CRA Radiation Physics & Safety Flashcards

Which regulatory body is responsible for overseeing radiation safety in medical facilities using radioactive materials in the United States?

Answer: NRC (Nuclear Regulatory Commission)

The NRC regulates the civilian use of radioactive materials, including those used in nuclear medicine and radiation therapy.

What is the purpose of collimation in diagnostic radiology?

Answer: To limit the X-ray beam to the area of clinical interest and reduce patient dose

Collimation restricts the X-ray beam to the area of interest, reducing unnecessary radiation exposure to the patient and improving image quality.

Which type of radiation interaction with matter is most responsible for photoelectric effect in diagnostic radiology?

Answer: Low-energy photons interacting with inner-shell electrons

The photoelectric effect occurs when a low-energy photon is completely absorbed by and ejects an inner-shell electron from an atom.

A lead apron used for radiation protection in diagnostic radiology typically provides an attenuation equivalent of:

Answer: 0.5 mm Pb

Standard lead aprons used in diagnostic radiology are typically equivalent to 0.5 mm of lead, providing approximately 90% attenuation of scatter radiation.

Radiation-induced health effects that have a threshold dose below which no harm occurs and increase in severity with dose are called:

Answer: Deterministic (non-stochastic) effects

Deterministic effects (e.g., radiation burns, cataracts) occur above a threshold dose and worsen in severity as dose increases.

In a radiology department, which area classification requires the MOST stringent radiation shielding design?

Answer: Radiographic room housing the X-ray equipment

The radiographic room is the primary radiation area with the highest dose rates, requiring the most robust shielding by design.