[constant thinker]

I have a question about Positron Emmision Topography (PET) scans.

Ok positrons are anti-electrons right. When anti-matter comes into contact with regular matter don't the two like obliterate each other. These scans are usually used to detect brain activity.

Ok question is:
In these scans are they detecting the left reminents of suchs obliterations or are they actually detecting positrons.

[mike]

I think they are detecting annihilation products

[Elgon]

Ok question is:
In these scans are they detecting the left reminents of suchs obliterations or are they actually detecting positrons.

When a positron is getting in contact with an electron, both particles are annihilated. The energy stored in both particles in converted into radiation and two gamma rays with an energy of 511 keV each are emitted. These gamma rays are being detected during a PET scan. The fact that you have two gamma rays originating from the same point gives you a better spatial resolution in the body than you get with other diagnostic techniques based on radioactive isotopes that only emit one gamma ray.

[constant thinker]

Cool thanks. I was assuming that it was the annhilation product, but I really didn't know what that product was. That also explains why PET scans are so accurate and give you a clear picture.