ARRT BONE DENSITY (DXA) PRACTICE EXAM
Questions And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A.
1. The primary purpose of a DXA exam is to measure:
A. Bone volume
B. Bone strength
C. Bone mineral density
D. Bone elasticity
Answer: C
DXA measures bone mineral density (BMD), which correlates with fracture risk.
2. Which bone type is most metabolically active and affected earliest by
osteoporosis?
A. Compact bone
B. Cortical bone
C. Trabecular bone
D. Lamellar bone
Answer: C
Trabecular bone has higher turnover and shows early bone loss, especially in the
spine.
3. DXA uses which principle to differentiate bone from soft tissue?
A. Ultrasound reflection
B. Single x-ray beam
C. Dual-energy x-ray attenuation
D. MRI signal intensity
,Answer: C
DXA uses two x-ray energy levels to distinguish bone from soft tissue.
4. Bone mineral density (BMD) is expressed in which units?
A. mg/cm
B. g/mm²
C. g/cm²
D. % bone mass
Answer: C
BMD is calculated as bone mineral content divided by area (g/cm²).
5. Which T-score indicates osteoporosis?
A. −0.8
B. −1.5
C. −2.0
D. −2.6
Answer: D
According to WHO, osteoporosis is defined as a T-score ≤ −2.5.
6. A T-score compares the patient to:
A. Age-matched population
B. Pediatric population
C. Young healthy adult reference
D. Same-sex population only
Answer: C
T-scores compare BMD to a young adult reference standard.
7. A Z-score is MOST appropriate for which patient?
, A. Postmenopausal woman
B. Male age 65
C. Premenopausal woman
D. Woman with hip fracture
Answer: C
Z-scores are used for premenopausal women, men under 50, and children.
8. Which scan site is the BEST predictor of hip fracture risk?
A. Lumbar spine
B. Forearm
C. Ward’s triangle
D. Total hip
Answer: D
Total hip BMD is the strongest predictor of hip fracture risk.
9. Standard lumbar spine DXA includes which vertebrae?
A. T12–L3
B. L2–L5
C. L1–L4
D. T11–L4
Answer: C
The standard spine DXA analysis includes L1 through L4.
10. Why are the patient’s legs elevated during a lumbar spine DXA?
A. Reduce radiation dose
B. Improve comfort
C. Flatten lumbar lordosis
D. Reduce scan time
Questions And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A.
1. The primary purpose of a DXA exam is to measure:
A. Bone volume
B. Bone strength
C. Bone mineral density
D. Bone elasticity
Answer: C
DXA measures bone mineral density (BMD), which correlates with fracture risk.
2. Which bone type is most metabolically active and affected earliest by
osteoporosis?
A. Compact bone
B. Cortical bone
C. Trabecular bone
D. Lamellar bone
Answer: C
Trabecular bone has higher turnover and shows early bone loss, especially in the
spine.
3. DXA uses which principle to differentiate bone from soft tissue?
A. Ultrasound reflection
B. Single x-ray beam
C. Dual-energy x-ray attenuation
D. MRI signal intensity
,Answer: C
DXA uses two x-ray energy levels to distinguish bone from soft tissue.
4. Bone mineral density (BMD) is expressed in which units?
A. mg/cm
B. g/mm²
C. g/cm²
D. % bone mass
Answer: C
BMD is calculated as bone mineral content divided by area (g/cm²).
5. Which T-score indicates osteoporosis?
A. −0.8
B. −1.5
C. −2.0
D. −2.6
Answer: D
According to WHO, osteoporosis is defined as a T-score ≤ −2.5.
6. A T-score compares the patient to:
A. Age-matched population
B. Pediatric population
C. Young healthy adult reference
D. Same-sex population only
Answer: C
T-scores compare BMD to a young adult reference standard.
7. A Z-score is MOST appropriate for which patient?
, A. Postmenopausal woman
B. Male age 65
C. Premenopausal woman
D. Woman with hip fracture
Answer: C
Z-scores are used for premenopausal women, men under 50, and children.
8. Which scan site is the BEST predictor of hip fracture risk?
A. Lumbar spine
B. Forearm
C. Ward’s triangle
D. Total hip
Answer: D
Total hip BMD is the strongest predictor of hip fracture risk.
9. Standard lumbar spine DXA includes which vertebrae?
A. T12–L3
B. L2–L5
C. L1–L4
D. T11–L4
Answer: C
The standard spine DXA analysis includes L1 through L4.
10. Why are the patient’s legs elevated during a lumbar spine DXA?
A. Reduce radiation dose
B. Improve comfort
C. Flatten lumbar lordosis
D. Reduce scan time
