Abstract
Introduction: The measurement of small stereotactic fields is difficult on many levels. The loss of charge particle equilibrium, perturbation of the field due to the detecting system, and energy spectrum changes contribute to uncertainties and errors in the measurement. Recent advances in detector technology and design have produced detectors that are smaller, less than 0.02mm3 active volumes, and near energy independence. Purpose: The purpose of this study was to measure the dosimetric quantities of small circular stereotactic fields and extend existing treatment planning data from the smallest field size of 15.0mm to 7.5mm. The second step was to determine if the Mapcheck‐2 device could be used for standard quality assurance checks for small stereotactic fields. Methods: Measurements were performed with three detecting systems and compared to institutional data obtained with Radiochromic film. Dosimetric data was collected with the Edge detector and the SFD. The Edge detector is a n‐type radiation harden silicondiode with an active volume of 0.019mm3, and the SFD is a p‐type high doped silicondiode with an active volume of 0.017mm3. The Mapcheck‐2 is a diode array containing 1527 diodedetectors. The dosimetric measurements performed included the TPR at 5cm depth, penumbra, FWHM, and the output factors for 15 stereotactic collimators. All measurements were done with a 6MV beam collimated by a Radionics collimating system. Results: Both systems provided consistent data as compared to the Radiochromic film measurements for field sizes between 15 mm and 40 mm. The SFD provided a sharper penumbra, and larger TPR values for the 10mm and 7.5mm cones. Conclusion: Both detecting systems provide consistent data for cone sizes of 15 mm to 40 mm. The smaller volume of the SFD provides more accurate penumbra data for the smaller cone sizes. The Mapcheck‐2 can be used for dosimetric measurements of stereotactic collimators.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
