DANB RHS Exam Flashcards

Q: How many questions are on the DANB RHS exam?

DANB's RHS exam outline lists 75 multiple-choice questions with a 60-minute testing window. The exam uses computer-adaptive testing (CAT) and is scored on a 100-900 scale with a minimum passing scaled score of 400.

Q: What domains are tested on DANB RHS?

DANB weights three domains: Purpose and Technique (50%), Radiation Characteristics and Protection (25%), and Infection Prevention and Control (25%). Half of your score comes from image purpose, positioning, and error correction.

Q: Does DANB RHS still test film radiography?

No. DANB states RHS has tested digital radiography only since July 7, 2022. Film-processing and darkroom concepts are no longer on the exam—focus on PSP, CCD/CMOS sensors, and digital image quality.

Q: What is the DANB RHS pass rate?

DANB's FY2025 exam performance report lists an RHS pass rate of 69% (9,905 passed of 14,272 delivered), up from 66% in FY2024. Focused domain-weighted study and timed practice improve first-attempt odds.

Q: How much does the DANB RHS exam cost in 2026?

The 2026 RHS application packet lists $270 for traditional applicants and $265 for active military. The fee includes a nonrefundable application portion. Eligible candidates who do not pass may qualify for a one-time 33% retake discount.

Q: Do I need prerequisites to sit for RHS?

No. DANB's RHS exam outline states there are no eligibility requirements. Anyone can apply, receive a 60-day testing window, and take the exam in person through Pearson VUE or by remote online proctoring.

Question 1

Periapical (PA) image

Accepted Answer

Shows the entire tooth from crown to apex plus surrounding bone. Used to evaluate apical pathology, root morphology, and periapical status of individual teeth.

Question 2

Bitewing (BW) image

Accepted Answer

Shows crowns of maxillary and mandibular teeth in occlusion and the alveolar crest. Primary use: detect interproximal caries and assess crestal bone levels.

Question 3

Full mouth series (FMS / FMX)

Accepted Answer

A complete set of intraoral images covering all teeth—typically a mix of periapicals and bitewings. Provides a comprehensive baseline of dentition and supporting structures.

Question 4

Occlusal radiograph

Accepted Answer

Large intraoral image that shows a broad area of the maxilla or mandible. Useful for locating supernumerary teeth, impacted teeth, sialoliths, and evaluating the palate or floor of the mouth.

Question 5

Panoramic radiograph

Accepted Answer

Extraoral image of both jaws, TMJs, and surrounding structures on one view. Used for overall survey, third-molar assessment, and pathology screening—not a substitute for detailed bitewings when caries detection is the goal.

Question 6

Cephalometric radiograph

Accepted Answer

Standardized lateral (or PA) skull image used mainly in orthodontics to evaluate craniofacial relationships, growth patterns, and treatment planning landmarks.

Question 7

CBCT (cone-beam computed tomography)

Accepted Answer

Three-dimensional imaging modality that produces multiplanar views. Used when 2D images are insufficient—implant planning, complex anatomy, and localization of impacted teeth or pathology.

Question 8

Paralleling technique

Accepted Answer

Receptor is placed parallel to the long axis of the tooth; the central ray is directed perpendicular to both. Preferred when anatomy allows because it minimizes dimensional distortion.

Question 9

Bisecting-angle technique

Accepted Answer

Central ray is aimed perpendicular to an imaginary line that bisects the angle between the tooth long axis and the receptor. Useful when paralleling is difficult (shallow palate, tori), but more prone to vertical distortion.

Question 10

Beam alignment device (XCP-type holder)

Accepted Answer

Instrument that holds the receptor and guides the PID so the central ray is centered and correctly angled. Improves consistency and reduces cone cuts and angulation errors.

Question 11

PID (position-indicating device)

Accepted Answer

Open-ended cylinder or rectangular tube that aims and shapes the useful beam toward the receptor. Longer PIDs increase source-to-receptor distance and can improve image sharpness.

Question 12

SLOB rule (Same Lingual, Opposite Buccal)

Accepted Answer

Object-localization method: take a second image with a horizontal tube shift. If the object moves in the Same direction as the tube, it is Lingual; if Opposite, it is Buccal.

Question 13

Patient preparation for radiographs

Accepted Answer

Review medical/dental history for contraindications, explain the procedure, remove eyeglasses/jewelry/piercings that can create artifacts, and position the patient for the selected technique.

Question 14

Technique modifications (tori, shallow palate, narrow arch)

Accepted Answer

Adapt receptor size/placement, use a different holder or bisecting approach, and adjust angulation carefully. Goal: diagnostic image without forcing anatomy that causes gagging or distortion.

Question 15

Panoramic patient positioning landmarks

Accepted Answer

Align the patient using planes such as the Frankfort plane and midsagittal plane, instruct the patient to bite on the bite block, and keep the tongue against the palate when indicated to avoid airway shadows.

Question 16

Overlapped proximal contacts

Accepted Answer

Caused by incorrect horizontal angulation—the central ray was not directed through the contacts. Correct by adjusting horizontal angulation so the beam passes through the interproximal spaces.

Question 17

Elongation

Accepted Answer

Teeth appear longer than actual size. Commonly caused by insufficient vertical angulation (especially with bisecting technique). Increase vertical angulation to correct.

Question 18

Foreshortening

Accepted Answer

Teeth appear shorter than actual size. Caused by excessive vertical angulation. Decrease vertical angulation to restore accurate tooth length.

Question 19

Cone cut

Accepted Answer

Clear, unexposed area on the image because the PID/beam did not cover the entire receptor. Center the beam over the receptor and verify alignment-device placement before exposing.

Question 20

Motion blur / patient movement

Accepted Answer

Unsharp or ghosted anatomy from patient or tubehead movement during exposure. Stabilize the patient's head, use a firm bite, and ensure the tubehead is locked before pressing expose.

Question 21

Underexposed digital image

Accepted Answer

Image appears too light or noisy with inadequate detail. Increase exposure factors (mA, time, or appropriate kVp per protocol) or check for incomplete exposure/sensor connection issues—avoid unnecessary retakes.

Question 22

Overexposed digital image

Accepted Answer

Image appears too dark with washed-out contrast. Reduce exposure quantity (mA × time) or adjust technique factors per office protocol; confirm the correct exposure setting was selected for the region.

Question 23

Radiopaque vs. radiolucent

Accepted Answer

Radiopaque structures (enamel, amalgam, metal) appear light/white because they absorb more x-rays. Radiolucent structures (pulp, soft tissue, caries) appear dark because more x-rays reach the receptor.

Question 24

Diagnostically acceptable image

Accepted Answer

Shows the intended anatomy with adequate density/contrast, correct angulation (open contacts when needed), sharp detail, and no artifacts that hide clinical findings. Retake only when diagnostic value is compromised.

Question 25

Image mounting / orientation cues

Accepted Answer

Arrange images in anatomical order using tooth numbers, maxillary vs. mandibular landmarks, and facial/lingual orientation. Correct orientation prevents misdiagnosis and supports legal chart documentation.

Question 26

Common radiographic landmarks

Accepted Answer

Examples: mental foramen, genial tubercles, maxillary sinus, zygomatic process, lamina dura, and alveolar crest. Recognizing normal landmarks prevents mistaking anatomy for pathology.

Question 27

kVp (kilovoltage peak)

Accepted Answer

Controls beam energy (quality) and penetrating power. Higher kVp increases penetration and generally produces a longer gray scale (lower contrast); also influences overall receptor exposure.

Question 28

mA and exposure time

Accepted Answer

Together they control the quantity of x-rays produced (mAs). Increasing milliamperage or time increases receptor exposure and image density; decreasing either reduces exposure.

Question 29

Primary vs. scatter radiation

Accepted Answer

Primary radiation is the useful beam from the tubehead. Scatter (secondary) radiation is produced when the primary beam interacts with matter (patient, objects) and contributes to occupational exposure and image fog.

Question 30

Inverse square law

Accepted Answer

Intensity varies inversely with the square of the distance from the source. Doubling distance reduces intensity to one-fourth; halving distance increases intensity fourfold—critical for operator standing distance.

Question 31

Filtration

Accepted Answer

Removes low-energy x-rays that would be absorbed by the patient without contributing to the image. Inherent plus added filtration hardens the beam and reduces unnecessary patient dose.

Question 32

Collimation

Accepted Answer

Restricts beam size and shape (preferably rectangular) so only the area of interest is irradiated. Reduces patient tissue exposure and scatter, improving both safety and image contrast.

Question 33

Cell / tissue radiosensitivity

Accepted Answer

Rapidly dividing, undifferentiated cells are generally more radiosensitive (e.g., blood-forming tissues, reproductive cells). Highly specialized cells with low turnover (muscle, nerve) are relatively radioresistant.

Question 34

Latent period

Accepted Answer

Time between radiation exposure and the appearance of observable biologic effects. Effects may appear hours to years later depending on dose and tissue type.

Question 35

Somatic vs. genetic effects

Accepted Answer

Somatic effects occur in the irradiated person (e.g., tissue injury, cancer risk). Genetic (heritable) effects involve damage to reproductive cells that could be passed to future offspring.

Question 36

Absorbed dose unit — Gray (Gy)

Accepted Answer

Gray measures energy absorbed per unit mass of tissue (1 Gy = 1 J/kg). The older traditional unit is the rad (100 rad = 1 Gy).

Question 37

Equivalent / effective dose unit — Sievert (Sv)

Accepted Answer

Sievert accounts for biologic effect of different radiation types and, for effective dose, tissue weighting. Traditional counterpart is the rem (100 rem = 1 Sv). Occupational limits are often stated in mSv.

Question 38

ALARA

Accepted Answer

As Low As Reasonably Achievable. Apply selection criteria, correct technique on the first exposure, collimation/filtration, shielding when indicated, and avoid unnecessary retakes to minimize dose.

Question 39

Time, distance, and shielding

Accepted Answer

Three core occupational controls: minimize time near the source, maximize distance (inverse square law), and stand behind a protective barrier or use shielding when a barrier is unavailable.

Question 40

Operator position without a barrier

Accepted Answer

Stand at least 6 feet from the tubehead and preferably at a 90–135° angle to the primary beam direction. Never hold the receptor or tubehead during exposure.

Question 41

Lead apron and thyroid collar

Accepted Answer

Patient shielding devices that attenuate scatter to the torso and thyroid. Use according to current ADA/FDA guidance and office policy; store flat or hung to avoid cracks in the lead/attenuating material.

Question 42

Maximum permissible dose (MPD)

Accepted Answer

Regulatory upper limit for occupational exposure. Commonly cited whole-body occupational MPD is 50 mSv (5 rem) per year; keep actual exposure far below limits through ALARA practices.

Question 43

Personal dosimeter (TLD / badge)

Accepted Answer

Monitors cumulative occupational radiation exposure. Wear at the assigned body location during work; do not leave it in the operatory near the tubehead or take it home for non-work exposure.

Question 44

Causes of unnecessary exposure

Accepted Answer

Retakes from technique errors, holding the receptor for the patient, standing in the primary beam, equipment leakage, and exposing without clinical indication. Prevention is the best protection strategy.

Question 45

CCD / CMOS digital sensors

Accepted Answer

Solid-state intraoral receptors that capture the image electronically and display it almost immediately. They cannot be heat sterilized—use a disposable barrier and disinfect per manufacturer IFU.

Question 46

PSP (phosphor storage plate)

Accepted Answer

Reusable plate that stores a latent image and is scanned to create a digital file. Handle carefully to avoid scratches; use barriers and follow infection-control and erasure protocols between patients.

Question 47

Standard precautions (radiography)

Accepted Answer

Treat all patients as potentially infectious. Use hand hygiene, appropriate PPE, barriers on clinical contact surfaces, and safe handling of receptors and holders for every radiographic procedure.

Question 48

Spaulding classification for radiography items

Accepted Answer

Critical items penetrate tissue (sterilize). Semi-critical items contact mucous membranes (e.g., reusable receptor holders—heat sterilize when heat-tolerant). Noncritical items touch intact skin or surfaces (disinfect).

Question 49

Barriers and surface disinfection

Accepted Answer

Place barriers on tubehead, control panel, chair controls, and other clinical contact surfaces before the procedure. After the patient, remove barriers carefully and disinfect underlying surfaces as needed.

Question 50

PPE and glove change sequence

Accepted Answer

Wear gloves, mask, and eye protection as indicated for intraoral imaging. After exposure, remove contaminated gloves before touching the computer/keyboard or clean areas; perform hand hygiene and use barriers on input devices.

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