Author: Alonso N. Gutierrez, Matthew D. Hall, Rupesh Kotecha, Yongsook C. Lee, Michael W. McDermott, Minesh P. Mehta, Ranjini P. Tolakanahalli, D. Jay J. Wieczorek 👨🔬
Affiliation: Miami Cancer Institute, Baptist Health South Florida 🌍
Purpose: The objective of this study is to systematically evaluate and validate the performance of a commercially available 3D Linear stage device as a quality assurance (QA) tool to validate positional accuracy of the Gamma Knife (GK) High Definition Motion Management (HDMM) system.
Methods: A commercially available, crossed roller bearing linear XYZ translation stage device with 2µm linear accuracy and 0.01mm micrometer resolution was assembled and rigidly mounted on the mask adapter using a 3D custom printed base. A patient marker was attached to the front face of the device for use with the HDMM camera. A zero XYZ position was defined and 1D displacements along ±X(Left-Right), ±Y(Post-Ant) and ±Z(Sup-Inf) directions were performed in 0.2mm increments up to 2mm. HDMM readings were obtained after each incremental movement of the stage device. HDMM readings were also recorded following displacements of 0.4mm and 0.8mm in 2D and 3D directions. Readings were recorded over the course of 3 months.
Results: 1D results show that absolute maximum differences between HDMM and stage motion readings were 0.03mm in the X and Y direction and 0.06mm in the Z direction. 2D and 3D results show an absolute maximum difference of 0.10 and 0.09 mm, respectively. Differences for 0.4mm 2D and 3D displacements were found to be larger in the XZ plane and in the -X+Y+Z direction, respectively. For the 0.8mm displacements, larger differences were found in 2D displacements along the -Z(INF) direction, and 3D displacements involving the +Y(POST) direction. All HDMM readings were within the ±0.1mm manufacturer-specified tolerance.
Conclusion: The commercially available XYZ linear stage device was found to be a suitable QA tool for positional accuracy assessment of the GK HDMM system. The HDMM’s response to known stage device displacements in 1D, 2D and 3D were within ±0.1mm tolerance.