Introductory Terms and Concepts:
- Leakage: X-rays that penetrate through a shielding material and that also contribute to occupational exposure,
- X-ray beam, the Primary X-ray Beam: The beam of x-ray photons directed at a subject for purpose of imaging or irradiation (aka the useful beam)
- Exposure: A loose term meaning to have been in the presence of ionizing radiation. When used specifically, it describes the intensity of exposure in terms of the ability of a source to ionize air. Normal units of measure: Roentgen (R) and milli-Roentgen (mR),
- Dose: Depending on context, may have the same loose meaning as exposure, or it may refer to specific types of dose, e.g. absorbed or effective.
- Absorbed dose: The amount of energy absorbed by a set mass of tissue, measured in Gray (Gy) or milli-Gray (mGy). 1 Gray is equivalent to 1 joule of energy absorbed by 1 kg of tissue,
- Effective dose: A measure of the biological effect of absorbed dose on tissue (or an entire group of tissues e.g. the whole human body). Normally expressed in Sieverts (Sv) or milli-Sieverts (mSv).