Stereotactic Radiosurgery

A parent in my class asked about the Gamma Knife (R) that Charlie Teo uses in his surgery and I thought I’d find out more about it.

Gamma radiation has a very low wavelength. Remember that in the electromagnetic spectrum, the lower the wavelength, the higher the energy associated with each photon (packet) of radiation.

This is my understanding of how the technique works.

Around 200 beams of gamma radiation are aimed at the tumour from different directions. Gamma radiation has such a low wavelength that it can pass through organic cells without affecting them, but this depends on the type of cells and the intensity of the radiation. The different beams pass through the rest of the body cells until they reach the tumour. When they join at the tumour site there is a very high intensity of radiation in a very small area. (Not only does each photon have high energy but there are many of them in one small space.)

220px-Gamma_Knife_Graphic

Cancer cells are characterised by rapidly dividing and multiplying (unlike most of the rest of the cells in our body) and gamma radiation damages cells by breaking bonds in DNA, so cancer cells are damaged more by gamma radiation than the surrounding healthy cells are.

4.0.4
Differences between normal animal cells and cancerous cells. Image from Wikimedia commons. 

This looks like a great use of scientific knowledge and advances in technology to target cancer cells without damaging the rest of the body. I read that, because it is so specific, people who are operated on with this technique tend to recover far quicker than those receiving radiotherapy or being operated on by other surgical techniques.

 

Here are some links if you are interested:

Gamma Knife FAQs from University of Arkansas for Medical Sciences

Stereotactic radiotherapy for brain tumours (from Cancer Research UK). This includes a description of how people’s heads are immobilised for the surgery. As you can imagine, it is essential that the person stays completely still because the surgeon needs the radiation to get to exactly the right spot.

Radiation treatment on the old BBC GCSE Bitesize site.

Radiation and living cells, also from the BBC Bitesize site. This doesn’t give much of an explanation about how or why DNA is damaged but it does tell you about how alpha, beta and gamma radiation affect the body differently.

Information on the Elekta site about the Gamma Knife (R).

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