Moyer R F
Radiol Technol. 1977 May-Jun;48(6):707-10.
The quantity, exposure, and its associated unit, the roentgen, have been employed for approximately 50 years for the practical measurement of x- and gamma-ray source "output." Practical exposure-measuring devices must be provided with a wall of critical thickness and composition. Confusion arises since the wall is not mentioned in the definition of "exposure." This mystery can be dispelled by the fact that exposure never is measured in the manner in which it is defined.
数量、照射量及其相关单位伦琴，已被用于实际测量X射线和γ射线源的“输出量”约50年了。实际的照射量测量装置必须配备具有临界厚度和组成的壁。由于“照射量”的定义中未提及该壁，因而产生了混淆。而实际测量照射量的方式与定义中的方式不同，这一事实可以消除这种困惑。
