ARRT Image Acquisition and Evaluation 5

Question 1

What does a high MTF (modulation transfer function) value indicate about an imaging system?

Accepted Answer

The system accurately reproduces fine detail

Answer

MTF measures how faithfully an imaging system reproduces spatial frequencies; a high MTF indicates excellent spatial resolution and detail reproduction.

Question 2

Which condition would cause a foreshortened appearance of a long bone on a radiograph?

Accepted Answer

Central ray angled along the long axis of the bone

Answer

Angling the central ray along (parallel to) the long axis of a bone causes it to appear foreshortened on the image.

Question 3

A radiograph of the abdomen shows a faint diagonal line pattern overlying the image. What is the most likely cause?

Accepted Answer

Moiré pattern from grid-detector frequency mismatch

Answer

A moiré pattern appears as a diagonal or wavy line artifact when the grid frequency and detector sampling frequency interact destructively.

Question 4

For an AP shoulder radiograph, which criterion indicates the glenohumeral joint space is adequately demonstrated?

Accepted Answer

A clear space is visible between the humeral head and glenoid fossa

Answer

Proper positioning demonstrates an open joint space between the humeral head and glenoid fossa, confirming adequate internal rotation and centering.

Question 5

Which factor has the greatest effect on reducing the amount of scatter radiation produced in the patient?

Accepted Answer

Collimating to the smallest field size necessary

Answer

Tighter collimation reduces the volume of irradiated tissue, which is the primary determinant of scatter production.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Image Acquisition and Evaluation 5