Impact of oral contrast agent for assisting in outlining small bowel on pelvic VMAT dose in patients with cervical cancer
10.3760/cma.j.issn.1004-4221.2014.06.003
- VernacularTitle:VMAT宫颈癌患者口服造影剂勾画小肠对盆腔剂量的影响
- Author:
Wendong GU
;
Qilin LI
;
Min GAO
;
Honglei PEI
;
Changping WU
- Publication Type:Journal Article
- Keywords:
Cervical neoplasms/volumetric modulated arc therapy;
Radiotherapy planning;
Normal tissue delineating
- From:
Chinese Journal of Radiation Oncology
2014;23(6):472-474
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the impact of oral contrast agent for assisting in outlining the small bowel on pelvic volumetric modulated arc therapy (VMAT) dose in patients with cervical cancer.Methods Nine cervical cancer patients for postoperative radiotherapy underwent CT scans,and the target volumes and organs at risk including the small bowel were contoured.The VMAT plan was designed for each case.Then another plan was generated by re-calculating the radiation dose after changing the electron density of the small bowel.The first plan (plan A) was the conventional VMAT plan,and the second one (plan B) specified the electron density of the small bowel.Paired t-test was used to compare the dose distribution between the two plans.Results The Dg8,D5o,conformity index,and homogeneity index of plans A and B were 4 989.1 vs.5 000.1 cGy (P =0.026),5 208.6 vs.5 191.6 cGy (P =0.005),0.766 vs.0.765 (P =0.920),and 0.081 vs.0.074(P =0.055),respectively.The volumes of the small bowel receiving at least 30 Gy for plans A and B were 309.3 vs.314.3 cm3(P =0.207),while bladder V45 of the two plans was 52.4％ vs.51.1％ (P =0.168).To achieve the same prescribed dose,plan A and plan B needed 893.3 MU and 865.8 MU (P =0.093).Conclusions The contrast agent filling the small bowel does not lead to a significant increase in the pelvic VMAT dose in patients with cervical cancer after surgery.
