An investigation of the reproducibility of Gamma Knife DVH data in the external beam treatment planning system

Jing-Ni Chen, Purdue University

Abstract

This study is to examine the accuracy of DVH data exported from the Gamma Knife treatment planning system (Leksell GammaPlan, LGP) to the external beam treatment planning system, Varian ECLIPSE version 10. Different sizes of target volume, ranging from approximately 0.5 cm3 to 30 cm3, were created in LGP and exported to ECLIPSE with different calculation grid sizes (0.6 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm). The relationships between the sizes of the target and the grid sizes were obtained by comparing the DVH data reviewed in ECLIPSE with the DVH calculated in LGP. A general DVH comparison method, gamma analysis, was used. The results indicated that dose grid resolution does not significantly influence DVHs of larger targets (> 5 cm3) . As the gamma criteria were set more strictly, gamma value became more sensitive to the grid size. There was a trend that the gamma analysis passing rate increased as the selected grid size decreased with the identical target and as the target size increased with the same grid size selected. To conclude, dose grid resolution, target size and the dose distribution around the edge of the target were the three principal factors which influenced the accuracy of LGP DVH data in the linear accelerator TPS. This study is not limited to LGP exporting to ECLIPSE, it can be applied to any TPS exporting to another TPS.

Degree

M.S.

Advisors

Stantz, Purdue University.

Subject Area

Medical imaging

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