Naked Science Forum

General Science => General Science => Topic started by: OldMan on 21/06/2005 04:07:14

Title: What is a SPEC scan?
Post by: OldMan on 21/06/2005 04:07:14

Pretty sure it was a SPEC scan so I'll have to edit this if I find out it is wrong but can someone fill me in on what it is? Similar to an MRI, CAT scan or what?

Tim

Title: Re: What is a SPEC scan?
Post by: daveshorts on 21/06/2005 14:35:44

I think it could be a Single Photon Emission Computed Tomography it is a version of PET (positron emmision tomography) this is where they inject you with a radioactive substance that emits low energy positrons (anti electrons). If one of these meets with an electron in your body it will anihilate to form a pair of gamma ray photons. These will fly off in opposite directions to conserve momentum. If you have a detector that picks up two gamma rays at the same time you can guess that they came from the same positron, and that positron must have anihilated on the line between the two gamma rays. If you watch enough of these events , draw lines between them all, then where lots of lines are crossing there are probably lots of postitrons anihilating.

Because the radioactive element was injected into your blood it will end up in the tissues that are using lots of blood and therefore energy, this can be useful as it will tell you about which bits of the brain are active, or what is cancerous  as cancer is by definition growing quickly and therefore using lots of energy.

A PET scanner has a ring of detectors where as a SPECT scanner only has 2 on opposite sides of your body so is slower but much cheaper to build.

Title: Re: What is a SPEC scan?
Post by: OldMan on 22/06/2005 01:08:19

Ah that certainly sheds light on a few things.

Thankyou kindly for your insight Mr Shorts

Tim