X-rays and Ultrasound
- Created by: eleanorcooperxo
- Created on: 03-03-17 16:44
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- X-rays and Ultrasound
- x-rays in medicine
- they are high frequency, short wavelength electromagnetic waves
- they pass through healthy tissue but are absorbed by denser materials such as bone and metal
- they affect photographic film and create a negative image
- can be used to diagnose medical conditions such as bone fractures or dental problems
- can be formed electronically using charge-coupled devices (silicon chips that divide into a grid of millions of identical pixels
- radiographers take precautions by wearing lead aprons and standing behind a lead screen or sometimes leaving the room when the scans take place to reduce the amount of radiation they are exposed to
- uses of x-rays in medicine
- CT scans
- use x-rays to produce high resolution images of soft and hard tissue
- patient goes inside a cylindrical scanner where an x-ray beam is fired through the body
- x-ray tubes and detectors are rotated during the CT scan
- a lot of x-rays are used which can be dangerous due to the radiation
- Treat Cancer
- x-rays can cause ionisation which kills living cells
- they have to be carefully focused and at just the right dosage to kill the cancer cells withut damaging any other cells
- the x-rays are focused on the tumour using a wide beam
- the beam is roated round the patient with the tumour at the centre
- CT scans
- Ultrasound
- has a higher frequency than we can hear
- some waves are reflected off the boundary and some is transmitted (partial reflection)
- you can point a pule of ultrasound at any object and it will get reflected back
- oscilloscopes can be used to find boundaries
- if given the seconds per divion you can work out the time between the pulses by measuring on the screen
- s = v x t s= distance v = speed t = time
- Ultrasound Uses
- Breaking Down Kidney Stones
- ultrasound beam concentrates high-energy waves at the kidney stones and turns them into sand-like particles
- the particles then pass out of the body through the urine
- good method because it is relatively painless and stops the patients from needing surgery
- Pre-natal Scanning of a Fetus
- ultrasound waves pass through the body but once they reach a boundary between two different media some of the wave is reflected back and detected
- the exact timing and distribution of these echoes are processed by a computer to produce a video image of the fetus
- Breaking Down Kidney Stones
- is medical imaging safe?
- ultrasound waves are non-ionising so safe
- x-rays are ionising, they can cause cancer if you are exposed to a too high dose
- x-rays are NOT safe to be used on developing babies
- CT scans use more radiation than ausual x-ray so are not taken unless they are really needed
- x-rays in medicine
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