x-rays

x-rays

1. Used to take internal images of bones and metal objects.

2. A type of electromagnetic wave which can travel through some objects but not through others.

   • If they can't travel through an object they will be absorbed instead.

3. How they are used:

   • Can travel through soft tissue and muscles but not through bone or metal.
   • 1) A transmitter is used to direct a beam of radiation onto the area of the patient which needs to be looked at internally.
     • 2) Some of the electrons in the beam of radiation are absorbed by the bone and some of them are transported through soft tissue and muscles.
     • 3) The electrons which are able to get through are then reflected back by the screen.
   • Parts of image which appear white are usually hard objects such as bone or metal. The darker parts of the image is usually soft tissue and muscle.

4. The danger of x-rays

   • A high dosage of x-rays can cause burns and even in small doses x-rays can ionise atoms, increasing the risks of cancer after every exposure.
   • When DNA is ionised it may cause a mutation to develop. This mutation may then develop into cancer.

5. Uses of x-rays

   • Diagnosis
     • Locating object such as metal
     • Diagnosing fractures and hard lumps.
   • Treatment
     • Radiotherapy
       • If radiation can cause mutations in normal cells radiotherapy can also be used to kill cancer cells by causing further mutation of the cancer cells.
     • When you emit ionising radiation these treatments are known as therapeutic implants or radioactive tracers.

6. Features of x-rays

   • Grids- Grids are made of lead. They prevent scattered x-rays from reaching the film by absorbing them, as scattered rays could make the image blurred.
   • Narrow beams- Narrow beams make the image sharper as they produce less scattered rays. The x-rays come from a single point and the beam size is reduced by a cone.
   • Image intensifying screens- Image intensifying screens are behind the x-ray film and reflect the x-rays back onto the film, intensifying the image.
   • Filtration- Filters are made of aluminium, they prevent low energy x-rays from reaching the film by absorbing them. High energy/frequencies show a sharper image and also reduces scatter.