August 6, 2004
Computerized Axial Tomography
This set of pictures shows the CAT (Computerized Axial
Tomography) Display Generator built for CRD who in turn was working for Medical
Systems. There's a picture of me with the lab test setup, a detail of the
display generator chassis, a detail of the optoelectronic control panel, and 3
images taken from the CRT. This work was done in 1976-77.
The display video memory utilized an unheard of 16K dynamic
CCD chips, at a time when 256 bit and 1K bit static RAMS were the workhorses. 4K
dynamic RAM "rumors" at best. The technical challenge was to multiplex all these
very slow memory chips into a high data rate video stream. The second major
challenge was to control the chip drive pulse wave shape so that a whole chassis
of these chips would perform similar to individual chips! The digital output was
processed with a video rate digital multiplier - summing logic with numerical
hard limit overflow control, which was pretty fast digital logic in those days.
The control panel was centered around a pair of flywheel
knobs with optical motion sensing to drive the display system. While GE couldn't
get it's act together on a patent for it, HP went on to produce a very
successful product line of these optical control devices!
There was a lot of politics involved on this job, with
Jerry Suran right in the middle of Medical Systems and CRD. But a highlight was
taking the whole unit down to Fairfield and demonstrating it to Jerry's boss
down there when it was done.
While the hard feelings persisted for a while, eventually
we had a second very successful follow up project on the nuclear medicine