Determination of the air-kerma in mammography x-rays at NIM

Breast cancer has become the top killer of women’s health in the world, and mammography X-ray has become the gold standard in various diagnostic methods, due to its low energy, low dose and high resolution. To meet the quality control requirements of mammography X-rays dose in clinical, the National Institute of Metrology (NIM,China) has established a mammography X-ray reference radiation facility. The radiation quality half-value layer (HVL) range from 0.274 to 0.364 mm (aluminum) meets the requirements of IEC61267, and a new parallel-plate free-air ionization is designed. At NIM, various correction factors were measured and simulated, and finally, the absolute measurement of the X-ray air kerma rate of the mammography was realized. By analysis, the combined standard uncertainty of the air kerma is 0.44%. Provide traceability services for the use and quality control of mammography in China.