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| Measurement and Evaluation of Dose Characteristics of DomesticFarmer Type Ionization Chamber |
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Abstract In the photon beam dose calibration of medical accelerators, the ionization chamber is excessively dependent on imports, and the domestic detector lacks systematic experiments in radiotherapy applications. Through the quantitative measurement of dosimetric parameters such as angular response, composite polarization correction, leakage current, dose linearity and energy response of domestic QF 60 series farmer ionization chamber in high-energy photon beams, and referring to the performance requirements of JJG912-2010 therapeutic horizontal ionization chamber dosimeter, the use suggestions of QF 60 detector are given. The results show that the maximum impact of the angular response of the detector is 0.88%, and the repeatability of the same model is 0.21%. The polarization correction factor is 1.001. The ion composite correction values in the dose rate range of conventional radiotherapy were less than 1.0049. The leakage current and dose linearity basically meet the requirements of JJG912-2010. The energy response of 6 MV, 10 MV, 25 MV photons relative to Co-60γ-rays is 0.9883, 0.9820, 0.9597, and the maximum relative deviation of energy and noise of the same model is 0.17%. However, due to the lack of influence on the angular response in the use of position cutting lines, timely and sufficient pre-irradiation should be conducted in the measurement, and the Co-60γ-ray water absorption dose and energy response calibration should be conducted regularly.
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Received: 12 March 2024
Published: 19 March 2025
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2025, Vol. 46 
