Research on calibration of ionizing chamber and semiconductor detector for calibration method
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Breast cancer is the most common cancer diagnosed in women. Mammography (a special x-ray of the breast) is the main test to screen for possible tumors. It can help reduce the number of deaths from breast cancer among women aged from 40 to 70. So, there are a great number of mammography machines in the Asia-Pacific region. However, mammography exposes people to x-ray radiation, and hence proper measurement of the radiation dose is important. This project is to study air kerma measurement of mammography and calibration of mammography detectors, and to establish the degrees of equivalence in APMP.
The purpose of this project is to aid the development of an APMP Key Comparison of mammography beams, with two expected goals.
1)Help NMI or DI in APMP TCRI to establish the capability of calibration of mammography detector, which is used in hospital to evaluate the exposure dose of medical examiner.Participating NMIs(or DI) include BARC, EIS, INER, KRISS, NIM, NMIJ, NMISA, OAP,PTKMR-BATAN, etc.
2)Support breast cancer mammography check by accurate measurement and comparison.
The project has helped some NMIs establish mammography radiation qualities(W/Mo).
For the ionization chamber, the experimental results show good agreement, but due to the physical characteristics of the semiconductor detector, the results are not ideal.Therefore, for international comparison, semiconductor measuring device is not a good choice.
Suggest that use more than one transfer standards in APMP TCRI Key Comparison of air kerma for mammography beams, and the position of the reference point and bias polarity should be clarified.