ISCD Certified Bone Densitometry Technologist (CBDT®) — Questions and Answers

Question 1: Which condition requires DEXA monitoring and is caused by elevated endogenous cortisol due to a pituitary or adrenal tumor?

Paget's disease of bone
Fibrous dysplasia
Cushing's syndrome (Correct answer)
Hyperparathyroidism

Correct answer: Cushing's syndrome

Cushing's syndrome causes endogenous glucocorticoid excess, leading to secondary osteoporosis that requires BMD monitoring via DEXA.

Question 2: Which factor affects BMD readings?

Patient movement (Correct answer)
Room lighting
Printer quality
Radiologist experience

Correct answer: Patient movement

Patient movement during a DEXA scan can significantly affect Bone Mineral Density (BMD) readings by introducing motion artifacts. These artifacts blur the image and distort the bone region of interest, leading to inaccurate measurements. Ensuring the patient remains still throughout the scan is critical for obtaining precise and reliable BMD results.

Question 3: What does a Z-score compare?

Fat mass
Bone density of age-matched peers (Correct answer)
Daily height changes
Water weight

Correct answer: Bone density of age-matched peers

A Z-score in DEXA scanning compares a patient's Bone Mineral Density (BMD) to the average BMD of individuals of the same age, sex, and ethnic background. This score is primarily used for children, premenopausal women, and men under 50 to determine if their bone density is lower than expected for their age, helping identify secondary causes of low bone mass.

Question 4: What is a potential side effect of radiation exposure?

Muscle strain
Dehydration
Increased cancer risk (Correct answer)
Fever

Correct answer: Increased cancer risk

While DEXA scans use a very low dose of radiation, any exposure to ionizing radiation carries a small, cumulative risk of cellular damage that can potentially lead to an increased risk of cancer over a lifetime. This is why radiation safety principles like ALARA are strictly followed to minimize exposure for both patients and staff.

Question 5: How long should a DEXA technologist wait before performing a follow-up BMD scan to assess treatment response for a patient on bisphosphonate therapy?

At least 1–2 years after initiating therapy (Correct answer)
Repeat annually regardless of treatment
3 months after starting therapy
6 months after starting therapy

Correct answer: At least 1–2 years after initiating therapy

ISCD guidelines recommend waiting 1–2 years before a follow-up DEXA to detect meaningful BMD changes that exceed the LSC on bisphosphonate therapy.

Question 6: What documentation is MOST critical to maintain for safety compliance in the DEXA Bone Density Scan Certification field?

Employee vacation schedules
Incident reports, training records, and inspection logs (Correct answer)
Client marketing preferences
Annual revenue reports

Correct answer: Incident reports, training records, and inspection logs

Incident reports, training records, and inspection logs are essential safety documentation for demonstrating compliance.

Question 7: What is precision in DEXA scanning?

Scan speed
High radiation dose
Reproducibility of results (Correct answer)
Image clarity

Correct answer: Reproducibility of results

In DEXA scanning, precision refers to the ability of the scanner to produce consistent and reproducible results when measuring the same patient multiple times under similar conditions. High precision is essential for accurately monitoring changes in bone mineral density over time, as it ensures that any observed differences are due to actual physiological changes rather than measurement variability. It reflects the reliability and consistency of the measurement technique.

Question 8: In DEXA Bone Density Scan Certification, what is the PRIMARY purpose of conducting regular safety drills and exercises?

To evaluate employee performance reviews
To ensure personnel can respond effectively in emergencies (Correct answer)
To reduce daily workload
To satisfy insurance requirements only

Correct answer: To ensure personnel can respond effectively in emergencies

Regular safety drills ensure that all personnel are prepared to respond effectively during actual emergencies.

Question 9: How should DEXA Bone Density Scan Certification professionals handle procedures that have been updated or revised?

Only apply updates to new cases
Wait for mandatory enforcement
Review updates, complete required training, and implement revised procedures (Correct answer)
Continue using the original method

Correct answer: Review updates, complete required training, and implement revised procedures

Professionals must review changes, complete training, and implement revised procedures.

Question 10: What is the purpose of DEXA scanning?

Measure bone mineral density (Correct answer)
Assess muscle strength
Visualize cartilage
Detect soft tissue damage

Correct answer: Measure bone mineral density

DEXA (Dual-energy X-ray Absorptiometry) scanning is a specialized medical imaging technique used to accurately measure bone mineral density (BMD). It is the gold standard for diagnosing osteoporosis and assessing an individual's risk of fractures. The scan uses two different X-ray beams to differentiate between bone and soft tissue, providing precise BMD values.

Question 11: What structure covers the bone surface?

Ligament
Synovium
Periosteum (Correct answer)
Endosteum

Correct answer: Periosteum

The periosteum is a tough, fibrous membrane that covers the outer surface of most bones. It contains blood vessels, nerves, and lymphatic vessels that nourish the bone, and it serves as an attachment point for tendons and ligaments. The periosteum also plays a vital role in bone growth, repair, and remodeling.

Question 12: When assessment results for a DEXA Bone Density Scan Certification evaluation are inconclusive, the BEST practice is to:

Delay reporting until results are favorable
Conduct additional assessment using alternative methods (Correct answer)
Report the results as definitive anyway
Discard the results and start over

Correct answer: Conduct additional assessment using alternative methods

Inconclusive results require additional assessment using alternative methods for triangulation.

Question 13: What should be done if a patient is pregnant?

Cancel immediately
Continue as usual
Notify radiologist (Correct answer)
Double scan

Correct answer: Notify radiologist

If a patient is pregnant or suspected of being pregnant, the radiologist must be immediately notified. DEXA scans involve ionizing radiation, which poses a risk to the developing fetus. The radiologist will then determine if the scan can be postponed, if alternative imaging is necessary, or if the benefits outweigh the risks with appropriate precautions.

Question 14: Why is follow-up recommended?

Track weight loss
Monitor changes over time (Correct answer)
Compare technician skills
Assess pain levels

Correct answer: Monitor changes over time

Follow-up DEXA scans are recommended to monitor changes in bone mineral density over time, especially for patients diagnosed with osteopenia or osteoporosis, or those undergoing treatment. These scans allow healthcare providers to assess the effectiveness of interventions, track disease progression, and adjust treatment plans as needed to prevent fractures.

Question 15: What does a sudden step-change (shift) in the daily QC control chart most likely indicate?

The phantom needs to be replaced with a newer model
Normal day-to-day measurement variability
Patient volume has increased significantly
A hardware or software change affecting system performance (Correct answer)

Correct answer: A hardware or software change affecting system performance

A step-change in QC data typically signals a discrete system event such as a detector swap, software update, or phantom replacement.

Question 16: When performing a whole-body DXA scan for body composition, the patient's arms must be:

Crossed over the chest to reduce scan area
Held tightly against the thighs
Positioned palms down, slightly separated from the body sides (Correct answer)
Raised above the head to avoid overlap with the trunk

Correct answer: Positioned palms down, slightly separated from the body sides

Arms are placed palms down with a slight gap from the torso so that the software can correctly separate arm from trunk regions during segmentation.

Question 17: What tool assists with scan interpretation?

Google Docs
Scan printer
Reporting software (Correct answer)
Ultrasound scanner

Correct answer: Reporting software

Specialized reporting software is an essential tool that assists with DEXA scan interpretation. This software processes the raw scan data, calculates BMD values, T-scores, and Z-scores, and often provides visual representations of bone density. It helps radiologists and clinicians efficiently analyze results and generate comprehensive patient reports.

Question 18: Which risk management approach is MOST effective for DEXA professionals when evaluating potential workplace hazards?

Reactive analysis after incidents occur
Relying solely on historical accident data
Proactive hazard identification and assessment (Correct answer)
Delegating all safety decisions to management

Correct answer: Proactive hazard identification and assessment

Proactive hazard identification and assessment allows professionals to identify and mitigate risks before incidents occur.

Question 19: In DEXA Bone Density Scan Certification practice, what is the CORRECT sequence when performing a technical procedure?

Document, execute, then plan
Execute, then plan and review
Plan, prepare, execute, verify, and document (Correct answer)
Execute immediately and document only if issues arise

Correct answer: Plan, prepare, execute, verify, and document

The correct sequence follows: plan, prepare, execute, verify, and document.

Question 20: What can affect interpretation accuracy?

Room color
Patient mood
Artifacts and positioning (Correct answer)
Technician name

Correct answer: Artifacts and positioning

The accuracy of DEXA scan interpretation can be significantly affected by artifacts and improper patient positioning. Artifacts, such as metal objects or previous medical procedures, can obscure bone structures or create false readings. Incorrect positioning can lead to inaccurate region-of-interest selection and skewed BMD measurements, compromising the reliability of the diagnosis.

Question 21: When conducting a risk assessment for DEXA operations, which factor should receive the HIGHEST priority?

Cost of implementing safety measures
Probability and severity of potential harm (Correct answer)
Time required for safety training
Convenience for daily operations

Correct answer: Probability and severity of potential harm

The probability and severity of potential harm are the primary factors in risk assessment.

Question 22: A patient on denosumab discontinues therapy without transitioning to a bisphosphonate. What bone density outcome is expected?

No change in bone density after discontinuation
Gradual slow decline over 5 years
Bone density stabilizes at the level achieved on denosumab
Rapid rebound bone loss (rebound osteoporosis) with increased fracture risk (Correct answer)

Correct answer: Rapid rebound bone loss (rebound osteoporosis) with increased fracture risk

Abrupt denosumab discontinuation causes rapid rebound bone loss, potentially below pre-treatment levels, with significantly elevated vertebral fracture risk.

Question 23: Which factor MOST significantly affects the quality of technical outcomes in DEXA practice?

The brand of equipment
The practitioner's training, preparation, and attention to detail (Correct answer)
The time of day
Speed of procedure completion

Correct answer: The practitioner's training, preparation, and attention to detail

Quality depends primarily on training, preparation, and attention to detail.

Question 24: What should be included in a DEXA report?

BMD, scan site, interpretation (Correct answer)
Insurance status
Only numerical data
Patient opinion

Correct answer: BMD, scan site, interpretation

A comprehensive DEXA report should include the measured Bone Mineral Density (BMD) values for all scanned sites (e.g., lumbar spine, hip), along with the corresponding T-scores and Z-scores. Crucially, it must also contain a clear interpretation of these findings by a qualified physician, including diagnostic classification and recommendations.

Question 25: What is the Visceral Adipose Tissue (VAT) region automatically estimated by advanced DXA software typically approximated from?

MRI co-registration
A biopsy of abdominal fat
The android region scan data combined with validated algorithms (Correct answer)
Direct measurement of the peritoneal cavity with ultrasound

Correct answer: The android region scan data combined with validated algorithms

Modern DXA systems estimate VAT using the fat distribution within the android region combined with proprietary validated algorithms, without requiring MRI or CT.

Question 26: What is the recommended DEXA monitoring interval for patients on long-term glucocorticoid therapy?

Every 1–2 years for patients on ongoing glucocorticoid therapy (Correct answer)
Only at initiation of steroid therapy
Every 5 years
Monthly scans during the first year

Correct answer: Every 1–2 years for patients on ongoing glucocorticoid therapy

ACR and ISCD recommend monitoring DEXA every 1–2 years in patients on ongoing glucocorticoid therapy due to the risk of rapid bone loss.

Question 27: When documenting assessment findings in DEXA practice, which approach is MOST appropriate?

Use jargon only experts understand
Include only positive findings
Summarize verbally without written documentation
Record objective findings, measurements, and observations factually (Correct answer)

Correct answer: Record objective findings, measurements, and observations factually

Assessment documentation must be objective, factual, and comprehensive.

Question 28: Which approach is MOST important for DEXA professionals when applying technical procedures?

Using the fastest method regardless of standards
Applying the same technique without variation
Adhering to established protocols while adapting to specific conditions (Correct answer)
Following personal shortcuts

Correct answer: Adhering to established protocols while adapting to specific conditions

Technical procedures require adherence to protocols with professional judgment for adaptation.

Question 29: What does a reduction in CTX levels within 3 months of starting antiresorptive therapy indicate?

The patient has low dietary calcium intake
The patient is responding to therapy and osteoclast activity is being suppressed (Correct answer)
The patient's kidney function is declining
Bone formation has increased significantly

Correct answer: The patient is responding to therapy and osteoclast activity is being suppressed

A significant early drop in CTX confirms that osteoclast-mediated bone resorption is being effectively suppressed by the antiresorptive medication.

Question 30: What T-score indicates osteoporosis?

Between -1 and -2.5
Above -1.0
Zero
Below -2.5 (Correct answer)

Correct answer: Below -2.5

According to the World Health Organization (WHO) criteria, a T-score of -2.5 or lower indicates osteoporosis. This signifies significantly reduced bone mineral density, placing the individual at a high risk for fragility fractures. T-scores between -1.0 and -2.5 indicate osteopenia, or low bone mass.

Question 31: Which class of medications is most commonly prescribed as first-line pharmacotherapy for postmenopausal osteoporosis in the US?

Selective estrogen receptor modulators (SERMs)
Bisphosphonates (e.g., alendronate, risedronate) (Correct answer)
Parathyroid hormone analogs (e.g., teriparatide)
Calcitonin nasal spray

Correct answer: Bisphosphonates (e.g., alendronate, risedronate)

Bisphosphonates are the most widely used first-line agents for postmenopausal osteoporosis due to their proven fracture reduction and cost-effectiveness.

ISCD Certified Bone Densitometry Technologist (CBDT®)

The CBDT® exam certifies technologists in performing and analyzing DEXA bone density scans, covering bone physiology, radiation safety, DXA equipment, scan acquisition, and clinical data interpretation for osteoporosis assessment.

Questions

35 min

Time Limit

70%

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These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

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iscd.org — Renewal, test delivery, eligibility, exam format, retake policy, score validity, passing score, score release, exam information · verified Oct 2026
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