Download How CT scanners Work Imagine an upright doughnut. This

Scanning the CT scanner
Overview
Computed tomography or computed axial tomography (CT and CAT respectively) is an ideal tool doctors
use for running patient diagnostic tests. Invented in 1972 by Godfrey Hounsfield and Allan Cormack, a CT
scanner is a specialized x-ray machine that creates images of bones, organs, tissues and veins. Because of the
machines versatile usage, doctors use CT scanners to identify tumors, organ damage and also are able to use
the images to create reconstruction models for facial trauma victims. The machine provides quick and
detailed images making this the go-to technology for most doctors in treating cancer and trauma victims.
How CT scanners Work
Imagine an upright doughnut. This doughnut is the CT
scanner, the hole of the doughnut/scanner is called the
gantry. Inside the gantry is the imaging machinery that
rotates around while the patient lies on the installed
table which moves back and forth through the hole.
The CT scanner is controlled by a computer
workstation which is attended by a CT technologist. At
the workstation, a host computer controls the CT
scanner and another computer takes the raw data from
the scanner and converts the data into a picture. This
technologist also administers contrast dye if needed. A
radiologist then will interpret the images and determine
what needs to be done.
While the table moves through the gantry,
the x-ray tube and CT detector gather
data as they rotate around the patient.
How CT Scanners Take Pictures
Imagine the doughnut hole/gantry. Now imagine a clock. Inside the gantry in the 12 o’clock position lies a
small box called the x-ray tube. A banana shaped box lies in the 6 o’clock position called the CT detector.
These two boxes spin relative to one another during each rotation whether clockwise or counterclockwise.
This rotation creates a spiral pattern of images, hence the naming of the pictures as slices. Once a round of
images is complete the machine will then spin in the opposite direction, allowing the workstation a complete
3D model of the specific area. Once the rotation starts, the x-ray tube will emit a degree of radiation which
the body absorbs at different rates based on the organs in that particular area of the body. The CT detector
then reads the levels of absorbed radiation and converts it into data which is then forwarded to the
workstation. This technique of imaging is called digital geometry processing.
At the workstation, the data is converted into an image also known as a slice. The CT technologist then piles
up the slices to create a 3D image of a specified area. Due to its density, bones appear white, soft tissues are
grey and air is black in each image. Due to the risk of blurring the image, the patient may be asked to hold
their breath for 30 seconds as the machine completes its first rotation round. If the image is still unclear,
contrast dye may be administered by needle, by drinking a barium meal or by using a barium enema to clear
up the image. After the CT scanning is complete, no radiation remains in the patient.