X-rays

X-rays

1. Properties

   • Part of the electromagnetic Spectrum
     • Have short wavelengths
     • High frequency
     • High energy
   • Are transverse waves
   • Cause ionisation
     • add or remove elctrons
   • Affect photographic film
     • Turn it black
   • Are absorbed by metal and bone
   • Transmitted by healthy body tissue
   • Are useful for medical diagnosis and treatment

2. Imaging

   • Photographic film
     • Used in medical imaging
       • Bone fractures
       • dental problems
     • Are transmitted through the body
       • But are absorbed by bone
     • White photographic film used in old X-ray machines
       • Film turns black where x-rays hit it
       • Stays white where the bones are
   • CCD's
     • Charged-Coupled Device
     • Modern X-rays use these
     • Images are formed electronically
     • Can be recorded and stored easily
   • CT scans
     • Gives a 3-D image
       • Takes multiple images from different angles and puts them together
     • Computerised tomography
     • Image can be manipulated to see certain strucutres
     • Gives doctors lots of insight into problems

3. Ionising effects

   • Can damage DNA in cells
   • Most damaging to actively dividing cells
   • Cancer treatment
     • Where cells divide uncontrollably
       • Due to damaged DNA
       • Forms tumours
     • Direct high-energy x-rays at the tumours
       • Causes lots of damage to cancerous cells
     • Radiotherapy
   • Low doses cause cancer
   • High doses kill cancer
   • Precautions
     • Can only have a limited number of X-rays
       • So they aren't exposed to too much radiation
     • X-ray machines produce low energy x-rays
       • Reduces risk of them damaging human tissue
     • Hospital staff are at an elevated risk
       • X-ray rooms are sheilded
         • Have lead built into walls
       • Have warning signs outside X-ray rooms
     • Radiographers
       • Have to routinely leave the room
       • Stand behind a screen containing lead
       • Wear lead aprons