The Effect Of MT-BBCF Carbon Fiber Belly Board On The Target And Critical Organs In Patients With Rectal Cancer Undergoing Postoperative 3D-CRT And The Position Deviation Analysis

Objective: To investigate the effect of MT-BBCF carbon fiber belly board on volume and dose distribution of the target and critical organs in patients with rectal cancer undergoing postoperative three-dimensional conformal radiation therapy and the position deviation during radiotherapy.Methods: This study enrolled 45 consecutive patients with rectal cancer who had undergone prior pelvic surgery. The belly board were applied in 20 patients, which were defined as group A, and the other 25 were defined as group B. All patients received 3D-CRT, and insured that 95% of PTV received 50Gy of radiation. Patients in group A underwent two sets of CT scans under two different methods as follows: group A1: prone alone; group A2: prone with the use of the belly board. Dose-volume information of the PTV, small bowel and bladder was observed by DVHs. Choosing ten patients from group A and group B, respectively,calculated their position deviation during radiotherapy by portal imaging system. To observe and record acute radiation reactions of all patients during radiotherapy.Results: No significant difference was found either in the volume of PTV, small bowel and bladder ,or in the mean dose to the PTV in groups A1 and A2 .The mean dose to the small bowel and bladder ,the volume of small-bowel irradiated at 10%～100% dose levels , and the volume of bladder irradiated at 30%～100% dose levels, were reduced significantly in group A2 ; Comparing to group B, the treatment position deviation was reduced significantly in the medio-lateral and cranio-caudal directions in group A (P<0.05),while the reduction in the antero-posterior direction was not of significance statistically. The incidence of 3 or more toxicity events were 15%(3/20) and 24%(6/25) in group A and group B, respectively, and there was no treatment break off or termination in group A, while 2 and 1 in group B,but statistic analysis revealed no difference.Conclusion: The application of MT-BBCF contoura carbon fiber belly board can reduce the irradiated dose and volume of small-bowel and bladder significantly in patients with rectal cancer undergoing postoperative three-dimensional conformal radiation therapy.The treatment position deviation is reduced significantly in the medio-lateral and cranio-caudal directions and the position reproducibility is good.The lower radiation-induced toxicity is discovered.So we recommend that the belly board should be applied clinically.