In radiology dose is the term for radiation related to the amount of energy absorbed in matter (for example absorbed dose, acute dose, effective dose, external dose, personal dose and committed dose equivalent). The SI standard unit of radiation dose is the gray.
Dose refers also to the amount of medication, radiopharmaceutical or contrast medium used in diagnostic imaging.

See also Deep Dose Equivalent, Critical Organ, Eye Dose Equivalent, Collective Effective Dose, Medical Internal Radiation Dose Committee, and Chronic Dose.

The acute dose is the amount of energy accommodated in human tissue or in biological systems.

See also Acute Exposure, Acute Radiation Syndrome, Biodosimetry and Annual Limit On Intake.

The dose limit is the highest value of an applied or allowed radiation exposure. The radiation dose is limited in order to prevent the occurrence of radiation-induced deterministic effects or to limit the probability of radiation-related stochastic effects to an acceptable level.

See also Whole Body Counter, Thermoluminescent Dosimeter, Dosimetrist, Annual Limit On Intake, Committed Effective Dose Equivalent, Computed Tomography Dose Index, Directional Dose Equivalent, Doubling Dose.

A dose is named chronic when the exposure is longer than one day.
Chronic radiation doses can be low enough to cause few effects, and they can be severe enough to be extremely dangerous.

The absorbed dose is the average energy absorbed per unit mass.

The tissue absorbed energy in a small mass volume:
D = (dW/dm) [ Gy ]
D = absorbed dose in Gray (Gy); dW = in the tissue energy absorbed; DM = small volume of the mass.

The SI unit of absorbed dose is the joule per kilogram and its special name is the gray (Gy). In units often used by federal and state agencies, absorbed dose is given in rad; 1 rad = 0.01 Gy.

Absorbed dose is a feature that should increase dose awareness and help users in dose optimization. Absorbed dose in CT is quoted using the CTDI (computed tomography dose index)

CTDIvol (volume-averaged CT dose index) and the dose-length product (DLP) give an indication of the average absorbed dose and relative radiation risk to a standard patient. The user is being warned to scan parameter settings that may lead to high doses, and can adjust the protocol if appropriate. It should be noted that CTDIvol and DLP do not take patient size into account, and will give overestimates and underestimates for large and small patients, respectively.