Radiographic image analysis ch. 2
2 digital systems -
Cassette-based system/ computed radiography (CR) &
Cassette-less detector system/ direct-indirect digital radiography (DR)
CR (computed radiography) -
Uses cassette . Placed in the bucky or on table
Image Acquisition -
Process of collecting x-ray transmission measurements from the patient.
The amount of light produced in each pixel is equivalent to the energy that was stored in -
Area of image plate (IP) during acquisition process
(infrared laser scan)
In acquisition the light is collected & converted to a electrical signal by -
Photomultiplier tube (PMT)
PMT sends the electrical signal to -
Analog-to-digital converter(ADC)
Were it is digitized (assigned to digital #/ gray shade value)
Greater radiation exposure are assigned values that represent -
Darker gray shades
Less radiation exposure are assigned values that represent -
Lighter gray shades
All shades of gray values -
The Raw/ Image Data
Additive Condition -
Condition that results in change to the normal bony structures, soft tissues, or air or fluid content
of the patient; may require technical changes to compensate for them prior to exposing the patient.
Additive diseases cause the tissues to increase atomic density or thickness, resulting in them being
more radiopaque.
Algorithm -
Set of rules or directions used by the computer for getting a specific outcome from a specific
input.
Anode Heel Effect -
Absorption of radiation in the heel of the anode that results in less x-ray intensity at the anode
side of a long IR when compared with the cathode side.
