Digital
radiography is performed by a system consisting of the following functional
components:
- A digital image receptor
- A digital image processing unit
- An image management system
- Image and data storage devices
- Interface to a patient information system
- A communications network
- Digital Image Display and Display Control
-the
device that intercepts the x-ray beam after it has passed through the patients
body and produces an image in digital form, that is, a matrix of pixels, each
with a numerical value.
-This
replaces the cassette containing intensifying screens and film that is used in
non-digital, film-screen radiography.
-different
types of digital radiography receptors:
v Direct digital radiographic
receptor as "a digital x-ray camera".
Ø The
receptor is in the form of a matrix of many individual pixel elements.
Ø When the
pixel area is exposed by the x-ray beam (after passing through the patient's
body), the x-ray photons are absorbed and the energy produces an electrical
signal.
Ø This
signal is a form of analog data that is then converted into a digital number
and stored as one pixel in the image.
v Stimulable phosphor receptor as being
like a conventional radiographic intensifying screen in that it absorbs the
x-ray photons and and then produces light.
Ø
First, a receptor (cassette) containing
only a stimulable phosphor screen is exposed to record an image. At this
stage the image recorded by the screen is an invisible latent image.
Ø
The next step is to process the
receptor through the reader and processing unit. In this unit the screen
is scanned by a very small laser beam. When the laser beam strikes a spot
on the screen it causes light to be produced (the stimulation process). The
light that is produced is proportional to the x-ray exposure to that specific
spot. The result is that an image in the form of light is produced on the
surface of the stimulable phosphor screen.
Ø
A light detector measures the light and
sends the data on to produce a digitized image.
