Dosimetric comparison of pencil beam scanning proton therapy with or without multi-leaf collimator versus volumetric-modulated arc therapy for treatment of malignant glioma.

This study aimed to examine the dosimetric effect of intensity-modulated proton therapy (IMPT) with a multi-leaf collimator (MLC) in treating malignant glioma. We compared the dose distribution of IMPT with or without MLC (IMPT or IMPT, respectively) using pencil beam scanning and volumetric-modulated arc therapy (VMAT) in simultaneous integrated boost (SIB) plans for 16 patients with malignant gliomas. High- and low-risk target volumes were assessed using D, V, V, homogeneity index (HI), and conformity index (CI). Organs at risk (OARs) were evaluated using the average dose (D) and D. Furthermore, the dose to the normal brain was evaluated using from V to V at 5 Gy intervals. There were no significant differences among all techniques regarding V, V, and CI for the targets. HI and D for IMPT and IMPT were significantly superior to those for VMAT (p < 0.01). The D and D of all OARs for IMPT were equivalent or superior to those of other techniques. Regarding the normal brain, there was no significant difference in V among all techniques whereas V to V in IMPT were significantly smaller than those in IMPT (with differences ranging from 0.45% to 4.80%, p < 0.05) and VMAT (with differences ranging from 6.85% to 57.94%, p < 0.01). IMPT could reduce the dose to OARs, while maintaining target coverage compared to IMPT and VMAT in treating malignant glioma.