F-factor (conversion factor)
The F-factor, in diagnostic radiology, is the conversion factor between exposure and absorbed dose. In other words, it converts between the amount of ionization in air and the absorbed dose in air. The two determinants of the F-factor are the effective Z of the material and the type of ionizing radiation being considered. Since the effective Z of air and soft tissue is approximately the same, the F-factor is approximately 1 for many x-ray imaging applications. However, bone has an F-factor of up to 4, due to its higher effective Z.The following table shows radiation quantities in SI and non-SI units.
