X-rays and Ultrasound Flashcards
Why do x-rays cause ionisation?
They are high frequency, high energy waves
What materials are x-rays absorbed by?
Dense materials like bone or metal
What materials do x-rays pass through?
Less dense materials like healthy tissue
Why do x-rays produce shadow images?
The x-rays not absorbed by bone pass through to the detectors
What happens during an x-ray?
The x-rays are produced in an x-ray tube when fast moving electrons hit a target and the energy from the collision is released as x-rays. The x-rays are then directed at the patient.
What does a flat panel detector do?
Collects x-rays that are not absorbed by the body
What does a flat panel detector contain and what does it do?
CCD. The sensors in a CCD are covered by a layer that converts x-rays to light.
The denser an object is, how does it appear on an x-ray?
Brighter
How do x-rays ionise substances?
They knock electrons off cell’s atoms
What can high doses of x-rays do?
Kill living cells
What can low doses of x-rays do?
Cause cell mutation that leads to cancer
What is radiotherapy?
When x-ray beams kill or slow the growth of cancer cells
How are x-rays detected?
Photographic film or electronic detectors that produce an electronic image to be seen on a screen
How do people working with x-rays protect themselves?
Lead lined suits, stand behind lead screens, wear film badges to monitor their exposure to x-rays
What do CT scanners do?
Use x-rays and computers to combine x-rays from different positions to produce 3D images of the body
