1. Digital Radiography: An Overview Flashcards
workhorse of radiology since 1895
Film-screen Radiography (Conventional)
Goal of Radiology Department
- Eliminate film-based imaging systems
- Introduce new technologies for the purpose of improving diagnostic interpretation and digital image management (ex. PACS and RIS)
- Reduce the radiation dose to patients (and rad tech)
filmless imaging
Digital Radiography
Digital image Acquisition Modalities
a. CR (Computed Radiography)
b. DR (Digital Radiography)
c. Digital Mammography
d. Digital Fluoroscopy for routine GI (Gastrointestinal) Fluoroscopy and Vascular imaging
e. CT (Computed Tomography)
f. MRI (Magnetic Resonance Imaging)
g. Nuclear Medicine
h. Diagnostic Medical Sonography
a computer process data collected from patients using special electronic detectors that have replaced the x-ray film cassette
Digital Radiography
filmless radiography
Digital Radiography
the detectors measure and convert x-ray attenuation data from the patient into electronic (analog) signals that are subsequently converted into digital data for processing by a computer
Digital Radiography
the result of this processing is a digital image that must be converted so that it can be viewed in a computer monitor
Digital Radiography
the displayed image can then be manipulated using a variety of digital image processing techniques to enhance the interpretation of diagnostic radiology images
Digital Radiography
also includes image and information management systems, image storage, and image and data communications
Digital Radiography
FILM-BASED RADIOGRAPHY BASIC STEPS IN IMAGE FORMATION
- X-ray pass through the patient and fall upon the film to form a latent image
- Rendered visible using chemical processing
- Displayed on a view box for viewing and interpretation by a radiologist
More exposure produces ____ blackening
more
Less exposure produces ___ blackening
less
blackening in the image
Film Density
differences in densities in the image
Film Contrast
The film, therefore, converts the radiation transmitted by the various types of tissues (tissue contrast) into ____
film contrast
refers to the collection of X-rays transmitted through the patient
Data Acquisition
first step in the production of the image
Data Acquisition
For DR, ________ are used that replaced the X-ray film cassette used in film-based radiography
special electronic (digital) detectors
Converts x-rays into light, followed immediately by the conversion of light into electrical signals
Indirect Detector
Avoids the light-electricity conversion process and convert x-rays directly into electrical signals
Direct Detector
The analog signals must then be converted into _______ for processing by a computer
digital data
is an electrical 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 (ADC)
the ADC send digital data for processing by a computer
Computer Data Processing
the computer uses special software to create or build up digital images using the binary number system
Computer Data Processing
HUMANS – ______ SYSTEM
DECIMAL
COMPUTERS – ______ SYSTEM
BINARY
Base 10 (10 different numbers) 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
DECIMAL SYSTEM
Base 2 (2 different numbers) 0 or 1 (Binary digits or bits)
BINARY SYSTEM
smallest unit of data in a computer
Bits
are not continuous, they are discrete units
Bits
The output of computer processing, the digital image, must first be converted into an analog signal before it can be displayed on a monitor for viewing by the observer
Image Display and Post Processing
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
Types of Image Storage
- Magnetic tapes
- Disks
- Laser optical disks (long-term storage)
- RAID (Redundant Array of Independent Disks)
use of computer communication networks to transmit images from the acquisition phase to the display/viewing and storage phase
Image and Data Communications