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12.1 Recognition, Impact, and Management of DXA Artifacts
ARRT Bone Densitometry Exam
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1 Chapter 1: Exam Orientation & the ARRT Blueprint
1.1 About the ARRT Bone Densitometry Examination 1.2 Eligibility, Structured Education, and Clinical Experience
2 Chapter 2: Osteoporosis, Bone Biology & Risk Factors
2.1 Osteoporosis: Definitions, Types, and WHO Diagnostic Criteria 2.2 Bone Functions, Structural Anatomy, and Bone Types 2.3 Bone Cells, the Remodeling Cycle, and Calcium Homeostasis 2.4 Risk Factors, Secondary Causes, and Bone-Compromising Medications
3 Chapter 3: Indications, Prevention & Treatment
3.1 The Bone Mass Measurement Act: Covered Indications and Coding 3.2 Prevention: Nutrition, Exercise, Smoking Cessation, and Fall Prevention 3.3 Osteoporosis Drug Therapy: Antiresorptive, Anabolic, and Hormonal Agents
4 Chapter 4: Patient Preparation, Support & Radiation Safety
4.1 Patient Support, Disabilities, Ergonomics, and Transfer Techniques 4.2 Patient Instructions: Explaining the Exam, Dose, Duration, and Motion Control 4.3 Patient History, Contraindications, and Pregnancy Screening 4.4 Scan Preparation: Patient Data Entry, Artifact Removal, and Infection Control 4.5 Radiation Safety in DXA: ALARA, Distance, and Dose Levels
5 Chapter 5: DXA Physics & Instrumentation
5.1 Physical Principles of Dual-Energy X-ray Absorptiometry 5.2 Beam Geometries: Pencil Beam and Fan Beam Systems 5.3 Fan-Beam Geometry: Source–Object–Detector Distances, Magnification, and Centering 5.4 The Scan Analysis Algorithm: Soft Tissue, Bone Edge Detection, BMC, Area, and BMD
6 Chapter 6: Measuring & Reporting Bone Mineral Density
6.1 Statistics for Densitometry: Mean, Standard Deviation, and Coefficient of Variation 6.2 T-Scores, Z-Scores, and Reference Database Selection 6.3 Clinical Indications for BMD Testing and the FRAX Tool 6.4 Vertebral Fracture Assessment and Trabecular Bone Score 6.5 Whole Body DXA, Body Composition, and Pediatric Scanning
7 Chapter 7: Quality Control, Precision & Equipment Management
7.1 Accuracy, Precision, and the Sources of Precision Error 7.2 Daily Quality Control, Phantoms, and Control Charts 7.3 In Vivo Precision Studies and RMS-SD Calculation 7.4 Determining and Applying the Least Significant Change 7.5 Maintenance, Repair, Relocation, Cross-Calibration, and Software Upgrades
8 Chapter 8: DXA Informatics & Data Management
8.1 DXA Informatics, DICOM, PACS, and Data Management
9 Chapter 9: Lumbar Spine DXA
9.1 Lumbar Spine Anatomy, Landmarks, and Regions of Interest 9.2 Lumbar Spine Scan Acquisition and ROI Edge Placement 9.3 Lumbar Spine: Compensating for Body Habitus, Variant Anatomy, Pathology, and Low Bone Density 9.4 Lumbar Spine Positioning: The Leg Block, Centering, and Common Challenges 9.5 Lumbar Spine Problems: Poor Bone Edge Detection and Obscured Intervertebral Spaces 9.6 Lumbar Spine: Variant Anatomy, Fractures, Degenerative Pathology, Calcification, and Surgery 9.7 Lumbar Spine Analysis: Vertebral Exclusion and Reporting Rules 9.8 Lumbar Spine Follow-Up Scans and Rate of Change
10 Chapter 10: Proximal Femur DXA
10.1 Proximal Femur Anatomy, Landmarks, and Regions of Interest 10.2 Femur Selection: Right, Left, and Dual Femur Scanning 10.3 Proximal Femur Scan Parameters and Compensation 10.4 Proximal Femur Positioning: Neck Rotation, Shaft Placement, and Positioning Aids 10.5 Proximal Femur Problems: Ischium, Short Neck, Arthritis, Fracture, and Hardware 10.6 Femoral ROI Analysis: Femoral Neck, Total Hip, and Ward's Area 10.7 Proximal Femur Follow-Up Scans and Rate of Change
11 Chapter 11: Forearm DXA
11.1 Forearm Anatomy, Landmarks, and Adjacent Structures 11.2 Forearm Indications and Side Selection 11.3 Forearm Length Measurement, Scan Parameters, and Positioning 11.4 Forearm Regions of Interest: One-Third, Mid, Ultradistal, and Total 11.5 Forearm Problems: Edge Detection, Artifacts, Low Bone Density, and Joint Disease 11.6 Scan Analysis: Region Placement, Window Level, and Reported Values 11.7 Forearm Follow-Up Scans and Rate of Change
12 Chapter 12: Cross-Site Artifacts & Clinical Integration
12.1 Recognition, Impact, and Management of DXA Artifacts 12.2 Clinical Interpretation, Serial Comparison, and Reporting
12.1 Recognition, Impact, and Management of DXA Artifacts
Key Takeaways Explain This Topic AI
Artifacts in dual-energy X-ray absorptiometry are categorized as internal (degenerative changes, vascular calcifications, surgical hardware, fractures) or external (clothing items, ingested contrast media, radiopaque medications).
Degenerative spinal pathology (osteophytes, facet sclerosis, disc space narrowing) and abdominal aortic calcifications project additional calcium mass over vertebrae in 2D PA acquisitions, artifactually elevating areal BMD and masking underlying osteoporosis.
Surgical hardware, vertebroplasty polymethylmethacrylate (PMMA) cement, and acute compression fractures cause marked focal BMD spikes; affected vertebral levels must be excluded from diagnostic analysis.
External radiopaque agents such as oral barium sulfate require a mandatory 10 to 14 day clearance interval, while iodinated contrast media and nuclear medicine radiopharmaceuticals require 48 to 72 hours before central DXA.
Under ISCD vertebral exclusion guidelines, a vertebra must be excluded if it shows focal structural artifacts or a T-score discrepancy >1.0 compared to adjacent levels, and at least two evaluable vertebrae are required for a valid lumbar spine diagnosis.
Last updated: September 2026
12.1 Recognition, Impact, and Management of DXA Artifacts
Quick Answer: Dual-energy X-ray absorptiometry (DXA) artifacts are categorized as internal (pathological/structural) or external (foreign objects/ingested substances). Internal artifacts—such as degenerative osteophytes, facet sclerosis, abdominal aortic calcifications, and healing compression fractures—falsely elevate measured areal BMD, masking osteoporosis. External artifacts—such as metal clothing fasteners, oral barium sulfate, undissolved calcium pills, and radiopharmaceuticals—severely distort photon attenuation. Technologists must visually inspect raw scan images, apply ISCD vertebral exclusion rules (excluding levels with artifacts or >1.0 T-score discrepancy, requiring at least two evaluable vertebrae, contiguous or not), and transition to the proximal femur or 33% radius when artifacts invalidate central sites.
Densitometric Principles of Artifact Formation
Dual-energy X-ray absorptiometry quantifies areal bone mineral density (g/cm²) by measuring the differential attenuation of high- and low-energy X-ray photons through bone mineral (hydroxyapatite) and soft tissue: BMD = Bone Mineral Content (BMC, g) Projected Bone Area (Area, cm 2 ) \text{BMD} = \frac{\text{Bone Mineral Content (BMC, g)}}{\text{Projected Bone Area (Area, cm}^2)} BMD = Projected Bone Area (Area, cm 2 ) Bone Mineral Content (BMC, g)
Because central DXA generates a 2D planar projection of 3D structures, any attenuating substance situated within the projection beam path—whether anterior, posterior, or internal to bone—is integrated into the total attenuation measurement. Consequently, non-skeletal calcifications, structural bone spurs, or dense foreign substances produce significant artifacts that distort calculated bone mineral density.
Internal Artifacts: Degenerative, Vascular, and Structural Pathology
Internal artifacts originate within patient anatomy. Most internal artifacts add radiopaque density to the beam path, artificially elevating measured BMD and generating falsely elevated T-scores that mask underlying osteoporosis:
Degenerative Spine Disease & Osteophytes
Pathological Changes: Marginal osteophytes, facet joint osteoarthritis (hypertrophy and sclerosis of posterior articular processes), intervertebral disc space narrowing, and subchondral endplate sclerosis.
Impact on BMD: PA lumbar spine acquisitions project posterior facet joints and marginal osteophytes directly over the vertebral bodies. This superimposed calcium falsely inflates bone mineral content (BMC) and areal BMD, often elevating measured density by 10% to 30%. Advancing osteoarthritis causes lumbar BMD to paradoxically increase with age, obscuring progressive trabecular bone loss.
Systemic Arthropathies: Diffuse idiopathic skeletal hyperostosis (DISH, flowing anterolateral ossification across ≥ 4 contiguous vertebrae) and ankylosing spondylitis (bilateral syndesmophytes forming a rigid "bamboo spine") produce marked artificial BMD elevations.
Atherosclerotic Vascular Calcifications:
Abdominal Aorta Calcification: Atherosclerotic plaques deposit calcium along the abdominal aorta directly anterior to L1–L4. On a 2D projection, calcified aortic walls overlap the lumbar vertebrae, adding false mineral content to the spine ROI.
Surgical Hardware and Bone Cement:
Spinal Instrumentation: Metallic pedicle screws, rods, and fusion cages exhibit extreme photon attenuation. The scanner software registers metal as hyper-dense bone, generating non-physiological BMD elevations.
Vertebroplasty and Kyphoplasty: Injection of polymethylmethacrylate (PMMA) bone cement creates an intensely radiopaque focal mass. The treated vertebral level must be excluded from diagnostic analysis.
Hip Arthroplasty: Prosthetic stems, cups, and cerclage wires invalidate proximal femur densitometry on the operated side.
Vertebral Compression Fractures:
A fractured vertebra collapses in height (>20% loss), compacting trabeculae into a reduced projected area. Healing fracture callus adds further mineralization, causing the fractured level to display a paradoxically higher BMD and T-score than adjacent uninjured vertebrae.
Non-Skeletal Calcified Entities:
Gallstones (cholelithiasis), renal stones (nephrolithiasis), calcified mesenteric lymph nodes, and calcified uterine fibroids project over the spine or pelvis, causing focal false density spikes.
External Artifacts: Clothing, Ingested Agents, and Contrast Media
External artifacts originate outside biological tissues or within the gastrointestinal tract and can be prevented through rigorous screening:
Clothing Fasteners and Personal Items:
Zippers, underwires, snaps, metal buttons, belt buckles, coins, jewelry, and piercings directly attenuate X-rays. Over bone, they falsely elevate BMD; over soft tissue baselines, they distort soft-tissue reference values. Patients should change into a metal-free gown.
Ingested Radiopaque Contrast Substances:
Oral Barium Sulfate: High-density barium suspensions linger in bowel loops. Superimposed over the spine or pelvis, barium produces extreme X-ray absorption, resulting in vast artifactual BMD spikes.
Clearance Interval: Central DXA must be postponed 10 to 14 days (1 to 2 weeks) following barium administration to permit complete intestinal clearance. Technologists must verify bowel clearance on raw scout images.
Water-Soluble Iodinated CT/IV Contrast: Excreted renally within 24 to 48 hours. Central DXA should be delayed 48 to 72 hours after contrast examinations.
Nuclear Medicine Radiopharmaceuticals: Diagnostic radionuclides (e.g., Tc-99m MDP, F-18 FDG) emit gamma or positron radiation that floods DXA detectors, causing count overflow. Central DXA must be postponed 48 to 72 hours to allow radioactive decay and excretion.
Undissolved Calcium Supplements: Ingesting calcium tablets shortly before scanning leaves dense, radiopaque pills in bowel loops overlying the lumbar spine. Patients must withhold oral calcium supplements for 24 hours prior to central DXA.
Troubleshooting Protocols and Vertebral Exclusion Criteria
Quality densitometry requires systematic quality control by the technologist:
Raw Image Scrutiny: Technologists must inspect raw grayscale images to verify accurate bone edge detection, correct L1–L4 intervertebral disc labeling, neutral patient positioning, and absence of foreign materials or soft-tissue artifacts.
ISCD Vertebral Exclusion Rules:
Vertebrae affected by local structural artifacts (severe osteophytes, fracture, aortic calcification, hardware, or PMMA cement) must be systematically excluded from the diagnostic L1–L4 mean.
T-Score Discrepancy Rule: If an individual vertebra exhibits a T-score differing by >1.0 standard deviation from adjacent levels, and visual inspection identifies focal artifact, that level must be excluded.
Minimum of Two Evaluable Vertebrae: A valid diagnostic lumbar spine evaluation requires at least two evaluable vertebrae ; diagnostic classification must never rest on a single vertebra. Contiguous levels are preferable, but ISCD does not impose contiguity as a requirement, so non-adjacent combinations such as L1 and L3 remain usable when the intervening level is excluded. If fewer than two evaluable levels remain, the spine is non-diagnostic.
Alternative Site Strategy:
If the lumbar spine cannot be interpreted due to multi-level artifacts, the technologist evaluates the proximal femur.
If bilateral hip replacements or severe bilateral deformities preclude hip densitometry, the technologist must immediately initiate a 33% (one-third) radius forearm scan .
Artifact Category Specific Artifact Effect on Measured BMD Technologist Remediation / Protocol
Internal (Degenerative) Marginal osteophytes, facet sclerosis, disc narrowing Falsely elevates areal BMD; masks osteoporosis Visually identify on raw image; exclude affected vertebra if T-score discrepancy >1.0 SD; ensure ≥ 2 evaluable levels remain.
Internal (Vascular) Calcified abdominal aorta overlying L1–L4 Falsely elevates lumbar spine BMD Correlate with lateral scout or VFA; exclude heavily calcified levels; utilize proximal femur or 33% radius if spine is invalid.
Internal (Surgical) Pedicle screws, rods, fusion cages, PMMA cement Extreme non-physiological BMD elevation Completely exclude instrumented or cemented levels; if fewer than 2 evaluable levels remain, declare spine non-diagnostic.
Internal (Traumatic) Vertebral compression fracture (height loss >20%) Falsely elevates BMD due to trabecular impaction/callus Exclude fractured level; document morphometric fracture; evaluate adjacent intact vertebrae and proximal femur.
External (Belongings) Zippers, snaps, buttons, wire bras, jewelry, piercings Falsely elevates BMD over bone; distorts soft tissue baseline Screen patient prior to scan; require gown change into metal-free attire; remove all jewelry and piercings over scan field.
External (Ingested) Oral barium sulfate GI contrast suspension Extreme radiopaque artifact; severe false BMD spike Postpone DXA scan 10 to 14 days (1–2 weeks) to permit complete GI clearance; verify clearance on raw scout image.
External (Ingested) Undissolved oral calcium supplement tablets Dense focal radiopacity over lumbar vertebrae Instruct patient to withhold oral calcium supplements for 24 hours prior to scan; reschedule if pill is visualized over spine.
External (Medical) IV/oral iodinated contrast, nuclear radiopharmaceuticals Distorts photon attenuation; detector count overflow Wait 48 to 72 hours following iodinated contrast or diagnostic radioisotopes before performing central DXA.