P3 1.1 X-rays

P3 1.1 X-rays

1. X-rays are high energy members of the electromagnetic spectrum that are produced when high energyelecterons are decelerated by hitting a heavy metal target

   • Similar to gamma rays

2. short wavelength, high energy, cause ionisation

   • wavelength - which are the size of an atom
     • As they are small this means that X-ras canpass throgu body tissues but they are absorbed by denser parts such as bones or any metal.

3. Alpha particles, beta particles and X-rays are called 'ionising raiation' because they will knock electrons off atoms aand cause ionisation.

   • Ions can cause harm to living tissue, possiby killing cells or cause mutations. Raidly dividing cells are harmful which is why preganant women can't have x-rays.

4. X-rays affect photographic film just like light. Nowadays film has been replaced by CCD's and they are stored on computers rather than being held up infront of a light

   • To take x-rays of your stomach you are given a drink of Barium Sulphate which coats the inside of your pipes. Dense liquid that absorbs x-rays.
   • Broken bones and wonky teeth show up clearly

5. X-ray picture is a shadow that reacts when it hits the film and turns black. Where there are bones x-rays are absorbed and none hit the film so they appear white.

   • Energy from x-rays is absorbed by the body when they are passed through

6. Computed Tomography (CT scans) or Computed Axial Tomography (Cat scan), is a medical imaging procedure that uses computer-processed x-rays to procedure tomographic images (slices of specific areas of the body)

   • Images are processed to generate three-dimonesional image of the inside of an onject from a large series of 2D x-ray images. Allows doctors to look at the object from any direction
   • CT scans disinguish between different types of soft tissues as well as between bone (or teeth) and soft tissue

7. X-rays and gamma rays are both used to treat cancer The dose ust be carefully controlled not to cause burns and additional cancers. One method is to direct high energy x-rays at the tumors.

   • To treat cancer the x-rays are focused on the tumor using a wide beam, the beam is rotated round the patient with the tumor at the centre which minimises the exposure of normal cells to radiation, and reduces the chances of damaging the rest of the body.

8. Avid areas of rapidly cell dividing (e.g. foetus) and avoid high doses - either by increasing distance or having a lead screen (which absorbs x-rays)

9. Radigraphers who work with X-ray machines or CT scanners need to take precautions to minimise their x-ray dose. Wear lead aprons, stand behind lead screen or leave the room when the scans are being done. Lead shields areas of the patient's body that aren't being scanned, and exposure time is always kept to a mnimum.