7.1 Reporting Flashcards
analog image processing is applied on analog signals and can be _____
periodic and non-periodic
The data collected from the patient during imaging is first converted into ____ to provide an input and output image, in an effort to improve and enhance diagnostic interpretation and management of images acquired from patients
digital data
refers to a continuously changing signal recorded in its original form
analog
In medical imaging for example, there are two types of images being generated –
analog and digital
An output signal generated by the PMT with continuously varying intensity depending on the location of light on an image
Analog Signal
The output of the photodetector is a time-varying _____ that is transmitted to a computer that has multiple functions
analog signal
The time-varying analog signal from the photodetector is processed for ______. This shapes the signal before the final image is formed
amplitude, scale, and compression
is an image formed by a 2D analog and digital signal that contains color information
Analog images
It is generally continuous and not broken into tiny components because although analog signals are real-world, they do not produce good quality images
Analog images
are subsequently displayed for human viewing and interpretation and in addition, these images can be digitally manipulated to suit the viewing needs of the observer
Analog images
Examples of analog images include:
television images, photographs, paintings, and medical images
is defined as numerical representation of the patient
Digital images
is divided into a matrix or array of small picture elements, or pixels
Digital images
that they can be processed, in many ways, by computer systems
Digital images
a necessary element in all modern medical imaging methods
Digital images
they are also easier to store, more accurate and reliable
Digital images
subjecting numerical representations of objects to a series of operations in order to obtain a desired result
digital image processing
Depending on how they are acquired, radiology images can be classified into two domains:
- Spatial Domain
2. Frequency Domain
all images use a right-handed X-Y coordinate system, to identify the location of any number that makes up the image. The X-axis is used to describe the rows or lines on the image, while the Y-axis is used to describe the columns
Spatial Domain
One of the main goals is to make image processing easier, so that particular features of the image can be enhanced or suppressed
Frequency Domain
Images can also be acquired in the frequency domain using the mathematical procedure of the ____
Fourier transform
a signal can be converted from time domain into frequency domain using mathematical operators called transforms
transformation
In the Frequency Domain, High frequency components correspond to ____ in an image. While Low frequency components in an image correspond to _____
edges (high), smooth regions (low)
in frequency domain,
the image can be enhanced for sharpness in which case the ______ are suppressed
low frequencies
in frequency domain, the image can be smoothed to enable better visualization of homogeneous structures by suppressing ______ via digital image processing
high frequencies
the purpose is to generate an image that is more pleasing to the observer
Image Enhancement
improvement of overall quality
Image Enhancement
Image Enhancement operations include
contrast enhancement, edge enhancement,
spatial & frequency filtering, imaging combining,
noise reduction
characteristics such as contour and shapes can be enhanced to improve such quality
Image Enhancement
improve images that have distortions or degradations
Image Restoration
a commonplace in “space craft”, these are usually images sent to earth and usually they have the instance to be blurred out thus can be filtered to make them sharper
Image Restoration
it begins with image segmentation operations, such as image enhancement or restoration operations
Image Analysis
features of the objects are extracted resulting in measures that describe & characterize the image
Image Analysis
are used in 3D medical imaging such as CT & MRI; where the goal is to simplify the representation of an image into something much easier to analyze
segmentation operations
reduces the size to save storage and transmission time
Image Compression
compression wherein there is no loss of info
Lossless
compression wherein there is loss of info and significant in images that have unnecessary data
Lossy
The main advantage is that there is no loss in both SPATIAL & FREQUENCY INFO
Wavelet Compression
recent form of compression which offers an approach that allows to reduce the size of the data while at the same time improving its quality through the removal of high frequency noise components
Wavelet Compression
it creates images that may be physically impossible or does not exist at all
Image Synthsis
basis for the production of CT & MRI images
image reconstruction technique
based on computer graphics technology
3D visualization technique
a digital image is made up of a two-dimensional array of numbers
Matrix
consists of columns (M) and rows (N) that define small square regions called picture elements or pixels
Matrix
Matrix size selected by an operator for imaging examinations is sometimes referred to as the _____
field of view (FOV)
he pixel size can be calculated using the relationship:
Pixel size = FOV/Matrix size
Pixels in a digital image that represent the information contained in a tissue volume in the patient
Voxels
it includes the Height, width and length
Voxels 3D
inclusion of time, width, length and time
Voxels 4D
refers to the color information stored in an image
Bit Depth
implies that every pixel in the digital image matrix M x N is represented by k binary digits
k bits
The number of bits per pixel
Bit Depth
The characteristics of a digital image, that is, the ______,
can affect the appearance of the digital image, particularly its spatial resolution and its density
resolution
matrix size, the pixel size, and the bit depth
matrix size, the pixel size, and the bit depth
Spatial Resolution
linked to bit depth | range of gray levels per pixel
Density Resolution
5 different cassette sizes used in film-screen radiography:
8x10, 10x12, 11,14 14x14, 14x17
A typical CR image matrix size
2048 x 2048
There are three steps to digitizing an image:
- scanning
- sampling,
- quantization
used to measure the brightness level
Photomultiplier Tube (PMT)
the image is first divided into an array of small square regions called pixels
Scanning
simply involves measuring the brightness level of each of the pixels using special devices such as a photomultiplier tube (PMT). The signal from the PMT is an analog signal (voltage waveform) that must be converted into a digital image for processing by a digital computer
Sampling
This is a process whereby the brightness levels obtained from sampling are assigned an integer (zero, a negative, or a positive number) called a gray level. The image is now made up of a range of gray levels. The total number of gray levels is called the gray scale
Quantization
one pixel value in the input image is mapped onto the same pixel location in the output image and depends on the input pixel value entire image is then transformed using what is referred to as pixel point process
Point processing operation
is most often used in digital imaging to change the contrast and brightness of an image displayed for viewing on a display monitor
Grayscale mapping (commonly known as “windowing”)
Image contrast and brightness transformations can be done using a variety of processing techniques two common methods used in digital radiology, the ______
look-up table (LUT) method, the windowing method
Changing the histogram of the image can alter the brightness and contrast of the image termed as
histogram modification/histogram stretching
Low-contrast image can be transformed into a high-contrast image using
Look-up table (LUT)
one in which the output image pixel value is obtained from a small
area of pixels around the corresponding input pixel.
Local processing operation
In Local processing operation, since a small area of pixels or group of pixels is
used, these operations are also referred to as _____
area or group processes
A notable example is that
of frequency filtering in which the process can sharpen, blur, smooth, and reduce the noise of an
image
Local processing operation
There are 4 different techniques in Local processing operation
- Convolution
- High – Pass Filtering
- Low – Pass Filtering
- Unsharp (Blurred) Masking
where a group of input image pixels surrounding the specific input pixel is used to
change the value of the output pixel value to arrive at a new value in the output image
Convolution
The group of pixels used to calculate this average in convolution is called
Convolution kernel
A typical kernel size is a _____
3 × 3 matrix2
During processing, the kernel scans across the entire image, pixel by pixel. Each input
image pixel, the pixels surrounding it, and the kernel are used to calculate the corresponding output
pixel value
Convolution
Suppresses the low frequencies, and the result is a much sharper image
than the original
High – Pass Filtering
Such a filter is used to sharpen or for edge enhancement
High – Pass Filtering
Note that in order to use
this filter, the input image is first changed from a spatial location image into a spatial frequency
image. The filter operates on the frequencies to sharpen the output image
High – Pass Filtering
This is referred to as image smoothing
Low – Pass Filtering
The output image appears blurred compared to the input image
Low – Pass Filtering
In this type of filtering, the output image noise is reduced, and the
image sharpness is compromised
Low – Pass Filtering
First, a low-pass filter is used to blur the image and subsequently
subtracts this blurred image from the original image.
Unsharp (Blurred) Masking
The result is a sharper image than the original.
Unsharp (Blurred) Masking
are mathematical functions that operate on the
pixels of the image
Digital filters
implies ALL the pixels in the input image
are used to change the value of ONE pixel in the output image
Global Processing Operations
These techniques can process images for
edge enhancement, image sharpening, and image
restoration
Global Processing Operations
One popular global operation is to use the ___ in filtering images in the frequency domain rather than in the spatial domain
Fourier Transform (FT)
it generates the frequency-space
representation of the image which is useful for many applications, including
segmentation, coding, noise removal, and feature classification
Fourier Transform (FT)
mapping colors to pixel values
Pseudocoloring
These techniques allow the user to change the position or orientation of pixels in the image rather that the
brightness of the pixels
Geometric operations
result in the scaling, sizing, rotation, and translation of images, once again, to enhance
diagnosis
Geometric operations
are techniques that allow the user to change the appearance of a
digital image displayed on a monitor for viewing and interpretation
Digital image processing
These techniques, for
example, allow both the grayscale and the sharpness of the image to be manipulated to
enhance diagnostic interpretation
Digital image processing
is now commonly used by all medical imaging professionals who
have the responsibility for assessing image quality and diagnostic interpretation of all images
produced in an examination
Image post-processing
Examples of the Digital image processing are on
Point processing operations, Local processing
operations,
Global processing operations
Halide can be:
- Chlorine
- Bromine
- Iodine
acts as an activator to improve the
efficiency of PSL
Europium
means color
Farbe
PSP IP is taken to a CR
reader, and to be scanned
automatically with the use of Helium Neon (HeNe) laser beam
- this process is called
Photo Stimulated Excitation
the transition of the electrons from conduction to valence bands or returning to their original state result in an emission of _____ with ___-nanometer wavelengths
bluish-purple lightbluish-purple light,
415 nm
It is a word that describes how long it takes for a latent image to dissolve
Fading
Traditional two-dimensional x-ray detectors are being replaced with photostimulable x-ray storage
phosphors in the form of
image plates
the PSL (photostimulable luminescence) decreases by about ___, if the time between exposure and image reading is 8 hours
25%
Used to identify, and scale the raw image data obtained when the IP is scanned in the CR reader
Pre-Processing Operation
Pre-Processing Operation are also referred to as ______
Acquisition Processing
are intended to correct the raw data collected from bad detector elements that would create problems in the proper functioning of the detector
Pre-Processing
It also deals with applying corrections to the raw data
Pre-Processing
It is where the shading corrections, pattern recognition, and exposure field recognition is done
Pre-Processing
used to
SELECT THE BEST VALUE OF AN IMAGE
Pre-Processing
is a data or values of data that is gathered from scanning and then later they will be
combine to create a digital image by choosing the best value of the data
Analog System
to improve the image data that suppresses undesired image or SELECT
some image features relevant for further processing
Pre-Processing
It is the manipulation of the radiographic image in order to create a qualitative or quantitative data
Post Processing
The use of any technique or technology to enhance the original image captured by the photographer
Post Processing
To optimize the image contrast and density to enhance diagnostic interpretation of the image
Contrast Enhancement
Any method of exaggerating the visible difference between adjacent structures on imaging by administering contrast media/agents
Contrast Enhancement
adjust or control the sharpness or detail of an image by adjusting the frequency components of the image
Edge Enhancement
is a 2-D isotropic measure of the 2nd spatial derivative of an image
Laplacian
leads to enhanced image quality (IQ) of radiographs
Multifrequency Enhancement
A commonly used method of digital postprocessing using Laplace segmentation of the image data
Multifrequency Enhancement
has been proposed as a method for producing material-specific images
Dual Energy Processing
permitting separate examination of bone and soft structures in the chest
Dual Energy Processing
improves the detection of certain parts of the anatomy such as detection of the Pulmonary Nodules and Nodule Calcification Compared
Dual Energy Processing
provides useful feedback to the radiographer about exposures delivered to the image receptor
Exposure Indicator
is a numerical parameter used to monitor the radiation exposure to the IP in CR imaging
Exposure Indicator
Exposure Indicator for Fujifilm Medical CR Systems
Sensitivity Number or S-Number
Exposure Indicator for Carestream CR Systems
Exposure Index Or EI
Exposure Indicator for Agfa Healthcare CR System
Log of Median Values or LgM
Exposure Indicator for Konika Minolta Healthcare
Sensitivity Values or S Values
S is inversely proportional to the exposure; hence a low exposure will result in a high S number and a high exposure will result in a low S-number
Fujifilm Medical CR Systems (Sensitivity Number or S-Number)
represents a linearly proportional estimate of the radiation exposure to the detector.
Carestream CR Systems (Exposure Index Or EI)
is related logarithmically to the median of the IP exposure
Agfa Healthcare CR System (Log of Median Values or LgM)
S-values is neither direct or proportional. Instead the relationship is inverse.
An S-value above the target range would indicate a under exposure; and an s-value below the target range would indicate an over exposure
Konika Minolta Healthcare (Sensitivity Values or S-Values)
200/Exposure to the IP (mR)
S-number
log(Exposure in mR) x 1000 + 2000
EI
2.2 + log(Exposure in mR)
LgM
Matrix size
m x n
collects the freed electrons
capacitor
Digital image processing operations
Image Enhancement, Image Restoration, Image Analysis, Image Synthesis, Image Compression
scintillator layer used to convert x-ray photons into light photons
Cesium Iodide,
Gadolinium Oxysulfide
photoconductor layer used to convert x-ray photons into electrical charge
Amorphous Selenium
