Radiology Flashcards
Define: Absorbed dose
the amount of energy deposited by ionizing radiation (x-ray)
Define: ALARA principle
As Low As Reasonably Possible
Keeping the dose of radiation as low as possible
Define: Algorithm
A computer code used to generate an radiograph image
Define: Anode
Where x-rays are produced (where the beam comes from)
Define: Artifact
Anything in the x-ray that isn’t supposed to be there (like a finger)
Define: Attenuation
The reduction of the intensity of an x-ray beam as it traverses matter
Meaning: Things that are more dense (like bones) allow less x-rays through so they are brighter on x-rays
Define: Binding energy
The energy required to completely remove an electron from an atom is called the electron binding energy.
Define: Bremsstrahlung Radiation
electromagnetic radiation produced by the acceleration or especially the deceleration of a charged particle after passing through the electric and magnetic fields of a nucleus.
Define: Cathode
the negatively charged side of x-ray tube circuit.
What positioning is this demonstating?
Caudocranial (CdCr)
Shooting from caudal to cranial
Define: Characteristic Radiation
are emitted when outer-shell electrons fill a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is “characteristic” to each element
Define: Charge Couple Device
a light-sensitive integrated circuit that captures images by converting photons to electrons.
Ex: our dental x-ray sensor
Define: Computed Radiography
Uses a reusable plate to take digital radiographs; needs to be placed in a scanner to produce the radiograph.
The phosphor layer in the plate stores the image. The scanner amplifies the image and converts it to a digital image
Define: Detail
The sharpness of the image
Define: Digital
A computer image instead of using film
Define: Digital detector
Receives the radiation going through the patient and converts it into a digital image that can be immediately visualized on a monitor.
Define: Digital Radiology (DR)
is an advanced form of x-ray inspection which produces a digital radiographic image instantly on a computer.
Define: Direct Digital Radiography (DDR)
sensors that send a digital image directly to a computer
Define: Distal
away from or farthest from the trunk or the point or origin of a part (example, the paw is located at the distal end of the leg).
What is this positioning?
Dorsopalmar (DPa)
Shot from doral to palmar (only counts for the front feet)
What is this positioning in letter A?
Dorsoplantar (Dpl)
Shot from the dorsal surface to the plantar surface of the foot (only the back foot)
What is this positioning called?
Dorsoventral (DV)
Shot from the dorsum to the vetrum
Define: Dose Creep
is the gradual acceptance over time by radiographers of the use of higher radiographic exposures
Define: Dosimeter
an instrument used to measure ionizing radiation exposure (like the badge you wear when taking rads)
Define: Dynamic range
the series of exposure values that will result in a radiographic image
Define: Electromagnetic radiation
an electric and magnetic disturbance traveling through space at the speed of light
Define: Electron
a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.
Define: Electron beam
machine-generated high-energy electrons
Define: Electron hole pair
Free charge carriers in the semi conductor
Define: Filament
the source of electrons (cathode) in x-ray tubes
Define: Film Contrast
density differences that result due to the type of film used, how it was exposed, and how it was processed.
Define: Film graininess
How to correct:
the visual appearance of irregularly spaced grains of black metallic silver deposited in the finished radiograph
Correct by increasing exposure (increase kVp or mAs)
Define: Film latitude
the range of receptor exposures over which an image and contrast will be formed
Define: Focal range
Focal spot is the area of the anode surface which receives the beam of electrons from the cathode. It is the apparent source of x-rays.
Define: Fogging
How to correct:
darkening of images by sources other than the radiation of the primary beam to which the film was exposed
Correct: look for signs of light exposure in the x-ray room
Define: Geometric unsharpness
How to correct:
The lack of sharpness in an image that results from variation in the geometry of an X-ray system set-up.
Correct: Have machine calibrated
Define: Grid cutoff
How to correct:
an unwanted absorption of x-rays via an x-ray grid, observed when a grid is employed incorrectly, most often seen with parallel grids
Correct: Be sure to direct beam directly towards area you want radiographed
Define: Heel Effect
How to correct:
refers to the lower field intensity towards the anode in comparison to the cathode due to lower x-ray emissions from the target material at angles perpendicular to the electron beam.
Correct: Increase distance from beam, be sure beam is at correct angle, collimate, be sure pet is in correct position
Define: Collimate
Decrease size of field of x-ray
What is this an example of?
A histograph which is a graphical display of the pixel intensity distribution for a digital image.
What is this an example of? What type of radiograph will it produce?
Imaging plate
Used in CR or computed radiography
Define: Ionization
the principal means by which ionizing radiations dissipate their energy in matter
Define: Kilovolt (kV)
the x-ray tube peak voltage during an exposure
Define: Latent image
the invisible product of x-ray or photographic film emulsions, build after radiation or light exposure (the image will only show up once it is developed)
Define: Maximum Permissible Dose
is the upper limit of allowed radiation dose that one may receive without the risk of significant side effects
Define: Windowing
the process in which the CT image greyscale component of an image is manipulated via the CT numbers
Define: Milliampere second (mAs)
a measure of radiation produced (milliamperage) over a set amount of time (seconds) via an x-ray tube
Define: Noise
How to correct:
a fluctuation in optical density on radiographic or mammographic images, often as a result of low radiation dose
Correct: Increase mAs
Define: Object image distance
The distance measured between the center mass of the patients anatomical organ and the center the x-ray cassette.
Define: Osmolality
Used to describe different contrast solutions used in radiography
Define: Penumbra
How to correct:
blurring at the edges of a structure
Correct: Collimate
Define: Photon
Photons are called x-rays if they are produced by electron interactions
Define: Photostimulable Phosphor
are materials that store absorbed energy within excited electrons and release it in the form of light on exposure to laser energy
Define: Pixel
the smallest discrete element of the physical display or to the smallest element of the image.
Define: Polychromatic beam
multiple optical frequencies
Define: Quantum mottle
How to correct:
is the main and the most significant source of noise in plain radiography. It is a random process due to fluctuations in the number of photons reaching the detector from point to point
Correct: Adjust kVp or mAs as needed
Define: Radiodense/Radiopacity
Ex:
is the relative transparency of a material to x-rays and other radiation.
Ex: Bladder stone, bones- Appear white on radiograph
Define: Radiographic contrast
the difference in density or difference in the degree of grayness between areas of the radiographic image.
Define: Radiographic Density
a measure of the light transmitted through the film.
Define: Radiography
the process or occupation of taking radiographs to assist in medical examinations
Define: Radiology
the science dealing with X-rays and other high-energy radiation, especially the use of such radiation for the diagnosis and treatment of disease.
Define: Radiolucent
Example
structures that are less dense and permit the x-ray beam to pass through them
Ex: Air- Appears black on an xray
Define: Rectification
The process of changing alternating current into direct current so it flows in one direction only
Define: Remnant Beam
resulting beam that is able to exit from the patient and produce the photographic image on radiographic film.
Define: Scatter or secondary radiation
Radiation that spreads out in different directions from a radiation beam when the beam interacts with a substance, such as body tissue.
Define: Scinillating Devices
an instrument for detecting and measuring ionizing radiation by using the excitation effect of incident radiation on a scintillating material, and detecting the resultant light pulses.
Define: Source image distance (SID)
The distance of the tube from the image receptor, affecting magnification
Define: Spatial resolution
is a measure of the smallest object that can be resolved by the sensor, or the ground area imaged for the instantaneous field of view
Define: Structure mottle
Uneven distibution of phosphor
Define: Thermionic emission
The emission of electrons from a heated metal (cathode).
How can you make an x-ray that is too dark lighter?
Too dark is an over exposure
Dark = Decrease mAs
How can you make a film that is too light, darker?
Too light is underexposed
Increase kVp
