I've had this idea for a while now that low-heat, very bright LEDs are available as light sources:
1. take an existing CAT scanner: Xray source, detector, mounting system (with the rotating arm) and image processing software.
2. replace the Xray source with a bank of LEDs
3. replace the Xray detector (a scintillation screen? whatever it is) with a CCD
4. start scanning
Obviously there's a whole bunch of experimentation needed to calibrate diffusion due to different types of tissue/bone/marshmallow but the software should be mostly unchanged, the mechanical mounting system would be mostly unchanged, and we'd be replacing a radioactive source with a low-power, low-heat light.
Is anybody working on this? I've asked a couple of professor at a biomedical engineering department but much silence ensued.
The ability to use off-the-shelf components seems like a big plus to me...
There would also be a need to check at what intensity cold light is detrimental to cells (and other small issues like that)