Radiation Protection and Safety Lecture

Vocabulary flashcards covering key concepts from the lecture on radiation protection, interactions, units, dose limits, monitoring devices, and safety principles.

Natural ionizing radiation

Radiation that originates from natural sources, such as cosmic rays and the sun.

ALARA

A radiation‐safety principle meaning ‘As Low As Reasonably Achievable,’ aimed at minimizing exposure.

Occupational dose limits

Regulatory limits on radiation exposure for workers, based primarily on man-made sources like medical imaging.

Prodromal stage (ARS)

The first phase of Acute Radiation Syndrome, characterized by early symptoms such as nausea and vomiting.

Lead shielding

Protective material (lead or lead-equivalent) used to attenuate ionizing radiation in radiology.

Photoelectric effect

X-ray interaction in which the photon is completely absorbed, giving the greatest dose to the patient.

Compton scattering

Interaction of moderate-energy X-rays with outer-shell electrons, causing scatter that is the main source of worker exposure.

Radiosensitive cells

Rapidly dividing cells—e.g., bone marrow or reproductive cells—most sensitive to radiation, as described by Gray & Schmidt.

DNA (radiation target)

The most critical cellular target; ionizing radiation is most harmful when it damages DNA in the nucleus.

Acute Radiation Syndrome stages

Sequence: Prodromal → Latent → Manifest Illness → Recovery or Death.

X-ray beam filter

Device that removes low-energy photons, reducing patient dose while maintaining image quality.

Radiation emergency actions

Key steps: evacuate, limit time, increase distance, and use shielding.

OSL dosimeter

Optically Stimulated Luminescence badge; the most common personnel radiation monitor today.

Pregnancy dose limit

Maximum permissible dose for a pregnant worker: 0.5 mSv per month.

Moderate-energy X-rays

Photon energies that commonly undergo Compton scattering.

Pocket dosimeter

Direct-reading device (often DIS) that provides immediate exposure readings.

Field survey meter

Instrument used to measure radiation levels in an area (area monitor).

Cardinal rules of radiation protection

Time, Distance, and Shielding—basic strategies to reduce dose.

Gray (Gy)

SI unit of absorbed dose; 1 Gy = 1 joule per kilogram.

Sievert (Sv)

SI unit of effective dose, accounting for radiation type and tissue sensitivity.

Public dose limit

Annual effective dose limit for the general public: 5 mSv per year.

Becquerel (Bq)

SI unit of radioactivity; equals one nuclear decay per second.

Beam restriction

Technique (e.g., collimation) that limits X-ray field size to lower patient exposure.

Gonadal shield

Flat contact or contour shield placed over reproductive organs to reduce dose.

Compton scattering mechanism

Incident photon strikes an outer electron, ejects a recoil electron, and scatters with reduced energy.

Classic coherent scatter

Low-energy photon excites an atom but causes no ionization; photon exits with same energy and wavelength.

Quality factor (QF) for X-rays

Radiation weighting factor of 1, used in dose calculations.

Dosimeter badge placement

Worn at collar level outside the lead apron; a second badge at waist level is used during pregnancy.

Modern radiation safety practices

Approaches such as beam restriction, high-speed receptors, filtration, and adherence to ALARA.

Ionizing radiation

Radiation with enough energy to remove tightly bound electrons from atoms, producing ions.

Shielding materials

Substances (e.g., lead, lead-equivalent composites) used to reduce radiation intensity.

Latent stage (ARS)

Symptom-free interval following the prodromal stage before manifest illness appears.