A topic I can speak intelligently about! (I am a Radiologist.)<p>This article is a great discussion of modern imaging technology and I 100% agree that MRI is incredible. But CT has become much more impressive than the single-slice scanners of yore.<p>Watch this video of a modern scanner rotating at full speed:<p><a href="http://www.youtube.com/watch?v=CWnjqeB7Mk8" rel="nofollow">http://www.youtube.com/watch?v=CWnjqeB7Mk8</a><p>Currently, the race to improvement is about speed and lower radiation dose. The newest scanners can take hundreds of 2D slices in a single rotation of less than a second and reconstruct the image with a huge variety of algorithms accounting for body part, patient size, etc. that all allow for lower dose and noise resulting in better diagnostic quality.<p>MRI is truly the cutting edge of human achievement. Watch this video to see the forces involved:<p><a href="http://www.youtube.com/watch?v=6BBx8BwLhqg" rel="nofollow">http://www.youtube.com/watch?v=6BBx8BwLhqg</a><p>And this for a detailed explanation of MRI principles:<p><a href="http://www.youtube.com/watch?v=pGcZvSG805Y" rel="nofollow">http://www.youtube.com/watch?v=pGcZvSG805Y</a><p>Medicine uses 1.5T and 3T routinely for imaging, but higher field strengths are in use for research purposes. Innovation lately has been about developing new sequences (ways to differentiate types of tissue), and increase speed of aquisiton and comfort.
On a related note, there are a couple of good open source projects for reading the standard imaging files (DICOM). DICOM itself is an interesting mishmash of a standard, but is pretty powerful. Images are shuffled around using a PACS (Picture Archiving and Communication System) which lets the scanning machines send their images to a central location at the clinic, the clinic to send images to your radiologist, your radiologist to send them to the hospital, etc etc. Interesting stuff.<p><a href="http://www.osirix-viewer.com/Downloads.html" rel="nofollow">http://www.osirix-viewer.com/Downloads.html</a>
OsiriX is a DICOM viewer and PACS for Macs and iOS<p><a href="http://www.dcm4che.org/" rel="nofollow">http://www.dcm4che.org/</a>
dcm4che is a collection of server based applications for DICOM and PACS. Sort of like OsiriX, but web based. It's Java Tomcat based and reasonably simple to setup.
It is a beautiful little machine, looking forward to seeing it in action.<p>A simpler approach to get a small CT scanner is to use a stationary source and detector. This requires a cone-beam source, which might cost a lot more, but it makes it a lot easier to experiment with phase-contrast and darkfield imaging, which can improve soft-tissue contrast.<p>For reconstruction from the projections the Cph CT Toolbox
<a href="https://code.google.com/p/cphcttoolbox/" rel="nofollow">https://code.google.com/p/cphcttoolbox/</a>
contains open source implementations of several reconstruction algorithms. It is written in python.<p>From my viewpoint, CS student focusing on medical imaging, no single imaging modality will rule them all. It is much more interesting to look at the combinations like PET/CT and PET/MR that gives us complimentary information.
This is a nice hack! It's unfortunate that medical CT scanning remains expensive due to reasons other than the cost of designing and manufacturing one of these devices. It's about image acquisition speed, safety, quality assurance, safety, rigorous testing, and of course safety.<p>While all those things (+ personnel costs) are of course worth paying for, I find it unbelievable that a simple scan could cost $5000 in the US! When I had to get a CT scan, it cost $2000, of which 90% was covered by the mandatory minimum health insurance. Nobody gets left out in the cold.
Hah. I was recently considering the feasibility of making a homebrew CT scanner, only I was thinking of using one of the cheap chinese dental xray machines you can get on ebay for ~$200. (I think I would have probably vacated the room while it was in operation. I'm not saying I don't trust cheap chinese x-ray technology but - well , actually - yes I am...)<p>Would have required an awful lot of scanning of xray film and would probably only have been able to image something around the size of a walnut.
Here's another home made CT scanner project someone did, not as polished, but he does a great job explaining the principles involved.<p><a href="http://www.youtube.com/watch?v=hF3V-GHiJ78" rel="nofollow">http://www.youtube.com/watch?v=hF3V-GHiJ78</a>
> Safety is very important to me. In medical diagnostic imaging it’s often important to have an image as soon as possible, but that’s not the case for scanning non-living objects purely for scientific or educational interest...[I] make use of a “check source”, which is an extremely low intensity source used to verify the functionality of a high-energy particle detector.<p>Thank you for doing this. It's easy to build something cool but extremely unsafe in your home, forgetting that medical devices are carefully controlled to ensure patient safety. All it takes is one irresponsible DIYer to cause problems for everyone.
related:
<a href="http://www.ru.nl/hfml/research/levitation/diamagnetic/" rel="nofollow">http://www.ru.nl/hfml/research/levitation/diamagnetic/</a><p>Frog levitating in 10 Tesla