Unit 1: Digital Imaging

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Terms in this set (...)

*Film-Screen Radiography
Used since its discovery by __ on __ as the means to obtain radiographic images
Roentgen, November 8, 1895
*Film-Based Radiography: A Brief Review
1. Basic steps in the production of a radiograph: 5
source of X-rays
subject to be prayed
film/screen cassette to receive the attenuated beam from subject
processor to develop the film
view box to display film
*Basic Steps in the Production of a Radiograph
1. Outside the ranges of __ to __ Optical Density due to improper technical settings
2. Low exposure:
3. High Exposure:
1. .25, 2.5
2. decreased density
3. increased density
*Basic Steps in the Production of a Radiograph
1. The characteristic curve is also known as the __
2. The curve is obtained by exposing a __ and measuring the OD of each step with a __. The OD measured and log relative exposure of each step can be plotted on a graph to produce a characteristic curve.
3. Measures Optical Density
1. H and D curve
2. step wedge, densitometer
3. Densitometer
Change __ to offer greater number of shades
gray bit depth
Bit depth determines __
latitude
*Film Speed
1. Refers to the __ of the film
2. Higher speed films:
3. Lower speed films:
4. Higher speed films have __ and __
5. Lower speed films have a __ and __
1. sensitivity
2. more sensitive
3. less sensitive
4. wider exposure latitude, lower contrast
5. narrow exposure latitude, higher contrast
*Three Limitations to Film-Screen Radiography
1. Film-screen cannot show tissue differences in tissue contrast less than __
2. Once exposure has been made with an inappropriate technique, the only means to correct is by __. Unlike digital radiography which allows for adjustments in __, __, and __ to be made without re-exposing
3. Requires manual __ and __
1. 10%
2. reexposing the pt, density, contrast, exposure latitude
3. archival and retrieval
*Digital Radiography: A Definition
1. Allows the attenuated beam to be received by either __ or __ digital detector rather than an X-ray film cassette
2. The output from a digital radiography detector is an __
3. This signal is sent to an __
4. The ADC change is continuous analog signal into __. This is an important step in generating a digital image, simply because a computer requires __ for operation
5. The result of computer processing is a __. Since radiologists and technologists do not view numerical representations.
1. CR, DR
2. analog(electrial) signal
3. analog to digital converter
4. discrete digital data, discrete data
5. digital image
*Digital Image Acquisition Modalities Include:
(8)
Computed Radiography
Digital Radiography
Digital Mammography
Digital Fluoro and Vascular Imaging
Computed Tomography
Magnetic Resonance Imaging
Nuclear Medicine
Diagnostic Medical Sonography
*Digital Radiography also includes:
1. Computer-based systems that process raw data to produce information in a useable form that can be used for various purposes such as problem solving, patient diagnosis, etc.
2. archiving of radiographic images using various kinds of storage devices such as magnetic tapes, disks, and laser optic disks
3. DICOM-Digital Imaging and Communications in Medicine
1. image and information management systems
2. image storage
3. image and data communication
*A Digital Radiographic Imaging System: Major Components
(7)
data acquisition
computer data processing
image display
post processing
image storage
image and data communications
image and information management
*Data Acquisition
1. Refers to the collection of __ transmitted through the pt. The collection of X-rays takes place at a __
2. Various types of detectors are used to convert X-rays to an __
3. Depending on the type of detector an extra step or steps may be needed in the __
4. Once in analog form, the signal must be sent through an _ before it can be reach the CPU
1. X-rays, detector
2. electronic signals
3. conversion process
4. analog to digital converter
*Computer Data Processing
1. The ADC sends the digital data for processing by the __
2. The computer uses special software to create or build up digital images using a __
3. Binary system operates on discrete values of __ or __
4. One digit makes a __
5. Eight bits makes a __
1. CPU
2. binary number system
3. 0,1
4. bit
5. byte
*Image Display and Post Processing
1. The output of computer processing must first be converted into an __ before it can be displayed on a monitor for viewing by the observer
2. After image is displayed via monitor, __ can alter the input image in order to enhance diagnosis
1. analog signal
2. post processing
*Image Display and Post Processing
-Post processing enhancements include: (5)
1. image noise reduction
2. enhance image sharpness
3. change image contrast
4. stitch several image together
5. gray scale mapping
__ really high, the exposure is low and increases noise
S number
adjustment ranges of gray that is measured in histograms
look up table
Wrong look up table affects __ and __
contrast and brightness
*Gray Scale Mapping
1. Can be used by __ when scanning luggage
2. Narrow histogram, Contrast __
3. Wider histogram, contrast __
4. S curve more verticle, __ exposure latitude, __ contrast
1. security
2. decreased
3. increased
4. narrow, increased
*Image Storage
1. The vast ant of images generated for the wide range of digital radiology exams must be stored not only for __ but also for __
2. Types of storage devices for image include: 4
1. retrospective analysis, medico-legal purposes
2. magnetic tapes, disks, laser optical disks, and RAID
RAID
redundant array of independent disks
*Image and Data Communications
1. Are concerned with the use of computer communications networks to transmit image from the __ to the __ and __
2. Five types
1. acquisition phase, display/viewing, storage phase
2. LANs, WANs, PACS, RIS, HIS
LANs
Local Area Network
WANs
Wide Area Network
PACS
Picture and Archiving Communication System
RIS
Radiology Information System
HIS
Hospital Information System
*Image and Data Communications
1. Due to large amt of storage required for digital images __ is used to reduce storage space and decrease the image transmission time
2. Two Types of Image Compression
3. No loss of information
4. Loss of Information
1. image compression
2. lossless or reversible image compression, Lossy of irreversible image compression
3. lossless or reversible image compression
4. lossy of irreversible image compression
*Image and Information Management
1. Refers to the use of __ and information systems such as __ and __ to manage the vast number of images and text data produced in a digital radiology department with databases and file management software
2. __ and _ handle textual information particularly dealing with business operations for the entire hospital
3. __ handles images generated by the various digital imaging modalities
1. PACS, HIS, RIS
2. RIS, HIS
3. PACS
*Integrating the Health Care Enterprise
1. Is a model for ensuring that the standards for communication such as __ and __ work effectively to facilitate integration. (Sending the images to where they need to go properly)
2. Originated in 1998 when Radiologic Society of North America and Healthcare Information Management Systems Society developed the technical framework based on: (3)
1. DICOM, HL-7
2. data model, an actor, and an integration profile
*Digital Radiography Modalities
1. Modalities taping in to to the PACS-RIS-HIS include:
5
1. CR
DR
DM
DF
laser film digitizer
Access pt information to move it to RIS
HIS
one of the greatest stored areas in hospital
Radiology
After verification of image it goes to __
PACS
Run X-ray under wrong pt name or histogram, it cannot be fixed if __
it is in PACS
*Computed Radiography
1. In 1983, __ introduced CR. Other companies are Agfa, Kodak, and Cannon to name a few
2. With CR, an __ replaces the traditional film in the cassette. The IP is coated with __ a photostimulable phosphor
1. Fuji Medical Systems
2. imaging plate, barium-fluoro-halide
*Basic Steps to the Production of a CR Image
1. IP plate is exposed to X-ray which causes __ in phosphor to move to a __ and remain trapped as the __
2. IP plate is fed into __ and exposed to a __. This beam causes the excited electron in the phosphors to release its energy in the form of __ and return to their original state.
3. The light is collected by a __ which transfers light energy to __ then it is sent through a __ to produce digital data
4. __ processes digital data to produce a CR image that can be viewed on a monitor
5. Very intense light scans __ prior to exiting the __ to erase in residual latent image
6. __ to be reused
1. electrons, higher energy level, latent image
2. Image Reading Device, laser beam, light
3. photomultiplier tube, electrical energy, ADC
4. Digital processer
5. IP, IRD
6. IP
*Flat-Panel Digital Radiography
1. Systems have been developed to overcome the shortcomings of __ and do not use the __
2. There are currently two categories of flat-panel detectors:
1. CR, IP
2. indirect and direct conversion
*Flat-Panel Digital Radiography
1. Indirect Conversion
2. Direct Conversion
1. X-rays, light, electrical, signal, image
2. xays, electrical signal, image
*Flat-Panel Digital Radiography
1. Scintillator is made up of __ and emits __
2. __ insulates electrons
3. Indirect flat panel detector: X-rays hit __ and convert electrons over to __ to read
1. cesium iodide, light
2. glass
3. scintillator, TFT
*Direct and Indirect DR
1. __ detectors have an X-ray photoconductor, such as __, that directly converts X-ray photons into an electric charge
2. __ detectors have an __ that first converts X-rays into visible light. That light is then converted into an electric charge by means of photodetectors such as __ or __
3. __ arrays may be used in both indirect and direct conversion detectors
1. direct, amorphous selenium
2. indirect conversion, scintillator, amorphous silicon photodiode arrays, CCDs
3. Thin-Film transistor
*Digital Mammography
1. Currently utilizing CR detectors and flat-panel digital detectors, including __, as well as __ to image the breast
2. __ software is also used in digital mammography which allow for enhancement of micro calcifications and malignant lesions. It also provide the capability of "second reader"
1. direct and indirect conversion detectors, CCD arrays
2. Computer aided diagnosis
*Digital Mammography
-Advantages of DR/CR over Traditional Mammography
1. DR/CR allows the observer to use __ to enhance diagnostic interpretation of the image
2. DR/CR uses computer-aided diagnosis software to help radiologists enhance their detection of __ and __ and also provides a __ approach.
1. digital image processing tools
2. microcalcifications, malignant lesions, second reader
*Digital Mammography
-Some of the applications available with digital mammography include: 4
1. telemammography
2. digital tomosynthesis
3. duel energy subtraction
4. breast angiography
*Digital Mammography
1. Shoots the X-ray with low and high energy
2. low absorbs more and high goes through better
1. duel energy
2. duel energy subtraction
*Digital Fluoroscopy
1. One of the major goals of DF is to improve the __, compared to convention fluoroscopy, by using digital image processing software.
2. Some advantages include: 3
1. reception of contrast
2. gray-scale processing, temporal frame averaging, and edge enhancement
Fluoro provides us with "X-ray movies" to visualize internal organs while __
in motion
An image intensifier decreases __
pt dose
What provides a better image, image intensifier and flat panel?
flat panel
Histogram narrowed, __ contrast
Narrow exposure latitude, __ H&D curve
lower
narrow
Digital Subtraction Angiography
reversing brightness levels
A comprehensive computer system that is responsible for the electronic storage and distribution of medical images in the medical enterprise. The system is highly integrated with digital acquisition and display devices and is often related closely to other medical information systems, such as the RIS and HIS
Picture Archiving and Communications Systems
*PACS
-Image Communication
1. Two standards are:
2. concerned primarily with images from the digital image acquisition modalities
3. concerned primarily with textual information from the HIS and RIS
1. DICOM, HL-7
2. DICOM
3. HL-7
*Quality Assurance in Digital Radiography
Quality Control and Quality Assurance procedures are effective strategies to ensure continuous quality improvement of a product. QA/QC policies and procedures and related activities are all extended too:3
1. ensure puts are exposed to minimum radiation using the ALARA principals
2. produce optimum image quality for diagnosis
3. reduce the costs of radiology operations
*Medical Imaging Informatics
1. All of the following use IT concepts: 4
2. It involves the use of__ coupled with __ to solve problems in society, including medical imaging and health care.
1. digital image processing, display, storage, archiving
2. computer technology, communications technology
*What is Medical Imaging Informatics?
1. The application of __ to __
2. Medical imaging plays a significant role in informatics because images are used for: 7
1. information technology, medical imaging
2. diagnosis, assessment, planning, guidance of procedures, communication, training, research
*Informatics Involves Topics Like:
1. Information Systems
2. Standards for communicating both text and images
3. computer communication networks
4. web technology
5. image and text handling
6. privacy
7. security
8. confidentiality issues
9. Digital imaging processing
...
Chapter 2: Digital Image Processing Concepts
...
*Definition of Digital Imaging
1. Digital Image __
2. Simply means __
3. The steps to processing include: (2)
4. Images are viewed in __ on the computer and then you can use __
5. __ takes electrical signal and sends it from detector to CPU
1. processing
2. the processing of images using a computer
3. 1) data collected a detector is converted into digital data which is made up of a series of binary codes of "0" and "1". This allows the information to be shared with the computer and is considered the "input image"
2) once the computer processes the digital image, it can be called the "output image". The digital image can be manipulated to please the viewer when it has been processed by the computer
4. analog form, post processing
5. TFT
*Brief History
-NASA
1. __ began several decades ago with the United States National Aeronautics and Space Administration space program. The program uses __ to manipulate images sent back by the ranger spacecraft.
2. The knowledge is also helped to benefit: 8
1. digital image processing, digital image processing
2. photography, forensics, biology, defense, remote sensing, medicine, medical imaging
*Brief History
1. Digital radiography imaging modalities include: 5
2. One of the first to use digital image processing
1. digital CT, digital MRI, ultrasound, DR, CR
2. CT
*Image Formation and Representation
1. __ (__) help to conceptualize images as a subset of all objects
2. Subsets of the image include: 4
1. Castleman(1994)
2. visible image, invisible image, optical image, mathematical image
*Comparison of Analog and Digital
1. Analog: waveform is a __
2. Computer uses __
3. CPU uses __
1. continuous flow
2. analog signal
3. digital signal
*Analog Image
1. An analog image is obtained by having a __ that scans from left to right in front of the object and __ positioned in behind the object. The PMT receives the __ in a continuous fashion as the object is scanned by a __
2. An __ hanging on a __ is considered an analog image
3. Converts light to electrical energy
4. Lower energies, __ wavelength, __ frequency
1. light source, PMT, varying levels of densities, light source
2. xray film, light box
3. PMT
4. long, low
*Digital Image
1. A digital image is simply a __ of the pt
2. The following takes place with digital imaging: (3)
3. A digital image is a bunch of __ which come together and form different __
1. numerical representation
2. 1) the output signal from the digital radiography detector is analog(electrical) signal
2) the ADC converts continuous analog signal into discrete digital data
3) after a computer has processed an image, it is referred to as a digital image. before viewing at the monitor, the digital image is converted to a visible physical image, an analog image
3. boxes filled with numbers, shades of gray
*Image Domains
1. In radiology, images are represented by two domains:
2. the digital image is a numerical image arranged in such a manner that the location of each number in the image can be identified using X-Y coordinate system
3. The term frequency refers to the number of times a signal changes direction in a given length. Small structures produce high frequencies while large objects produce low frequencies.
4. __ frequency to see small structures
1. Spatial location domain and spatial frequency domain
2. spatial location domain
3. spatial frequency domain
4. high
*Image Domains
1. More beneficial for the techs
spatial location domain
*Image Domains
-Spatial Frequency Domain
1. Measuring __
2. Helpful for __
1. energy
2. physicist, engineers, QA people
*Image Domains
-Fourier Transformation
1. The Fourier Transform allows for radiography digital processing to change __ to __
2. The Inverse Fourier Transform changes __ to __
1. spatial location domain, spatial frequency domain
2. spatial frequency domain, spatial location domain
*Image Domains
1. __ would probably prefer to view in the spatial location domain
2. __ would prefer to view images in frequency domain
1. radiologists
2. physicist and engineers
*Classes of Digital Image Processing Operations
1. Theses classes are operations used in digital processing to transform an __ into an __ to suit the needs of the human observer
2. Five fundamental classes of operations include: 5
3. Lossy, lossless
4. remove certain parts of the body not needed
5. add to or change picture
1. input image, output image
2. image enhancement, image resoration, image analysis, image compression, image synthesis
3. image compression
4. image restoration
5. image synthesis
*Image Enhancement
1. Purpose is to __
2. It uses operations to generate a quality image like: 5
3. get rid of low frequencies because of lack of information
1. generate an image that is more pleasing to the observer
2. contrast enhancement, edge enhancement, spatial and frequency filtering, image combining, and noise reduction
3. noise reduction
*Image Enhancement:
-Spatial and Frequency Filtering
1. smaller objects
2. larger objects
3. absorb in soft tissue better
1. high frequency
2. low frequency
3. low energies
*Image Enhancement
-Image Combining
1. Lung detail
2. Rib detail
1. soft
2. hard
There is noise on an image because of __ and it relates to __
mAs, low energies
*Image Restoration
1. Image restoration improves the quality of an image that has __ and __
distortions, degradations
*Image Restoration
1. Image analysis of digital imaging processing allows __ and __ to be performed, as well as __, __, and __
2. Image restoration and image analysis are used to __ and __
1. measurements, statistics, image segmentation, feature extraction, and classifications of objects
2. isolate, highlight objects of interest
*Image Compression
1. Image compression of digital images is to __ of the image in order to __ and __
2. Two types of compression of data: 2
1. reduce the size, decrease transmission time, reduce storage space
2. lossless and lossy
*Image Compression
1. __ is the newest addition to image compression
2. The main advantage of this form of compression is that there is __
3. It is able to store more with __
1. wavelet(special waveforms)
2. no loss in either spatial or frequency information
3. less memory space
*Image Compression
-Image Synthesis
1. Creates images with __ or __. These operations are used when a desired image is either __ or __ to acquire or does not exist in a __ at all (Baxes, 1994)
2. Is used with __, and __, which are based on computer graphics technology
1. other images, non-image data, physically impossible, impractical, physical form
2. CT and MR images, 3D visualization
*Characteristics of Digital Imaging
1. The following are characteristics or fundamental parameters used to describe digital imaging: 5
1. matrix
2. pixels
3. voxels
4. bit depth
5. Appearance or Digital Images
*Matrix
1. A image is made up a __ called a matrix. In radiology, we refer to matrix as the __
2. It consists of a __ and __ that define small squares called __, or __
3. The formula to calculate the size of the image is:
4. You never change the matrix __
1. 2D array of numbers, Field of View
2. columns, rows, picture elements, pixels
3. MxNxbits
4. size
*Pixels
1. The pixels make up the __ and are generally __. The brightness of each pixel is determined by its __
2. For digital imaging, the larger the matrix size the __ the pixels and __ resolution
3. Pixel size is calculated using:
4. how light or dark the pixels are
5. Larger Matrix, __ pixels, __ number of pixels
1. matrix, square, discrete value/number
2. smaller, better
3. pixel size= FOV/Matrix Size
4. pixel value
5. smaller, increased
*Voxel
1. Pixels in a digital image represent the information contained in a __ in the pt
2. __ referred to as a voxel
3. Volume of a pixel or element
1. volume of tissue
2. volume of tissue
3. voxel
*Bit Depth
1. What is bit depth?
2. Increase bit depth, the number of possible shades of gray __
3. __ to the power of __ available calculates the total number of shades available
4. Three modalities look at by voxels:
5. Increase bit depth, __ shades of gray
1. number of bits per pixel
2. increase
3. 2 bits
4. ultrasound, MRI, CT
5. increase number
*Bit Depth
As bit depth increases, the shades offered __
increase
*Appearance of Digital Images
1. Factors affecting the characteristics of the digital image include: 3
matrix size, pixel size, bit depth
*Appearance of Digital Images
1. Increase matrix, __ spatial resolution
2. __ FOV, decreases size of pixel while matrix remains the same causes an ___ in detail
3. Affects the number of shades of gray hence density resolution
4. Detail
5. Resolution
1. increase
2. decrease, increase
3. bit depth
4. analog
5. digital
*Steps in Digitizing an Image
1. Three steps to digitizing an image are:
2. More light, __ energy, __ X-ray received by detector
3. __ determines how much quantization takes place
1. scanning, sampling, quantization
2. higher, more
3. histogram
*Steps in Digitizing an Image
1. The image is first divided into an array of pixels
2. Simply involves measuring the brightness level of each of the pixels using special devices such as PMT
3. PMT gives out an __ and must be converted to __ by a __ before it can be processed by the computer
4. Sampled obtained by the sampling are assigned an integer called a gray level. The image is made up of a range of gray levels. The total number of gray levels is called the gray scale.
1. scanning
2. sampling
3. analog signal, digital, ADC
4. quantization
*Steps in Digitizing an Image
-Concept of quantization
1. As the gray levels offered increases, the visibility detail __
1. increases
*Digital Imaging Processing Operations: General Concepts
1. Gray scale processing: 3
2. Local Processing Operations: 3
3. Image processing operations are intended to change the __ of the pixels in the input image and display the resulting changes in the output images
4. __ gives you the detail of the small parts
5. All done in __ area before it reaches the monitor
1. windowing, image subtraction, temporal averaging
2. spatial filtering, edge enhancement, and smoothing
3. intensity values
4. high frequency
5. CPU
*Digital Imaging Processing Operations: General Concepts
1. reversing brightness levels
2. filtering frequencies
3. Low frequency removal
4. high frequency removal
1. image subtraction
2. spatial filtering
3. edge enhancement
4. smoothing
*Point Processing Operations
1. The value of the pixel at __ corresponds with the value of the pixel at the same coordinates on the __
2. A common point processing operation is gray-level mapping or gray processing. Other terms to describe gray-level mapping are: 4
3. Image contrast and brightness transformations can be made using __ or __
4. Reduce number of shades, __ contrast
1. input, output
2. contrast stretching/enhancement, histogram modifications/stretching, LUT, windowing
3. LUT, windowing method
4. increase
*Point Processing Operations
1. Narrow histograms offer __ contrast while wider histograms offer __ contrast
2. When you stretch contrast, __ contrast, __ gray scale
1. lower, higher
2. increase, decrease
a graph of the number of pixels in the entire image or part of the image having the same gray levels
histogram
*Histogram
1. Changing the histogram can alter __ and __
2. Narrow histogram implies __ contrast while a wide histogram implies __ contrast.
3. Images look __ when histogram concentration is at the tallest points and __ when concentrated at the lower points
1. contrast, brightness
2. low, high
3. light, darker
*Window Processing Operations
1. Windowing: __ changing brightness
2. Increase WL, __ brightness
1. window level
2. decreases
*Point Processing Operations
1. Windowing: __ changing contrast
2 Increase WW, __ contrast
1. window width
2. increase
*Point Processing Operations
-Look Up Table
1. Allow __ and __ to be changed when values are out of the norm
1. brightness, contrast
*Local Processing Operations
The __ is obtained from a small area around the __
output pixel values, corresponding input pixel
The value of the output pixel depends on a group of pixels in the input image that surround the input pixel of interest: in this case P5. The new value for P5 in th output image is calculated by obtaining its weighted average and that of its surrounding pixels. The average is computed using a group os pixels called a convolution kernel, in which each pixel in the kernel has a weighting factor, or a matrix. Depending on the type of processing, different types of convolution kernels can be used, in which case the weighting factor is different
spatial location filtering convolution
*Local Processing Operations
-Spatial Frequency Filtering: High-Pass Filtering
1. Used to__ an image that appears blurred by suppressing the __
2. AKA 2
1. sharpen, low frequencies
2. edge enhancement, sharpening
*Local Processing Operations
-Spatial Frequency Filtering: Low-Pass Filtering
1. Uses blurred image produced from the __ and subtracts it form the __ to produce a sharp image
1. low pass filtering process, original image
*Global Processing Operation
1. Implies that all of the pixels in the entire __ are use to change the value of a pixel i the __
2. One of the popular global operations is __ in filtering images in the __ rather than the __
3. Theses techniques can process images for:3
1. input image, output image
2. FT, frequency domain, spatial location
3. edge enhancement, image sharpness, image restoration
*Geometric Operations
1. Allows for the __ or __ of the pixels within the image to be changed in order to enhance __
2. Geometric Operations result in:4
1. position, orientation, diagnosis
2. sizing, scaling, rotation, translation