Chapter 22: Exposure & Technique Errors Flashcards
Identification of Exposure and Technique Errors and How to Prevent Them
Define the term: forshortening
- a term describing the image of a tooth that appears shorter than the actual tooth
- results from steep or excessive vertical angulation
What is the cause of the error in missing apical structures?
the image receptor was not positioned in the patient’s mouth to cover the apical regions
Define the term: subject contrast
the characteristics of the subject (patient) that influence contrast, including the size and thickness of the patient
Define the term: diagnostic image
a dental image that allows for the identifying and monitoring of diseases or injuries
Define the term: overexposed image
an exposure error that results in a dark image from excessive exposure time, kilovoltage, or milliamperage, or a combination of these factors
Define the term: x-ray beam angulation
one of the influencing factors for image distortion that refers to the direction of the x-ray beam
Define the term: double image
- an exposure error that occurs when a PSP receptor is exposed twice in the patient’s mouth
- appears dark as the result of two superimposed images
Define the term: contrast
- how sharply dark and light areas are differentiated or separated on an image
- the difference in the degrees of blackness (densities) between adjacent areas on a dental image
How do you correct a cone-cut error when not using a beam alignment device?
ensure the x-ray beam is centered over the receptor and the entire receptor is covered by the diameter of the position-indicating device
What is the cause of error with a dropped receptor corner?
- the edge of the receptor was not placed parallel to the incisal/occlusal surfaces of the teeth
- this can be caused by the patient not correctly biting on the bite block
What is the cause of the wired cable appearing on an image?
the wired cable of the digital sensor was was placed in front of the image receptor during exposure
Define the term: forshortened image
an image of a tooth that appears short and distorted
How do you prevent an error of a dropped receptor corner?
- ensure the patient is firmly biting on the bite block
- ensure that the edge of the receptor is placed parallel to the incisal/occlusal surfaces of the teeth
How do you correct overlapped contacts when exposing a periapical image?
direct the central ray of the x-ray beam through the proximal contacts of the teeth
How do you prevent an movement error from occurring?
- stabilize both the x-ray tubehead and the patient’s head prior to exposure
- instruct the patient to remain still during exposure
- never press the exposure button if you know the x-ray tubehead is drifting or the patient is moving
How does an image appear that has debris accumulation?
debris on the surface of the sensor may cause permanent radiopaque artifacts or radiolucent scratch marks on the sensor
Define the term: periodontal
around a tooth
Define the term: negative vertical angulation
the positioning of the position-indicating device below the occlusal plane that directs the central ray upward
What type of image receptor can result in a creased image?
PSP plates
What is the cause of a phalangioma error?
when using the finger-holding method, the patient’s finger was incorrectly positioned in front of the image receptor instead of behind it during exposure
Define the term: elongation
- a term used in imaging to describe an image of a tooth that appears longer than the actual tooth
- results from flat or insufficient vertical angulation
What is the cause of a cone-cut error when using a beam alignment device?
the position-indicated device was not properly aligned with the beam alignment device and the x-ray beam did not exposure the entire receptor
Define the term: apex
the area of a tooth that allows for blood vessels and nerves to enter the tooth and maintain the vitality of the tooth
Define the term: subject thickness
the thickness of soft tissue and bone in a patient
Define the term: bisecting technique
- an intraoral imaging technique used to expose periapical receptors
- the image receptor is placed along the lingual surface of the tooth, the central ray of the x-ray beam is directed perpendicular to the imaginary bisector formed by the image receptor and the long axis of the tooth
- receptor holder is used to stabilize the image receptor
What is the cause of a forshortened image error?
the vertical angulation was too steep
Define the term: radiopacity / radiodensity
an area on a dental image appearing radiopaque (light/white) due to resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the image receptor
Define the term: parallel
moving or lying in the same plane; always separated by the same distance and not intersecting
Define the term: elongated image
an image of a tooth that appears long and distorted
Define the term: periapical image
intraoral image that is used to examine the crowns and roots of teeth
Define the term: central ray (CR)
the central portion of the primary beam of x-radiation
Define the term: radiolucency
an area on a dental image appears radiolucent ((dark/black) due to readily allowing the passage of the x-ray beam so that more x-rays reach the image receptor
Define the term: non-diagnostic image
an image that is not diagnostically accurate due to technique errors and must be retaken
Define the term: low contrast
a term describing an image with many shades of gray and few areas of black and white
How do you prevent an accumulation of debris on a digital sensor?
- gentle handling
- correct infection prevention and cleaning procedures
How does an image appear if the PSP plate has been bent?
the image appears stretched and distorted
Define the term: density
the overall darkness or blackness of an image
How does an image appear with a phalangioma error?
the patient’s finger is seen on the image
Define the term: perpendicular
intersecting at or forming right angles
Define the term: cone-cut
a clear, unexposed area on a dental image that occurs when the position-indicating device is misaligned and the x-ray beam is not centered over the image receptor
Define the term: contact areas
the areas where adjacent tooth surfaces touch each other
What image technique can cause a phalangioma error?
the bisecting technique with the finger-holding method
Define the term: kilovoltage
in dental imaging, the x-ray tube peak voltage used during an exposure
How does an image appear if the image receptor has been creased?
the creased area appears as a white line
Define the term: image receptor
a recording medium (ex: PSP plate, digital sensor)
Define the term: phalangioma
the distal phalanx (bone) of the finger is seen on the image as a result of the finger-holding method
How do you prevent a wired cable of the digital sensor from being imaged?
ensure that the wired cable is not in front of the image receptor prior to exposure
How do you prevent the error of an unexposed image receptor from occurring?
- ensure the x-ray machine is turned on
- ensure the position-indicating device is positioned over the image receptor
- listen for the audible exposure signal
Define the term: radiolucent
the portion of an image that is dark or black, due to the structure readily permitting the passage of the x-ray beam and allowing more x-rays to reach the image receptor
How do you prevent a phalangioma error?
never allow a patient to hold an image receptor during exposure
What is the cause of an elongated image error?
the vertical angulation was too flat
How does a forshortened image appear?
the teeth appear short with blunted roots
What is the cause of a double image error?
the same receptor was exposed twice in a patient’s mouth
What imaging techniques can cause an error with a dropped receptor corner?
paralleling or bisecting
How does the image appear from an underexposed image receptor error?
light or low in density
True or false: A double image cannot be produced with a digital receptor.
True
Define the term: vertical angulation
the positioning of the position-indicating device in a vertical plane
What is the cause of a bent image receptor?
- improper handling of the PSP plate
- the receptor could have been bent because of the curvature of the patient’s hard palate
Define the term: paralleling technique / extension cone paralleling (XCP) technique / right-angle technique / long-cone technique
- an intraoral imaging technique used to expose periapical receptors, where the receptor is placed parallel to the long axis of the tooth, the central ray is directed perpendicular to the receptor and the long axis of the tooth
- a beam alignment device must be used to keep the receptor parallel to the long axis to the tooth
Define the term: angulation
the alignment of the central x-ray beam in the horizontal and vertical planes
What type of angulation causes forshortened images?
incorrect vertical angulation
Define the term: high contrast
a term describing an image with many very dark areas and very light areas and few shades of gray
Define the term: ground glass appearance / orange-peel appearance
a term used to describe a radiopacity viewed on a dental image that resembles pulverized glass
What is the cause of a creased image receptor?
improper handling
How does an elongated image appear?
the teeth appear long and distorted
Define the term: vertical bite-wing
the bite-wing receptor is placed in the mouth with the long portion of the receptor in a vertical direction
What is the cause of a movement error?
either the x-ray tubehead, the image receptor, or the patient moved during exposure
How does the image appear with an unexposed image receptor error?
blank
Define the term: object-receptor distance
- the distance from the object being imaged *(tooth)) to the image receptor influences image magnification
- less image magnification results when the tooth and the image receptor are as close as possible, and more magnification results when the tooth and receptor are far apart
Define the term: magnification
- a geometric characteristic that refers to an image that appears larger than the actual size of the object it represents
- influenced by target-receptor distance and object-receptor distance
Define the term: irregular radiopacity
a term used to describe a radiopacity viewed on a dental image that has irregular, ill-defined borders
Define the term: radiopaque
the portion of an image that is light or white, due to the structure resisting the passage of the x-ray beam and limiting the amount of x-rays that reach the receptor
Define the term: occlusal technique
the method used to expose a receptor in occlusal examination
What type of image receptor can result in a bent image?
PSP plates
Define the term: horizontal bite-wing
the bite-wing receptor is placed in the mouth with the long portion of the receptor in a horizontal direction
Define the term: bite-wing technique / interproximal technique
an intraoral imaging technique in which the interproximal surfaces of teeth are examined
What imaging techniques can cause an error of missing apical structures?
paralleling and bisecting
Why is a double image error a serious error on the part of the dental radiographer?
it requires two retakes, one for each of the two areas previously exposed, which doubles the exposure to x-radiation
What is the cause of an underexposed image receptor error?
the image receptor was not exposed to enough x-radiation, due to incorrect exposure settings
Define the term: positive vertical angulation
the positioning of the position-indicating device above the occlusal plane that directs the central ray downward
Define the term: sharpness
- refers to the capability of the image receptor to reproduce the distinct outlines of an object
- influenced by focal spot size and movement
Define the term: open contacts
on a dental image, appears as a thin radiolucent line between adjacent tooth surfaces
Define the term: movement
motion of the image receptor or patient during image exposure that results in an image with decreased sharpness
How do you correct the error of a bent image receptor?
- check receptor placement prior to exposure
- if the receptor is bent because of the patient’s hard palate, cotton rolls can be used with the paralleling technique, or you can switch to the bisecting technique
- use a beam alignment device
- use caution with handling PSP plates
How does an image appear that has a cone-cut error?
a clear, unexposed area is seen on the image
What type of angulation causes overlapped contacts?
incorrect horizontal angulation
What image receptor can result in a double image error?
PSP plates
How do you correct the error of missing apical structures?
- ensure that the patient is firmly biting on the bite block of the receptor holder
- ensure that no more than 1/8 of an inch of the receptor edge extends beyond the incisal/occlusal surfaces
Define the term: vertical
an up-and-down plane
Define the term: overlapped contacts
on a dental image, the area where the contact area of one tooth is superimposed over the contact areas of an adjacent tooth
Define the term: image receptor placement
the specific area where the image receptor must be positioned before exposure
Define the term: control devices
- the components of the control panel of the x-ray machine that regulate the x-ray beam
- includes the timer, kilovoltage and milliamperage selectors
Define the term: ghost image
an artifact on a dental image produced when a radiodense object (ex: earring) is penetrated twice by the x-ray beam (appears radiopaque)
What type of angulation causes elongated images?
incorrect vertical angulation
Define the term: milliamperage
in dental imaging, the quantity (number) of x-ray emitted from the tubehead
Define the term: image receptor holder
a device used to hold an intraoral image receptor in the mouth and stabilize the receptor’s position during the exposure
Define the term: periapical
around the apex of a tooth
Define the term: beam alignment device
- a device used to align the position-indicating device in relation to tooth and image receptor
- positions the intraoral image receptor in the mouth and retains the image receptor in position during exposure
- helps stabilize the image receptor in the mouth and reduces the chances of movement, thus reducing the patient’s exposure to x-radiation
How do you prevent an image receptor from becoming creased?
- use caution when handling
- if needed, gently soften the corners if the PSP plate prior to placement intraorally
What is the cause of an unexposed image receptor error?
- the image receptor was not exposed to x-radiation
- this could be due to the x-ray machine not being turned on, an equipment malfunction, or failure to align the position-indicating device over the receptor
How does an image appear with an error of a dropped receptor corner?
the occlusal plane appears tipped or tilted
How does the image appear from an overexposed image receptor error?
dark or high in density
What is the cause of an accumulation of debris on a digital sensor?
improper handling or cleaning can cause dirt or dust particles to accumulate on the surface of the sensor
How does an image appear when an error of movement occurs?
a blurred image
Define the term: storage phosphor imaging
an indirect method of obtaining a digital image in which the image is recorded on phosphor-coated plates and then placed into an electronic processor, where a laser scans the plate and produces an image on a computer screen
What is the cause of a cone-cut error when not using a beam alignment device?
the position-indicating device was not positioned properly at the center of the receptor, and the central ray of the x-ray beam did not expose the entire receptor
Define the term: underexposed image
an exposure error that results in a light image due to inadequate exposure time, kilovoltage or milliamperage, or a combination of these factors
How do you prevent a double image error?
always separate the exposed and unexposed PSP plates during the exposure sequence
What is the cause of an overexposed image receptor error?
- the image receptor was exposed to too much x-radiation, due to incorrect exposure settings
Define the term: exposure time
the interval during which x-rays are produced
How does the image appear if the receptor was placed backward during exposure?
a blank or white image is seen with no anatomic structures recorded
Define the term: sensor
in digital imaging, an image receptor that is used to capture an intraoral or extraoral image
Define the term: exposure factors
factors that influence the density of an image (ex: milliamperage, kilovoltage, exposure time)
Define the term: scale of contrast
the range of useful densities on a dental images
Define the term: penumbra
the unsharpness or blurring of the edges of a structure viewed on a dental image
How does an image appear if the wired cable of the digital sensor is captured in the image?
the wired cable appears as a radiopaque outline
What image receptor can result in a debris accumulation error?
digital sensors
Define the term: distortion
- a geometric characteristic that refers to a variation in the true size and shape of the object being imaged
- influenced by object-receptor alignment and the vertical angulation of the x-ray beam
Define the term: horizontal angulation
the positioning of the position-indicating device in a horizontal plane
How does an image appear when a double image error occurs?
a double image will present and appears dark with superimposed structures
Define the term: periapical receptor
an intraoral image receptor used to examine the entire tooth (crown and root) and supporting bone
How do you correct a cone-cut error when using a beam alignment device?
ensure that the position-indicating device and the aiming ring are flush and properly aligned
