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CDA · 15% of the exam

RHS: Purpose and Technique practice questions

10 free RHS: Purpose and Technique questions for the Certified Dental Assistant (CDA) Exam exam, each with the correct answer and an explanation for every option.

Start the questionsFree 10-question CDA quiz

What this domain covers

Half of the RHS component and the second-largest CDA domain: taking, processing and evaluating diagnostic dental images.

Exam weight
15%
On a real exam
≈ 37 questions
In our bank
86 questions

Topics that come up most

  • Paralleling and bisecting techniques
  • Bitewing, periapical and occlusal projections
  • Panoramic imaging and positioning errors
  • Identifying and correcting technique errors
  • Anatomical landmarks and mounting

How to study it

Study pictures of common errors, such as elongation, foreshortening, overlap and cone cuts, with their cause; questions show or describe the error and ask what went wrong.

Sample RHS: Purpose and Technique questions

Try each one before opening the answer. Original questions written to the official exam objectives.

  1. Question 1

    What does the raised dot on a film help with?

    • ABlocking scatter radiation
    • BMeasuring exposure time
    • CShowing the patient's name
    • DOrienting and mounting the image
    Show answer and explanation

    Answer: D) Orienting and mounting the image

    • AIncorrect. It's for orientation.
    • BIncorrect. It's for orientation.
    • CIncorrect. It's for orientation.
    • DCorrect. It shows which side faced the tube.

  2. Question 2

    Enamel appears on radiographs as:

    • AThe darkest structure
    • BRadiolucent
    • CRadiopaque
    • DInvisible
    Show answer and explanation

    Answer: C) Radiopaque

    • AIncorrect. It's radiopaque.
    • BIncorrect. It's radiopaque.
    • CCorrect. It's the densest tissue in the body.
    • DIncorrect. It's radiopaque.

  3. Question 3

    Bitewing images are mainly used to detect:

    • AInterproximal caries
    • BPeriapical abscesses
    • CImpacted third molars
    • DTMJ disorders
    Show answer and explanation

    Answer: A) Interproximal caries

    • ACorrect. And crestal bone levels.
    • BIncorrect. That's periapical images.
    • CIncorrect. That's panoramic or periapical.
    • DIncorrect. Bitewings don't show the TMJ.

  4. Question 4

    For young children, a common modification is to use:

    • ASmaller receptors
    • BLarger receptors
    • CLonger exposure times
    • DNo holders at all
    Show answer and explanation

    Answer: A) Smaller receptors

    • ACorrect. Such as size 0.
    • BIncorrect. Use smaller receptors.
    • CIncorrect. Children need less exposure.
    • DIncorrect. Use smaller receptors.

  5. Question 5

    A PSP image shows thin, irregular white (radiopaque) lines that appear in the same place on every image taken with that plate. Which is the most likely cause?

    • AScratches in the phosphor layer from rough handling or excessive bending
    • BPatient movement during the exposure of the posterior teeth
    • CAn exposure time set too long for the patient's size
    • DInsufficient vertical angulation of the position-indicating device
    Show answer and explanation

    Answer: A) Scratches in the phosphor layer from rough handling or excessive bending

    Physical damage to a PSP plate, such as scratches or bends, produces radiopaque line artifacts that repeat on every image taken with that plate. Handle plates carefully and replace damaged ones.

    • ACorrect. Scratches on the phosphor surface show up as straight or irregular radiopaque lines. They can come from careless placement, bending, biting or rough insertion into the scanner. Damaged plates should be replaced.
    • BIncorrect. Movement blurs the image of that one exposure. It would not create fixed lines that repeat on every image taken with the same plate.
    • CIncorrect. Overexposure makes the whole image too dark or dense. It does not produce discrete white lines.
    • DIncorrect. Too little vertical angulation elongates the teeth on the image. It does not leave white line artifacts on the plate.

  6. Question 6

    Which statement best describes the effective radiation dose of a typical dental cone beam CT (CBCT) scan compared with a digital panoramic image?

    • AGenerally higher, with the amount varying widely by unit, field of view and settings
    • BGenerally lower, because the beam makes only a single rotation around the head
    • CAbout the same, because both are extraoral exposures using a rotating source
    • DLower whenever a large field of view is chosen to image both arches
    Show answer and explanation

    Answer: A) Generally higher, with the amount varying widely by unit, field of view and settings

    CBCT generally gives a higher effective dose than a panoramic image, and the dose depends heavily on field of view and settings. Use it only when it is clinically justified, with the smallest suitable FOV.

    • ACorrect. Published dose studies show CBCT effective doses are generally higher than panoramic doses, often by a large factor. Small-FOV, low-dose protocols can come close to a panoramic dose, so CBCT should be used only when a 2D image can't answer the clinical question.
    • BIncorrect. A panoramic unit also rotates around the head. A CBCT scan collects many projections of a volume and usually delivers a higher effective dose.
    • CIncorrect. Both are extraoral and rotational, but their doses are not equivalent. CBCT doses are typically several to many times higher than panoramic doses.
    • DIncorrect. A larger field of view irradiates more tissue and raises the dose. Limiting the FOV to the region of interest is how CBCT dose is reduced.

  7. Question 7

    Teeth that appear too long on an image result from:

    • AToo little vertical angulation
    • BToo much vertical angulation
    • CIncorrect horizontal angulation
    • DToo much exposure time
    Show answer and explanation

    Answer: A) Too little vertical angulation

    • ACorrect. This is elongation.
    • BIncorrect. That causes foreshortening.
    • CIncorrect. That causes overlap.
    • DIncorrect. That causes a dark image.

  8. Question 8

    Overlapped interproximal contacts are caused by incorrect:

    • AVertical angulation
    • BHorizontal angulation
    • CExposure time
    • DKilovoltage peak (kVp) setting
    Show answer and explanation

    Answer: B) Horizontal angulation

    • AIncorrect. That causes elongation or foreshortening.
    • BCorrect. The beam isn't through the contacts.
    • CIncorrect. That affects density.
    • DIncorrect. That affects contrast.

  9. Question 9

    The lingual foramen appears as:

    • AA small radiolucent dot within the genial tubercles
    • BA large radiolucency over the maxillary molars and premolars
    • CA radiopaque line on the ramus
    • DA dark line between the maxillary centrals
    Show answer and explanation

    Answer: A) A small radiolucent dot within the genial tubercles

    • ACorrect. It's on mandibular incisor images.
    • BIncorrect. That's the sinus.
    • CIncorrect. That's the external oblique ridge.
    • DIncorrect. That's the median palatine suture.

  10. Question 10

    How are exposure settings usually adjusted for children?

    • ADoubled, since children move more
    • BReduced, since their tissues are smaller
    • CKept at adult settings
    • DIncreased for the anterior teeth only, where tissue is thicker
    Show answer and explanation

    Answer: B) Reduced, since their tissues are smaller

    • AIncorrect. Settings are reduced.
    • BCorrect. This lowers dose.
    • CIncorrect. Settings are reduced.
    • DIncorrect. Settings are reduced.

RHS: Purpose and Technique: FAQs

How much of the CDA exam is RHS: Purpose and Technique?

RHS: Purpose and Technique is 15% of the CDA exam by the official exam guide's weighting, which on a 245-question form works out to roughly 37 questions. The real exam's exact split varies by form.

What does the RHS: Purpose and Technique domain cover?

Half of the RHS component and the second-largest CDA domain: taking, processing and evaluating diagnostic dental images.

How should I study RHS: Purpose and Technique for CDA?

Study pictures of common errors, such as elongation, foreshortening, overlap and cone cuts, with their cause; questions show or describe the error and ask what went wrong.

Where can I practise more RHS: Purpose and Technique questions?

This page has 10 free RHS: Purpose and Technique questions with answers. The ExamWize CDA question bank has 86 questions in this domain. Every practice exam result breaks your score down by domain, and Review Mode re-drills the questions you missed.

Other CDA topics

Also: 15 free questions across all topics, the CDA cheat sheet and the study guide.

Get RHS: Purpose and Technique exam-ready

The full CDA bank has 86 RHS: Purpose and Technique questions. Timed practice exams match the real exam's length and domain weights, every result shows your score per domain, and Review Mode re-drills the questions you missed.

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Not affiliated with DANB; questions are original, written from the official exam outline, and never copied from the real exam.