ARRT Image Acquisition and Evaluation 4

Question 1

A lateral knee radiograph shows the femoral condyles are not superimposed. Which positioning correction is needed?

Accepted Answer

Rotate the patient's foot internally or externally to align the condyles

Answer

Failure to superimpose the femoral condyles on a lateral knee indicates the leg is rotated; adjusting internal or external rotation corrects this.

Question 2

In digital radiography, what is the purpose of the exposure index (EI) deviation index (DI)?

Accepted Answer

To indicate how far the actual exposure deviates from the target exposure

Answer

The deviation index (DI) compares the actual EI to the target EI, indicating over- or underexposure so the technologist can adjust technique.

Question 3

Which technical factor change reduces patient dose while maintaining adequate image quality on a chest radiograph?

Accepted Answer

Increase kVp and decrease mAs proportionally

Answer

Increasing kVp and reducing mAs (high-kVp technique) maintains exposure to the detector while lowering patient dose due to increased beam penetration.

Question 4

A PA hand radiograph shows significant motion blur. Which receptor/technique change would most improve sharpness?

Accepted Answer

Use a smaller focal spot and immobilize the hand

Answer

A smaller focal spot reduces geometric unsharpness, and immobilization eliminates motion unsharpness, both improving recorded detail.

Question 5

Which term describes the minimum detectable difference in tissue density that can be distinguished on a radiograph?

Accepted Answer

Contrast resolution

Answer

Contrast resolution is the ability to distinguish between tissues of similar attenuation — the minimum density difference that can be detected.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Image Acquisition and Evaluation 4