CT COMPONENTS Flashcards
the ring-shaped part of the CT scanner. It houses many of the components necessary to produce and detect x-rays.
Gantry
Characteristics of Gantry
APERTURE / BORE
TILTING RANGE
Most of the scanners have ____ aperture
70 cm
There are also scanners that have an ___ bore.
85cm
Tilting range of most scanners
+30 TO -30 DEGREES
tubes produce the x-ray photons that create the CT image
X-ray Tube
Atomic number of Tungsten
74
Anode Material used in xray tube for ct
Tungsten
Contain more than one size of focal spot
0.5 and 1.0 mm are common sizes
Because of ______ small focal spots in CT tubes produce sharper images
reduced penumbra
used to shape the x-ray beam
Filters
Reduce the radiation dose to the patient and help to minimize image artifact
Filters
helps to reduce the range of x-ray energies that reach the patient since xrays are polychromatic
Filters
Creates a more uniform beam intensity improves the CT image by reducing artifacts that result from beam hardening
Filters
Collimation in CT serves two purposes:
To reduce unnecessary dose to the patient
To ensure good image quality by reducing scatter radiation.
two types of collimation
prepatient collimation
postpatient collimation
In CT, we use ____ to collect the information.
detectors
a single element or a single type of detector used in a CT system
detector
used to describe the entire collection of detectors included in a CT system.
detector array
optimal characteristics of a detector
High detector efficiency Low, or no afterglow High scatter suppression High stability High reproducibility Wide dynamic range
TYPES OF DETECTORS
Xenon gas detector
Scintillation (solid-state) detectors
use high-pressure (about 25 arm) nonradioactive xenon gas, in long thin cells between two metal plates.
Xenon detectors
The long, thin ionization plates of a xenon detector
highly directional
must be positioned in a fixed orientation with respect to the x-ray source.
xenon detectors