NDHCE Dental Radiography 2 — Questions and Answers
Question 1: What is the maximum permissible dose (MPD) of radiation for an occupationally exposed dental worker per year according to NCRP guidelines?
- 1 mSv (0.1 rem)
- 5 mSv (0.5 rem)
- 50 mSv (5 rem) (Correct answer)
- 100 mSv (10 rem)
Correct answer: 50 mSv (5 rem)
The NCRP recommends a maximum permissible dose of 50 mSv (5 rem) per year for occupationally exposed workers.
Question 2: Which film placement error results in a foreshortened image on a periapical radiograph?
- Insufficient vertical angulation
- Excessive vertical angulation (Correct answer)
- Incorrect horizontal angulation
- Film placed backwards
Correct answer: Excessive vertical angulation
Excessive positive (downward) vertical angulation causes the image to appear foreshortened, making teeth look shorter than they actually are.
Question 3: Which radiographic landmark appears as a radiolucent oval area above the roots of the maxillary central incisors?
- Incisive foramen (Correct answer)
- Mental foramen
- Nasal fossa
- Maxillary sinus
Correct answer: Incisive foramen
The incisive foramen (nasopalatine foramen) appears as a round or oval radiolucency located at the midline between the roots of the maxillary central incisors.
Question 4: During fixer processing, what is the primary chemical action on the exposed radiographic film?
- Develops latent image by reducing silver ions
- Removes unexposed silver halide crystals (Correct answer)
- Hardens and clears the emulsion
- Neutralizes the developer solution
Correct answer: Removes unexposed silver halide crystals
The fixer solution removes unexposed and undeveloped silver halide crystals, clearing the non-image areas of the film.
Question 5: Which dental condition would appear radiopaque on a radiograph?
- Pulp chamber
- Periapical abscess
- Dental caries
- Amalgam restoration (Correct answer)
Correct answer: Amalgam restoration
Amalgam restorations are highly radiopaque because the metal alloy absorbs X-rays, appearing white on the radiograph.
Question 6: What does the term 'long-cone technique' refer to in dental radiography?
- Bisecting angle technique using a long cone
- Paralleling technique using a 16-inch focal-film distance (Correct answer)
- Panoramic technique with extended source distance
- Occlusal technique for large areas
Correct answer: Paralleling technique using a 16-inch focal-film distance
The long-cone technique refers to the paralleling technique using a 16-inch (40 cm) focal-film distance to reduce image magnification.
NDHCE Dental Radiography 2
What is the maximum permissible dose (MPD) of radiation for an occupationally exposed dental worker per year according to NCRP guidelines?