Digita Radiograohy: An Overview Flashcards
Workhouse of radiology since 1895
Film-Screen Radiography
What are the Goals of Digital Radiography?
- Eliminate film-based imaging systems
- Introduce new technologies for the purpose of improving diagnostic interpretation & digital management
- Reduce the radiation dose to patient
What are the 8 Digital Image Aquisition Modalities
- CR - Computed Radiography
- DR - Digital Radiography
- Digital Mammography
- Digital Fluoroscopy for routine GI Fluoroscopy & vascular imaging
- CT - Computed Tomography
- MRI -Magnetic Resonance Imaging
- Nuclear Medicine
- Diagnostic Medical Sonography
A digital way of doing general radiography with the use of CONVENTIONAL RADIOGRAPHY
Computed Radiography
- An advanced form of x-ray inspection which prouces a digital radiographic image instantly on a computer
- Uses x-ray sensitive plates to capture data during object examination, which is immediately transferred to a computer without the use of an immediate cassette
Digital Radiography
low energy x-rays to produce low contrast in soft tissues
Digital Mammography
real time; more radiation dose because simultaneous contrast media
Digital Fluoroscopy
series of x-ray images at different angles
Computed Radiography
injects contrast media to the patient durig the procedure
automatic injector
1 CT BRAIN SCAN = ?
10,000 Chest PA
- strong magnetic fields
- non-ionizing
- much more expensive for more sophisticated brain images
Magnetic Resonance Imaging
- small amounts of radioactive materials
Nuclear Medicine
- sound waves
Diagnostic Medical Sonography
- Computer process data collected patient using special electronic detectors that have replaced the X-ray film cassette
- Filmless radiography
Digital Radiography
What are the steps (8) for the process of Digital Radiography
- X-ray tube
- Digital detector
- Analog-to-digital converter
- Digital data stream
- Computer processing
- Digtal Image
- Digital-to-analog converter
- Analog image
Includes image and information managem systems, image storage, and image & data communications
Digital Image processing
3 Basic steps of Film-based Radiography
- X-rays pass through the patient & fall upon the fim to form a latent image
- Rendered visible using chemical processing
- Displayed on a view box for viewing & interpretation by radiologist
The film appears with ____ as a result of the amount of exposure transmitted by different parts of the anatomy
varying degrees of blackening
standard SID for Chest PA
72 in”
More exposure produces ____ & Less exposure produces _____
more blackening, less blackening
a tool to measure density
Penetrometer
Blackening in the image
Film Density
Differences in densities in the image
Film Contrast
-Refers to the collection of X-rays transmitted through the patient
- first step in the production of the image
Data Acquisition
Types of Detectors
CCD - Charged Coupled Devices
TFT - Thin Film Transistors
Converts X-ray into light, followed by the conversion of light into electrical signals
Indirect Capture Devices
Avoids the light-electricity conversion process & convert X-rays directly into electrical signals
Direct Capture Devices
An electronic integrated circuit used to convert the analog signals such as voltages to digital or binary form consisting of 1s and 0s
Analog to Digital Converter
-The ADC sends digital data for processing by a computer
- The computer uses special software to create or build up digital images using the binary number system
Computer Data Processing
Smallest unit of data in computer, discrete units
Bits
Smallest unit of data, discrete units
Bits
1 alpha numeric character = ?
1 Byte - 8 bits
The digital image, must be converted into an analog signal before it can be displayed on a monitor for viewingby the observer
Image Display & Post Processing
digital to analog converter (turns code to visible picture)
Monitor
Numerical Values of Pixels to Color Value
0 - 50 - Black
60 - 100 - Grey
100 -250 - White
The vast amount of images generated for the wide range of digital radiology examinations must be stored not only for retrospective analysis but also for medico-legal purposes
Image Storage
4 Image Storage Devices
- Magnetic Tapes
- Disks
- Laser Optical Disks (Long-term Storage)
- RAID (Redundant Array of Independent/Inexpensive Disks)
Use of computer networks to transmit images from the acquisition phase to the display/viewing & storage phase
Image & Data Communications
Image transmission within the hospital
LAN (Intranet)
Outside hospital/Remote locations
WAN (Internet)
used for storing/archiving & communicating images in the digital radiology department
PACS - Picture Archival and Communication System
RIS/HIS is integrated with the PACS via computer networks, using communication standards such as DICOM & HL7, for effective managements of patient information
Information Systems
an important element of image and data communications
Image Compression
two advantages of Image Compression
- To reduce storage space
- decrease the image transmission time
all data from the original file is preserved
Lossless or Reversible Compression
- removes some data from the original file and saves the image with a reduced file size
-method which eliminate unnoticeable data
Lossy or Irreversible Compression
Refers to the use of PACS & RIS and HIS to manage the vast number of images & text data produced in a digital radiology department with databases and management software
Image & Information Management
Handles essential textual information
RIS/HIS
Handles images generated by the various digital imaging modalities
PACS
what concept was originated in 1998
IHE - Integrating the Health Care Enterprise
IHE was developed by
Radiological Society of North America (RSNA) & Healthcare Information and Management Systems Society (HMSS)
The RSNA and HMSS developed what they refer to as?
Technical Framework
3 essential elements of Technical Framework
- Data Model
- An actor
- An Integration Profile
Makes use of photostimulable or storage phosphors to produce digital images using existing X-ray imaging equipment
Computed Radiography
A computer is used to process data collected by radiographic means to produce digital images of the patient
Computed Radiography
When and Who: Introduced CR Imaging System?
1983, Fuji Medical Systems
What does PMT stand for?
Photomultiplier Tube
The IP can be used until how many times?
10,000 times
What are the 6 steps to processing a CR Image
- Exposure of the imaging plate
- Scan IP with laser beam
- Light collection
- Digital processor
- Image Display on the Monitor
- Erase IP
- IP ready for another exposure
What converts light into an electrical signal
PMT (Photomultiplier tube)
- Limited ability to image detaill (spatial resolution) 3-5 lp/mm
- Contrast resolution can be manipulated
- Better DQE (converts X-ray into useful image)
CR Systems
Major PACS components
- Image Acquisition devices
- PACS computer
- Device called interfaces
- Display workstations
2 standards used in a PACS environment
DICOM and HL7