What Is RTBD Certification?

What This Credential Actually Is

Registered Technologist - Bone Densitometry is a postprimary certification offered by the American Registry of Radiologic Technologists (ARRT). "Postprimary" means you cannot start here. You must already hold a qualifying primary credential, and the bone densitometry certification builds on it by documenting that you have the education, hands-on experience and tested knowledge to perform bone density scans competently.

In practical terms, the credential tells employers that you have been evaluated on three things: how you care for patients undergoing densitometry, how you produce a technically sound scan, and how you carry out the procedures themselves. If you want the shorter definitional pages on this topic, our overview at What Is RTBD? and the explainer on what RTBD stands for cover the basics. This article goes deeper into how the certification works from application through renewal.

Not the Other Bone Densitometry Credentials

Bone densitometry is a field with more than one route to professional recognition, and candidates sometimes mix them up. The credential discussed here is the ARRT postprimary Bone Densitometry (BD) certification. It is not the ISCD CBDT certification, and it is not a state Bone Densitometry Equipment Operator examination. Those are separate programs with their own rules, fees and content outlines.

This matters for a few reasons. Fees, eligibility rules and exam content from one program do not transfer to another. A study resource built around a different program's blueprint may emphasize the wrong material. And if your employer or state licensing board requires a specific credential, you need to know which one you are pursuing. Check with your state and your employer before you commit.

Who Can Apply: Pathways and Prerequisites

Because this is a postprimary credential, the first gate is holding a current supporting credential. ARRT recognizes these pathways:

• Current ARRT certification in Radiography
• Current ARRT certification in Radiation Therapy
• Current certification in Nuclear Medicine Technology, which may be held through ARRT or through the NMTCB

You must also meet ARRT's ethics requirements, which cover both conduct standards and the disclosure of certain legal or disciplinary matters. If your supporting credential lapses, your eligibility is affected, so keep it current throughout the application process.

For a fuller walkthrough of prerequisites and how to qualify, see our dedicated guide to RTBD requirements.

The Education and Clinical Experience Requirements

Many candidates underestimate this part of the process. Passing the exam is only one piece of earning the credential. ARRT also requires documented education and documented hands-on experience, both completed inside a defined window.

Structured education

You need 16 approved hours of structured education completed within the 24 months before you apply. The hours must include at least one credit in each of the major content categories. ARRT's requirements document includes some boilerplate language that mentions safety, but the actual category table and the examination blueprint both use three major categories. Do not plan around a fourth "Safety" domain; it is not a separate exam category.

Clinical experience

Within that same qualifying 24-month window, you must complete 125 mandatory procedures:

• 25 daily quality-control activities
• 50 lumbar spine scans
• 50 femur scans

On top of those, you must complete at least three elective activity types at their specified repetitions. This is a common point of confusion: the electives are not simply three extra scans. Each elective is an activity type with its own required number of repetitions, so read the clinical experience document closely before you plan your clinical time. Actual scanning must be performed physically onsite, so simulation or remote observation will not substitute.

How the Exam Is Built and Delivered

The certification exam is computer-based and administered at Pearson VUE testing centers. Here are the mechanics that matter on test day:

Three details deserve attention. First, 30 of the 105 questions do not count. ARRT uses them to pilot new items, and you cannot tell which ones they are, so treat every question as scored. Second, the 105 minutes of testing is separate from the 125-minute appointment; the extra time covers check-in and onboarding steps, not additional exam time. Third, while one-best-answer multiple choice is the dominant format, other item formats permitted by ARRT's handbook can appear, so do not assume every question will look the same.

The exam is closed-book. You may not bring a personal calculator, but a test-center-supplied calculator and an on-screen calculator are available. That is relevant in a field where T-scores, Z-scores and precision calculations come up.

For perspective on how demanding this format feels in practice, read How Hard Is the RTBD Exam?

The Three Content Domains

ARRT organizes the exam into three major categories. The published scored-question allocations are below. Note that these are question counts from the content specifications, and we are deliberately not converting them into percentages, since ARRT does not present them that way.

With 38 of the scored questions, Procedures is the largest domain by a wide margin, bigger than the other two combined (37). That should shape how you divide your study time. Our deeper breakdown is in RTBD Exam Domains: Complete Guide to All 3 Content Areas.

Scoring, Passing Score and Pass Rate

ARRT reports results on a scaled score from 1 to 99, and the passing score is 75. This is the single most misunderstood point about ARRT exams: a 75 does not mean you must answer 75% of questions correctly. Scaled scoring adjusts for differences in difficulty between exam forms so that a given score represents the same level of competence regardless of which form you receive. The raw number of correct answers needed can differ from form to form.

For the deeper explanation, see RTBD Passing Score: Exactly What You Need to Pass.

As for how candidates have fared, ARRT's Annual Exam Report for 2025 shows a first-time pass rate of 66.7% among 303 candidates. Treat this as an observed result for one cohort in one year, not a prediction for 2026. Still, it is a useful reminder that roughly one in three first-time candidates in that cohort did not pass, which is a good argument for thorough preparation. More context is in RTBD Pass Rate: What the Data Shows.

Fees, Attempts and Application Mechanics

The application and exam fee is $225 USD. If you qualify using NMTCB Nuclear Medicine Technology as your supporting credential, the fee is $450 USD. A reapplication after an unsuccessful attempt costs $200.

You are permitted three examination attempts within three years before you must requalify. Because each attempt carries a fee, and because the three-year window creates a hard stop, it pays to treat your first attempt seriously rather than as a trial run. For the full financial picture, including indirect costs such as education hours, see RTBD Certification Cost: Complete Pricing Breakdown. For scheduling details, see RTBD Exam Dates: Testing Windows, Deadlines and Scheduling.

The 2026 vs. 2027 Specification Boundary

One of the most important details for anyone planning a test date is that ARRT publishes the exam content specifications in versions with defined effective periods. The specification relevant to current testing was board approved in July 2021, became effective July 1, 2022, and applies through December 31, 2026.

A replacement specification takes effect January 1, 2027. It changes the scored-question allocations to 19 for Patient Care, 19 for Image Production and 37 for Procedures, and it also changes some of the topics covered.

Keeping the Credential Active

Earning the certification is not the end of the obligation. ARRT requires ongoing maintenance:

• Annual registration renewal: $65 per year, regardless of how many ARRT credentials you hold.
• Continuing education: ordinarily 24 approved CE credits per two-year biennium.
• Continuing Qualifications Requirements (CQR): required every ten years for credentials earned on or after January 1, 2011.

Because the renewal fee is flat across credentials, adding bone densitometry to an existing ARRT registration does not multiply your annual registration cost. Verify current CE and CQR rules directly with ARRT, since requirements can be updated.

Sequencing Your Preparation by Domain

Rather than a generic study calendar, let the blueprint drive your sequencing. Procedures holds the largest share of scored questions, and it builds on concepts from the other two domains, so a sensible order moves from foundations to application:

Adjust the length to fit your clinical schedule. For a fuller plan, see the RTBD Study Guide, and when you want a condensed review sheet close to test day, use the RTBD Cheat Sheet. To test yourself against exam-style questions, try the practice tests at RTBD Exam Prep.

Where the Credential Fits in Your Career

Bone densitometry technologists typically work in settings where osteoporosis screening and monitoring happen: hospital radiology and imaging departments, outpatient imaging centers, physician practices such as rheumatology, endocrinology and women's health, and mobile screening services. Employers in these settings often value a recognized credential because it signals documented competence in a specialty with technical and patient-safety demands.

Whether the credential pays off for you depends on your market, your current role and your employer's expectations. We cover this from several angles in RTBD Salary Guide, RTBD Jobs and Is the RTBD Certification Worth It?. We deliberately avoid quoting specific salary figures here, since pay varies widely by region and employer.

Frequently Asked Questions

For definitions and related background, you can also browse RTBD Certification and What Is RTBD Certification? in our resource library.