Absorbed dose is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg or gray (Gy) where 1Gy = 1Jkg-1.
The absorbed dose is not a good indicator of the likely biological effect. 1 Gy of alpha radiation would be much more biologically damaging than 1 Gy of photon radiation for example. Appropriate weighting factors can be applied reflecting the different relative biological effects to find the equivalent dose.
The risk of stochastic effects due to radiation exposure for the population can be quantified using the effective dose, which is a weighted average of the equivalent dose to each organ depending upon its radiosensitivity.
Other related values include
- absorbed dose rate (Gy.s-1): amount of radiation delivered over a time period
- rad: the international unit of absorbed dose pre-1980 where 1 Gy = 100 rad
- kerma (Gy): kinetic energy released to matter
- 1. Mcnitt-gray MF. AAPM/RSNA Physics Tutorial for Residents: Topics in CT. Radiation dose in CT. Radiographics. 22 (6): 1541-53. Radiographics (citation) - Pubmed citation
- 2. Allisy-Roberts P, Williams J. Farr's Physics for Medical Imaging. Saunders Limited. (2007) ISBN:0702028444. Read it at Google Books - Find it at Amazon
- 3. Bushberg JT. The essential physics of medical imaging. Williams & Wilkins. (2002) ISBN:0683301187. Read it at Google Books - Find it at Amazon
- x-ray production
- x-ray tubes
- tube rating
- interaction with matter
- beam collimators
- intensifying screen
- x-ray film
- image intensifier
- digital radiography
- x-ray artifacts
- radiation units
- radiation detectors