ý

The total internal reflection of waves – WJECMedical uses of optical fibres

This topic explores the conditions necessary for total internal reflection of light. It discusses applications of total internal reflection using optical fibres, like medical uses and communication.

Part of Physics (Single Science)Electricity, energy and waves

Medical uses of optical fibres

Endoscope

use optical fibres to produce an image of inside the body. A doctor can insert a bundle of optical fibres into the body. Some carry light into the body, and some carry light reflected off internal body surfaces back out. This allows the doctor to see an image of the inside of the body clearly, and help them diagnose diseases like cancer, or see what they are doing during keyhole surgery.

Another method for generating an image of the inside of the body is a CT scan. CT scans use X-rays to generate a 3D image of the body.

You may be required to compare the use of endoscopes with CT scans in the exam.

CT scans

Traditional X-ray imaging gives a two-dimensional (2D) view of the body from one angle. This can result in detail being obscured by other structures in the body. (CT) scans involve taking a range of X-ray images from various positions.

These are processed by a computer to build a three-dimensional (3D) image. This image can be manipulated in order to see the structures within the body at different layers and from different points of view. This lets a doctor gain a much greater insight into what is wrong with a patient.

Endoscope v CT scans

Endoscopy is used to investigate specific areas of the body. It is less harmful than CT scans. It uses light rather than X-rays. CT scans are used to generate more overall images of the body, and are a higher risk than endoscopes due to the fact that they use X-rays.

The properties of X-rays mean that they can damage the in cells. The ionising effect of X-rays is more damaging to actively dividing cells in the body. Low doses of X-rays may cause cancer, whereas high doses may kill cancerous cells.