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Session: Therapy General ePoster Viewing [Return to Session]

The Impact of Applying TRS 483 Recommendations Correction Factor for Cyberknife Cones Output with Different Types of Detectors

M Alfishawy*, I Al Amri, M Gurumani, N Babu, Sultan Qaboos Comprehensive Cancer Center (SQCCC), Muscat, MuscatOM,


PO-GePV-T-370 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: The small field dosimetry measurement is one of the critical parts in treatment requirements, especially in the era of SRS and SBRT.TRS 483 recommended detector based correction factor (CF) for the output factor measurements, this study aimed to compare the measurements of CyberKnife output factors for fixed and iris collimators, with and without applying CF and comparing to composite data provided by Accuray.

Methods: PTW 60019 CVD detector, PTW 60018 unshielded diode, and Sun Nuclear Edge detectors are used in these output factor measurements for 24 Fixed and Iris cones (5mm to 60mm) of Cyberknife S7.

Results: The study results divided into three groups according to cone size, group A: (20 to 60mm) cones, group B: (10 to 15mm) cones, group C: (5 and 7.5mm) cones, and comparing our result relative to composite data from Accuray.The study data of fixed cones without applying CF shows an average variance percentage of (0.12%, 0.49%, and 1.63%) with maximum of (0.3%, 1.31%, and 4.52%) for A, B, and C groups respectively. Furthermore, when applying CF, results present an average variance percentage of (0.13%, 0.99%, and 3.42%) with maximum of (0.52%, 1.39%, and 6.91%) for A, B, and C groups respectively.On the other hand, for iris without applying CF, the result shows an average variance percentage of (0.2%, 0.8%, 1.6%) with maximum of (0.49%, 1.64%, 2.95%) for A, B, and C groups respectively. Moreover, when applying CF, the study displays an average variance percentage of (0.23%, 0.6%, and 2.58%) with maximum of (0.49%, 0.95%, 5.38%) for A, B, and C group respectively.

Conclusion: This study showed that the variance percentage between measured and composite data from Accuray is less when not applying the CF, especially for small fixed and iris Cyberknife cones.


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