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SU‐FF‐T‐528: Retrospective Analysis On Patient Localization Accuracy for Linac‐Based Intracranial Stereotactic Radiosurgery Using Frameless System
Author(s) -
Wang J,
Rice R,
Pawlicki T,
Mundt A,
Murphy K
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3182026
Subject(s) - isocenter , fiducial marker , radiosurgery , nuclear medicine , medicine , image guided radiation therapy , medical imaging , imaging phantom , radiology , medical physics , radiation therapy
Purpose: The frameless system has been used in our clinic for intracranial stereotactic radiosurgery. This study reports our retrospective analysis and findings on patient setup and isocenter localization of radiosurgery treatment. Method and Materials: The frameless immobilization consists of a bite‐block with fiducial markers and an infra‐red camera system. To test bite‐block seating, patient was taken for reseat verification before imaging. The SRS‐plan and images were sent to the camera computer for fiducials digitization. Prior to treatment, patient setup was guided by the camera readings on fiducials for isocenter localization. Orthogonal kV‐images were taken as verification only. In this study, we have analyzed reseat test and fiducial digitization data of 53 patients. Retrospective comparison of KV‐images with planning DRRs was carried out. Results: The patient reseat test is found of no correlation with the actual 3D treatment isocenter displacements. The sample mean of predicted error at isocenter from fiducial digitization is 0.46 mm. The histogram of 3D iso‐displacement shows that 86.8% of patients have localization error E⩽1 mm, 5.7% of 1