Abstract: A retrospective study was conducted on 20 patients who received craniospinal irradiation in our hospital's radiotherapy center in 2019. After sketching the target area and organs at risk (OAR), the scanning CT images were transmitted to Treatment Planning System (TPS),Oncentra 4.A clinically feasible radiotherapy plan was designed for ss-IMRT and VMAT. Conformality index (CI), homogeneity index (HI), V₁₀₇, maximum dose (D_max), organ at risk (OAR) dose volume level, monitor units and treatment time were used to analyze in these groups.In VAMT group CI, HI, V₁₀₇, D_max and OAR of target areas were significantly superior to ss-IMRT group, the organ at risk dose volume level in the VAMT group was lower than the ss-IMRT groups. The VAMT group also had the less monitor units and the shorter treatment time. Dose radiation is extended and the overall dose is increased. Illustration VAMT has advantages over ss-IMRT in whole brain and spinal cord radiotherapy, but most of the patients undergoing CSI irradiation are children. Whether the increase of low dose radiation area brings adverse reactions and its clinical effects need to be further observed and studied.

Key words: Craniospinal irradiation (Step and shoot), Intensity modulated radiotherapy, Volumetric modulated arc therapy