- Which Credential This Cheat Sheet Covers
- The One-Glance Exam Snapshot
- The Three Domains and Their Scored Questions
- Procedures: The Facts Worth the Most Points
- Image Production: Must-Know Concepts
- Patient Care: Must-Know Concepts
- Scoring Facts That Trip People Up
- Eligibility, Education and Clinical Experience Numbers
- Fees, Attempts and Renewal
- The 2026 vs. 2027 Version Boundary
- Scheduling the Domains in a Short Review Window
- Frequently Asked Questions
- The exam is 105 questions: 75 scored plus 30 unscored pilots, with 105 minutes of testing time.
- Procedures carries 38 of 75 scored questions, more than Patient Care (17) and Image Production (20) combined.
- A passing score is 75 on ARRT's 1-99 scaled system, not 75% of questions correct.
- Eligibility requires 16 structured education hours and 125 mandatory clinical procedures within the 24-month window.
Which Credential This Cheat Sheet Covers
This one-page-style review covers the ARRT postprimary Bone Densitometry (BD) examination, which leads to the Registered Technologist - Bone Densitometry credential. "RTBD" is simply the label this site uses for it. It is not the ISCD CBDT certification, and it is not a state Bone Densitometry Equipment Operator examination. Those programs have their own bodies, fees and content outlines, so none of the numbers below transfer to them.
If you are still orienting yourself, start with What Is RTBD Certification? and then return here for the condensed facts. If you want a longer, structured plan after this review, the RTBD study guide covers the full preparation arc.
The One-Glance Exam Snapshot
Memorize this table first. Everything else in the article hangs off these numbers.
| Item | Fact |
|---|---|
| Certifying body | American Registry of Radiologic Technologists (ARRT) |
| Delivery | Computer-based, through Pearson VUE testing centers |
| Total questions | 105 (75 scored + 30 unscored pilot questions) |
| Testing time | 105 minutes (the appointment itself is 125 minutes) |
| Format | Primarily one-best-answer multiple choice; other handbook-permitted formats possible |
| Book rules | Closed-book; no personal calculator (test-center and on-screen calculators available) |
| Passing score | 75 on the 1-99 scaled-score system |
| Exam fee | $225 USD ($450 using NMTCB Nuclear Medicine Technology as the supporting credential) |
| Reapplication fee | $200 |
| Attempts | Three within three years before requalification |
You cannot tell which questions are the 30 unscored pilots, so treat every item as if it counts. For more on the testing-window mechanics, see RTBD exam dates and scheduling.
The Three Domains and Their Scored Questions
The content specifications (board approved July 2021, effective July 1, 2022, version 2021.07.28, applicable through December 31, 2026) define three major examination categories. There is no fourth "Safety" domain, even though some boilerplate text elsewhere mentions the word.
| Domain | Scored Questions (of 75) | Relative Weight |
|---|---|---|
| Domain 1: Patient Care | 17 | Smallest |
| Domain 2: Image Production | 20 | Middle |
| Domain 3: Procedures | 38 | Largest |
Those are published scored-question counts. Don't convert them into percentages and quote them as official figures, because ARRT publishes the counts, not percentages. What the counts do tell you is where to put your hours: Procedures is a little over half of everything that is scored. For a deeper breakdown of each category, read the complete RTBD exam domains guide.
Procedures: The Facts Worth the Most Points
Domain 3: Procedures (38 scored questions)
This is the clinical core of bone densitometry: performing and troubleshooting the scan itself. Expect scenario questions that ask what you would do next, what a result implies, or what went wrong.
- Patient positioning for the standard scan sites, especially lumbar spine and femur, the same two sites that dominate the clinical experience requirement
- Selecting and correctly defining regions of interest, and recognizing when analysis placement is wrong
- Recognizing artifacts and conditions that distort bone density results, such as degenerative changes, prior fractures, hardware, or objects in the scan field
- Knowing when a different or alternate scan site is appropriate
- Comparing a current scan with previous studies and understanding what makes a comparison valid
- Daily quality-control procedures and what to do when the QC check fails
Notice how closely this mirrors the clinical experience requirements: 25 daily quality-control activities, 50 lumbar-spine scans and 50 femur scans. The exam rewards candidates who have actually done those scans, because the questions are written from the technologist's chair, not the radiologist's.
Image Production: Must-Know Concepts
Domain 2: Image Production (20 scored questions)
This domain covers the equipment and physics side: how the densitometer generates data and what keeps that data trustworthy.
- Basic principles of how bone densitometry equipment acquires measurements
- Quality control: calibration, phantom scanning, and the purpose of trend monitoring over time
- Factors that affect precision and accuracy, and how technologist technique contributes to both
- Scan acquisition parameters and why they matter
- Radiation exposure principles as they apply to densitometry, including the very low dose involved relative to other imaging
Image Production is a smaller slice than Procedures, but it is also where candidates with strong clinical experience but light physics exposure lose points. Review the quality-control concepts especially carefully, since they appear in both this domain and in Procedures. For a sense of how this domain compares to the others in perceived difficulty, see how hard the RTBD exam really is.
Patient Care: Must-Know Concepts
Domain 1: Patient Care (17 scored questions)
The smallest domain, but the most approachable. Candidates who already hold a primary radiography, nuclear medicine or radiation therapy credential often find these questions familiar.
- Patient identification, communication and obtaining the relevant history before scanning
- Recognizing history items that can affect a scan, such as recent contrast studies, nuclear medicine procedures, prior surgery or implanted hardware
- Pregnancy screening and radiation safety considerations
- Patient safety, comfort and handling of patients with limited mobility
- Professional ethics, privacy and documentation
Because this domain is the smallest, resist the urge to either ignore it or over-invest in it. Seventeen scored questions is enough to matter on a pass-or-fail exam, and these are among the most winnable points.
Scoring Facts That Trip People Up
Three scoring misconceptions come up constantly.
- 75 is not 75%. ARRT reports results on a 1-99 scaled score and the passing mark is 75. Scaling adjusts for differences in difficulty between exam forms, so a scaled 75 does not map to a fixed percentage of raw questions answered correctly.
- Unscored questions are invisible. Of the 105 questions, 30 are unscored pilots. You cannot identify them, so skipping effort on "weird" questions is a mistake.
- The pass rate is a snapshot. The first-time 2025 pass rate was 66.7% among 303 candidates, per the ARRT Annual Exam Report - 2025. That is an observed cohort result, not a prediction for 2026 test-takers.
For a closer reading of what that cohort number does and does not tell you, see the RTBD pass rate data analysis, and for the scoring mechanics in plain language, see what the RTBD passing score actually means.
Eligibility, Education and Clinical Experience Numbers
You cannot sit for the exam until the paperwork is complete, so these numbers belong on any cheat sheet.
Eligibility Checklist
All of these must be satisfied before you are cleared to test.
- A current supporting credential in Radiography, Nuclear Medicine Technology or Radiation Therapy (Nuclear Medicine Technology may be held through NMTCB)
- Compliance with ARRT ethics requirements
- 16 approved structured education hours completed within the 24 months before you apply, with at least one credit in each major category
- Clinical experience completed within the qualifying 24-month window
Clinical Experience: The 125 Mandatory Procedures
The mandatory portion breaks down as follows.
- 25 daily quality-control activities
- 50 lumbar-spine scans
- 50 femur scans
- Plus at least three elective activity types, each at its own specified number of repetitions. This means three types of activity, not merely three extra scans.
- Actual scanning must be performed physically onsite
Full prerequisite detail lives in the RTBD requirements guide. Pay particular attention to the 24-month clock: education and clinical work that falls outside that window will not count.
Fees, Attempts and Renewal
| Cost or Rule | Amount or Detail |
|---|---|
| Application/exam fee | $225 USD |
| Fee with NMTCB Nuclear Medicine Technology as supporting credential | $450 USD |
| Reapplication fee | $200 |
| Annual ARRT registration renewal | $65, regardless of how many ARRT credentials you hold |
| Continuing education | Ordinarily 24 approved CE credits per two-year biennium |
| Continuing Qualifications Requirements (CQR) | Every ten years for credentials earned on or after January 1, 2011 |
The attempt rule is worth restating: you get three examination attempts within three years before you must requalify. A failed attempt costs you a reapplication fee, so the financial case for thorough preparation is straightforward. A full cost walk-through is in the RTBD certification cost breakdown, and if you are weighing the return on that spend, the RTBD ROI analysis is the place to go.
Always confirm current fees on ARRT's own pages before paying, since fee schedules can change.
The 2026 vs. 2027 Version Boundary
This is the single most important detail for anyone studying from mixed sources. The content specifications in force for 2026 testing are the ones effective July 1, 2022 and applicable through December 31, 2026. A replacement version takes effect January 1, 2027.
| Content Specification Version | Patient Care | Image Production | Procedures |
|---|---|---|---|
| 2026 exam (effective July 1, 2022 through Dec. 31, 2026) | 17 | 20 | 38 |
| Replacement effective January 1, 2027 | 19 | 19 | 37 |
The 2027 version also changes topics, not just counts. If you are testing in 2026, study to the 2026 outline and do not blend in 2027 material you may find in newer prep resources. If your timeline could stretch into January 2027 or later, confirm which version applies to your test date before you finalize your plan. The exam dates and scheduling article is a good companion for that decision.
Scheduling the Domains in a Short Review Window
If you have a few weeks left, sequence your review by exam weight and by how much each domain depends on the others. This is a deliberately compact plan; the full approach is in the complete study guide.
Image Production first
- Review equipment principles and quality-control concepts, since QC feeds directly into Procedures questions
- Rehearse what a failed QC check means and what you do about it
Procedures, the big domain
- Work through lumbar spine and femur positioning and analysis step by step
- Drill artifact recognition and alternate-site decisions with scenario questions
- Spend roughly half of your total review time here, matching its 38 of 75 scored questions
Patient Care and full mock exams
- Review history-taking, pregnancy screening, ethics and documentation
- Sit timed practice sets at 105 questions in 105 minutes and review every miss by domain
Taking timed mixed sets on the RTBD Exam Prep practice test site shows you which of the three domains is dragging down your performance, which is more useful than a raw overall score.
Who Hires Bone Densitometry Technologists
This credential is a postprimary add-on, so most holders are already working radiographers, nuclear medicine technologists or radiation therapists who add bone densitometry to their scope. Typical settings include hospital radiology and nuclear medicine departments, outpatient imaging centers, and physician practices that offer densitometry, such as those in endocrinology, rheumatology and women's health. The clinical experience requirement is performed onsite, so many candidates earn their hours inside the department that employs them. For the job-market side, see RTBD jobs and, for compensation context, the RTBD salary guide. Earnings vary by region and setting, so treat any single figure with caution.
Frequently Asked Questions
The exam has 105 questions, of which 75 are scored and 30 are unscored pilot questions. You have 105 minutes of testing time inside a 125-minute appointment. It is delivered by computer at Pearson VUE testing centers.
Procedures, with 38 of the 75 scored questions. Image Production has 20 and Patient Care has 17. Because quality-control topics cross domains, a solid grasp of Image Production also helps your Procedures performance.
No. ARRT uses a 1-99 scaled-score system and the passing score is 75 on that scale. Scaled scores account for form-to-form difficulty differences, so the raw percentage needed to reach 75 is not a fixed number.
A current supporting credential in Radiography, Nuclear Medicine Technology or Radiation Therapy, ARRT ethics compliance, 16 approved structured education hours within the prior 24 months (at least one credit in each major category), and 125 mandatory clinical procedures plus at least three elective activity types, all within the qualifying window.
You cannot bring a personal calculator. The test center supplies calculator options and an on-screen calculator is available. The exam is closed-book.
You may reapply for a $200 reapplication fee. You are allowed three examination attempts within three years before you must requalify, so a failed attempt is recoverable but costs both time and money.
Keep this cheat sheet next to the RTBD cheat sheet companion pages and verify every fee, date and document version against ARRT's official pages before you test, since that is where final authority sits.