Chapter 10: Imaging: Conventional and Digital Flashcards
Uses x-ray film and intensifying screen in image formation.
Film Screen Imaging
Composed of emulsion spread on a thin transparent sheet of polyester plastic.
Radiographic film
Spread on both sides of the polyester base sheet except in special cases like mammography.
Emulsion
The film is placed between…
Intensifying Screens
Are made of phosphor crystals that will fluoresce when struck by x-rays,
Intensifying Screens
2 Types of Processing
Manual & Automatic Processing
Any image acquisitioning process that produces an electronic image that can be viewed and manipulated in a computer.
Digital Imaging
2 Types of Digital Imaging
Computed & Digital Radiography
Contains photostimulable storage phosphor which store the radiation level receive.
Imaging Plate
The CR ID Station transfers patient identification data from the modality workstation to the CR cassettes.
ID Tablet
It scans the phosphor plate and extract the electronic latent image.
Image Reader
Converts signals to digital form
Digital Electronics
The latent image in DR is recorded on the electronic device. Cassette-less.
Digital Radiography
2 Types of Digital Radiography
Direct and Indirect Capture
One which first converts x-rays into light.
Indirect Method
Light is emitted when x-rays strike a sensitive phosphor that must be converted to electric signal.
Indirect Imaging
Does not require a light-emitting phosphor because x-rays interact directly with the element selenium, creating an electric charge.
Direct Digital Imaging
Factors Affecting the Image (Rad. Quality)
Photographic & Geometric Quality
Factors Affecting the Image (Rad. Density)
Air, Fat, Muscle, Bone, Metal
Controls the current supplied to the filament of the x-ray tube.
mAs
Time of exposure in seconds.
sec
Voltage applied across the x-ray tube; energy of the x-rays
kVp
Distance from the source of radiation to the image receptor.
Distance
Increases the overall density of the image.
Fog
Devices attached to the x-ray tube to reduce exposure field size thus decrease a proportion of the amount of scatter radiation.
Cones and Collimators
Variations in density available on the radiograph.
Contrast
Contrast inherent in the atomic part being examined.
Subject Contrast
Any medium introduced into the anatomic part being radiographed that has a different radiation-absorbing potential increases the contrast.
Contrast Media
A device placed between the patient and the image receptor that absorbs scatter radiation emitted by the patient before it reaches the film and therefore decreases density.
Grid
The position of the x-ray beam does affect contrast.
X-ray Beam Angle
A false representation of the true shape of the object.
Image Distortion
The alignment of the object in relation to the x-ray tube and image receptor will determine the shape as seen in the radiograph.
Beam Alignment
Distortion and Magnification result when the object of interest is located at some distance away from the image receptor.
Object-to-Image Distance
Magnification can be reduced by increasing the SID
SID
May be defined as the distinctness with which images of structures are recorded for viewing.
Radiographic Detail
Geometric unsharpness is directly proportional to the size of the focal spot size; the smaller the focus, the sharper the structure lines
X-ray Tube Focal Spot Size
Detail in the image is also controlled by the distance from the focus to the object or patient.
Focal-Object Distance
