ACRR key terms

A radiation protection principle meaning that exposures are kept as low as reasonably achievable, taking economic and social factors into account while still allowing the intended purpose of the exposure to be met.

The amount of radiation energy deposited per unit mass of material, measured in gray, where one gray equals one joule per kilogram and describes physical energy transfer rather than biological harm.

A radiation protection quantity obtained by multiplying absorbed dose by a radiation weighting factor to reflect differing biological effectiveness of radiation types, expressed in sieverts.

A whole-body risk index that sums equivalent doses to individual organs and tissues after multiplying each by a tissue weighting factor, allowing comparison of stochastic risk across different exposure situations.

The SI unit for equivalent and effective dose, representing the biological impact of radiation exposure; commonly used in whole-body dose limits and occupational monitoring records.

The SI unit of absorbed dose, equal to one joule of deposited radiation energy per kilogram of matter; used to quantify dose delivered to patients, equipment, and materials.

The maximum permitted radiation dose to a radiation worker over a defined period, typically an annual effective dose limit of 50 mSv with cumulative limits based on age and prior exposure.

A wearable device such as a film badge, thermoluminescent dosimeter, or optically stimulated luminescence badge that records cumulative radiation dose received by an individual worker over a monitoring period.

A small direct-reading ionization chamber device worn by workers that provides an immediate visible indication of accumulated dose, allowing prompt recognition of unexpected exposure during procedures.

A gas-filled detector operating at high voltage that produces a large output pulse for each ionizing event, useful for detecting low-level contamination and surveying areas but not for measuring dose rate accurately.

A gas-filled detector operated at a voltage where collected charge is proportional to radiation energy deposited, commonly used in dose calibrators and survey meters because response is relatively energy independent.

A well-type ionization chamber instrument used to assay the activity of radiopharmaceutical doses before administration, requiring daily constancy checks and correction for radionuclide, volume, and geometry.

A shielded sodium iodide detector with a well-shaped crystal that accommodates small samples, used to measure low levels of radioactivity in wipe tests, blood samples, and excretion collections.

The time required for half of the atoms in a radioactive sample to decay, a fixed characteristic of each radionuclide used to predict activity remaining at a future time.

The fraction of radioactive atoms decaying per unit time for a given radionuclide, related to half-life by the natural logarithm of two divided by the half-life.

A number supplied by the manufacturer that converts the activity of a radiopharmaceutical at the reference date and time to its activity at the time of calibration or administration.

The fraction of total radioactivity in a preparation attributable to the intended radionuclide, distinguishing it from contaminating radionuclides that may add unnecessary dose or degrade imaging.

The proportion of radioactivity present in the desired chemical form of a radiopharmaceutical, as opposed to free radionuclide or other labeled species, assessed by chromatography before patient use.

A separation technique in which a solvent migrates up a coated strip, moving different chemical species different distances so that radiochemical purity of a preparation can be calculated from measured activity distributions.

The radioactive solution obtained by passing saline through a parent-daughter generator system, containing the daughter radionuclide used for labeling plus any parent breakthrough or other impurities.

The unwanted appearance of parent radionuclide in generator eluate, which must be measured and kept below regulatory limits because the parent typically has a long half-life and delivers excess dose.

A survey method in which a surface is wiped with an absorbent material that is then counted in a well counter to detect removable radioactive contamination that a direct survey meter might miss.

A systematic check of surfaces, equipment, and personnel for unintended radioactive material using survey meters and wipe tests, performed at defined intervals and after spills or procedures.

The total radiation dose that will be received by an organ or tissue over time from an intake of radioactive material, integrated until the material has fully decayed or been excreted.

The estimation of radiation dose resulting from radioactive material taken into the body by inhalation, ingestion, or absorption, using biokinetic models and measured body or excreta activity.

Measurement of radioactivity in samples such as urine, blood, breath, or whole-body counts to estimate the amount of radioactive material present inside a person after a possible intake.

The three fundamental techniques for reducing external radiation exposure: limiting time near a source, increasing distance because dose falls with the inverse square, and placing absorbing material between source and person.

The relationship stating that radiation intensity from a point source decreases in proportion to the square of the distance from the source, so doubling distance reduces exposure to one quarter.

The thickness of a specified material that reduces the intensity of a radiation beam to one half of its original value, used to characterize shielding and beam quality.

The process of asking patients of childbearing potential about possible pregnancy before administering radioactive material, allowing modification of the procedure to protect the fetus when indicated.

The radiation protection principle requiring that a procedure producing exposure yield more benefit than harm, considering alternatives and whether the examination is appropriate for the clinical question.

The principle of adjusting procedure parameters, administered activity, and technique so that the diagnostic information or therapeutic benefit is obtained with the lowest reasonable radiation exposure.

The process of explaining a procedure's purpose, risks, benefits, and alternatives to a patient and documenting voluntary agreement before administration of radioactive material or participation in research.

Inadvertent infiltration of a radiopharmaceutical into tissue surrounding the injection site, causing local radiation dose, altered biodistribution, and the need to document and manage the event.

The structured documentation and communication of unintended occurrences such as misadministration, extravasation, or equipment failure to appropriate supervisors and regulatory bodies within required timeframes.

A misadministration in which the administered dose or radionuclide differs substantially from the prescribed amount, requiring notification of the patient, referring physician, and regulator per defined criteria.

The requirement to keep specified documents such as dose records, quality control results, and administration logs for defined periods so that compliance and traceability can be demonstrated during inspection.

A physician or other qualified individual named on a license who is permitted to use radioactive material for specified purposes based on documented training and experience requirements.

The individual responsible for implementing and overseeing a facility's radiation protection program, including policies, monitoring, training, and compliance with license conditions and regulations.

Biological effects of radiation whose probability increases with dose but whose severity does not, typically arising from DNA damage and including cancer induction and hereditary effects.

Radiation effects that occur only above a threshold dose and whose severity increases with dose, caused by cell killing and including skin erythema, cataract formation, and bone marrow suppression.