Objective To investigate the relationship between the body mass index (BMI)/body mass index improved (BMIIMPd) and the dose of the small intestine as well as the acute radiation colitis in the intensity-modulated radiation therapy after cervical cancer surgery.Methods Thirty-nine cervical cancer patients underwent postoperative adjuvant radiotherapy.All patients received Philips large bore CT scan for enhanced CT scan,target delineation and organ at risk.All patients were treated with a single arc 10 MV VMAT plan.The correlation between the radiation dose of the small intestine and the acute radiation enteritis and BMI/BMIIMPd was analyzed.Results The BMI was calculated as (22.23±2.80) kg/m2,BMIIMPd was (21.49±3.95) kg/m2,the small intestine volume VSI was (1 155.71 ± 419.33)cc3.The volume of the small intestine received more than 10 Gy (V10_SI) VMAT was (66.50± 27.01) ％,and the equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) were (4 098.87± 184.93) cGy and (7.98±8.73)％.One way ANOVA demonstrated that under the VMAT technology,the BMIIMPd,V30,V40,EUD (or=50) and NTCP in the small intestine were the influencing factors of the occurrence of acute radiation enteritis.Conclusions If the improved BMIIMPd is utilized to distinguish the BMI,the high dose area of the small intestine will be larger and the incidence of acute radiation enteritis will be higher for patients with BMIIMPd between 10.1 and 16.9(normal and thin).Conventional BMI cannot be utilized as a basis for the prediction of the incidence of acute radiation enteritis in patients with cervical carcinoma.