DRC Radiographic Techniques & Procedures 2 — Questions and Answers
Question 1: Which bisecting angle technique error results in foreshortened teeth on the radiograph?
- Vertical angulation too steep (Correct answer)
- Vertical angulation too flat
- Horizontal angulation error
- Insufficient exposure time
Correct answer: Vertical angulation too steep
Excessive vertical angulation (too steep) causes the x-ray beam to strike the tooth at too great an angle, resulting in foreshortened images.
Question 2: When using the paralleling technique, the image receptor should be positioned:
- Against the tooth surface
- Parallel to the long axis of the tooth (Correct answer)
- At a 45-degree angle to the tooth
- Perpendicular to the occlusal plane
Correct answer: Parallel to the long axis of the tooth
The paralleling technique requires the receptor to be placed parallel to the long axis of the teeth to minimize geometric distortion.
Question 3: A 'cone cut' on a periapical radiograph is caused by:
- Incorrect vertical angulation
- Incorrect horizontal angulation
- PID not centered over the receptor (Correct answer)
- Patient movement during exposure
Correct answer: PID not centered over the receptor
A cone cut (clear unexposed area) occurs when the position-indicating device is not properly aligned to cover the entire image receptor.
Question 4: Which type of image receptor holder is specifically designed for use with digital sensors to maintain proper paralleling technique?
- Snap-A-Ray
- Rinn XCP (Correct answer)
- EEZEE-Grip
- Hemostat
Correct answer: Rinn XCP
Rinn XCP (Extension Cone Paralleling) instruments are designed to hold the receptor parallel to the tooth and guide PID placement for accurate paralleling technique.
Question 5: During a maxillary molar periapical exposure using the paralleling technique, the receptor is placed:
- Horizontally in the palate
- Vertically as far lingual as possible (Correct answer)
- Against the buccal surfaces of the molars
- At the midline of the palate
Correct answer: Vertically as far lingual as possible
For maxillary molars, the receptor must be positioned as far palatally as possible (vertical placement) to achieve parallelism with the long axis of the teeth.
Question 6: What is the purpose of the bite-wing tab or loop on a bitewing radiograph?
- To reduce patient radiation dose
- To stabilize the receptor between the teeth (Correct answer)
- To increase image sharpness
- To center the PID over the receptor
Correct answer: To stabilize the receptor between the teeth
The bite-wing tab or loop is placed between the teeth so the patient bites down to stabilize the receptor in the correct position during exposure.
Question 7: When exposing a mandibular incisor periapical radiograph using paralleling technique, the greatest challenge is:
- Patient cooperation
- Placement of the receptor due to shallow floor of mouth (Correct answer)
- High radiation scatter in this region
- Excessive vertical angulation required
Correct answer: Placement of the receptor due to shallow floor of mouth
The shallow floor of the mouth limits how far the receptor can be placed apically, making true parallelism difficult to achieve for mandibular anterior teeth.
DRC Radiographic Techniques & Procedures 2
Which bisecting angle technique error results in foreshortened teeth on the radiograph?