1.1 About the ARRT Bone Densitometry Examination

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

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:

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.