Dosimetric Analysis of DVO and PO Algorithm in Pediatric Craniospinal Irradiation With Intensity-Modulated Radiotherapy

Abstract

To investigate the dosimetric characteristics between dose volume optimization (DVO) algorithm and photon optimization (PO) algorithm in postoperative intensity-modulated radiotherapy (IMRT) of pediatric craniospinal irradiation, especially comparing the volume of cervical planning target volume (PTV) receiving lower than 95% of the prescription dose. Fifteen patients who received postoperative craniospinal irradiation with IMRT were enrolled in this study. After target areas and organs-at-risk were delineated, two kinds of IMRT plans, namely DVO plan and PO plan, were designed based on DVO algorithm and PO algorithm, separately. The dosimetric characteristics and optimization efficiency of the two kinds of treatment plans were evaluated. No significant difference was found in the D2%, D98%, homogeneity index and gradient index (GI) of PTV. However, compared with PO plan, the conformity index (CI) of PTV was better in DVO plan (p = 0.015, t = -2.442),the volume of cervical PTV receiving lower than 95% of the prescription dose is lower in DVO plan (p = 0.001, t = -3.28).The Dmax, V5 and V10 of left lung,Dmax,V5 and V10 of right lung, Dmax of right kidney and heart in DVO plan were lower than those in PO plan (p = 0.02,0.002,0.002,0.005,0.002,0.013,0.02,0.002),while Dmax of left kidney, liver, eyes and lens in PO plan were no significant difference. Compared with those of PO plan, the monitor units in DVO plan was increased by an average of 4.3%, and the optimization time was extended by an average of 248.6s. The application of DVO algorithm in pediatric craniospinal irradiation with IMRT can improve the target conformity, only increased few monitor units, but can increase the optimization time. Above all, the DVO algorithm can reduce the volume of cervical PTV receiving lower than 95% of the prescription dose, which can reduce the opportunity of tumor recurrence. So, we suggest the DVO algorithm in pediatric craniospinal irradiation with IMRT.