Comparison of Film and Diamond Detector Small Field Dosimetry Commissioning Measurements
S Zabinski1*, J Giltz2, (1) University of Kentucky, Lexington, KY, (2) Alyzen Medical Physics, Fort Smith, AR
Presentations
(Saturday, 3/26/2022) [Central Time (GMT-5)]
Purpose: To ascertain whether an additional correction factor for output and energy may be needed when using a micro diamond detector for small field dosimetry measurements during commissioning through film measurement comparison.
Methods: Beginning with calibration of new film, percent depth-dose curves were measured with the aid of a custom-built film holder for the water tank and output factors were measured with solid water. This was done at field sizes of 0.5, 1.0, 1.5, 2.0, and 3.0. Diamond detector measurements of the same field sizes and energies followed in a water tank as well. These measurements, taken on a Varian TrueBeam with HD120 MLCs with the 6X-FFF energy, were compared to film and potential correction factors were obtained.
Results: Film output factors were compared to both treatment planning system values and diamond detector measurements using IAEA TRS Report 483 Table 26 small field correction factors for the appropriate diamond detector. PDDs were cross compared as well to both measurement methods and the most recent annual PDD.
Conclusion: Film has high resolution and is cheap to use once a film dosimetry program is established, making it a good choice for small field dosimetry. However, it may not be practical for commissioning projects at sites without a robust film dosimetry program. Therefore it is useful to have a robust comparison between film and diamond detector measurements for small field dosimetry, as well as any appropriate corrections found.
Funding Support, Disclosures, and Conflict of Interest: Alyzen Medical Physics is the employer of both authors, Stephanie Zabinski being an affiliate resident through the University of Kentucky.
ePosters
- 174-60678-16011654-182637-2059326159.pdf (S Zabinski)
Keywords
Commissioning, Film, Small Fields
Taxonomy
TH- External Beam- Photons: Small field experimental dosimetry
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