X-rays and CT scans Flashcards
How do x-rays work?
They pass through low density materials such as healthy bone tissue. Denser materials such as bone and metals absorb x-rays
What does an x-ray photograph or scan show?
It shows an image of an object having absorbed the x-rays
Why are x-rays useful?
They can help the diagnosis of medial conditions including bone fractures and dental problems
How are x-ray images formed electronically and displayed on a computer screen?
A charge coupled device (CCD) is used to convert the transmitted x-rays into electrial charges
What does a microprocessor do?
It produces the image that is displayed on the screen
What can x-rays also be used for?
Used to kill cancer cells, slow down the growth if a cancer and shrink tumours
What do low energy x-rays do?
They destroy cancer cells on or near the surface of the body
What do high energy x-rays do?
These are more penetrating and are used to deliver radiation to deeper tissue and body organs
What does a CT scanner do?
It emits several beams of x-rays from different directions at the same time. The strength of each x-ray beam is measured after it has passed through the patients body
How is a 2D image produced?
A computer uses the information to produce a 2D image showing a slice through the patients body
How is a 3D produced?
By joining lots of ‘slices’ together.
Why is a 3D image better?
It can show the size and exact position of something, eg a tumour
What are advantages of CT scans? (4)
More detailed than ordinary x-ray photographs, show different types of tissue such as bone, muscle and blood vessels, can be 3D, can pinpoint the position of a tumour
What are the risks of an x-ray?
X-rays are ionising radiations and can be absorbed by cells and will ionise some atoms, which may cause changes to the molecules that control the way a cell works. This may cause a gene mutation, damage to the central nervous system or cancer
What is the disadvantage and advantage of using a CT scan instead of x-ray?
A CT scan delivers a higher dose of radiation to the body than an x-ray. But an CT scan is much better as it can diagnose a problem more accurately
