CT - History & Basics Flashcards
What does CT stand for?
Computed Tomography
Who invented CT?
Sir Godfrey Hounsfield and Allan Cormack
When was the first a CT scan ever taken?
The first clinical CT scan was taken on October 1st 1971
How was the first CT scan taken?
It was a 28,000 individual data measurements per slice
The scanner produced this image had an 80 by 80 image matrix (80 cubes down one side 80 cube across the other)
It took 10 hours in total with 5 minutes for physically scanning each slice and a similar time to process the image data
What is dual energy CT (DECT)?
X-ray photons primary interacts with the matter via the photoelectric and Compton scattering, producing diagnostic images
When the atom undergoes the photoelectric effect, the electron from that respective shell is ejected via the incident photon as that electron is excited, the vacant space is filled by the neighbouring electron, releasing energy as a photon electron
The dual source has two extra tubes and the single source has the attitude with two detectors and they have the consequencive and sequinsential and their fast KVP switching
Whst is a 3rd generation CT scanner?
It is a single source that has multiple detectors and the x-ray beam hits those detectors and they’re wide enough to image the whole slice, the two rotate around the image together and is repeated until a single scan is sliced and then the arrays move to a different axial scanning
What technology is used to allow the spin to happen?
The slip ring technology is what makes it possible as it allows the CT scanner to spin together to get a spiral or helical scanning which cuts down the dose and helps with reconstructions
What are the three principal system components of the gantry?
Gantry
Operating console
Computer
The x-ray source
Detector array
Columator assembly
A higher voltage generator
The Gantry
What does the console and computer do?
It controls the image acquisition
It controls the image reconstruction
You can change the way images are viewed and manipulate them and decide where they are stored or going to be deleted
The computer controls the data acquisition, processing, display, and storage, it is also capable of multi processing and can perform several functions simultaneously such as scan control and image reconstruction
Why is slip ring important?
It enables continuous rotation of the CT scanner gantry with brushes on the rotating gantry and through contact with the stationary ring, this allows power to be supplied to the gantry and the signal to be passed to the computer.
It is faster for imaging, and allows for spiral scanning or continuous table feed, it allows less wear and tear on the machines
