RDA Radiographic Techniques and Errors 5 — Questions and Answers
Question 1: Which of the following BEST describes the appearance of an elongated image on a periapical radiograph?
- The tooth image appears shorter than actual length
- The tooth image appears longer than actual length (Correct answer)
- The tooth image appears wider than actual width
- The tooth image appears with double outlines
Correct answer: The tooth image appears longer than actual length
Elongation means the radiographic image of the tooth is longer than the actual tooth, caused by insufficient vertical angulation.
Question 2: A radiograph exhibits a light (underexposed) image overall. Which of the following is the LEAST likely cause?
- Insufficient mA setting
- Insufficient exposure time
- Excessive source-to-object distance
- Excessive kVp setting (Correct answer)
Correct answer: Excessive kVp setting
Excessive kVp would produce a darker (overexposed) image, not a lighter one; all other options reduce X-ray energy reaching the receptor.
Question 3: During a mandibular molar periapical exposure, the patient complains the receptor is painful on the floor of the mouth. The BEST solution is to:
- Use a cotton roll under the receptor to redirect it (Correct answer)
- Increase vertical angulation to compensate
- Switch to a larger receptor size
- Use the bisecting angle technique instead
Correct answer: Use a cotton roll under the receptor to redirect it
Placing a cotton roll under the edge of the receptor cushions it and redirects pressure away from sensitive tissues on the floor of the mouth.
Question 4: Which panoramic positioning error causes a Cheshire cat or ghost image of the spine to appear in the center of the film?
- Patient's head tilted to one side
- Patient's chin tipped too far down
- Patient positioned with spine not erect (slouching) (Correct answer)
- Patient's tongue not on the palate
Correct answer: Patient positioned with spine not erect (slouching)
When the patient slouches or the cervical spine is not straight and upright, the dense vertebral column creates a ghost image superimposed over the midline of the panoramic image.
Question 5: Static electricity artifacts on dental radiographs appear as:
- Uniform overall darkening of the image
- Black branching or lightning bolt-like marks (Correct answer)
- Clear circular spots on the image
- Yellow-brown staining across the film
Correct answer: Black branching or lightning bolt-like marks
Static electricity discharge produces characteristic dark, branching, lightning bolt-shaped marks on the processed radiograph.
Question 6: A bitewing radiograph shows the maxillary teeth occupying more than half of the film. Which error occurred?
- Receptor placed too high in the mouth
- Receptor placed too low in the mouth
- Negative vertical angulation used
- Excessive positive vertical angulation used (Correct answer)
Correct answer: Excessive positive vertical angulation used
Excessive positive (downward) vertical angulation projects the maxillary teeth toward the lower portion, making them appear larger and occupy more of the image.
Question 7: Which of the following will MOST directly reduce patient radiation dose during dental radiography without sacrificing image quality?
- Using faster image receptors (F-speed film or digital) (Correct answer)
- Increasing the number of exposures taken
- Using a shorter PID (cone)
- Removing the aluminum filter from the tubehead
Correct answer: Using faster image receptors (F-speed film or digital)
Faster receptors (F-speed film or digital sensors) require less radiation to produce a diagnostic image, directly reducing patient dose.
RDA Radiographic Techniques and Errors 5
Which of the following BEST describes the appearance of an elongated image on a periapical radiograph?