System Operation And Components. Flashcards
(35 cards)
Console:
Where instructional commands are entered by the CT tech and images are viewed.
Host computer:
Each command is shuttled through the host computer, translated into the system machine’s language, and passed on to the scan controller. Final images are also transferred to the host computer so it can be stored in PACS or displayed on the console.
Scan controller:
Is responsible for the timing and operation of the pt table, gantry & high-voltage generator.
DAC:
Digital Analog Converter: receives electronic signals from the scan controller and converts these digital signals to analog.
High voltage generator:
Produces high voltage potential that exists between the cathode and anode.
Amplifier:
Amplifies electrical signals from the detectors.
S/H component:
Where amplified signals are sampled and then sent to the ADC.
ADC:
Analog to Digital Converter. Electrical signals are received from the S/H component and digitized here, then sent to the array processor.
Array processor:
Where the raw digitized information is calculated into an image.
When was the first CT system introduced for clinical use?
1973
What kind of beam & detectors did first generation scanners use?
Pencil beam & single detector.
What was the shortest scan time for a first generation scanner?
5 minutes.
What part of the body was first generation scanners used for and why?
Head, patient motion was more easily controlled for head images.
What kind of beam and detector does second generation scanners use?
Fan beam and a detector array (a group of detectors.).
How fast can a second generation scanner scan?
As little as 20 seconds vs a first generation scanning 5 minutes.
What are the two most important features of second generation scanners?
Fan beam geometry and the introduction of the detector array.
When were third generation scanners introduced?
1975
What improvements do third generation scanners have?
Curved detector array (improves reproducibility and minimizes artifacts), Tube & detector rotate around pt, detectors range from several hundred to several thousand, & scan times can be less than 1 second per image.
Fourth generation scanner improvements:
4th generation scanners did not end up with more advancements, rather different approaches to achieve similar results (stationary detector ring that angles during the scanning process.).
What was the major improvement introduced with continuous rotation scanners?
The slip ring, solving the problem of needing to “unwind” the cables after each scan. This led to the development of helical scanning.
All major manufacturers offered MDCT by what year?
1998
Improvements seen with MDCT:
*Faster scans
*Increased anatomical coverage
*Scanning with thinner slices to improve resolution along slice direction.
EBCT: what does it stand for & when was it made available?
Electron beam CT & 1980’s
What was EBCT used for until MDCT scanners were introduced?
Cardiac images
