Medical uses of light
Endoscopes
An Endoscope is a thin tube containing optical fibres that lets surgeons examine inside the body.
Endoscopes consist of two bundles of optical fibres- one to carry light to the area of interest and one to carry an image back so that can be viewed.
The image can be seen through an eyepiece or displayed as a full colour moving image on a TV screen.
The big advantage of using endoscopes is that surgeons can now perform many operations without cutting a massive hole into the body, endoscopes have allowed us to use keyhole surgery which only needs a small hole.
Pulse Oximeters
These use light to check the percentage of oxygen in the blood.
This helps measure a patients help before and after surgery as it measures the amount of oxygen carried by the haemoglobin in the patients blood.
The haemoglobin carries oxygen around your body from your lungs to your cells, it is also the pigment that makes your blood red.
Haemoglobin changes colour depending on the bloods oxygen content.
Endoscopes
An Endoscope is a thin tube containing optical fibres that lets surgeons examine inside the body.
Endoscopes consist of two bundles of optical fibres- one to carry light to the area of interest and one to carry an image back so that can be viewed.
The image can be seen through an eyepiece or displayed as a full colour moving image on a TV screen.
The big advantage of using endoscopes is that surgeons can now perform many operations without cutting a massive hole into the body, endoscopes have allowed us to use keyhole surgery which only needs a small hole.
These use light to check the percentage of oxygen in the blood.
This helps measure a patients help before and after surgery as it measures the amount of oxygen carried by the haemoglobin in the patients blood.
The haemoglobin carries oxygen around your body from your lungs to your cells, it is also the pigment that makes your blood red.
Haemoglobin changes colour depending on the bloods oxygen content.
- When high in oxygen the blood is a bright-red colour(oxyhaemoglobin)
- When low in oxygen( after its given up to cells) your blood is a more purply in colour and this is called reduced haemoglobin.
The pulse oximeter has a transmitter, which emits two beams of red light. It also has a photo detector to measure light.
These are placed either side of a thin part of thee body, e.g an ear lobe
The beams of light pass through the tissue. On the way some of the light is absorbed by the blood, reducing the amount of light detected by the detector.
The mount of light absorption depends on the colour of the blood. The colour of the blood depends on the oxyhaemoglobin content. Healthy people have about 95% oxyhaemoglobin and 5% reduced haemoglobin.
Reflection pulse oximetry uses a similar technique- it reflects light off red blood cells instead of shining light through a part of the body.
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