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Verification of Stereotactic Center of GammaKnife Machine Determined by CBCT

J Feng1*, Y Yang2 , S Miao1 , Y Du3 , (1) Tianjin University, Tianjin,(2) Department of Radiotherapy,Tianjin First Central Hospital, Tianjin,(3) Johns Hopkins University, Baltimore, MD


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: A CBCT imaging system is available with Leksell GammaKnife ICON machine (Elekta) and a stereotactic reference can be set up by a CBCT scan of patient when the GammaKnife Frame G and index box are or cannot be used. We conducted a phantom study to analyze the accuracy of the stereotactic center definition by CBCT.

Methods: A phantom (Standard Imaging, Lucy 3D QA) was scanned with a CT simulator (GE, Optima CT580) and one point within the phantom center region was chosen as the reference point for the verification study. A T1 image set of the phantom was obtained using an MRI scanner (GE, Signa Artist) for treatment planning. The two image sets were registered in Leksell Gamma Plan (LGP) and one shot was created, placed at the reference point in the phantom and made coincident with the center of ICON (at 100mm,100mm,100mm). The first CBCT scan of the phantom was then acquired for stereotactic reference definition of ICON. After completion of planning, the second CBCT scan was acquired for verifying the positions of the shot and ICON center determined by the CBCT. Locations of four fiducial marks with known positions inside the phantom were measured for quantification of the accuracy.

Results: Data from nine repeated experimental tests were analyzed. The averaged displacement of stereotactic center definition was 0.07mm in X, 0.08mm in Y and 0.05mm in Z directions, respectively. The maximum standard deviation was 0.04mm.

Conclusion: The reported method can be used for QA check of the stereotactic reference definition by CBCT.


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Not Applicable / None Entered.

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