Free-air ionization chambers (FAC) are accepted as the primary standard of x-ray dosimetry. The low-energy x-rays are important for basic beam quantities of diagnostics at the mammography level. This research explains the FAC characteristics of the Office of Atoms for Peace (OAP) that was developed by cooperation between the OAP, Thailand, and the Korea Research Institute of Standards and Science, Republic of Korea. The applied correction factors that are necessary for determination of the air kerma rate were investigated using an experimental method and Monte Carlo simulation methods with their uncertainties. The beam characteristics, computed using the Monte Carlo method and demonstrated in this paper, are important for calculation of the correction factors. Finally, the correction factors and uncertainties of the standard beam qualities, which are recommended by the Consultative Committee for Ionizing Radiation, and W/Mo beam qualities are shown in this paper.

自由空气电离室 (FAC) 被认为是 X 射线剂量测定的主要标准。低能 X 射线对于乳房 X 线照相术诊断的基本光束量很重要。本研究解释了由 OAP、泰国和韩国标准与科学研究院合作开发的原子促进和平办公室 (OAP) 的 FAC 特征。使用实验方法和蒙特卡罗模拟方法及其不确定性研究了确定空气比释动能率所需的应用校正因子。使用蒙特卡罗方法计算并在本文中演示的光束特性对于校正因子的计算很重要。最后，标准光束质量的校正因子和不确定性，