DRC Image Acquisition & Interpretation 3 — Questions and Answers
Question 1: When using a phosphor plate (PSP) system, what happens if the plate is not erased between patients?
- The image will appear overexposed
- Residual images from previous exposures will appear ('ghost images') (Correct answer)
- The receptor will be permanently damaged
- The image will not be read by the scanner
Correct answer: Residual images from previous exposures will appear ('ghost images')
PSP plates must be erased with bright light between uses; residual latent images cause artifact overlaps called ghost images.
Question 2: Which type of vertical angulation error produces elongation of the radiographic image?
- Too much positive angulation
- Too little angulation (shallow/insufficient) (Correct answer)
- Negative angulation on a maxillary image
- Correct angulation but excessive exposure time
Correct answer: Too little angulation (shallow/insufficient)
Insufficient (too little) vertical angulation causes the X-ray beam to strike at too flat an angle, elongating the image of the tooth.
Question 3: The mental foramen most commonly appears radiographically as a:
- Radiopaque dot at the apex of the mandibular second premolar
- Well-defined radiolucency near the apex of the mandibular premolars (Correct answer)
- Diffuse radiolucency along the inferior border of the mandible
- V-shaped radiolucency in the symphysis region
Correct answer: Well-defined radiolucency near the apex of the mandibular premolars
The mental foramen is a normal anatomic structure that appears as a well-defined, round radiolucency near the apex of the mandibular premolars and can mimic periapical pathology.
Question 4: A patient has a full-mouth series prescribed. During exposure of the maxillary canine periapical film, the patient's nose tip appears in the image. Which error occurred?
- Negative vertical angulation
- Receptor placed too far anteriorly
- Receptor was bent during placement
- Positive vertical angulation was too steep (Correct answer)
Correct answer: Positive vertical angulation was too steep
Excessively steep positive vertical angulation on the maxillary canine projection causes the beam to project the nose tip shadow onto the receptor.
Question 5: Which radiographic feature best differentiates a periapical granuloma from a periapical cyst?
- A granuloma has a corticated border; a cyst does not
- A cyst tends to be larger with a well-defined corticated border (Correct answer)
- A granuloma is radiopaque; a cyst is radiolucent
- Cysts show widening of the PDL space; granulomas do not
Correct answer: A cyst tends to be larger with a well-defined corticated border
Periapical cysts are generally larger and more likely to have a well-defined corticated (sclerotic) border compared to granulomas, though definitive diagnosis requires histopathology.
Question 6: During digital radiography, which of the following will decrease patient dose while maintaining diagnostic quality?
- Increasing the exposure time by 50%
- Using faster image receptor settings and rectangular collimation (Correct answer)
- Switching from F-speed film to D-speed film
- Using a larger FOV cone
Correct answer: Using faster image receptor settings and rectangular collimation
Faster receptor settings and rectangular collimation significantly reduce radiation dose by minimizing beam size and required exposure.
Question 7: On a maxillary anterior periapical radiograph, a radiopaque oval structure is seen superimposed on the roots of the maxillary central incisors. This most likely represents:
- Nasopalatine cyst
- Anterior nasal spine (Correct answer)
- Incisive canal
- Dens invaginatus
Correct answer: Anterior nasal spine
The anterior nasal spine is a bony projection at the base of the nasal septum that appears as a radiopaque oval superimposed on the maxillary incisor roots.
DRC Image Acquisition & Interpretation 3
When using a phosphor plate (PSP) system, what happens if the plate is not erased between patients?