DANB RHS Exam Prep
Free prep for DANB's Radiation Health and Safety (RHS) exam, built on the current RHS outline (effective March 12, 2025): 75 questions, 60 minutes, digital radiography only. Start with where the points are, then work the questions.
How the RHS blueprint is weighted
| Domain | Blueprint share | Rough planning equivalent out of 75* | What it tests |
|---|---|---|---|
| I. Purpose and Technique | 50% | 37–38 | Image types and their purpose, paralleling and bisecting technique, panoramic positioning, error correction, receptor care, landmarks and mounting, legal rules for images |
| II. Radiation Characteristics and Protection | 25% | 18–19 | kVp, mA and time, primary and scatter radiation, radiation biology, units, dose limits, ALARA, operator and patient protection |
| III. Infection Prevention and Control | 25% | 18–19 | Standard precautions for imaging: barriers, sensors and holders, clinical contact surfaces, hand hygiene, PPE |
*Planning arithmetic from DANB's published weights (75 × 50% and 75 × 25%). These are not point values: DANB uses computer-adaptive testing and reports a scaled score, not a raw percent-correct score. DANB says candidates receive the same percentage of questions from each domain, and a small number of unscored pretest questions may appear.
Study Purpose and Technique first unless the questions below show it's already your strongest area — it's half the exam, and error correction is packed into it. Skip film processing. DANB has tested only digital radiography on RHS since July 7, 2022.
Practice questions
32 original, unofficial questions — not DANB questions — weighted like the real exam: 16 Purpose and Technique, 8 Radiation, 8 Infection Control. Pick your answer, then reveal the explanation.
Domain I: Purpose and Technique
Q1. You are exposing a maxillary molar periapical image with the paralleling technique. Where should the central ray be directed?
Reveal answer
Answer: B. Paralleling places the receptor parallel to the long axis of the tooth and aims the central ray at a right angle to both. That geometry is why paralleling is considered the most accurate intraoral technique. A is the bisecting-angle rule. C ignores where the receptor is, which is the whole point of beam alignment. D describes a bitewing-range vertical angle, not paralleling geometry.
RHS-PT-01 · Paralleling technique · Source: Dentalcare CE559, Intraoral Radiographic Techniques
Q2. A patient's shallow palate won't let you place the receptor parallel to a maxillary central incisor, so you switch to the bisecting-angle technique. Where is the central ray aimed now?
Reveal answer
Answer: D. In bisecting angle, the receptor rests close to the tooth, an imaginary line splits the angle between the receptor and the long axis, and the central ray goes perpendicular to that line. The two matching triangles that result keep the image length equal to the tooth length. A and B each aim at only one side of the angle, which elongates or foreshortens the image. C sends the beam along the bisector instead of through it.
RHS-PT-02 · Bisecting-angle technique · Source: Dentalcare CE559, Intraoral Radiographic Techniques; DE 115: Dental Radiography (open textbook), section 20.1
Q3. Using the bisecting-angle technique, a maxillary canine image comes out shorter than the actual tooth. What is the most likely cause, and what is the fix?
Reveal answer
Answer: A. A too-steep vertical angle foreshortens the image; the correction is to decrease the vertical angulation. B produces the opposite error, elongation. C causes overlapped contacts, not a change in tooth length. D changes how dark the image is, not its shape.
RHS-PT-03 · Error correction: vertical angulation · Source: Brian & Cooper, "Little details, little errors mar and blemish X-rays," RDH
Q4. A premolar bitewing shows the contacts between the first and second premolars overlapped, so the proximal surfaces can't be evaluated. What caused it?
Reveal answer
Answer: C. Overlap happens when the central ray isn't directed straight through the interproximal spaces in the horizontal plane. Fix it by aiming the beam through the contacts. B changes the length of teeth on the image. A causes distortion. D causes blur, not a clean overlap.
RHS-PT-04 · Error correction: horizontal angulation · Source: Brian & Cooper, "Little details, little errors mar and blemish X-rays," RDH
Q5. A digital periapical image is normal except for a curved, clear (white) unexposed area along one edge. What happened?
Reveal answer
Answer: C. That's a cone cut: part of the receptor sat outside the x-ray beam, received no exposure and shows as a clear area. Re-center the PID so the beam covers the whole receptor. B darkens the entire image. A overlaps contacts. D blurs the image.
RHS-PT-05 · Error correction: cone cut · Source: Brian & Cooper, "Little details, little errors mar and blemish X-rays," RDH; DANB RHS Exam Outline and References (effective 03/12/2025)
Q6. You take two periapical images of an impacted maxillary canine. For the second, you shift the tubehead toward the mesial. On the second image, the canine appears to have moved mesially relative to the incisor roots. Where is the canine?
Reveal answer
Answer: A. The buccal object rule — SLOB, "Same Lingual, Opposite Buccal." An object that moves in the same direction as the tube shift is lingual; one that moves the opposite way is buccal. B would require movement opposite the shift. C would show no relative movement. D is wrong because two intraoral images taken at different angles are exactly how this localization is done.
RHS-PT-06 · Localization: buccal object rule · Source: DE 115: Dental Radiography (open textbook), section 23.2
Q7. A panoramic image shows a flat, "frowning" occlusal plane and condyles that look splayed outward. What positioning error caused it?
Reveal answer
Answer: D. A raised chin flattens the occlusal plane and splays the condyles; lower the chin. B produces the opposite — an exaggerated "smile." C makes the anterior teeth narrow and blurred. A produces a dark band over the maxillary apices.
RHS-PT-07 · Panoramic positioning · Source: Dhillon et al., "Positioning errors and quality assessment in panoramic radiography," Imaging Science in Dentistry 2012;42(4):207–212
Q8. A panoramic image shows a dark (radiolucent) band across the apices of the maxillary teeth. Which instruction would have prevented it?
Reveal answer
Answer: B. When the tongue drops away from the palate, the air space between them shows as a dark shadow over the maxillary apices. In one published study it was the most common panoramic error. A changes the occlusal-plane curve. C doesn't fill the air space between tongue and palate. D is a posture cue; a slumped posture causes a different artifact.
RHS-PT-08 · Panoramic positioning · Source: Dhillon et al., "Positioning errors and quality assessment in panoramic radiography," Imaging Science in Dentistry 2012;42(4):207–212
Q9. On a panoramic image, the incisors look narrow and blurred. Where was the patient's head?
Reveal answer
Answer: A. Teeth in front of the focal trough appear narrow and fuzzy; move the patient back so the incisors sit in the bite groove. B makes the anterior teeth look wide. C makes one side's teeth and ramus wider than the other. D tilts the lower border of the mandible and puts one condyle higher.
RHS-PT-09 · Panoramic positioning · Source: Dhillon et al., "Positioning errors and quality assessment in panoramic radiography," Imaging Science in Dentistry 2012;42(4):207–212
Q10. What is the main purpose of a posterior bitewing image?
Reveal answer
Answer: C. Bitewings show the crowns of both arches and the bone crest, which is why they're the image for interproximal decay and bone levels. B is the periapical's job. A and D are extraoral territory (panoramic, among others).
RHS-PT-10 · Purpose of dental images · Source: Dentalcare CE559, Intraoral Radiographic Techniques
Q11. For a horizontal posterior bitewing, what vertical angulation is directed through the contacts of the teeth in occlusion?
Reveal answer
Answer: B. The central ray goes through the posterior contacts at a slight positive angle of about +5° to +10°. A and D don't match that slight tilt. C is steep enough to distort the crowns and bone crest.
RHS-PT-11 · Bitewing technique · Source: Dentalcare CE559, Intraoral Radiographic Techniques
Q12. How does an amalgam restoration appear on a digital image, and why?
Reveal answer
Answer: D. Dense materials absorb more x-ray photons, so fewer reach the receptor and the area shows light. Radiopaque means light; radiolucent means dark. B gets both the mechanism and the appearance wrong. C ignores that metal is far denser than enamel. A is irrelevant to how the image forms.
RHS-PT-12 · Radiopaque vs radiolucent · Source: Dentalcare CE571, The Radiographic Image; DANB RHS Exam Outline and References (effective 03/12/2025)
Q13. On a mandibular premolar periapical image, a small, round radiolucency sits near the apex of the second premolar. Which normal landmark is found in this region and can be mistaken for a periapical lesion?
Reveal answer
Answer: D. The mental foramen opens on the facial side of the mandible in the premolar region and can be superimposed over a premolar apex, where it can mimic periapical disease. B and C are maxillary landmarks; they don't appear on a mandibular premolar image. A is part of the mandible, but it's a radiopaque projection seen behind the maxillary molars, not a round radiolucency at a premolar apex.
RHS-PT-13 · Anatomical landmarks · Source: Lakshman et al., "Mental foramen mimicking as periapical pathology," Journal of Health Sciences 2014;4(2):126–129; DANB RHS Exam Outline and References (effective 03/12/2025)
Q14. Every image taken with one particular phosphor storage plate (PSP) shows the same thin line in the same spot, on different patients and with different operators. What should you do?
Reveal answer
Answer: B. A defect that follows one receptor across patients and operators is a receptor problem, not a technique problem. Retakes on a damaged plate add patient exposure without fixing anything. A and C adjust technique that isn't the cause. D is wrong because an artifact can hide or mimic findings.
RHS-PT-14 · Receptor integrity · Source: DANB RHS Exam Outline and References (effective 03/12/2025)
Q15. A patient arrives for a panoramic image wearing hoop earrings and eyeglasses. What do you do?
Reveal answer
Answer: C. Metal and dense objects in the head and neck create radiopaque artifacts, including ghost images, that can cover anatomy. Removing jewelry, glasses and piercings is part of preparing the patient. A and B leave artifacts in place. D builds a retake — and extra exposure — into the plan.
RHS-PT-15 · Patient preparation · Source: DANB RHS Exam Outline and References (effective 03/12/2025); Dhillon et al., "Positioning errors and quality assessment in panoramic radiography," Imaging Science in Dentistry 2012;42(4):207–212
Q16. A patient changing dentists asks for her dental images. What's the right response?
Reveal answer
Answer: A. Under HIPAA, individuals have a right to inspect and obtain a copy of their health information, which includes images in the record. The practice still keeps its record under its retention rules. B denies a legal right. C destroys the office's record. D adds a restriction the patient's right of access doesn't have. Retention periods come from state law — check yours.
RHS-PT-16 · Legal requirements for images · Source: 45 CFR 164.524, access of individuals to protected health information; DANB RHS Exam Outline and References (effective 03/12/2025)
Domain II: Radiation Characteristics and Protection
Q17. Which exposure-factor change increases the energy and penetrating ability of the x-ray beam?
Reveal answer
Answer: A. Kilovoltage peak (kVp) controls beam quality: increasing kVp increases x-ray photon energy and penetrating ability. Exposure time and mA mainly change the quantity of photons produced, not their energy.
RHS-RC-01 · Beam quality and kVp · Source: Dentalcare CE570, Beam Quality
Q18. If mA is increased while kVp and exposure time stay the same, what changes most directly?
Reveal answer
Answer: A. Milliamperage (mA) affects beam quantity. Increasing mA increases the number of electrons crossing the tube and therefore the number of x-ray photons produced. kVp is the main control of beam energy and penetrating ability.
RHS-RC-02 · Beam quantity and mA · Source: Dentalcare CE570, Beam Quantity
Q19. You move from 3 feet to 6 feet away from the radiation source. What happens to the intensity reaching you?
Reveal answer
Answer: C. The inverse square law: intensity is proportional to 1 ÷ distance². Doubling the distance gives 1 ÷ 2² = 1/4. B assumes a straight-line relationship. A and D get the direction or the effect wrong.
RHS-RC-03 · Inverse square law · Source: Dentalcare CE571, The Radiographic Image
Q20. Which cells are the most radiosensitive?
Reveal answer
Answer: D. In general, rapidly dividing, less-specialized cells are most sensitive (the law of Bergonié and Tribondeau). Lymphocytes are the notable exception that's highly sensitive anyway. Nerve cells, muscle cells and mature red blood cells don't divide and are among the most radioresistant.
RHS-RC-04 · Radiation biology · Source: Stanford EH&S, Biological Effects of Radiation and Units of Dose
Q21. Which unit measures dose equivalent in the SI system, and how does it convert?
Reveal answer
Answer: A. The sievert is the SI unit of dose equivalent, and 1 Sv = 100 rem. The gray is the SI unit of absorbed dose and equals 100 rad, not rem (B). C/kg is the SI exposure unit that replaces the roentgen, but C invents the conversion. D flips it.
RHS-RC-05 · Units of radiation measurement · Source: U.S. NRC, 10 CFR Part 20 (§20.1004 units; §20.1201 occupational dose limits)
Q22. What is the annual occupational dose limit (the maximum permissible dose) for an adult radiation worker, expressed as total effective dose equivalent?
Reveal answer
Answer: D. The federal annual limit for adult occupational exposure is 5 rem (0.05 Sv) total effective dose equivalent. B is a separate limit for the sum of deep-dose and any single organ dose, not the TEDE limit. C is 100 times too high, and A is 10 times too low. Dental x-ray equipment is regulated by your state, so follow its rules on the job.
RHS-RC-06 · Maximum permissible dose · Source: U.S. NRC, 10 CFR Part 20 (§20.1004 units; §20.1201 occupational dose limits)
Q23. The operatory has no protective barrier. Where should you stand during the exposure?
Reveal answer
Answer: B. Without a barrier, the ADA's 2024 recommendations call for at least 2 meters from the primary beam path, and NCRP Report 177 suggests the 90°–135° angle to the beam. A is too close. C stands in the primary beam. D is never acceptable for the operator.
RHS-RC-07 · Operator protection · Source: Benavides et al., "Optimizing radiation safety in dentistry," JADA 2024;155(4):280–293
Q24. Which change is recommended to reduce unnecessary patient exposure during routine intraoral imaging?
Reveal answer
Answer: C. Restricting the beam to the area being imaged reduces unnecessary exposure, and current ADA guidance recommends rectangular collimation for intraoral imaging when feasible. Routine thyroid collars and lead abdominal aprons are no longer recommended by the ADA because they can interfere with the primary beam and lead to retakes. A and D add exposure rather than reducing it. Follow applicable federal, state and local requirements.
RHS-RC-08 · Patient protection · Source: ADA, X-Rays/Radiographs
Domain III: Infection Prevention and Control
Q25. How does the CDC classify an intraoral digital sensor?
Reveal answer
Answer: C. The CDC states that digital radiography sensors are semicritical: they touch mucous membranes but don't penetrate tissue. A barrier doesn't change the classification (A). Critical items penetrate soft tissue or bone (B). Electronics don't get their own category (D).
RHS-IC-01 · Item classification: sensors · Source: CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection
Q26. A digital sensor can't tolerate heat sterilization or high-level disinfection. What's the minimum the CDC calls for between patients?
Reveal answer
Answer: B. When a sensor can't take heat sterilization or high-level disinfection, the CDC's minimum is a barrier plus cleaning and intermediate-level disinfection between patients — always within the manufacturer's instructions. A skips disinfection, and barriers can fail without a visible tear. C can destroy the sensor. D is too weak and too infrequent.
RHS-IC-02 · Sensor reprocessing · Source: CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection; Dimensions of Dental Hygiene, "Radiology chain of asepsis"
Q27. After a phosphor storage plate (PSP) has been exposed inside a barrier envelope, which handling principle best prevents cross-contamination before scanning?
Reveal answer
Answer: C. The clean/dirty separation matters: the contaminated exterior of the barrier should not contact the plate or scanner. Exact opening, cleaning and disinfection steps vary by PSP system, so follow the manufacturer's instructions for use. A can contaminate the scanner, B can damage some plates, and single-use barriers should not be reused.
RHS-IC-03 · PSP workflow · Sources: CDC, Sterilization and Disinfection; Air Techniques ScanX PSP instructions
Q28. During exposures, you adjusted the tubehead and pressed the control panel with gloved hands. Neither had a barrier. What's required before the next patient?
Reveal answer
Answer: A. Surfaces touched with contaminated gloves during care are clinical contact surfaces. The CDC says to barrier-protect them or clean and disinfect them between patients. B ignores glove contamination. C isn't possible for x-ray equipment. D is neither a disinfectant nor between patients.
RHS-IC-04 · Clinical contact surfaces · Source: CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection
Q29. A heat-tolerant receptor-holding and beam-alignment device was used in a patient's mouth. How is it reprocessed?
Reveal answer
Answer: D. A holder that goes in the mouth contacts mucous membranes, so it's semicritical, and the CDC's standard for semicritical items is cleaning followed by heat sterilization or high-level disinfection between patients. When the device tolerates heat, sterilize it. B and C fall short of that standard. A does nothing to kill pathogens.
RHS-IC-05 · Receptor holders · Source: CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection
Q30. The position indicating device (PID, or cone) touches the patient's intact cheek during an exposure. How does the CDC classify it?
Reveal answer
Answer: C. The CDC lists the radiograph head/cone as an example of a noncritical patient-care item: it touches only intact skin. B confuses the procedure with the item — the PID doesn't contact mucous membranes. A misreads the definition; critical items penetrate tissue. D is wrong because the CDC names it as a patient-care item.
RHS-IC-06 · Item classification: PID · Source: CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection
Q31. Why must you wear gloves when placing intraoral receptors, even when no bleeding is expected?
Reveal answer
Answer: A. OSHA's Bloodborne Pathogens standard requires gloves when hand contact with blood, other potentially infectious materials or mucous membranes can reasonably be anticipated, and it lists saliva in dental procedures as potentially infectious material. B and D misread the rule. C is not the reason.
RHS-IC-07 · PPE · Source: 29 CFR 1910.1030, Bloodborne Pathogens — (b) definitions and (d)(3)(ix) gloves
Q32. When should you perform hand hygiene around gloving for imaging?
Reveal answer
Answer: B. The CDC says to clean your hands before putting on gloves and always after removing them; gloves are not a substitute for hand hygiene. A, C and D each leave a gap where contamination gets through.
RHS-IC-08 · Hand hygiene · Source: CDC, Clinical Safety: Hand Hygiene for Healthcare Workers
Check your results
Count your misses in each block: Q1–16 (Technique), Q17–24 (Radiation), Q25–32 (Infection Control). Reopen every explanation you missed and every one you guessed. Then go to the matching section below — the error fix table for technique misses, the radiation sheet or the infection control list.
This is a 32-question practice set, not a DANB score. It shows you where to study next; it can't predict whether you'll pass, and DANB's scaled score can't be worked out from a percent correct.
What each image is for
| Image | What it shows | Typical use |
|---|---|---|
| Periapical | Whole tooth, crown to root tip, plus surrounding bone | Root and apex problems, bone around a specific tooth |
| Bitewing | Crowns of upper and lower teeth together, plus the bone crest | Decay between teeth, bone levels |
| Full mouth series | A set of periapicals plus bitewings covering every tooth | Comprehensive intraoral survey |
| Occlusal | A large area of one arch, receptor held in the bite | Larger areas of the jaws, impacted teeth, foreign objects |
| Panoramic | Both jaws and surrounding structures in one image | Overall view, third molars, jaw and TMJ region |
| Cephalometric | Side view of the skull and facial profile | Orthodontic planning |
| CBCT | Three-dimensional images | Implant planning and other cases that need 3-D detail |
The dentist decides which images a patient needs. The ADA's 2026 patient-selection recommendations say images should be taken only when clinically necessary, based on the patient's history, prior images and the clinical exam. For the exam, know what each image is for; on the job, follow the prescription.
Sources: DANB RHS Exam Outline, I.B; Dentalcare CE559; ADA, January 5, 2026 patient-selection announcement.
Image error fix table
Error correction is where Purpose and Technique gets dense. Read this table left to right, then cover the first column and work it right to left.
| What you see | Likely cause | Fix |
|---|---|---|
| Teeth look too short (foreshortened) | Vertical angulation too steep | Decrease vertical angulation |
| Teeth look too long (elongated) | Vertical angulation too flat, or a curved receptor | Increase vertical angulation; keep the receptor flat |
| Overlapped contacts | Horizontal angulation wrong | Aim the central ray straight through the contacts |
| Clear (white) curved area on one edge — cone cut | PID not centered over the receptor | Center the PID so the beam covers the whole receptor |
| Apices cut off | Receptor not placed far enough, or too little vertical angulation | Reposition the receptor; correct the angle |
| Blurred image | Patient moved | Stabilize the patient, explain, then re-expose only if necessary |
| Same artifact, same spot, every patient | Damaged receptor | Take that receptor out of service |
| Panoramic: flat or "frowning" occlusal plane, splayed condyles | Chin tipped up | Lower the chin |
| Panoramic: exaggerated "smile," fuzzy lower incisor apices | Chin tipped down | Raise the chin |
| Panoramic: dark band over maxillary apices | Tongue not on the palate | Swallow, then tongue flat against the palate |
| Panoramic: narrow, blurred anterior teeth | Too far forward | Move back so incisors sit in the bite groove |
| Panoramic: wide anterior teeth | Too far back | Move forward into the bite groove |
| Panoramic: one side's teeth and ramus wider | Head turned | Align the midsagittal plane |
| Panoramic: one condyle higher, mandible border slanted | Head tilted | Level the head |
| Panoramic: extra radiopaque shapes | Jewelry, glasses or other metal left on | Remove before exposure |
Every retake is extra patient exposure, which is why the outline lists retakes as a cause of unnecessary radiation.
Sources: Brian & Cooper, RDH (intraoral geometry errors); Dhillon et al., Imaging Science in Dentistry 2012 (panoramic errors).
Radiation numbers and terms to know cold
| Item | What to know |
|---|---|
| kVp | Controls beam quality, including energy and penetrating ability. Higher kVp → higher-energy, more penetrating beam |
| mA and exposure time | Control beam quantity. Increasing either increases the number of x-ray photons produced; use the unit-specific technique chart and manufacturer instructions |
| Inverse square law | Double the distance → one-quarter the intensity |
| Absorbed dose | Gray (Gy), SI; rad, traditional. 1 Gy = 100 rad |
| Dose equivalent / effective dose | Sievert (Sv), SI; rem, traditional. 1 Sv = 100 rem |
| Exposure | Coulombs per kilogram (C/kg), SI; roentgen (R), traditional |
| Adult occupational limit (MPD) | 5 rem (0.05 Sv) per year, total effective dose equivalent |
| Most radiosensitive | Rapidly dividing, less-specialized cells — plus lymphocytes |
| Most radioresistant | Nerve and muscle cells |
| ALARA | As Low As Reasonably Achievable — every exposure justified and kept as low as reasonably achievable |
| Operator protection | Barrier; with no barrier, at least 2 m from the primary beam, ideally 90°–135° to it |
| Patient dose reduction | Collimate the beam to the receptor size when possible; current ADA guidance favors rectangular collimation for intraoral imaging |
| Unnecessary exposure | Leakage radiation and retakes |
Shielding changed — know why. The ADA no longer recommends thyroid collars for any dental imaging, and its 2024 recommendations call for removing routine patient shielding from regulations that still require it. Shields can block the primary beam and cause retakes; rectangular collimation protects the thyroid better. State laws set their own radiation requirements, so on the job follow your state's rule and your office's protocol.
Sources: Dentalcare CE570, Beam Quality and Beam Quantity; 10 CFR Part 20, §§20.1004 and 20.1201; Stanford EH&S; Benavides et al., JADA 2024; ADA, X-Rays/Radiographs (updated March 26, 2026).
Infection control for imaging: the short version
- Digital sensors are semicritical. Use an FDA-cleared barrier, then clean and heat-sterilize or high-level disinfect between patients. If the sensor can't tolerate that, the minimum is the barrier plus cleaning and disinfection with an EPA-registered hospital disinfectant with intermediate-level (tuberculocidal) activity between patients — within the manufacturer's instructions.
- Heat-tolerant holders and beam-alignment devices go in the mouth, so they're semicritical too: clean and heat-sterilize between patients.
- The tubehead and PID are noncritical items when they touch only intact skin.
- Clinical contact surfaces — tubehead, control panel, keyboard and mouse — get a barrier, or cleaning and disinfection between patients.
- PSP plates: disinfect the barrier envelope, then open it so the clean plate drops out untouched by contaminated gloves. Soiled gloves come off before you touch the scanner.
- Gloves for every intraoral exposure. Clean your hands before gloving and every time you remove gloves.
Sources: CDC, Sterilization and Disinfection summary; CDC, Hand Hygiene for Healthcare Workers; 29 CFR 1910.1030; Dimensions of Dental Hygiene, "Radiology chain of asepsis".
Your 4-week RHS study plan
20 sessions, about 60 minutes each, five days a week. It fits inside DANB's 60-day testing window and needs nothing beyond this page and DANB's free outline. If you have a dental radiography textbook from your program, read the matching chapter in each session.
| Session | Focus | Do this | Done when |
|---|---|---|---|
| Week 1 — Radiation | |||
| 1 | Baseline | Work all 32 questions untimed. Count misses by domain. Skim the outline, pages 3–6 | You know your weakest domain |
| 2 | X-ray production | kVp, mA, time; density vs contrast; primary, scatter and leakage radiation. Redo Q17–19 | You can say what each setting changes on the image |
| 3 | Biology and units | Radiosensitivity, latent period, short- vs long-term effects, somatic vs genetic. Make cards for Gy, Sv, R, rem, C/kg | You can match every unit to what it measures |
| 4 | Protection | ALARA, MPD, barrier/position/distance, filtration, collimation, PID, patient size and age, retakes | You can list five ways to cut unnecessary exposure |
| 5 | Patients and equipment | Patient concerns, informed consent and refusal, suspected x-ray unit malfunction. Redo Q20–24 | You can explain each wrong option aloud |
| Week 2 — Technique | |||
| 6 | Image types | The image table above: periapical through CBCT | You can name the image for any purpose |
| 7 | Paralleling | Receptor placement by area, holders, central ray. Redo Q1 | You can sketch receptor, tooth and beam |
| 8 | Bisecting and modifications | Bisecting angle; tori, cleft palate, shallow palate, narrow arch; anxious or limited-mobility patients. Redo Q2 | You can explain when bisecting replaces paralleling |
| 9 | Bitewings and receptors | Bitewing angulation; PSP, CMOS and CCD receptors and their care. Redo Q10, Q11, Q14 | You can name the bitewing vertical angle |
| 10 | Technique checkpoint | Redo Q1–Q6 and Q10–Q15 without notes | 10 or more of 12 correct, or the misses go into Session 11 |
| Week 3 — Errors, panoramic, landmarks, infection control | |||
| 11 | Error correction | Work the fix table both directions until you can fill it in blank. Redo Q3–Q5 | You can fill every intraoral row from memory |
| 12 | Panoramic | Positioning and every panoramic row of the table. Redo Q7–Q9, Q15 | You can fill every panoramic row from memory |
| 13 | Anatomy and mounting | Maxillary and mandibular landmarks, radiopaque vs radiolucent, mounting order, orientation, Universal tooth numbering for primary and permanent teeth. Redo Q12–Q13 | You can place each landmark in the right arch |
| 14 | Legal and quality | Diagnostically acceptable images; HIPAA, retention, transfer, charting. Redo Q16 | You can say what makes an image acceptable |
| 15 | Infection control | Sensors, holders, PSP workflow, clinical contact surfaces, PPE, hand hygiene. Redo Q25–Q32 | You can classify every imaging item |
| Week 4 — Mixed review | |||
| 16 | Timed mixed set | All 32 questions, shuffled, in about 26 minutes — the real exam's average pace | You finished on time |
| 17 | Repair | Re-teach every miss from Session 16 in your own words | Every miss has a one-sentence rule in your notes |
| 18 | Full-length timing | If your program or another source gives you a full-length 75-question practice exam, take it in 60 minutes. If not, run two timed rounds of your flashcards plus the blank fix table | You've practiced a full 60-minute stretch |
| 19 | Vocabulary | Go through DANB's acronym list and radiography terms list (outline pages 8–12) | You can define every term on the lists |
| 20 | Logistics and light review | Work the exam-day checklist below; review your weakest domain only | Nothing about exam day is a surprise |
Pace: 60 minutes ÷ 75 questions = 48 seconds per question on average (our arithmetic). 32 × 48 seconds ≈ 26 minutes. That's a pacing reference, not a rule for every question.
Two weeks? Do Sessions 1, 2+3, 4+5, 6+9, 7+8, 11, 12, 13+14, 15, 16, 17 and 20 — twelve sessions. Don't cut Session 11.
One week? About 90 minutes a day. Day 1: Session 1, then 11. Day 2: Sessions 7–9. Day 3: Sessions 12–13. Day 4: Sessions 2–4. Day 5: Session 15. Day 6: Sessions 16–17. Day 7: Sessions 19–20.
Exam tomorrow? Don't start new chapters. Reread your misses, cover and fill the error fix table, skim the radiation sheet and the infection control list, then work the exam-day checklist and sleep.
Adjusting: If your misses cluster in one domain, add a session there each week and drop the checkpoint for your strongest domain.
How the RHS exam works
- 75 multiple-choice questions, 60 minutes, at a Pearson VUE test center or through online proctoring — your choice.
- Computer adaptive testing. Each question's difficulty depends on how you're doing, and scoring is based on the difficulty of the questions you answer correctly. DANB says the average candidate answers around 50% correctly, so a question that feels hard isn't a sign you're failing.
- No skipping and coming back. DANB says you can't skip a question and return to it later. Make your best choice before you submit, then move on.
- Answer everything. DANB requires every question to be answered to receive a pass or fail result. Unscored pretest questions may appear, and you won't know which ones they are.
- Scaled score. Scores range from 100 to 900, and you need 400 to pass. It isn't percent correct, and you aren't compared with other candidates.
- An acronym list is available during the exam. It's printed in the outline (pages 8–10), so learn it beforehand.
- Results post to your online DANB account within 1–3 business days.
Sources: DANB RHS Exam Outline, pages 2, 8 and 13; DANB, "4 important details to know about DANB exams" (January 10, 2024); 2026 Candidate Handbook, pages 13–14.
Applying, scheduling and retakes
| Question | Official answer |
|---|---|
| Who can take it? | Anyone — DANB lists no eligibility requirements for RHS |
| Fee | $270; $265 for active military personnel. Includes a $75 nonrefundable application fee |
| Testing window | 60 days from the date your application is approved. You can request a new 60-day window once |
| Rescheduling | Test center: up to 24 hours before. Online: up until the appointment time |
| Breaks | Test center: at the proctor's approval, and the exam clock keeps running. Online: no breaks |
| Under 18 | Online exams need the Parent/Guardian Consent Form, and the parent or guardian must be present at check-in |
| Languages | Also offered in Spanish and Vietnamese |
| Missed exam | Can be rescheduled once at a reduced fee within 60 days of the missed date |
| Retakes | No limit. Reapply and pay the full fee. DANB also announced in January 2025 a one-time 33% RHS retake discount, offered directly to eligible candidates — ask DANB if you didn't pass |
| 2026 applications | Accepted through December 31, 2026 |
Exam-day checklist
- The name on your government-issued, unexpired photo ID matches your DANB account exactly
- Appointment confirmed in the Pearson VUE email — if no email arrived, scheduling didn't finish
- Testing online: system test passed on the same computer and network, private room with a clear desk, phone within hearing but out of reach
- Testing online: check in up to 30 minutes early; after 15 minutes past the start time the exam is recorded as missed
- No notes, study guides or reference materials — the acronym list is the only reference provided
Sources: DANB RHS exam page; 2026 RHS Application Packet (updated May 11, 2026), pages 3–5 and 8–9; 2026 Candidate Handbook (updated June 22, 2026), pages 4–12; DANB news, January 14, 2025.
Apply for the RHS exam on DANB's site
Does passing RHS let you take x-rays in your state?
Not by itself. Passing RHS earns a DANB certificate, and it's one component of the NELDA and CDA certifications. DANB states that passing its exams conveys authority to perform duties only in states that recognize those exams. Your state dental board decides who may take radiographs and what training or supervision is required. Check DANB's state requirements, then your state dental board, before you count on RHS for a job duty.
Comparing credentials? Dental assistant certification lays out DANB CDA, NELDA, AMT RDA and state paths.
Common questions
Is film radiography on the RHS exam? No. DANB has tested only digital radiography on RHS since July 7, 2022.
Is RHS a certification? By itself, it's a certificate. RHS is one of three exams for the CDA (with GC and ICE) and one of three for NELDA (with AMP and ICE).
What pass rate does DANB report? DANB publishes exam pass rates each year in its Exam Pass Rates reports.
Sources
Last verified October 26, 2026: DANB's RHS exam page, outline, application packet, Candidate Handbook and study guides, and the clinical and regulatory sources below.
- DANB, Radiation Health and Safety exam page
- DANB, RHS Exam Outline and References, effective March 12, 2025
- DANB, 2026 RHS Application Packet, updated May 11, 2026
- DANB, 2026 Candidate Handbook, updated June 22, 2026
- DANB, "4 important details to know about DANB exams", January 10, 2024
- DANB, "Free RHS study guide plans and more", January 14, 2025
- DANB, Reports and State Requirements
- ADA, X-Rays/Radiographs, updated March 26, 2026, and patient-selection recommendations announcement, January 5, 2026
- Benavides E, et al. "Optimizing radiation safety in dentistry: Clinical recommendations and regulatory considerations." JADA 2024;155(4):280–293
- CDC, Summary of Infection Prevention Practices in Dental Settings: Sterilization and Disinfection
- CDC, Clinical Safety: Hand Hygiene for Healthcare Workers
- 29 CFR 1910.1030, OSHA Bloodborne Pathogens standard
- U.S. NRC, 10 CFR Part 20, §20.1004 (units) and §20.1201 (occupational dose limits)
- 45 CFR 164.524, individuals' access to protected health information
- Stanford EH&S, Biological Effects of Radiation and Units of Dose
- Dentalcare, CE559 Intraoral Radiographic Techniques, CE570 Basic Radiation Physics, and CE571 The Radiographic Image
- Brian JN, Cooper MD. "Little details, little errors mar and blemish X-rays." RDH
- Dhillon M, et al. "Positioning errors and quality assessment in panoramic radiography." Imaging Science in Dentistry 2012;42(4):207–212
- Lakshman AR, et al. "Mental foramen mimicking as periapical pathology." Journal of Health Sciences 2014;4(2):126–129
- Air Techniques, ScanX PSP intraoral operating instructions (manufacturer workflow example; follow the IFU for the system in use)
- DE 115: Dental Radiography (open textbook), section 20.1 and section 23.2
Citation note: Stanford's original web page for Biological Effects of Radiation and Units of Dose is no longer available. Stanford links on this page now point to the same material in Stanford's Radiation Safety Manual PDF, section 1.8.
Written by the Castleport Test Prep Editorial Team. All 32 practice questions are original and are not DANB exam questions.
Castleport Test Prep is an independent exam prep publisher and is not affiliated with, endorsed by, or approved by the Dental Assisting National Board (DANB). Exam and credential names, including RHS, CDA and NELDA, are used to identify the exams discussed; trademarks belong to their respective owners.