Program Information
Using the Installer Diode Tool to Track Stability of a Gamma Knife Perfexion
J Donaghue1*, S Gajdos2 , (1) The Cleveland Clinic Foundation, Cleveland, OH, (2) Cleveland Clinic Akron General, Akron, OH
Presentations
SU-I-GPD-T-552 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: By using the Elekta Install Diode Tool, establish an efficient and reproducible process in measuring key dosimetric parameters for the Gamma Knife Perfexion over time.
Methods: The Elekta Install Diode Tool (IDT) mounts directly to the treatment table and measures profile data for the Elekta Gamma Knife Perfexion for three collimator settings. The results show the offset of the isocenter position compared to the expected calibrated isocenter, which was found at install of the unit. Full Width Half Max (FWHM) and penumbra data can also be extracted from the profiles.The profiles are measured on a semi-annual basis by Elekta field service engineers. The IDT sweeps twice along the major axes in both the positive and negative directions. The center of the profile is determined by averaging the center position of the FWHM of the profile taken in both directions. For FWHM and penumbra measurements, the maximum deviation over the median range was determined.
Results: Profile data was tracked across 18 months. The FWHM, penumbra, and isocenter offset were analyzed across this time frame. All FWHM measurements were within a maximum deviation of 0.04 mm, 0.06 mm, and 0.11 mm for the 4-mm, 8-mm, and 16-mm collimators respectively. All penumbra measurements were within a maximum deviation of 0.04 mm, 0.07 mm, and 0.19 mm for the 4-mm, 8-mm, and 16-mm collimators respectively. The maximum center offset was found to be 0.061 mm, 0.066 mm, and 0. 0.81 mm for the 4 mm, 8 mm, and 16 mm collimators respectively.
Conclusion: The IDT can be used to verify that the Gamma Knife Perfexion is stable over time. Based on the reproducible results, the IDT can be valuable asset in replacing film dosimetry which can be cumbersome to utilize.
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