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Topic: PET Scans  (Read 8960 times)

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Offline constant thinker

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PET Scans
« on: November 29, 2005, 07:40:12 PM »
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.
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Offline mike

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Re:PET Scans
« Reply #1 on: November 29, 2005, 08:00:31 PM »
I think they are detecting annihilation products
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Offline Elgon

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Re:PET Scans
« Reply #2 on: November 30, 2005, 11:47:51 AM »
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.

Offline constant thinker

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Re:PET Scans
« Reply #3 on: November 30, 2005, 09:22:50 PM »
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.
"The nine most terrifying words in the English language are, 'I'm from the government and I'm here to help.' " -Ronald Reagan

"I'm for anything that gets you through the night, be it prayer, tranquilizers, or a bottle of Jack Daniels." -Frank Sinatra

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