Application of beam angle optimization for multiple intracranial metastases

Objective To study the dosimetric impact of different angle fields in intensity-modulated radiotherapy (IMRT) and the feasibility of beam angle optimization (BAO) for multiple intracranial metastases. Methods In total, 11 patients with multiple intracranial metastases were included in these analyses. Two treatment techniques were designed for each patient: the 7 equal spaced fields (BAF group) IMRT, and 7 fields by beam angle optimization (BAO group) IMRT. The dose distribution in the target, the dose to the organs at risk and normal brain tissues, and total MU in two groups were compared to explore the dosimetric differences. Results In comparison to the BAF group, the BAO group reduced the maximum dose to left and right lenses by an average of 45%, 37% (t=-5.707, -4.438, P 0.05). The BAO group reduced the maximum dose of the brainstem and the optic chiasm, as well as the number of MU, however, the differences were not statistically significant (P>0.05). Conclusions In comparison to the BAF group, the BAO group shows a similar target dose and reduces the dose for the organs at risk. For multiple intracranial metastases, IMRT protocols with BAO are feasible and beneficial. Key words: Multiple intracranial metastases; Intensity-modulated radiotherapy; Beam angle optimization; Dosimetry