AbstractID: 8052 Title: Quality Asssurance for the Gamma Knife using the LUCY phantom
Objectives: Stereotactic radiosurgery is a valuable tool for precise and effective treatment of brain malignances. Since the imaging,
planning and treatment with the high radiation dose occur on the same day for single fraction treatment, accuracy is critical to success. LUCY is a
spherical phantom, developed by Sandstrom Corporation, intended to be used for quality assurance purposes in stereotactic radiosurgery. The
objective of this study is to implement a QA program for the Gamma Knife based on LUCY.
Methods and Materials: Spatial accuracy and anticipated vs. measured dose output verification were evaluated using the Leksell frame
attachment in conjunction with the LUCY phantom and appropriate inserts. The deviation between stereotactic frame coordinates and volume
sizes based on CT and MRI slices in Leksell 5.31 were evaluated. Output measurements were performed with PTW ion chamber for varying
collimator helmets and compared with software generated output.
Results: The volumes, as measured with the GK software, demonstrated relatively good agreement with expected values. The
fiducial markers coordinates for CT and MRI images as well as dose congruency, both yield encouraging results. Spatial accuracy and linearity
was easily measured with the grid insert and corresponding fiducials.
Conclusion: LUCY is designed to be an all-purpose phantom for stereotactic radiosurgery. Although all components of LUCY were
not tested here, LUCY was found to be a valuable tool, particularly for Gamma Knife QA as there are no similar phantoms which can be directly
attached to the Leksell frame.
Research supported in part by Sandstrom Corporation