RADIATION DETECTORS AND SURVEYS (VOCABULARY)

Vocabulary flashcards covering key terms and definitions from the lecture notes on radiation detectors and surveys.

Pulse mode

A detector mode where the presence of radiation is indicated by a ticking, chirping, or beeping sound.

Rate mode

A detector mode in which the instrument response is expressed as a dose rate (e.g., mGy/h or mR/h).

Integrate mode

A detector mode that accumulates the signal to respond with a total exposure (dosimetry).

Dosimeter

A device that measures and records cumulative radiation exposure (used in dosimetry).

Gas-filled detectors

Detectors where radiation ionizes gas; released electrons produce a signal proportional to radiation intensity.

Scintillation detectors

Detectors that emit light when irradiated; light output is proportional to energy absorbed.

Area monitors / Survey monitors

Devices used to determine the extent of possible contamination or radiation in an area.

Ionization chamber

Gas-filled detector that measures radiation intensity by collecting ion pairs; used around fluoroscopes, radionuclide generators, patient areas, and for calibration.

Portable Survey Meter

An ionization chamber instrument used for area radiation surveys spanning a wide range of intensities.

Dose Calibrator

Device used in nuclear medicine to assay and calibrate radioactive material (dose delivery).

Proportional counter

A gas-filled detector that is highly sensitive and can distinguish between alpha and beta radiation; typically used for small quantities of radioactivity.

Geiger‑Müller (GM) counter

A portable detector used for contamination control; not ideal as a dosimeter due to calibration challenges; detects single ionizing events and often produces an audible click.

OSLD (Optically Stimulated Luminescence Dosimeter)

A personnel dosimeter using aluminum oxide (Al2O3); irradiation stores energy and laser light stimulates electrons to emit light proportional to dose.

Aluminum oxide (Al2O3)

Material used in OSLDs as the radiation detector medium.

Thermoluminescence Dosimeter (TLD)

A dosimeter that glows when heated after exposure; used for personnel monitoring and patient dose measurement.

Mammography filtration

Mammography tubes use 30 μm Mo or 60 μm Rh filtration to shape the beam.

Filtration

Thin metal filtration (e.g., Al) added to x-ray tubes to remove low-energy photons; filtration specifications vary by kVp.

Primary protective barrier

Barriers that shield against the primary radiation beam; typically shielding for walls directly in the path of the beam.

Secondary protective barrier

Wall barriers that shield against scatter and leakage; the patient is a major source of exposure to these walls.

Leakage radiation

Radiation escaping from the tube during operation; typically limited to 100 mR/h in the examples.

Controlled Area

Area used by occupationally exposed personnel where radiation protection controls apply.

Occupancy (area to be protected)

Area designation used to determine protection needs based on how people occupy the space.

General Survey

Evaluation of work areas for leakage or contamination; survey results are documented and kept for staff and Radiation Safety Office access.

Equipment Survey

Survey checking the physical parameters of radiographic equipment (e.g., leakage, housing integrity) and related system parameters.

Protective housing/leakage control

Protective enclosure and construction elements designed to minimize leakage and exposure from the x-ray tube.

Collimation

System for restricting the x-ray beam with a light-localized, variable-aperture rectangular collimator (or cones/diaphragms); accuracy within 2% of SID.

Beam alignment

Mechanism to ensure the x-ray tube is properly aligned to the image receptor and that light and beam align with the film.

Filtration levels by kVp

Specifies minimum Al filtration: >70 kVp = 2.5 mm Al; 50–70 kVp = 1.5 mm Al; <50 kVp = 1.0 mm Al.

General Survey considerations

Involves evaluating room design factors (machine location, tube movement, adjoining rooms, floor level) to optimize shielding and safety.