DEXA Scan Operation & Technique 4

Question 1

During a serial DXA exam, which factor is MOST critical for ensuring valid comparison to a prior scan?

Accepted Answer

Replicating the same positioning, ROI placement, and scan mode as the baseline

Answer

Reproducible positioning and ROI placement on the same DXA system and mode are essential for detecting true BMD change versus measurement error.

Question 2

A patient has a hip prosthesis on the right side. Which scan should be performed?

Accepted Answer

Left hip, and note that left was scanned due to right prosthesis

Answer

The contralateral (left) hip should be scanned when a prosthesis is present on one side, and this substitution must be documented.

Question 3

What minimum time interval is generally recommended between DXA serial scans to detect clinically meaningful BMD change?

Accepted Answer

1 to 2 years

Answer

A 1–2 year interval is recommended because it allows enough time for detectable change to exceed the machine's precision error (least significant change).

Question 4

Which of the following correctly describes 'short-term precision' in DXA?

Accepted Answer

The coefficient of variation from repeat scans on the same patient under identical conditions

Answer

Short-term precision is expressed as the coefficient of variation (CV%) from repeated scans performed close together under the same conditions to quantify operator and machine variability.

Question 5

When scanning the total body, which of the following patient instructions is MOST important before starting the acquisition?

Accepted Answer

The patient must remove all metal objects and lie still with arms at sides, palms down

Answer

Metal objects create artifacts, and the arms-at-sides palms-down position with stillness ensures accurate whole-body composition and BMD analysis.

(DEXA) DEXA Bone Density Scan Certification Practice Test

(DEXA) DEXA Bone Density Scan Certification Practice Test

DEXA Scan Operation & Technique 4