DRC Radiographic Techniques & Procedures 3 — Questions and Answers
Question 1: Which occlusal radiographic projection is used to examine the entire maxillary arch in one image?
- Lateral jaw projection
- Maxillary topographic occlusal (Correct answer)
- Mandibular cross-sectional occlusal
- Panoramic projection
Correct answer: Maxillary topographic occlusal
The maxillary topographic occlusal projection uses a large receptor placed horizontally in the palate to capture the entire maxillary arch in a single image.
Question 2: For a patient with a strong gag reflex, which modification can help when exposing maxillary posterior periapical radiographs?
- Increase the kVp setting
- Use the bisecting angle technique instead of paralleling (Correct answer)
- Reduce the exposure time by half
- Use a larger receptor size
Correct answer: Use the bisecting angle technique instead of paralleling
The bisecting angle technique allows the receptor to be placed closer to the teeth (not deep in the palate), reducing stimulation of the gag reflex compared to paralleling technique.
Question 3: When taking a bitewing radiograph, the correct horizontal angulation directs the central beam:
- Perpendicular to the curvature of the arch through the contact points (Correct answer)
- At a 15-degree mesial angle
- Parallel to the long axis of the teeth
- Perpendicular to the occlusal plane
Correct answer: Perpendicular to the curvature of the arch through the contact points
Correct horizontal angulation positions the beam perpendicular to the dental arch and directed through the contact points to open them on the radiograph.
Question 4: A periapical radiograph shows overlapping of posterior contact areas. The most likely cause is:
- Excessive vertical angulation
- Incorrect horizontal angulation (Correct answer)
- Underexposure of the film
- Patient movement
Correct answer: Incorrect horizontal angulation
Overlapping of contact areas results from incorrect horizontal angulation, where the beam is not directed perpendicular through the interproximal contacts.
Question 5: Which receptor size is most appropriate for a full-mouth series in an adult patient?
- Size 0 throughout
- Size 1 for anteriors, size 2 for posteriors (Correct answer)
- Size 2 throughout
- Size 3 for all posterior areas
Correct answer: Size 1 for anteriors, size 2 for posteriors
A standard adult full-mouth series uses size 1 receptors for the narrower anterior teeth and size 2 receptors for the wider posterior areas.
Question 6: The source-to-object distance (SOD) in dental radiography primarily affects:
- Image density
- Geometric magnification and sharpness (Correct answer)
- Contrast of the image
- Patient radiation dose only
Correct answer: Geometric magnification and sharpness
Increasing the SOD reduces geometric magnification and improves image sharpness by making the x-ray beam more parallel as it reaches the object.
Question 7: When exposing radiographs on a pediatric patient, which statement is most accurate regarding receptor size selection?
- Adult-size receptors should always be used for diagnostic quality
- Size 0 or size 1 receptors are preferred for comfort and accuracy (Correct answer)
- Size 2 receptors are used to reduce the number of exposures
- Receptor size does not matter as long as the area is covered
Correct answer: Size 0 or size 1 receptors are preferred for comfort and accuracy
Smaller receptors (size 0 or 1) are used for pediatric patients to ensure comfortable placement and accurate positioning within the smaller oral cavity.
DRC Radiographic Techniques & Procedures 3
Which occlusal radiographic projection is used to examine the entire maxillary arch in one image?