Diagnostic Imaging

6% of the VTNE · blueprint VTNE content outline approved by the AAVSB Board, March 2023

Short answer

Diagnostic Imaging is 9 of the 150 scored VTNE items. It covers radiographic positioning and the use of technique charts, exposure factors and their effect on the image, identifying artefacts and their causes, radiation safety including ALARA and dosimetry, film and digital processing, and preparing patients for ultrasound and other imaging modalities.

Why it matters on this exam

Imaging items are technical and objective: positioning terminology, exposure relationships and safety rules.

Key concepts

Positioning terminology: the direction the beam travels — ventrodorsal versus dorsoventral, lateral recumbency naming, and standard views for each body region.
Exposure factors: kVp controls beam penetration and contrast; mAs controls the quantity of radiation and therefore density; adjust one variable at a time using the technique chart.
Artefacts: motion blur, grid lines, double exposure, static, processing marks in film and detector artefacts in digital systems.
Radiation safety: ALARA, distance and shielding, never holding a patient manually where positioning aids or sedation can be used, dosimeter placement and reporting.
Ultrasound preparation: clipping and coupling gel, patient positioning, and fasting where abdominal imaging requires it.

Common mistakes

Raising kVp to correct an underexposed film when mAs is the density control.
Manually restraining for radiographs when sedation and positioning devices are available.

Worked example

Radiographs are consistently too dark. Density is governed by mAs, so the technique chart's mAs is reduced; changing kVp first alters contrast and penetration and confuses the diagnosis of the problem.

Original practice questions

Diagnostic ImagingDifficulty 3/5

Radiographs from a machine are consistently too dark. Which adjustment corrects the density?

AReduce the mAs, because it controls the quantity of radiation and density
BReduce the kVp, because it controls the contrast of the resulting image
CIncrease the source-to-image distance to reduce beam intensity
DIncrease the exposure time to allow the image to develop properly

Show answer and rationale

Correct: A. mAs controls the quantity of radiation and therefore image density. kVp controls penetration and contrast, so changing it first confuses the diagnosis of an over-exposure problem.

B — Lowering kVp changes contrast and penetration rather than correcting density cleanly.
C — Changing distance alters technique in a way the chart does not account for.
D — Increasing time increases mAs and makes the image darker still.

Diagnostic ImagingDifficulty 2/5

Which practice best reflects the ALARA principle during radiography?

AManually restraining patients so that repeat exposures are avoided
BUsing sedation and positioning aids so no one remains in the room
CStanding behind the technician holding the patient during exposure
DWearing a dosimeter under the lead apron to record true exposure

Show answer and rationale

Correct: B. ALARA means keeping exposure as low as reasonably achievable: sedation and positioning devices remove people from the room entirely. Dosimeters are worn outside the apron at collar level.

A — Manual restraint places staff in the primary beam area unnecessarily.
C — Being in the room at all is the exposure that ALARA removes.
D — A dosimeter under the apron under-reports true exposure.

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Primary references

VTNE Candidate Information Handbook — American Association of Veterinary State Boards (AAVSB) · primary · retrieved 2026-09-22, verified 2026-09-22

Last reviewed: 2026-09-22Next review by: 2026-11-06Draft — pending editorial reviewHow we verify facts