Effect of RapidArc and IMRT target doses at various bladder filling status on early cervical cancer / 中国肿瘤临床

ABSTRACT

Objective:To evaluate the performance of RapidArc technique on cervical cancer patients with various filling status of the bladder. Methods: Conventional fixed field intensity modulation radiated therapy (IMRT) is used as the benchmark. In 10 fe-males suffering from cervical cancer, two CT scans were performed for treatment planningone with an empty bladder and the other with filled bladder. The prescribed dose was 50 Gy. The images of that with an evacuated bladder and that with filled bladder were planned in the dual-arc RapidArc and the 7-field IMRT, respectively. The implementor of the plan was the Varian TrueBeam linear ac-celerator. Dose-volume histogram was used to evaluate the data from each plan. Results:When the bladder was filled, IMRT and Rapi-dArc homogeneity were 1.05 and 1.04 (P>0.05), respectively. When the bladder was emptied, the homogeneity was 1.04 for both plans (P>0.05). With or without bladder filling, the conformity index was 0.71 and 0.73 for IMRT and RapidArc (P>0.05), respectively. The effect of V30 and V40 (volume for receiving doses of 30 and 40 Gy) on the intestine and the bladder was more favorable in a full than in an empty bladder. No significant difference between the two plans was observed. IMRT exhibited improved V30 on the rectum and on the bladder. RapidArc was much better in terms of monitor unit (MU) and deliver time. Conclusion:No significant differences in the homogeneity and conformity index between dual-arc RapidArc and 7-field IMRT were observed. Filled bladder is better than empty bladder in intestine and bladder protection in both RapidArc and IMRT. IMRT is better on V30 of the rectum and the bladder, whereas RapidArc improved MU and deliver time.