- What RTBD Means on This Site
- Who Issues the Credential and Who It Is For
- The Exam at a Glance
- The Three Exam Domains
- Why the Content Specifications Version Matters
- Eligibility, Education and Clinical Experience
- Fees, Attempts and Scoring
- After You Pass: Renewal and CQR
- Where Bone Densitometry Technologists Work
- Sequencing Your Preparation Around the Blueprint
- Frequently Asked Questions
- Here, RTBD means ARRT's postprimary Bone Densitometry (BD) credential, not ISCD CBDT or a state equipment operator exam.
- The exam has 105 questions: 75 scored plus 30 unscored pilots, with 105 minutes of testing time.
- Procedures carries the most scored questions (38), ahead of Image Production (20) and Patient Care (17).
- Passing means a scaled score of 75 on ARRT's 1-99 scale, not 75% of questions correct.
What RTBD Means on This Site
On this site, RTBD refers to Registered Technologist - Bone Densitometry: the postprimary Bone Densitometry (BD) credential awarded by the American Registry of Radiologic Technologists (ARRT). "RTBD" is simply the identifier this site uses for that credential, and everything in this article describes the ARRT pathway and nothing else.
That clarification matters because bone densitometry has more than one credential in circulation. ARRT's postprimary Bone Densitometry credential is a different thing from the ISCD's CBDT, and it is also different from the state-level Bone Densitometry Equipment Operator examination some jurisdictions use. Fees, eligibility rules, exam content and renewal obligations differ across those programs, so when you research this topic, confirm that any number or deadline you read belongs to the ARRT credential before you rely on it.
If you want other framings of the same question, we also cover the RTBD meaning, what RTBD stands for and what RTBD certification is in separate articles. This one is the broad orientation: what the credential is, how the exam works, who qualifies and what the blueprint expects.
Who Issues the Credential and Who It Is For
ARRT is best known for primary pathway credentials in radiography, nuclear medicine technology and radiation therapy. Bone Densitometry is a postprimary credential, meaning you add it on top of a primary credential you already hold rather than entering the profession through it. The BD credential recognizes technologists who perform bone density scans, typically DXA, and who can show structured education, documented clinical experience and a passing exam result.
In practice, the credential suits technologists who already work in imaging and want formal recognition of bone densitometry competence. A radiographer who is regularly assigned DXA, or a nuclear medicine technologist whose department runs a bone density unit, is the typical candidate. The credential documents that the person at the scanner has met a national standard for patient care, image production and procedural skill.
The Exam at a Glance
The Bone Densitometry exam is a computer-based test delivered at Pearson VUE testing centers. Here is how the format breaks down:
| Feature | What to Expect |
|---|---|
| Delivery | Computer-based, Pearson VUE testing center |
| Total questions | 105 |
| Scored questions | 75 |
| Unscored pilot questions | 30 |
| Testing time | 105 minutes (the appointment itself runs 125 minutes) |
| Item style | Primarily one-best-answer multiple choice; other handbook-permitted formats are possible |
| Reference materials | Closed-book |
| Calculator | No personal calculator; test-center-supplied and on-screen options are available |
Two details trip up first-time candidates. First, 30 of the 105 questions are unscored pilots, and you cannot tell which ones they are. Treat every question as if it counts. Second, the 105 minutes of testing time is distinct from the 125-minute appointment; the extra time covers check-in and administrative steps, not extra time on questions. For more on the difficulty side of the format, see our guide on how hard the RTBD exam is.
Because the exam is closed-book and personal calculators are not permitted, you need to be comfortable with any arithmetic the blueprint touches using only the test-center tools. Practice that skill before exam day rather than discovering the on-screen calculator in the middle of a question.
The Three Exam Domains
The official exam content specifications organize the exam into three major categories. ARRT publishes the number of scored questions in each, and those counts are the only allocation figures this article uses. They should not be converted into percentages or treated as anything other than question counts.
| Domain | Scored Questions |
|---|---|
| Domain 1: Patient Care | 17 |
| Domain 2: Image Production | 20 |
| Domain 3: Procedures | 38 |
Those three counts add up to the 75 scored questions. Procedures is the largest domain by a wide margin, which tells you where the most exam weight sits. For a deeper breakdown, read our complete guide to all three RTBD content areas.
Domain 1: Patient Care
This domain covers the interaction between technologist and patient: the practical and ethical side of working with people who are often older, often at fracture risk and sometimes anxious about the result.
- Patient identification, communication and preparation before a scan
- Screening for factors that can affect the exam, such as recent contrast studies, nuclear medicine procedures or prior surgery
- Radiation safety principles as they apply to patients, staff and others in the room
- Professional conduct and patient rights within a densitometry practice
Domain 2: Image Production
This domain concerns the equipment and the quality of the data it produces. It rewards candidates who understand why a scan can be wrong, not just how to start one.
- How the densitometry equipment works and what its settings mean
- Daily quality-control routines and what a failed check implies
- Recognizing artifacts and other factors that compromise accuracy
- Precision and the logic behind reproducible measurements
Domain 3: Procedures
Procedures is the heart of the exam and the domain to master first. It covers performing the scan itself and handling the decisions that surround it.
- Patient positioning for lumbar spine and femur scans
- Selecting appropriate scan sites and handling situations where a standard site cannot be used
- Scan acquisition, analysis and region-of-interest placement
- Recognizing when a result is technically unacceptable and what to do about it
The domain descriptions above reflect the three official categories; for the precise task-level list of what can be tested, always go to the ARRT content specifications themselves rather than relying on any summary, including this one.
Why the Content Specifications Version Matters
ARRT revises its content specifications on a schedule, and the version in force on your exam date determines what you are tested on. The current document was board approved in July 2021, took effect July 1, 2022, and applies through December 31, 2026.
A replacement version 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 topics. If you are testing in 2026, study the 2022 specifications. Do not blend 2027 material into your preparation, and do not assume a study resource written for the new version matches the exam you will take.
Eligibility, Education and Clinical Experience
Earning the credential involves three separate gates before you ever sit the exam: a supporting credential, structured education and documented clinical experience. Our full RTBD requirements guide goes into more depth; here is the overview.
Supporting credential and ethics
You need a current Radiography, Nuclear Medicine Technology or Radiation Therapy credential. Nuclear Medicine Technology may be held through NMTCB. You must also meet ARRT's ethics requirements, which cover conduct and compliance history.
Structured education
Candidates complete 16 approved education hours within the 24 months before applying, with at least one credit in each of the major categories. The structured education document's boilerplate mentions Safety, but its requirements table and the examination blueprint both contain three major categories, so do not plan around a fourth Safety domain.
Clinical experience
Within the qualifying 24-month window, you must document 125 mandatory procedures:
- 25 daily quality-control activities
- 50 lumbar spine scans
- 50 femur scans
On top of those mandatory items, you must complete at least three elective activity types at their specified repetitions. This is not the same as performing three extra scans; each elective activity has its own repetition requirement, so read the clinical experience document closely. Actual scanning must be performed physically onsite, which means this requirement cannot be satisfied through simulation or remote observation.
Key Takeaway
Start logging clinical procedures before you start studying hard. The 24-month window governs both education and clinical experience, and a gap in documentation is far harder to fix than a gap in knowledge. Technologists who already scan daily can often accumulate the 50 lumbar spine and 50 femur scans quickly, but the daily QC activities and elective items need deliberate tracking.
Fees, Attempts and Scoring
What you pay
The application and exam fee is $225 USD. If your supporting credential is Nuclear Medicine Technology through NMTCB, the fee is $450. Reapplication after an unsuccessful attempt costs $200. For the complete financial picture, including renewal costs, see our RTBD certification cost breakdown.
How many attempts you get
You are allowed three examination attempts within three years before you must requalify. That window makes it worth treating the first attempt seriously rather than as a trial run.
What a passing score means
ARRT reports results on a 1-99 scaled-score system, and the passing score is 75. A scaled score of 75 is not "75% correct." Scaling adjusts for differences in difficulty between exam forms so that the same standard applies to every candidate, which means the raw number of questions you need to answer correctly can vary slightly between forms. Our RTBD passing score guide explains this in more detail.
What the 2025 data shows
In ARRT's 2025 Annual Exam Report, the first-time pass rate for Bone Densitometry was 66.7% among 303 candidates. Treat that as an observed result for one cohort, not a forecast for 2026. It does suggest that roughly one in three first-time candidates in that group did not pass, which is a fair reason to prepare thoroughly. More context is in our RTBD pass rate analysis.
After You Pass: Renewal and CQR
Earning the credential is not the end of the obligation. ARRT requires ongoing maintenance:
- Annual registration renewal: $65, regardless of how many ARRT credentials you hold, so adding Bone Densitometry does not raise the annual fee if you already renew another ARRT credential.
- Continuing education: ordinarily 24 approved CE credits each two-year biennium.
- Continuing Qualifications Requirements (CQR): credentials earned on or after January 1, 2011 require CQR every ten years.
Because the annual fee is shared across credentials, the incremental cost of keeping BD active is mostly the CE effort rather than an extra fee. If you are weighing the long-term commitment, our analysis of whether the credential is worth it covers the trade-offs.
Where Bone Densitometry Technologists Work
Bone density testing happens wherever osteoporosis risk is assessed and monitored, which makes the employer base broader than many candidates expect. Typical settings include:
- Hospital radiology and nuclear medicine departments, where DXA is one of several modalities a technologist may cover
- Outpatient imaging centers that offer DXA as part of a women's health or screening menu
- Physician practices, including rheumatology, endocrinology and orthopedic groups that run their own scanners
- Women's health and primary care clinics with an on-site bone density unit
Employers value the credential as a signal that the technologist has documented training and has been assessed against a national standard, which can matter for accreditation and quality programs. Specific compensation varies by region, employer and your primary credential, and we avoid quoting figures we cannot source; for a qualitative look, see our RTBD salary guide and our overview of RTBD jobs.
Sequencing Your Preparation Around the Blueprint
You do not need a generic study plan; you need one that follows the exam's own weighting. Since Procedures holds 38 of the 75 scored questions, it deserves the largest share of your time, and it is also the domain where hands-on experience can reinforce what you read. A sensible order looks like this:
Procedures first
- Work through positioning, scan site selection and analysis for the lumbar spine and femur
- Tie each concept to scans you have actually performed during your 125-procedure log
- Review what makes a scan technically unacceptable
Image Production
- Study equipment principles, daily QC logic and artifact recognition
- Practice reasoning from a described problem to its likely cause
Patient Care, then mixed review
- Cover screening, communication, radiation safety and professional conduct
- Finish with timed mixed sets under closed-book conditions
Adjust the length to your own situation, but keep the principle: front-load the heaviest domain, then use the remaining time for the other two and for timed practice. Because the exam gives you 105 minutes for 105 questions, you have roughly a minute per question, so build pacing into your practice. Our RTBD study guide and one-page cheat sheet can help you organize review, and our practice tests let you rehearse the one-best-answer format before test day. For a structured learning path, see our overview of RTBD training.
Frequently Asked Questions
It stands for Registered Technologist - Bone Densitometry, the ARRT postprimary Bone Densitometry (BD) credential. It is not ISCD's CBDT or a state Bone Densitometry Equipment Operator examination.
There are 105 questions in total. Of those, 75 are scored and 30 are unscored pilot questions. You cannot tell which are which, so answer every question carefully.
No. ARRT uses a 1-99 scaled-score system, and 75 is the passing scaled score. Scaling accounts for differences in difficulty between exam forms, so it does not translate directly into a percentage of questions answered correctly.
Procedures. It carries 38 of the 75 scored questions, compared with 20 for Image Production and 17 for Patient Care. Candidates should still cover all three domains, since each contributes to the final score.
You need a current supporting credential in Radiography, Nuclear Medicine Technology or Radiation Therapy. Nuclear Medicine Technology may be held through NMTCB, though the application fee is higher in that case. You must also meet ethics requirements, 16 education hours and the clinical procedure requirements.