X-Message-Number: 798 Date: 04 May 92 02:20:47 EDT From: Brian Wowk <> Subject: brain scanning To: >INTERNET: David Stodolsky: >X-ray holography would, if it worked, allow examination of internal >structure in the storage media, just as internal structure can be recovered >from a brain by electron microscope. That is, you adjust the focal depth to >see a certain distance inside the specimen. I presume you are suggesting viewing the brain hologram with some device which has a one-micron depth of focus at a distance of 10cm. While this is interesting, I suspect it is mathematically equivalent to a computed tomography reconstruction, the constraints of which I have already discussed. Getting down to nitty-gritty details, 50 keV x-rays have a wavelength that is about 1/10th of an atomic diameter. How are you going to record the interference patterns of such waves? Also, how do you produce coherent x- rays without an atomic bomb? If one is hell bent on imaging a brain with external x-rays, CT (as enormously impractical as it is) is the only way to do it. X-ray holography has no advantages, and has the distinct disadvantage of being physically impossible. There are far better ways to ascertain the microscopic structure of a brain than by frying it with x-rays. One near-term method (proposed by Ralph Merkle and others) is simple sectioning and electron microscopy. In the long term, invasive (but not necessarily injurious) nanoscopic probing will be the way to do it. Micromachines and nanomachines equipped with MRI gradient/receive coils could do the job nicely, with capabilities for in-situ molecular analysis as well. What, though, is the point of this discussion? Are you suggesting that capabilities for recovering patient identity (and perhaps uploading) will be available before the capability of actual revival from cryonic suspension? This I seriously doubt. --- Brian Wowk Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=798