Your FREE DANB RHS Flashcards 2026 – 200+ Cards

The preferred intraoral technique: the image receptor is placed parallel to the long axis of the tooth and the central ray is directed perpendicular to both. Produces the most accurate, dimensionally correct images and is used with a beam-alignment (holder) device.

The receptor rests against the tooth and the central ray is aimed perpendicular to an imaginary line bisecting the angle formed by the tooth's long axis and the receptor. More prone to dimensional distortion than paralleling.

Direct the central ray at a right angle (90°) to the imaginary bisector of the angle between the long axis of the tooth and the plane of the receptor.

Shows the entire tooth — crown to root apex — plus the surrounding bone. Used to evaluate apical pathology, root structure, and periodontal bone levels.

Shows the crowns of maxillary and mandibular teeth and the interproximal areas on one film. Primary image for detecting interproximal caries and evaluating crestal bone.

A complete set of intraoral periapical and bitewing images that records all teeth and surrounding structures; used for a comprehensive diagnostic baseline.

A larger intraoral receptor placed on the occlusal (biting) surface to show a broad area of the maxilla or mandible — useful for impacted teeth, supernumerary teeth, and localizing foreign objects.

An extraoral image showing both arches, the TMJs, and sinuses on a single film. The patient bites a block to position teeth in the focal trough.

An extraoral lateral image of the skull and facial bones used in orthodontics to evaluate growth, development, and skeletal relationships.

A 3-D imaging modality that captures a volume of data in one rotation; used for implant planning, impactions, and complex anatomy. Delivers a higher dose than 2-D intraoral images.

The curved zone of sharpness in panoramic imaging; structures inside it appear clear, while teeth positioned outside it look blurred, widened, or narrowed.

The open-ended cone or tube extending from the tubehead that aims and shapes the X-ray beam; rectangular PIDs reduce patient exposure versus round PIDs.

A receptor-holding instrument (with a ring/arm) that keeps the receptor parallel to the tooth and aligns the PID to the receptor, reducing cone cuts and retakes.

The component of a receptor holder the patient bites on to stabilize the receptor and maintain its position during exposure.

A paper or plastic tab attached to a receptor that the patient bites to hold a bitewing in position.

The component housing the X-ray tube, transformers, and oil; it produces the X-ray beam and connects to the extension arm and control panel.

The operator interface used to set kilovoltage (kVp), milliamperage (mA), and exposure time and to initiate the exposure from a safe position.

An image with proper density and contrast, correct anatomy without distortion, minimal overlap, no cone cut, and free of artifacts — usable for diagnosis.

Incorrect side-to-side angulation of the beam relative to the contacts; the characteristic result is overlapped (superimposed) proximal contacts.

Incorrect up/down angulation; too much vertical angulation foreshortens the image and too little elongates it.

Teeth appear too short on the image; caused by excessive vertical angulation (bisecting technique).

Teeth appear too long on the image; caused by insufficient vertical angulation (bisecting technique).

A clear (unexposed) area on the image where the PID/beam was not centered over the receptor, leaving part of it outside the beam.

Superimposition of adjacent proximal surfaces caused by incorrect horizontal angulation; obscures interproximal caries.

The overall darkness or blackness of an image; controlled primarily by milliamperage (mA) and exposure time.

The difference between the light and dark areas of an image; controlled primarily by kilovoltage (kVp).

An image that is too dark from excessive density — typically too much mA, time, or kVp; correct by reducing exposure factors.

An image that is too light from insufficient density — typically too little mA, time, or kVp; correct by increasing exposure factors.

The device that captures the X-ray image — a digital sensor (CCD/CMOS), a photostimulable phosphor (PSP) plate, or conventional film.

A charged-coupled device: a wired solid-state digital sensor that converts X-rays to an electronic signal for near-instant image display.

A complementary metal-oxide semiconductor: a wired solid-state digital sensor similar to CCD, producing an immediate digital image.

A wireless, reusable flexible plate that stores the image as energy and is scanned by a laser to produce the digital image; thinner and more comfortable than rigid sensors.

Image capture with electronic sensors or PSP plates instead of film; since July 7, 2022 the RHS exam tests digital radiography only.

Image capture with a wired sensor (CCD/CMOS) that sends data directly to the computer for immediate viewing.

Image capture with a PSP plate that must be scanned, or digitization of a film, before the image appears.

Structures that absorb more X-rays and appear light/white on the image — e.g., enamel, bone, metallic restorations.

Structures that absorb fewer X-rays and appear dark/black on the image — e.g., the pulp chamber, caries, and air spaces.

The ADA-adopted numbering used in the U.S.: permanent teeth 1–32 (#1 = maxillary right third molar) and primary teeth A–T.

The maxillary right third molar — the starting point of the Universal Numbering System (1–32).

Primary teeth are designated A through T, beginning with A at the maxillary right second primary molar.

Arranging images in an anatomically correct holder/screen view so the viewer reads them as if facing the patient; the embossed dot's convex side points toward the operator.

The raised dot on film/PSP that establishes left/right orientation; mounting with the raised (convex) side toward you yields the labial mounting method.

Disease at the root apex (e.g., periapical abscess, cyst, or granuloma) typically seen as a radiolucency around the apex on a periapical image.

Decay between adjacent teeth, best detected on bitewing radiographs as a radiolucent notch in the proximal enamel/dentin.

An extra tooth beyond the normal complement; localization may require occlusal or additional angled images.

An arch with no teeth; radiographs evaluate residual ridge, retained roots, and bone for prosthetic or implant planning.

A radiopaque endosseous fixture; radiographs assess osseointegration, bone level, and proximity to anatomic structures.

Methods (e.g., the buccal-object rule / SLOB) using two images at different angles to determine the buccal or lingual position of an object.

Same Lingual, Opposite Buccal: when the tube head shifts, a lingual object moves the same direction as the tube and a buccal object moves the opposite direction.

An air-filled radiolucency in the posterior maxilla; its floor may appear near molar roots on periapical and panoramic images.

The jaw joint evaluated on panoramic and specialized images to assess condylar position and bony changes.

Bony outgrowths (palatal or mandibular) that interfere with receptor placement; place the receptor distal to the torus or use a holder to accommodate it.

An anatomic opening that complicates receptor placement; modify technique and use careful positioning to obtain diagnostic images.

A low palatal vault that resists parallel receptor placement; the bisecting-angle technique may be substituted.

A constricted arch limiting receptor placement; reposition the receptor or use a smaller receptor/holder.

Before exposure, review the medical/dental history for contraindications and remove eyeglasses, jewelry, piercings, and removable appliances in the beam path.

Checking the patient record for contraindications, prior imaging, and the clinical need before exposing — supporting the prescribing-for-need (selection-criteria) principle.

ADA/FDA guidelines stating radiographs should be prescribed based on the individual patient's needs, not taken routinely, to limit unnecessary exposure.

Blurring of the entire image caused by the patient moving during exposure; corrected by stabilizing the patient and the receptor.

Unintended movement of the tubehead during exposure causing blurring; the operator must ensure the tubehead is stable before exposing.

Bitewings typically use about +8° to +10° of vertical angulation to project the crests of bone and crowns accurately.

On mounted images, anterior images show narrow single-rooted teeth toward the midline and posterior images show wider multirooted teeth toward the back.

Mesial is the proximal surface toward the midline; distal is the proximal surface away from the midline — key for orienting and reading images.

Maxillary images show the upper arch (roots point up in the mouth); mandibular images show the lower arch (roots point down), aiding mounting.

The Health Insurance Portability and Accountability Act governs the privacy and security of protected health information, including dental radiographs.

Dental radiographs are part of the legal patient record and must be retained per state and federal requirements; they are diagnostic-quality documents, not to be altered.

The dental practice generally owns the original radiographs as part of the record, while the patient has the right to copies.

Use clear explanation, reassurance, and efficient technique to reduce a patient's apprehension and the need for retakes.

Adapt positioning, receptor holders, and technique for patients with mobility, gag-reflex, or other limitations to obtain diagnostic images safely.

Minimize stimulation of the soft palate, work efficiently, distract the patient, and consider receptor placement adjustments to control gagging during imaging.

Use the smallest appropriate receptor, fastest technique, child-appropriate settings, and shielding; children are more radiosensitive than adults.

Adjusting brightness, contrast, and sharpness of a captured digital image with software — but enhancement cannot fix a non-diagnostic exposure or positioning error.

Bitewings are the primary radiograph for detecting early interproximal caries and assessing alveolar crest height.

Vertical and horizontal bone loss, crestal changes, and calculus are assessed on bitewing and periapical images to evaluate periodontal status.

The midsagittal plane is centered and vertical, the Frankfort plane is parallel to the floor, the chin rests on the chin rest, and the patient bites the block and stands/sits still.

An artifact appearing on the opposite side, higher and blurred, produced by a dense object (e.g., earring) on the contralateral side; remove metal objects to avoid it.

A radiopaque pyramidal shadow over the anterior region caused by improper posture; have the patient stand/sit erect with the spine straight.

A foreign-object artifact from the lead backing or a metallic object left in the beam; recognize and remove the object, then retake if needed.

Aligning the central ray to the center of the receptor prevents cone cuts and ensures the full area of interest is captured.

Radiographs are exposed only on the dentist's order based on clinical need, supporting ALARA and avoiding unnecessary exposure.

Reusable holders/bite blocks contacting mucosa are semicritical and must be heat-sterilized (or single-use) between patients.

A periapical centered on the canine with the long axis aligned; the canine's long root often requires careful vertical angulation to avoid apex cutoff.

A periapical capturing the molars and surrounding bone; the receptor is placed lingual to the teeth toward the floor of the mouth with appropriate angulation.

A diagnostic periapical must include several millimeters of bone beyond the root apex so periapical pathology is not missed.

Placing a PSP plate or sensor backward so the beam passes through the lead foil/back first, producing a light image with a herringbone/tire-track pattern (film) or signal loss.

Two images recorded on one receptor from exposing it twice; produces a superimposed, non-diagnostic image — track receptors to avoid it.

No image captured — often from a sensor/PSP that was not activated, a backward plate, or an exposure/processing failure.

Enlargement of the image caused by increased object-to-receptor distance or decreased source-to-receptor distance; minimized by paralleling with a holder.

Inaccurate shape or proportion from improper receptor or beam alignment; controlled by parallel placement and perpendicular central-ray direction.

The clarity of fine detail and edges; improved by a small focal spot, minimal movement, and proper geometry — collimation does not affect sharpness.

A longer PID (greater source-to-receptor distance) reduces magnification and improves sharpness by producing a more parallel beam.

Commonly uses about +40° to +45° vertical angulation to record the long maxillary central incisor roots without foreshortening.

Mandibular periapicals use a smaller (often negative for some teeth) vertical angulation than maxillary projections because of arch orientation.

Documenting findings (caries, restorations, bone levels) interpreted from images into the patient record — a legal and diagnostic responsibility.

Mounting images so the arches, midline, and tooth positions match the patient's actual anatomy enables correct interpretation and reduces errors.

Routine checks of equipment, sensors, processing/scanning, and technique that keep images diagnostic and minimize retakes and dose.

Re-exposing because of a non-diagnostic image; each retake adds patient dose, so technique and positioning should be correct the first time (ALARA).

To verify minimum national competence in radiation health and safety tasks critical to the safety of patients and oral healthcare workers.

The active surface of the sensor faces the beam/teeth and is held parallel to the long axis with a holder; correct placement avoids cone cuts and distortion.

Teeth positioned anterior to the focal trough appear narrowed; teeth positioned posterior to it appear widened/blurred.

As Low As Reasonably Achievable — the guiding radiation-protection principle to keep patient and operator exposure to the minimum needed for diagnosis.

Beam intensity is inversely proportional to the square of the distance from the source: $I \propto \dfrac{1}{d^2}$. Doubling the distance reduces intensity to one-fourth.

If distance doubles, intensity becomes $\left(\tfrac{1}{2}\right)^2 = \tfrac{1}{4}$ of the original — a key basis for the operator standing back.

Controls the energy/penetrating power of the X-ray beam and the radiographic contrast; higher kVp produces a more penetrating beam and lower (longer-scale) contrast.

Controls the quantity (number) of X-rays produced per unit time; together with time it governs radiographic density.

The duration of the exposure; with mA it determines the total quantity of radiation (mAs) and the image density.

The product of mA and exposure time $(\text{mAs}=\text{mA}\times s)$; the primary control of radiographic density/quantity.

Increases beam penetration and produces lower-contrast (longer grey-scale) images; allows reduced exposure time and can lower patient dose.

The useful beam emitted from the tubehead/PID and directed at the patient and receptor.

Radiation created when the primary beam strikes and interacts with matter (the patient and tissues).

A form of secondary radiation deflected in all directions after striking matter; the patient is the main source of scatter and the chief occupational hazard.

Radiation escaping the tubehead in directions other than the useful beam; a properly maintained, shielded tubehead minimizes it.

Aluminum filters placed in the beam remove low-energy, long-wavelength photons that only add to patient dose without improving the image (beam hardening).

Removal of low-energy photons by filtration, leaving a beam with a higher average energy that is more penetrating and reduces patient skin dose.

Restricting the size and shape of the beam (with a lead diaphragm or PID) to the area of interest; reduces patient exposure and scatter radiation.

Shapes the beam to roughly the size of the receptor; reduces patient exposure significantly more than round collimation.

A lead-equivalent shield draped over the patient's torso to protect radiosensitive organs from scatter; used per ADA/FDA guidance.

A lead-equivalent shield protecting the radiosensitive thyroid gland; recommended for children and when it does not interfere with the image.

Stand at least 6 feet away and at a 90°–135° angle to the beam (the safe zone), or behind a barrier, during exposure.

A wall or shield the operator stands behind during exposure to block primary and scatter radiation.

The upper limit of occupational radiation an individual may receive; for occupationally exposed workers the whole-body limit is $50\ \text{mSv/year}$ ($5\ \text{rem/year}$).

The whole-body effective dose limit for radiation workers is $50\ \text{mSv}$ ($5\ \text{rem}$) per year; non-occupationally exposed public limit is far lower ($1\ \text{mSv/year}$).

The total accumulated lifetime occupational dose; one historical guideline is $(N-18)\times 1\ \text{rem}$, where N is age in years.

The SI unit of absorbed dose — energy absorbed per unit mass of tissue (1 Gy = 1 J/kg).

The SI unit of dose equivalent (and effective dose), accounting for the biological effect of the radiation type.

The traditional unit of radiation exposure in air (ionization), being replaced by the SI coulombs per kilogram (C/kg).

The SI unit of radiation exposure, expressing ionization produced in air; replaces the roentgen.

The traditional unit of dose equivalent; $1\ \text{Sv}=100\ \text{rem}$ (so $1\ \text{rem}=10\ \text{mSv}$).

The amount of radiation energy absorbed per unit mass of tissue, measured in gray (Gy) or rad.

Absorbed dose weighted for the biological effectiveness of the radiation, measured in sieverts (Sv) or rem.

A whole-body dose estimate weighting each irradiated organ's dose by its radiosensitivity; used to compare risk across procedures.

The time between radiation exposure and the appearance of observable biological effects; it shortens as dose increases.

Radiation effects occurring in the exposed individual's own body tissues (e.g., skin or tissue damage), not passed to offspring.

Radiation effects on reproductive (germ) cells that may be passed to future generations.

Effects appearing soon after a large dose over a short time (e.g., erythema); rare in routine dental imaging.

Effects appearing years after exposure, such as increased cancer risk; the concern driving ALARA in dentistry.

Cells that are rapidly dividing and undifferentiated (e.g., blood-forming, reproductive, young) are the most sensitive to radiation.

Mature, specialized, slowly dividing cells (e.g., nerve, muscle) are relatively resistant to radiation damage.

Radiosensitive structures of concern in dental imaging include the thyroid gland, bone marrow, lens of the eye, and gonads.

Retakes, improper technique, lack of collimation/filtration, leakage, and imaging without clinical justification all add avoidable dose.

Filtration, collimation, shielding (apron/collar), receptor speed/sensor sensitivity, technique, and PID length all influence patient dose.

Digital sensors and PSP plates require less radiation than older film, reducing patient dose for the same image.

The patient's right to understand the need, benefit, and risk of radiographs and to consent or refuse before exposure.

A patient may decline radiographs; document the refusal, and recognize that diagnosis/treatment may be limited without needed images.

Stop using the unit, follow the office protocol, tag it out, and have it inspected/serviced before resuming exposures.

X-rays are short-wavelength, high-frequency electromagnetic radiation; shorter wavelength means higher energy and greater penetrating power.

The ability of the beam to pass through matter; increased by higher kVp (more energetic, shorter-wavelength photons).

Joint guidance recommending radiographs based on individual need (selection criteria) and the use of protective measures to keep dose low.

A monitoring device worn by occupationally exposed workers to measure accumulated radiation dose over time.

Because intensity falls off as $1/d^2$, increasing distance from the source is one of the most effective ways to reduce operator exposure.

Treating all blood, body fluids, and contaminated items as potentially infectious for every patient — the foundation of dental infection control.

A system that ranks patient-care items as critical, semicritical, or noncritical to determine the required level of reprocessing.

Items that penetrate soft tissue or bone; they must be heat-sterilized (or single-use). Few imaging items are critical.

Items that contact mucous membranes but do not penetrate tissue (e.g., reusable receptor holders/bite blocks); they require heat sterilization.

Items contacting only intact skin (e.g., X-ray tubehead, control panel); they require barriers or intermediate/low-level disinfection.

Surfaces touched during care (tubehead, PID, control panel, chair, counter) that must be barrier-protected or cleaned and disinfected between patients.

Single-use, fluid-resistant covers placed on clinical contact surfaces (tubehead, PID, control panel, work area) and changed between patients.

A disposable plastic cover over a digital sensor or PSP plate to prevent contamination; removed and discarded after each patient.

Even when barrier-protected, sensors that cannot be heat-sterilized must be cleaned and disinfected (per manufacturer) with an EPA-registered, intermediate-level disinfectant after each use.

Washing with soap and water or using an alcohol-based hand rub before gloving and after glove removal to prevent cross-contamination.

Gloves, mask, protective eyewear, and gown/clothing worn to protect the clinician from exposure to blood and saliva during imaging.

Put on PPE in order: gown, then mask, then eyewear, then gloves (gloves last, over the gown cuffs).

Remove PPE in order: gloves first, then eyewear, then gown, then mask — most-contaminated items first, then perform hand hygiene.

Single-use gloves worn for patient imaging and changed between patients; never washed and reused.

Clear plastic gloves placed over contaminated treatment gloves to handle clean items (e.g., a computer mouse or drawer) without contaminating them.

The spread of microorganisms from one person, surface, or item to another; prevented by barriers, hand hygiene, PPE, and proper instrument handling.

A process that kills all microorganisms including bacterial spores; achieved by heat (autoclave) for critical and semicritical heat-tolerant items.

Sterilizes heat-tolerant instruments with saturated steam under pressure (commonly $121\,^{\circ}\text{C}$ at $15\ \text{psi}$); used for reusable receptor holders.

Reducing or eliminating most microorganisms on a surface; classified as high-, intermediate-, or low-level depending on the product.

An EPA-registered, tuberculocidal hospital disinfectant used on clinical contact surfaces and barrier-protected items contaminated with blood/saliva.

A surface disinfectant approved by the EPA for use against specified pathogens; chosen by required level (e.g., tuberculocidal for intermediate-level).

Before the patient, place fresh barriers, set out sterilized/disposable items, and prepare equipment so contamination is contained during imaging.

After imaging, remove and discard barriers, dispose of single-use items, and clean and disinfect uncovered contaminated surfaces.

Use a barrier sleeve, open it without touching the plate with contaminated gloves, and disinfect the plate per manufacturer instructions to prevent contamination of the scanner.

Move barrier-covered or contained receptors to the processing/scanning area without contaminating surfaces along the way; remove barriers with clean technique.

The federal regulation requiring employers to protect workers from exposure to blood and other potentially infectious materials (PPE, training, exposure control).

Federal recommendations (Standard Precautions, PPE, sterilization, surface management) that guide dental infection control including radiography.

Professional recommendations aligning dental practices with CDC/OSHA standards for safe, contamination-free imaging.

Items intended for one patient and then discarded (e.g., bite tabs, sensor sleeves); never reprocessed or reused.

Dispose of contaminated single-use items in the appropriate waste stream; in imaging this mainly involves barrier sleeves and disposable tabs.

Weekly testing of a sterilizer with bacterial spores to confirm it achieves sterilization.

When a surface is not barrier-protected: clean to remove bioburden, then disinfect with an EPA-registered product for the labeled contact time.

The time a disinfectant must remain visibly wet on a surface to be effective, as stated on the product label.

Use barriers or overgloves on the imaging computer, mouse, and keyboard, or disinfect them, to prevent transfer of contamination from sensors.

Working to avoid introducing contamination — clean hands, gloves, barriers, and careful handling of receptors and equipment.

Reusable holders/bite blocks are heat-tolerant and sterilized; digital sensors are heat-sensitive and must be barrier-protected plus disinfected.

Items contacting oral mucosa (receptor holders, bite blocks) are semicritical and require heat sterilization between patients.

Remove and discard the contaminated barrier sleeve before handling the bare sensor with clean gloves to avoid cross-contamination.

Glasses with side shields worn during imaging to protect the eyes from spatter; cleaned and disinfected between patients.

A surgical mask covering the nose and mouth filters spatter and aerosols; changed when wet or between patients.

Surfaces and instruments must be cleaned of visible bioburden first, because organic debris inactivates disinfectants and impairs sterilization.

Soaking contaminated reusable holders in a solution prevents debris from drying before cleaning and sterilization.

Mechanical pre-sterilization cleaning of instruments by cavitation to remove debris, reducing the need to scrub contaminated holders by hand.

Wrapping or pouching instruments before autoclaving maintains sterility until the package is opened at point of use.

Remove and discard gloves, perform hand hygiene, and don fresh gloves for each new patient and after touching contaminated surfaces.

Separating contaminated handling areas from clean image-processing/computer areas to prevent cross-contamination during imaging.

OSHA-required measures (barriers, safe handling procedures, sharps containers) that reduce the risk of occupational exposure during imaging.

Steps after a blood/saliva exposure: wash the area, report the incident, and follow the office's post-exposure evaluation procedure.

Disinfect or re-barrier the dental chair, headrest, and counter contacted during imaging before seating the next patient.

Always follow the device maker's validated cleaning, disinfection, or sterilization instructions for sensors and holders to ensure safety and avoid damage.