Objectives: To validate the calculated absolute dose and dose distribution from a new commercial planning software dedicated for treating multiple brain metastases using a single setup isocenter and multiple non-coplanar dynamic conformal arcs technique.

Methods: Three types of measurements were performed to validate the planning software: 1, dual micro ion chambers were used with acrylic phantom to measure the absolute dose; 2, three dimensional cylindrical phantom with dual diode array was used to evaluate 2D dose distribution and Gamma Index (GI) passing rate for four different plans; and 3, three dimensional pseudo-in-vivo patient specific phantom filled with Vinyl-pyrrolidone polymer gels was used to evaluate the accuracy of 3D dose distribution and radiation delivery.

Results: Micro chamber measurement of two targets of 1.2 cc and 0.9 cc showed that the percentage differences of the absolute dose at both targets are less than 1%. Averaged GI passing rate of four different plans measured with diode array phantom is above 98%, using a gamma analysis criteria of 3% dose difference, 1 mm distance to agreement (DTA), and 10% low dose threshold. 3D gel phantom measurement results demonstrated a 3D displacement of nine targets of 0.7 ± 0.4 mm (range 0.2~1.1 mm). By the use of selected axial slices that encompass each one of the nine targets, the GI passing rate is 98.7% (5% dose difference, 2mm DTA, and 10% low dose threshold). Measured D95, the minimum dose that covers 95% of the target volume, of the nine targets is 0.7% less than the calculated D95.

Conclusions: Three different types of dosimetric verification methods were used and proved the dose calculation of the new automatic brain metastases planning (ABMP) element is clinical acceptable. The 3D pseudo-in-vivo patient specific gel phantom test also served as an end-to-end test for validating not only the dose calculation, but the treatment delivery accuracy as well.