This overview includes information to help you prepare for the DANB Radiation Health and Safety exam. You will find details about the current test format, digital dental radiography, radiation protection, infection prevention, registration, testing options, scoring, retakes, and study resources.
Questions
75 multiple-choice questions
Time Limit
60 minutes
Passing Score
Scaled score of 400
Current Fee
$270
What Is the DANB RHS Exam?
The Radiation Health and Safety exam, commonly called the RHS exam, is administered by the Dental Assisting National Board.
It evaluates whether a candidate meets the national knowledge standard for safely acquiring dental radiographic images and protecting patients and oral healthcare workers from unnecessary radiation exposure.
The exam covers image purpose and technique, radiation characteristics and protection, and infection prevention and control as they apply to dental radiography.
Key point: The current RHS exam tests digital radiography only. Conventional film processing and other film-based concepts have not been tested since July 2022.
Is the RHS Exam a Certification?
The RHS exam is a component examination rather than a complete dental assisting certification by itself.
It is included in two DANB certification programs:
NELDA
The National Entry Level Dental Assistant certification includes the RHS, Infection Control, and Anatomy, Morphology and Physiology exams.
CDA
The Certified Dental Assistant certification includes the RHS, Infection Control, and General Chairside Assisting exams.
A candidate may apply for and take the RHS exam separately. Passing the individual exam demonstrates knowledge-based competence in radiation health and safety and may result in an RHS certificate and digital badge.
Passing RHS alone does not grant full NELDA or CDA certification. Candidates seeking one of those certifications must satisfy its complete eligibility and examination requirements.
Are There Eligibility Requirements?
There are no education, training, or employment prerequisites to take the national RHS exam.
Candidates must still:
- Submit a complete application and examination fee
- Answer the required background-information questions
- Provide any supporting documentation required by DANB
- Present acceptable identification at the appointment
- Follow all examination security and candidate-conduct policies
Candidates Younger Than 18
A candidate younger than 18 who chooses online proctoring must submit the required parent or guardian consent form. The parent or guardian must also participate in the online check-in process and present acceptable identification.
Does Passing RHS Allow Me to Take Dental X-Rays?
Not necessarily. Dental assisting and radiography requirements are established by individual states.
Depending on the state, a dental assistant may also need to:
- Complete an approved radiography course
- Complete clinical training
- Apply for a state permit, registration, or certificate
- Pass a state law or jurisprudence examination
- Hold CPR or basic life support certification
- Work under a specified level of dentist supervision
Verify your state’s current dental assisting requirements before registering. Passing RHS only authorizes radiographic duties when the applicable state recognizes the exam and every other state requirement has been satisfied.
Current RHS Test Overview
The RHS exam contains 75 computer-adaptive multiple-choice questions and has a 60-minute time limit.
Questions contain three or four response options, with one best answer. Some unscored pretest questions may be distributed throughout the exam and are not identified.
Computer Adaptive
Question difficulty changes as the testing system estimates the candidate’s ability.
No Skipping
Candidates must answer the current question before moving forward.
No Returning
An answer cannot be changed after it has been submitted.
Testing Options
Pearson VUE test center or online remote proctoring
Sixty minutes for 75 questions provides an average of 48 seconds per question. Make your best choice before submitting because you cannot return to an earlier item.
Current RHS Content Outline
Every candidate receives the same percentage of questions from each of the three official domains.
I. Purpose and Technique
50%
Dental image purposes, anatomical landmarks, digital image receptors, patient positioning, acquisition techniques, image quality, error correction, equipment care, image orientation, and legal record requirements.
II. Radiation Characteristics and Protection
25%
Radiation physics, x-ray production, biological effects, measurement units, occupational protection, patient protection, exposure reduction, equipment malfunction, and informed consent or refusal.
III. Infection Prevention and Control
25%
Standard precautions, treatment-room setup and breakdown, surface barriers, disinfection, sterilization, hand hygiene, personal protective equipment, and prevention of cross-contamination.
Purpose and Technique
Purpose and Technique is the largest domain, accounting for approximately half of the exam.
Candidates must understand why different images are acquired and how to produce diagnostically acceptable digital images safely and accurately.
Dental Image Types
Intraoral Images
- Periapical
- Bitewing
- Full-mouth series
- Occlusal
Extraoral and Advanced Images
- Panoramic
- Cephalometric
- Cone-beam computed tomography
Structures and Conditions
Candidates should recognize common anatomical landmarks, normal structures, pathologies, and restorative materials visible on dental images.
- Apical pathology
- Caries
- Dental anomalies
- Dental implants and restorative materials
- Edentulous arches
- Impacted teeth and foreign objects
- Periodontal conditions and bone loss
- Sinus areas
- Temporomandibular joints
Image Acquisition and Positioning
Questions may address:
- Reviewing medical and dental histories
- Removing jewelry, glasses, piercings, and other objects
- Positioning the patient and image receptor
- Using holders, bite blocks, tabs, and beam-alignment devices
- Positioning the tubehead and central ray
- Using paralleling and bisecting-angle techniques
- Acquiring panoramic images
- Modifying techniques for anatomical differences
- Managing anxiety, physical limitations, and medical conditions
Digital Receptors and Equipment
Candidates should understand the purpose, use, and care of:
- Photostimulable phosphor plates
- Complementary metal-oxide-semiconductor sensors
- Charge-coupled device sensors
- Image-receptor holders and beam-alignment devices
- X-ray control panels, extension arms, and tubeheads
- Computers, monitors, keyboards, and imaging software
Image Errors and Corrections
Exposure and Receptor Errors
- Underexposure or overexposure
- Incorrect receptor placement
- Damaged or contaminated receptors
- Artifacts and foreign objects
Positioning and Angulation Errors
- Overlapped contacts
- Elongation or foreshortening
- Cone cuts
- Incorrect tubehead placement
- Patient movement
Image Viewing and Records
Candidates should be able to orient and organize images using anatomical landmarks, tooth numbers, radiopaque and radiolucent appearance, and directional terminology.
The exam may also address legal requirements involving image ownership, retention, transfer, chart documentation, and patient privacy.
Radiation Characteristics and Protection
This domain combines radiation physics, radiation biology, occupational protection, and patient protection.
Radiation Physics
- Factors affecting x-ray production, including kilovoltage, milliamperage, exposure time, and dose
- Wavelength, frequency, velocity, and penetrating ability
- Absorption and attenuation
- Primary, secondary, and scatter radiation
- Relationships among exposure settings and image appearance
Radiation Biology
Candidates should understand:
- Cell and tissue radiosensitivity
- Latent and recovery periods
- Short-term and long-term biological effects
- Somatic and genetic effects
- Cumulative exposure
- Absorbed, equivalent, and effective dose
- Radiation measurement units
Operator Protection
Operator-protection questions may involve:
- Standing behind an appropriate protective barrier
- Maintaining proper distance from the source
- Standing at an appropriate angle to the primary beam
- Avoiding holding the receptor or tubehead
- Using personnel-monitoring devices when required
- Understanding occupational exposure limits
Patient Protection
- Applying the ALARA principle
- Acquiring images only when clinically indicated
- Selecting exposure settings appropriate for patient size and age
- Using proper filtration, collimation, and position-indicating devices
- Preventing unnecessary retakes
- Responding appropriately to patient concerns
- Respecting informed consent and documented refusal
- Following protocol when an x-ray unit may be malfunctioning
Infection Prevention and Control
This domain focuses on preventing the transmission of infectious material while acquiring dental radiographic images.
Room and Equipment
- Treatment-room setup
- Treatment-room breakdown
- Surface barriers
- Clinical-contact surfaces
- Equipment disinfection
Patient and Operator
- Hand hygiene
- Gloves and other PPE
- Safe receptor handling
- Cross-contamination prevention
- Standard precautions
Instrument Classification
Candidates should know how critical, semicritical, and noncritical patient-care items are classified and processed.
- Critical items: Penetrate soft tissue or bone and require heat sterilization.
- Semicritical items: Contact mucous membranes or nonintact skin and should be heat sterilized when possible.
- Noncritical items: Contact intact skin and require appropriate cleaning and disinfection.
Exam Languages
The national RHS exam is available in English and Spanish.
The English and Spanish versions follow the same exam outline, use the same question bank, and have the same passing standard.
Candidates taking the Spanish version can also view questions in English. A candidate who has already applied but has not tested may be able to request a language change using the required DANB form.
Registration, Fee, and Testing Window
Candidates may submit an RHS application through a DANB account or by using the current application packet.
Registration Basics
- Create or sign in to a DANB account.
- Complete the RHS application and background-information questions.
- Submit any required supporting documentation.
- Pay the $270 examination fee.
- Wait for the examination authorization email.
- Schedule through Pearson VUE.
- Take the exam within the authorized 60-day testing window.
Appointments may be limited, so candidates should schedule soon after receiving authorization.
Active-duty military personnel may qualify for a DANB examination discount when they submit the required documentation.
Changing an Appointment
A test-center appointment must be canceled or rescheduled through Pearson VUE at least 24 hours before the appointment.
An online-proctored appointment may be canceled or rescheduled up to the scheduled starting time.
Candidates must confirm that Pearson VUE sent an email showing the new appointment or cancellation. Without that confirmation, the change may not have been completed.
Requesting Another Testing Window
A candidate who cannot test during the original 60-day window may request one additional 60-day window under the current DANB policy. The request must be submitted within the required period and may involve an additional fee.
Test Center or Online Proctoring?
Pearson VUE Test Center
- Testing computer is provided
- Appointments depend on local availability
- Personal items are stored in a locker
- Security screening may include photographs and a palm scan
- A restroom break may be approved, but the timer does not stop
Online Proctoring
- Available through Pearson OnVUE
- Requires a compatible desktop or laptop computer
- Requires a webcam, microphone, mobile phone, and reliable internet
- Requires a private, distraction-free room
- No breaks are permitted
The examination fee is the same for test-center and online appointments.
Online candidates are responsible for their computer, internet connection, testing room, software setup, and system test. A technical or environmental problem can result in a missed appointment.
What Should I Expect on Test Day?
Test-Day Checklist
- Confirm the appointment time and testing method.
- Bring one current, unexpired, government-issued photo ID containing a signature.
- Make sure the name on the ID exactly matches the DANB account.
- Arrive or begin online check-in approximately 30 minutes early.
- Store notes, books, phones, watches, bags, food, and unauthorized electronics.
- Follow all security screening and room-inspection instructions.
- Read each question completely before selecting an answer.
- Make a final choice before submitting because earlier questions cannot be reopened.
Acceptable Identification
Examples of acceptable identification include:
- United States driver’s license
- State identification card
- Valid passport
- United States permanent resident card
- Military identification card
Temporary identification documents and photocopies are not accepted.
How Is the RHS Exam Scored?
DANB uses computer-adaptive testing. The score reflects the difficulty of the questions answered correctly, not simply the percentage answered correctly.
Scores range from 100 to 900. A scaled score of at least 400 is required to pass.
Understanding the Score
- The score is not a percentage.
- The score is not based on comparison with other candidates.
- Different candidates may receive questions of different difficulty.
- Every candidate receives the same domain percentages.
- A candidate must meet or exceed the established competency standard.
The average DANB candidate may answer approximately half of the adaptive questions correctly. This does not mean that 50% is automatically a passing score.
When Are Results Available?
Official results are normally posted to the candidate’s online DANB account within one to three business days after the exam.
Passed examination results, earned certificates, and certain failed state-exam results may also be mailed within two to four weeks.
Candidates are not officially considered to have passed or failed until DANB issues the official result.
Can I Retake the RHS Exam?
A candidate who does not pass may apply to take the RHS exam again.
Retake Rules
- DANB does not set a lifetime limit on failed-exam retakes.
- A new application must be submitted.
- The full examination fee must be paid again.
- The candidate receives a new testing window after approval.
- State laws may require additional education after one or more unsuccessful attempts.
Candidates generally may not retake an exam they have already passed. A candidate whose state board or employer requires an unusual retest should contact DANB before applying.
How Can I Prepare for the RHS Exam?
Begin by comparing your current knowledge with the three official domains. Purpose and Technique accounts for half of the examination, but Radiation Characteristics and Protection and Infection Prevention and Control together make up the other half.
Study current digital-radiography procedures rather than outdated film-processing material.
DANB RHS Study Checklist
- Review the purpose of periapical, bitewing, occlusal, panoramic, cephalometric, and CBCT images.
- Learn major radiopaque and radiolucent anatomical landmarks.
- Review caries, bone loss, apical pathology, implants, restorations, and common dental anomalies.
- Practice paralleling, bisecting-angle, bitewing, and panoramic positioning concepts.
- Study horizontal and vertical angulation errors, cone cuts, receptor-placement errors, and movement.
- Review digital sensors, PSP plates, holders, tubeheads, and imaging equipment.
- Study x-ray production, radiation characteristics, biological effects, and measurement units.
- Review ALARA, filtration, collimation, shielding, distance, positioning, and exposure reduction.
- Study hand hygiene, PPE, barriers, disinfection, sterilization, and cross-contamination prevention.
- Complete timed practice at an average pace of approximately 48 seconds per question.
- Review the reason behind every missed answer and every answer obtained through guessing.
Computer-Adaptive Testing Strategy
- Read the complete question before considering the choices.
- Identify whether the question concerns technique, safety, or infection control.
- Eliminate choices that conflict with standard precautions or radiation-protection principles.
- Select the single best answer rather than an answer that is merely possible.
- Do not panic when questions become difficult; increasing difficulty can be part of adaptive testing.
- Submit each answer carefully because it cannot be changed later.
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