A dosimetric study of helical tomotherapy in radiotherapy after ovarian-conserving radical surgery for young patients with early-stage cervical cancer

Abstract:

Objective：To investigate the dosimetric characteristics of helical tomotherapy（TOMO） versus intensity-modulated radiother－apy（IMRT） in radiotherapy after ovarian-conserving radical surgery for young patients with early-stage cervical cancer. Methods：A total of 21 young patients with early-stage cervical cancer were enrolled，and each of them received radiotherapy with both TOMO and IMRT. The two methods were compared in terms of conformity index（CI） and homogeneity index（HI） of target volume，dose dis－tribution in target volume and organs at risk（OARs），number of monitor units（MUs），and delivery time（DT）. Results：TOMO had sig－nificantly better CI and HI of the target volume than IMRT（CI：0.894±0.006 vs. 0.855±0.008，P=0.000；HI：1.082±0.006 vs. 1.106±0.006，P=0.023）. As for ovarian protection，TOMO had significantly lower V5 and Dmean than IMRT（V5：17.20±0.18 vs. 38.92±0.70，P=0.000；Dmean：4.21±0.03 vs. 4.82±0.04）. TOMO also had dosimetric advantages for the normal tissues，but TOMO needed a significantly higher number of MUs than IMRT（7 729±42 vs. 1 974±23，P=0.000）. These two methods had a similar DT. Conclusion：Compared with IMRT，TOMO can obtain better conformity and homogeneity of target volume and better protect the ovary and the pelvic cavity，and therefore，it is the best choice for radiotherapy after ovarian-conserving radical surgery for young patients with early-stage cervical cancer.