X-Message-Number: 3659
From:  (Brian Wowk)
Newsgroups: sci.cryonics
Subject: Re: Medical scanners
Date: 9 Jan 1995 21:00:13 GMT
Message-ID: <3es84t$>
References: <>

	Joe has explained MRI (NMR) well, so I'll tackle the remaining two.

SPECT- Single Photon Emission Computed Tomography

	SPECT, also known as Nuclear Medicine or Gamma Camera radiography,
builds a three dimensional image of organs by detecting gamma rays
emitted by injected radioisotopes.  Images are typically noisy and of
low spatial resolution.

	PET (Positron Emission Tomography) is a two-photon version of
SPECT that achieves better image quality by simultaneously detecting
two gamma rays emitted in opposite directions by positron annihilation
and then triagulating to determine the source position.


SQUID (superconducting quantum interference device) is the technological
innovation that makes Magnetoencephalography (MEG) possible.  MEG detects
the extremely subtle changes in magnetism created by neuronal acitivity
and allows the acquisition of crude brain activation maps.

--- Brian Wowk

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