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 MLC+ or IMPT MLC- , 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 2% , V 90% , V 95% , homogeneity index (HI), and conformity index (CI). Organs at risk (OARs) were evaluated using the average dose (D mean) and D 2%. Furthermore, the dose to the normal brain was evaluated using from V 5Gy to V 40Gy at 5 Gy intervals. There were no significant differences among all techniques regarding V 90% , V 95% , and CI for the targets. HI and D 2% for IMPT MLC+ and IMPT MLC- were significantly superior to those for VMAT (p < 0.01). The D mean and D 2% of all OARs for IMPT MLC+ were equivalent or superior to those of other techniques. Regarding the normal brain, there was no significant difference in V 40Gy among all techniques whereas V 5Gy to V 35Gy in IMPT MLC+ were significantly smaller than those in IMPT MLC- (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 MLC+ could reduce the dose to OARs, while maintaining target coverage compared to IMPT MLC- and VMAT in treating malignant glioma. [ABSTRACT FROM AUTHOR]