DXA MOCK Exam Prep EXAM with
Questions and Answers/Plus a Rationale
Updated 2026 A+/Instant Download PDF
EXAM COVERAGE
1. Bone Densitometry Physics, Instrumentation, and Technology (DXA, QCT, Ultrasound)
2. Radiation Safety, Quality Assurance, and Quality Control Procedures
3. Patient Positioning, Anatomy, Scan Acquisition, and Technical Artifacts
4. Clinical Interpretation, T-Scores, Z-Scores, and WHO Diagnostic Criteria
5. Metabolic Bone Diseases, Risk Assessment (FRAX), and Pharmacological Management
1. A 68-year-old postmenopausal female presents for a baseline dual-energy X-ray absorptiometry
(DXA) scan. During the lumbar spine acquisition, the technologist observes that the L1-L4
vertebrae do not show the expected progressive increase in vertebral body size and density from
superior to inferior. Instead, L2 demonstrates a significantly higher BMD than L3 and L4. Upon
reviewing the lateral scout view, what is the most likely technical or pathological cause for this
anomaly?
A. Normal physiological variation in trabecular bone remodeling due to aging.
B. Severe localized degenerative disc disease, osteophytosis, or facet arthrosis artificially
inflating the bone mineral density of L2.
C. Proper beam hardening correction artifact inherent to pencil-beam densitometers.
D. Severe osteomalacia selectively targeting the lower lumbar segments.
CORRECT ANSWER : B
Rationale: Degenerative changes such as osteophytes, syndesmophytes, and facet sclerosis add
dense cortical and mineralized bone tissue to the scan area, falsely elevating the measured bone
mineral density (BMD). Options A, C, and D are incorrect because normal vertebral size
increases sequentially inferiorly, bone-hardening artifacts affect the entire field uniformly rather
, than a single isolated segment, and osteomalacia lowers rather than abnormally spikes BMD
readings.
2. When analyzing a total hip DXA scan for a 72-year-old male, the technologist notices that the
lesser trochanter is prominently visible and projecting medially from the femoral shaft. How
does this specific positioning error impact the calculation of the total hip bone mineral density
and T-score?
A. Internal rotation artifacts cause an underestimation of the femoral neck BMD.
B. External rotation of the femur superimposes the lesser trochanter, which alters the
automated region-of-interest (ROI) placement and artificially increases the measured hip
BMD.
C. It has zero impact because modern fan-beam software automatically corrects for rotational
variance.
D. It completely invalidates the scan by shifting the region of interest entirely outside the pelvic
girdle.
CORRECT ANSWER : B
Rationale: External rotation causes the lesser trochanter to roll into view, which interferes with
the bone edge-detection algorithm and falsely elevates total hip and femoral neck BMD
calculations. Options A, C, and D are incorrect because external (not internal) rotation causes
this, software cannot completely fix physical structural superimposition, and it shifts the ROI
placement rather than invalidating the entire skeletal scan.
3. A bone densitometry technologist is performing daily quality control (QC) on a fan-beam DXA
system using the manufacturer's anthropomorphic spine phantom. The resulting baseline BMD
value falls outside the established 1.5 standard deviation (SD) control limits, though within 2.5
SD. What is the appropriate immediate clinical protocol?
A. Proceed with patient scanning because up to 3 SD drift is acceptable under emergency
guidelines.
B. Stop all patient scans, repeat the QC scan to check for positioning errors or air bubbles,
and consult the service manual or manufacturer if the out-of-control status persists before
scanning patients.
C. Adjust the calibration baseline manually in the software settings to force the phantom value
into the passing range.
D. Continue scanning only spine patients while suspending hip scans until further notice.
CORRECT ANSWER : B
, Rationale: A QC result outside 1.5 SD control limits warrants an immediate repeat to rule out
artifact, and patient imaging must not proceed until instrument calibration stability is confirmed.
Options A, C, and D are incorrect because ignoring QC limits compromises diagnostic
precision, manually overriding baseline data violates regulatory standards, and partial patient
scanning is methodologically unsound.
4. A clinical research coordinator is comparing bone density measurements obtained from a
peripheral dual-energy X-ray absorptiometry (pDXA) device of the calcaneus against central
axial DXA measurements of the lumbar spine. Why must these two distinct assessment
modalities not be used interchangeably for clinical diagnosis according to ISCD guidelines?
A. Peripheral devices only measure cortical bone, whereas axial DXA measures pure adipose
tissue.
B. T-scores derived from different skeletal sites and technologies are not mathematically or
diagnostically interchangeable due to disparate rates of bone turnover and varying ratios
of cortical-to-trabecular bone.
C. Peripheral devices utilize high-dose ionizing radiation that exceeds annual occupational
limits.
D. Central axial DXA is strictly qualitative, whereas pDXA is fully quantitative.
CORRECT ANSWER : B
Rationale: Skeletal sites lose bone mass at varying rates; T-scores are site-specific, and
peripheral screening devices cannot replace central spine and hip DXA for WHO osteoporosis
diagnosis. Options A, C, and D are incorrect because pDXA measures bone (not adipose),
radiation doses for pDXA are extremely low, and central DXA is quantitative.
5. A 59-year-old man undergoes a baseline DXA scan. The lumbar spine T-score is -1.8, the
femoral neck T-score is -2.6, and the total hip T-score is -2.1. According to the World Health
Organization (WHO) diagnostic criteria, how should this patient's bone status be formally
categorized?
A. Normal bone density
B. Osteoporosis, based on the lowest T-score observed at the femoral neck.
C. Osteopenia, because the lumbar spine average is above the osteoporotic threshold.
D. Severe established osteoporosis with fragility fracture history.
CORRECT ANSWER : B
Questions and Answers/Plus a Rationale
Updated 2026 A+/Instant Download PDF
EXAM COVERAGE
1. Bone Densitometry Physics, Instrumentation, and Technology (DXA, QCT, Ultrasound)
2. Radiation Safety, Quality Assurance, and Quality Control Procedures
3. Patient Positioning, Anatomy, Scan Acquisition, and Technical Artifacts
4. Clinical Interpretation, T-Scores, Z-Scores, and WHO Diagnostic Criteria
5. Metabolic Bone Diseases, Risk Assessment (FRAX), and Pharmacological Management
1. A 68-year-old postmenopausal female presents for a baseline dual-energy X-ray absorptiometry
(DXA) scan. During the lumbar spine acquisition, the technologist observes that the L1-L4
vertebrae do not show the expected progressive increase in vertebral body size and density from
superior to inferior. Instead, L2 demonstrates a significantly higher BMD than L3 and L4. Upon
reviewing the lateral scout view, what is the most likely technical or pathological cause for this
anomaly?
A. Normal physiological variation in trabecular bone remodeling due to aging.
B. Severe localized degenerative disc disease, osteophytosis, or facet arthrosis artificially
inflating the bone mineral density of L2.
C. Proper beam hardening correction artifact inherent to pencil-beam densitometers.
D. Severe osteomalacia selectively targeting the lower lumbar segments.
CORRECT ANSWER : B
Rationale: Degenerative changes such as osteophytes, syndesmophytes, and facet sclerosis add
dense cortical and mineralized bone tissue to the scan area, falsely elevating the measured bone
mineral density (BMD). Options A, C, and D are incorrect because normal vertebral size
increases sequentially inferiorly, bone-hardening artifacts affect the entire field uniformly rather
, than a single isolated segment, and osteomalacia lowers rather than abnormally spikes BMD
readings.
2. When analyzing a total hip DXA scan for a 72-year-old male, the technologist notices that the
lesser trochanter is prominently visible and projecting medially from the femoral shaft. How
does this specific positioning error impact the calculation of the total hip bone mineral density
and T-score?
A. Internal rotation artifacts cause an underestimation of the femoral neck BMD.
B. External rotation of the femur superimposes the lesser trochanter, which alters the
automated region-of-interest (ROI) placement and artificially increases the measured hip
BMD.
C. It has zero impact because modern fan-beam software automatically corrects for rotational
variance.
D. It completely invalidates the scan by shifting the region of interest entirely outside the pelvic
girdle.
CORRECT ANSWER : B
Rationale: External rotation causes the lesser trochanter to roll into view, which interferes with
the bone edge-detection algorithm and falsely elevates total hip and femoral neck BMD
calculations. Options A, C, and D are incorrect because external (not internal) rotation causes
this, software cannot completely fix physical structural superimposition, and it shifts the ROI
placement rather than invalidating the entire skeletal scan.
3. A bone densitometry technologist is performing daily quality control (QC) on a fan-beam DXA
system using the manufacturer's anthropomorphic spine phantom. The resulting baseline BMD
value falls outside the established 1.5 standard deviation (SD) control limits, though within 2.5
SD. What is the appropriate immediate clinical protocol?
A. Proceed with patient scanning because up to 3 SD drift is acceptable under emergency
guidelines.
B. Stop all patient scans, repeat the QC scan to check for positioning errors or air bubbles,
and consult the service manual or manufacturer if the out-of-control status persists before
scanning patients.
C. Adjust the calibration baseline manually in the software settings to force the phantom value
into the passing range.
D. Continue scanning only spine patients while suspending hip scans until further notice.
CORRECT ANSWER : B
, Rationale: A QC result outside 1.5 SD control limits warrants an immediate repeat to rule out
artifact, and patient imaging must not proceed until instrument calibration stability is confirmed.
Options A, C, and D are incorrect because ignoring QC limits compromises diagnostic
precision, manually overriding baseline data violates regulatory standards, and partial patient
scanning is methodologically unsound.
4. A clinical research coordinator is comparing bone density measurements obtained from a
peripheral dual-energy X-ray absorptiometry (pDXA) device of the calcaneus against central
axial DXA measurements of the lumbar spine. Why must these two distinct assessment
modalities not be used interchangeably for clinical diagnosis according to ISCD guidelines?
A. Peripheral devices only measure cortical bone, whereas axial DXA measures pure adipose
tissue.
B. T-scores derived from different skeletal sites and technologies are not mathematically or
diagnostically interchangeable due to disparate rates of bone turnover and varying ratios
of cortical-to-trabecular bone.
C. Peripheral devices utilize high-dose ionizing radiation that exceeds annual occupational
limits.
D. Central axial DXA is strictly qualitative, whereas pDXA is fully quantitative.
CORRECT ANSWER : B
Rationale: Skeletal sites lose bone mass at varying rates; T-scores are site-specific, and
peripheral screening devices cannot replace central spine and hip DXA for WHO osteoporosis
diagnosis. Options A, C, and D are incorrect because pDXA measures bone (not adipose),
radiation doses for pDXA are extremely low, and central DXA is quantitative.
5. A 59-year-old man undergoes a baseline DXA scan. The lumbar spine T-score is -1.8, the
femoral neck T-score is -2.6, and the total hip T-score is -2.1. According to the World Health
Organization (WHO) diagnostic criteria, how should this patient's bone status be formally
categorized?
A. Normal bone density
B. Osteoporosis, based on the lowest T-score observed at the femoral neck.
C. Osteopenia, because the lumbar spine average is above the osteoporotic threshold.
D. Severe established osteoporosis with fragility fracture history.
CORRECT ANSWER : B
