RDA Radiation Safety, Protection, and Physics

Question 1

The ALARA principle in dental radiography stands for:

Accepted Answer

As Low As Reasonably Achievable

Answer

All Levels Are Radiation Absorbed

Answer

Absolute Limit of Allowable Radiation Administration

Answer

Automatic Limiting of Avoidable Radiation Areas

Question 2

A rectangular collimator is preferred over a round (cylindrical) cone in dental radiography because it:

Accepted Answer

Significantly reduces the area of the patient's face exposed to the primary beam

Answer

Increases the sharpness of the image by reducing scatter

Answer

Allows more radiation to reach the receptor for a shorter exposure time

Answer

Eliminates the need for a lead apron during the exposure

Question 3

According to radiation safety guidelines, the operator should stand at least how far from the x-ray tube head during an exposure, if no structural protective barrier is available?

Accepted Answer

6 feet (1.8 meters)

Answer

1 foot (30 cm)

Answer

2 feet (60 cm)

Answer

10 feet (3 meters)

Question 4

Aluminum filtration is built into the x-ray tube housing primarily to:

Accepted Answer

Remove low-energy (long-wavelength) x-rays that would increase patient dose without contributing to the diagnostic image

Answer

Prevent the patient from seeing the x-ray beam during exposure

Answer

Increase the intensity of the beam to reduce exposure time

Answer

Reduce electrical interference during exposure

Question 5

Which of the following best describes the purpose of the lead apron and thyroid collar during dental radiography?

Accepted Answer

They protect radiosensitive organs (gonads, thyroid) from scatter radiation

Answer

They shield the patient from direct (primary) beam exposure

Answer

They allow the dental assistant to stand closer to the patient during exposure

Answer

They are required only for pediatric patients under age 12

Question 6

The maximum permissible dose (MPD) of occupational radiation exposure for a dental worker is:

Accepted Answer

50 mSv (5,000 mrem) per year

Answer

1 mSv (100 mrem) per year

Answer

5 mSv (500 mrem) per year

Answer

100 mSv (10,000 mrem) per year