(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: To extend the absorbed dose range of alanine reference dosimeters for radiotherapy dosimetry and establish the mailed audit reference system in China.
Methods: The national institute of metrology of China has alanine absorbed dose standard in the range of (0.1-40) kGy with uncertainty of 4.0% (k=2) used for industry applications. With the updating of the fabrication and measurement setup for the alanine dosimeter, and the background subtraction and dosimetry calibration, the dose of alanine dosimeter (2.8mm in height and 4.3 mm in diameter) can come to lower than 10 Gy.
Results: alanine dosimeter at the range of 2 Gy to 100 Gy, with the linearity of 0.99999, can give the typical precision of ±1% at 1s. The temperature dependence of the dosimeters from 20 ?C to 25?C is within 0.7%, and the repeatability is within 0.5%. The directional response and longtime stability were also investigated. Comparing the ion chamber and mailed alanine dosimeter in the hospitals, the water absorbed dose measured by different dosimeters was agreed better than 1% at 10 MV photon beams.
Conclusion: Alanine dosimeter can be used to a range of radiation therapy beams, such as absolute dosimetry, dose verification, and end to end dosimetry. The accurate of alanine at better than 1% for mailed audit dosimeters was verified for 10 MV photon beams in China.
Funding Support, Disclosures, and Conflict of Interest: Supported by the National Key Technologies R&D Program of China (Grant No. 2016YFF0200804 and 2018YFF0212403)
Keywords
Dose Response, Quality Assurance, Radiation Dosimetry
Taxonomy
TH- External Beam- Photons: Calibration protocol and primary standards
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