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Characterization of the PTW MicroSilicon Detector

A Turnidge1*, M Heard1, S Junell1, (1) Oregon Health & Science University, Portland, OR

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To characterize the PTW-60023 microSilicon?? (PTW, Freiburg, Germany) for small field dosimetry applications.

Methods: The dose linearity, dose-per-pulse dependence, effective point of measurement (EPOM), small field profiles, and small field output factors were measured. Dose linearity was measured over a range of clinically relevant MU’s for all energy/dose rate combinations. Dose-per-pulse dependence was measured over a range of source-to-surface distances. EPOM was measured using PDD scans taken with both the microSilicon and microDiamond. Small field profiles were measured with the microSilicon, PTW-60019 microDiamond (PTW, Freiburg, Germany), and Gafchromic film (Ashland Inc., Covington, KY, USA). Small field output factors were measured.

Results: A linear line of best fit was applied to dose linearity data: r² values were equal to or very close to 1.000 for all plots. PDD scans were overlaid to determine the difference between the microSilicon’s nominal and measured EPOM’s. A shift of less than 0.5 mm was observed at dmax for each PDD scan overlay for all energy/field size combinations. For field sizes down to 1 x 1 cm² field size microSilicon and microDiamond profile widths were within 0.5 mm of each other.

Conclusions: The following conclusions have been made: (1) the response is linear with dose for all energy/dose rate combinations, (2) the nominal and measured EPOM’s align, (3) the microSilicon is appropriate for measuring small field profiles down to 1 x 1 cm² field sizes.

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Keywords

Dosimetry, Diodes, Small Fields

Taxonomy

TH- Radiation Dose Measurement Devices: diodes/solid state

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