DEXA DEXA Quality Assurance & Equipment Calibration

Question 1

How often should daily phantom QA scans be performed on a DEXA system?

Accepted Answer

Every day before patient scanning

Answer

Once per week

Answer

Once per month

Answer

Only when error alerts appear

Question 2

What is the primary purpose of a spine phantom (e.g., Hologic or GE Lunar phantom) in DEXA QA?

Accepted Answer

To calibrate the system and detect BMD measurement drift

Answer

To test patient positioning aids

Answer

To measure radiation output levels

Answer

To verify detector pixel alignment only

Question 3

A DEXA system's daily QC phantom result falls outside ±1.5% of the long-term average. What is the correct action?

Accepted Answer

Do not scan patients; investigate and contact the manufacturer

Answer

Scan patients and document the variance

Answer

Repeat the phantom scan 10 times and use the average

Answer

Reset the system and proceed normally

Question 4

Which statistical tool is typically used to track DEXA daily phantom data over time and identify trends?

Accepted Answer

Shewhart control chart (QC chart)

Answer

Histogram

Answer

Scatter regression plot

Answer

Kaplan-Meier curve

Question 5

When should a DEXA system's cross-calibration be performed?

Accepted Answer

After major repairs, software upgrades, or detector replacement

Answer

Only at initial installation

Answer

Every 5 years regardless of changes

Answer

Before every patient scan

Question 6

What does a sudden step-change (shift) in the daily QC control chart most likely indicate?

Accepted Answer

A hardware or software change affecting system performance

Answer

Normal day-to-day measurement variability

Answer

The phantom needs to be replaced with a newer model

Answer

Patient volume has increased significantly