、y、z direction was get by comparing the set-up image and DRR on iviewGT workstation.Questionnaires of comfort were also made for patients of the two groups.Results: Compared with matched group,the research group is decreased in different part of intestine volume radiated by different dose level.The reserch group's set-up error in x 、y、z directions is 0.28 cm±0.11 cm、0.24 cm±0.06 cm、0.28 cm±0.13 cm separately.The matched group's set-up error in x 、y、z directions is 0.32 cm±0.10 cm、0.26 cm±0.14 cm、0.29 cm±0.12 cm.According feedback of Questionnaires,patient's comfort is similar for the two groups.Conclusions: Compared with matched group,the in-house fixation device can decrease delivered dose of intestine obviously and has the similar setup error and comfort.