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1.1 About the ARRT Bone Densitometry Examination
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
1.1 About the ARRT Bone Densitometry Examination
Key Takeaways Explain This Topic AI
The ARRT Bone Densitometry exam contains 105 total items: 75 scored questions and 30 unscored pilot questions that do not affect the reported score.
Test time is 105 minutes, but the scheduled appointment is 125 minutes because it adds an 8-minute tutorial, a 2-minute nondisclosure agreement, and a 10-minute exit survey.
ARRT reports results as scaled scores on a 1 to 99 scale, and a scaled score of 75 is required to pass every ARRT examination.
Through December 31, 2026 the scored blueprint is Patient Care 17 items, Image Production 20 items, and Procedures 38 items; the specifications effective January 1, 2027 shift this to 19, 19, and 37.
Candidates receive three attempts to pass, and all three must fall within three years of the date the first exam window opens.
Last updated: September 2026
1.1 About the ARRT Bone Densitometry Examination
Quick Answer: The American Registry of Radiologic Technologists (ARRT) Bone Densitometry (BD) examination is a postprimary certification exam of 105 computer-delivered multiple-choice items — 75 scored and 30 unscored pilot items. Test time is 105 minutes within a 125-minute appointment. A scaled score of 75 passes. Scored content is divided into three categories: Patient Care, Image Production, and Procedures.
What the BD Credential Is
Bone Densitometry is a postprimary ARRT credential. Unlike a primary discipline such as Radiography, you cannot enter bone densitometry as your first credential — you must already hold a qualifying supporting credential before you may apply. The credential is designated BD and appears after your name as, for example, R.T.(R)(BD)(ARRT) .
The examination's stated purpose, in ARRT's own words, is to assess whether an individual has obtained "the knowledge and cognitive skills underlying the intelligent performance of the tasks typically required in bone densitometry for practice at entry level." Those tasks come from a nationwide practice analysis survey of working bone density technologists, published as the Task Inventory for Bone Densitometry . Every content category in the examination specifications links back to one or more tasks on that inventory.
That linkage matters for how you study. The exam is not a physics course and not a radiology-interpretation course. It tests what a technologist must know to acquire, analyze, and quality-check a DXA study correctly, and to prepare and protect the patient while doing it.
Exam Format and Timing
- Element Value
- Scored items 75
- Pilot (unscored) items 30
- Total items presented 105
- Test time 105 minutes
- Tutorial 8 minutes
- Nondisclosure agreement (NDA) 2 minutes
- Exit survey 10 minutes
- Total appointment length 125 minutes (2 hours, 5 minutes)
Two timing facts are routinely confused, and the distinction is worth fixing now. Test time is 105 minutes. Appointment length is 125 minutes. The extra 20 minutes is consumed by the tutorial, the nondisclosure agreement, and the post-exam survey — none of which draws down your testing clock.
Across 105 items in 105 minutes, your average pace is one item per minute . That is generous for recall items and adequate for the calculation items (least significant change, coefficient of variation, percent change) you will meet in the Image Production category, provided you have practiced the arithmetic in advance rather than deriving it at the test center.
Pilot items are embedded, unidentified, and statistically evaluated for future exam forms. You cannot tell which 30 of the 105 are unscored, so treat every item as scored.
How the Exam Is Scored
ARRT reports scaled scores , not raw scores. A raw score is simply the number of items answered correctly; a scaled score converts that raw score onto a common metric so that results are comparable across different exam forms of differing difficulty. Scaled scores range from 1 to 99 , and a scaled score of 75 is required to pass .
Because the conversion depends on form difficulty, ARRT does not publish a fixed number of correct answers needed for a 75. Section-level scaled scores also appear on your score report, showing how you performed in each content category as though that category had made up the whole exam. Those section scores are diagnostic — useful for directing a retake study plan — but only the total scaled score determines pass or fail.
The Scored Content Blueprint
ARRT publishes Examination Content Specifications that state exactly how many scored items come from each category. A revision takes effect during the useful life of this guide, so both versions are listed:
- Content category Scored items (through Dec 31, 2026) Scored items (effective Jan 1, 2027)
- Patient Care — Bone Health, Care, and Radiation Principles 17 (22.7%) 19 (25.3%)
- Image Production — Equipment Operation and Quality Control 20 (26.7%) 19 (25.3%)
- Procedures — DXA Scanning 38 (50.7%) 37 (49.3%)
- Total scored 75 75
The single most important planning fact in that table: Procedures is roughly half the exam under both versions. Lumbar spine, proximal femur, and forearm scanning — anatomy, acquisition parameters, positioning, problem recognition, and analysis — carry more weight than Patient Care and Image Production combined. Study time should be allocated accordingly, and this guide is structured to match.
What Changed for January 1, 2027
The ARRT Board approved a revised content outline in January 2026 with an implementation date of January 1, 2027 . The exam you sit determines which outline applies. Substantive differences include:
Patient Care: adds explanation of radiation dose and effects to the patient-instruction topic, and updates dosimetry terminology from entrance dose and dose equivalent to absorbed dose (mGy) and effective dose (mSv) .
Image Production: adds trabecular bone score (TBS) and whole body DXA (including pediatric ages 5–19 and total body less head), expands informatics to name PACS, DICOM, networks, and HIS/RIS/EMR, and adds recording QC results and reconfiguring report settings. Cross-calibration is removed as a named topic.
Procedures: adds window level to scan analysis at all three sites, and adds an explicit follow-up scans topic (rate of change in BMD and T-/Z-score, reproducing the baseline study) for lumbar spine, proximal femur, and forearm.
This guide teaches the union of both outlines. That is deliberate: a candidate testing in late 2026 is accountable for cross-calibration and equipment management, while a candidate testing in 2027 is accountable for TBS, whole body DXA, and window level. Learning both costs little and leaves no exposure on either side of the transition.