ADAT Dental Radiology & Imaging 1 — Questions and Answers
Question 1: Which radiographic technique positions the image receptor parallel to the long axis of the tooth and directs the central beam perpendicular to both?
- Bisecting angle technique
- Paralleling technique (Correct answer)
- Occlusal technique
- Panoramic technique
Correct answer: Paralleling technique
The paralleling technique places the receptor parallel to the teeth and aims the beam perpendicularly, minimizing geometric distortion compared to the bisecting angle technique.
Question 2: Which type of radiograph is most effective for detecting interproximal caries in posterior teeth?
- Periapical radiograph
- Occlusal radiograph
- Bitewing radiograph (Correct answer)
- Panoramic radiograph
Correct answer: Bitewing radiograph
Bitewing radiographs image the crowns of both arches simultaneously and are the gold standard for detecting early interproximal carious lesions.
Question 3: Which radiation unit accounts for the biological effect of ionizing radiation on human tissues?
- Roentgen (R)
- Gray (Gy)
- Sievert (Sv) (Correct answer)
- Coulomb per kilogram (C/kg)
Correct answer: Sievert (Sv)
The Sievert (Sv) is the SI unit of equivalent dose, incorporating both the absorbed dose and the radiation weighting factor to reflect biological damage.
Question 4: A processed periapical radiograph appears light and lacks adequate image density. Which processing error is the most likely cause?
- Excessive development time
- Developer solution that is too cool (Correct answer)
- Overexposure
- Prolonged fixation time
Correct answer: Developer solution that is too cool
A developer solution that is too cool slows the chemical reduction reaction, resulting in an underdeveloped, light radiograph with poor density.
Question 5: What does the ALARA principle stand for in dental radiation protection?
- Always Limit and Restrict All Radiographic Angles
- As Low As Reasonably Achievable (Correct answer)
- Authorized Levels for Allowable Radiation Administration
- Adequate Limitation of Radiographic Absorption
Correct answer: As Low As Reasonably Achievable
ALARA — As Low As Reasonably Achievable — is the guiding principle in radiation protection, requiring operators to minimize patient and occupational exposure at all times.
Question 6: Which anatomical structure appears as a dense radiopaque U-shaped or linear structure overlying the maxillary molar region on a periapical radiograph?
- Maxillary sinus floor
- Nasopalatine canal
- Zygomatic process of the maxilla (Correct answer)
- Coronoid process of the mandible
Correct answer: Zygomatic process of the maxilla
The zygomatic process of the maxilla (malar bone attachment) appears as a dense, inverted U-shaped or wedge-shaped radiopacity superimposed over the maxillary molar region.
Question 7: When using the bisecting angle technique, a foreshortened image results from which error in vertical angulation?
- Insufficient positive angulation
- Excessive positive angulation (Correct answer)
- Insufficient negative angulation
- Excessive horizontal angulation
Correct answer: Excessive positive angulation
Excessive positive vertical angulation causes the central beam to strike the bisecting plane at too steep an angle, compressing the image and producing foreshortening.
ADAT Dental Radiology & Imaging 1
Which radiographic technique positions the image receptor parallel to the long axis of the tooth and directs the central beam perpendicular to both?