There are 2 types of Digital Radiography.
1.__ __- Uses a photostimulable storage phosphor (PSP) inside a cassette.
2.__ __- Uses a detector built in to Bucky or inside a cassette (wireless)
1. Computed Radiography (CR)
2. Digital Radiography (DR)
Binary Machine Language
Computers operate using a binary (base 2) system
____ = off
____ = on
Each binary number is called a ___ “binary digit”
_____ - a unit of data (word) that contains 8 bits. Also is the unit most computers use to represent a character such as a letter, number, or typographic symbol.
_____ - A series of boxes displayed in a layout of rows & columns.
——- Each box is called a ___ that corresponds to a 2-dimensional location in the image (x & y coordinates)
A _____ represents a 3-dimensional volume of tissue (z coordinate)
The ____(_) is the overall dimension of the image matrix.
——- is determined by the size of the detector in digital radiography.
——- if remains constant but matrix size increases, the pixels must get ____.
- Field of View (FOV)
Each pixel assigned a numeric value (_______) that represents a shade of gray or brightness level based on the attenuation characteristics of the volume of tissue x-rayed.
Bone attenuates (absorbs) x-rays to a large degree, so the pixel value will be ___, producing high brightness. (Low density)
Air attenuates x-rays to a lesser degree, so the pixel value will be ____, producing low brightness (high density)
High brightness = ___ density
Low brightness = ___ density
___ ___ is the number of bias used to represent each pixel. The greater the __ __, the more shades of gray that can be displayed.
___ ___ refers to the range of values or number of gray shades that an imaging system can reproduce.
The 3 types of Image Processing Operations
- Point Processing
- Local Processing
- Geometric Processing
____ - a graphical display of the pixel intensity distribution for a digital image.
- Is generated from the image data based on signal intensity from each pixel
- The shape corresponds to the specific anatomy and technique used for an exam.
_-axis represents the amount of exposure
_-axis represents the incidence of pixels for each exposure level
A computer analyzes the histogram to determine the ____ & _____.
- Values of interest (VOI)
- Exposure index number (indicator)
A _____ is data stored in the computer used to manipulate the values of gray levels (contrast). It does this by substituting new values for each pixel during point processing.
Look-up table (LUT)
___ ___ is why an underexposed or overexposed digital image may display with acceptable brightness on the monitor.
____ is a process that changes the contrast & brightness (density) of a digital image on the monitor. This is done through varying the numerical values of each pixel manually.
The ____ ___ is the range of brightness (densities) that will be displayed on a monitor. It is primarily used to control image ____
- Window Width (WW)
The ____ ____ is the center of the window width, or the midpoint of the entire range of brightness (densities) displayed on a monitor. It is primarily used to control image ___.
Narrow WW - ___ contrast
Wide WW - ___ contrast
Low window level - ___ brightness
High window level - ___ brightness
____ ____ - is a process used to sharpen the image by amplification of the frequencies of the area of interest.
____ - is a process used to intentionally blur the image
- low-pass filter applied
- Produces an output image with decreased noise & brightness level of pixels
___ ___ - is a process used to subtract a low-pass (blurred) image from the original image
- Suppresses some frequencies
- Produces a sharper output image
____ ____ - processes used to change the position or orientation of the pixels in the image
Factors that affect the quality of a digital image.
____ ___ - the degree of geometric sharpness of the structural lines (edges) recorded in the image.
____ - grainy or uneven appearance of an image
____ ___ ___ - a measure of the sensitivity & accuracy by which an image receptor converts the incoming data to the output device (monitor)
Detective Quantum Efficiency (DQE)
Small pixels = ____ spacial resolution
Large pixels = ____ spacial resolution
___ ___ ___ - results from undesirable signals from the digital system that do not contribute to the image.
___ ___ ___ - results from an insufficient quantity of photons reaching the IR (mAs and/or kV set too low)
Electronic system noise
Quantum mottle noise
The ___ ___ is a comparison between the actual exposure & the proper exposure received by the IR.
___ layer - base for the other layers
___ layer - insulates plate from handling trauma
___ layer - active component of plate; holds photostimulable phosphors that are energized when exposed to x-rays
___ layer - grounds plate and absorbs light
__ __ layer - prevents light from erasing data on plate
___ layer - prevents light leak
- Support layer
- Protective layer
- Phosphor layer
- Conductor layer
- Light shield layer
- Backing layer
Indirect Flat Panel - uses ___ ___ as a scintillator that emits light when struck by x-rays
—— ___ ___ transforms light into electronic signal
- Cesium iodide
- Amorphous silicon
Direct Flat Panel - no scintillator; uses ___ ___ to convert x-rays directly into an electronic signal