CT

Question 1

COMPUTED TOMOGRAPHY

Answer 1

X-ray spins around
To produce cross sectional images through anatomy

Question 2

CT advantages

Answer 2

Images are acquired in slices
Soft tissue
Blood vessels can be visualised
Large areas imaged in a short space of time

Question 3

Who made CT

Answer 3

Godfrey hounsfield

Question 4

Gantry

Answer 4

Round machine
Polo mint

Question 5

Equipment in CT

Answer 5

Injector pump
Table
Gantry

Question 6

What is inside the gantry

Answer 6

X ray tube
Detectors

Question 7

Operator console

Answer 7

Control panel
Phone - call for help
If patients can have contrast reaction

Question 8

Basic principles

Answer 8

CT scan - X-ray tube that spins around patient 360*

Question 9

Principles of CT scanning

Answer 9

X-ray tube collimation device
Tube emits a very narrow, flat fan beam (forms an arch)
Beam is aligned to an array of detectors in the form of an arch
Each detector is equidistant to the focal spot

Question 10

The tube continually rotates around the patient moves through the

Answer 10

Gantry

Question 11

Attenuation

Answer 11

• the denser the tissue the more attenuation will occur

-bone will attenuate more x-rays than fat / tissue

Question 12

Detectors

Answer 12

The array of detectors divide the body into linear strips

Each detector measures the attenuation that has occurred within its own strip

This information is then digitised and fed into a computer

Question 13

The computer

Answer 13

Assigns a numerical value to data from each detector
This value is based upon the amount of attenuation that has been taken place

Question 14

Image reconstruction

Answer 14

Through the examinations many exposures are undertaken as the patient goes through the gantry

In order to obtain data to reconstruct the image.

Question 15

Data set

Answer 15

Data is stored in a matrix or data set

Question 16

What is a single square in the matrix called?

Answer 16

Pixel

Question 17

each pixel corresponds to the volume of tisssue the volume is called?

Answer 17

Voxel

Question 18

Hounsfeild units

Answer 18

Each pixel is assigned a numerical value based on the average attenuation value of the whole voxel.

This number is compared to the attenuation value of water.

HU

Question 19

Spiral/helical CT

Answer 19

Most significant developments in CT
Decrease in acquisition time, reduction of mis-registration artefacts
Continuous coverage of anatomy
Improved reformatted images
Capable of tracking injected contrast agents

Question 20

Dual source

Answer 20

-two x-ray tubes and two detectors
-used for cardiac imaging