Terminology Flashcards
Stage 0 survival rate
100%
Stage 1 survival rate
100%
Stage 2 survival rate
93%
Stage 3 survival rate
72%
Stage 4 survival rate
22%
Why compress?
-breast uniform thickness throughout the whole image
-reduce breast thickness, which reduces geometric blur
-reduce motion, unsharpness
-reduce scatter radiation
-increase contrast
-separates superimposed breast tissue
-reduces radiation dose
Basis for digital mammo
-lower dose
-improved image quality
-computer-aided diagnosis software
-softcopy review and digital storage
-elimination of physical storage
-large dynamic range or depth of recorded signals (# of grey-scale shades)
-window width/window level
-increased exposure latitude which is related to dynamic range of exposure technique that will produce an acceptable range of densities. Directly related to contrast. This is a wider range of acceptable exposures without repeating.
Indirect capture
First converts xrays into visible light with a scintillator. The visible light is then converted into an electrical signal
Amorphous silicon (a-si)
Uses a scintillator made of cesium iodide to convert xrays into light, which is then captured by the photodiodes
Direct capture
The xrays are not converted into light, but directly into an electrical signal
Amorphous selenium (a-se)
The scintillator is replaced with the amorphous selenium plate that converts the xray photons directly onto electron-hole pairs
Contrast resolution
The number of shades of grey that a detector can capture
High contrast resolution
Capable of capturing thousands of shades of gray. This permits the imaging of areas that would otherwise be under or overexposed on conventional film
CCD (charged coupled device)
Small computer chips which create a digital image used in Fischer SenoScan
Micron
A unit of length equal to one million (1/1,000,000) of a meter
Pixel
The basic unit of the composition of an image on a television screen, computer monitor, or a similar display (picture element)
Pixel pitch
Center of one pixel to the center of another pixel
Scintillator
A substance that glow when hit by high-energy particles or photons
DEL
detector element
BIT
Information single binary digit like 0 or 1. 8 bits=1 byte
Latitude
1000:1 - wide in digital allowing a broader range of exposures that will produce an acceptable image. Wide latitude allows digital visualization of the skin and penetration of dense breast tissue
Dynamic range
Depth of the recorded signal intensity, as grey-scale shades
What is window width?
Contrast of the image. Grey tones of the image. Controlled by the kVp value.
What happens when you increase or widen the window width range in pixel values?
Will give less contrast or more gray toning. Reduce detail of image.
What happens when you decrease or narrow the window width range in pixel values?
Will give high contrast or more black and white.
Window centering (level)
Can manipulate or adjust the brightness of the image. Pixel brightness w/in different portions for image quality. Ma can control brightness alone w/ post processing.
Increasing window centering (level) results in
darker/blacker image
Decreasing window centering (level) results in
lighter/whiter image
Thickness equalization/compensation
Detector looks are variations in pixel density across the image and estimates the thickness of the breast at each pixel
DQE (detective quantum efficiency)
measure of dose efficiency
MTF (modulation transfer function)
measure of resolution/spatial frequency response.
measure of the transfer of modulation from the subject to the image
Increasing signal and decreasing noise (some
electronic noise) in the system does what?
Increases visibility of small structures
Indirect detector
Direct Detectors
Matrix
