
Towards an inexpensive open-source desktop CT scanner - matthewbadeau
http://www.tricorderproject.org/blog/towards-an-inexpensive-open-source-desktop-ct-scanner/
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Shinkei
A topic I can speak intelligently about! (I am a Radiologist.)

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.

Watch this video of a modern scanner rotating at full speed:

[http://www.youtube.com/watch?v=CWnjqeB7Mk8](http://www.youtube.com/watch?v=CWnjqeB7Mk8)

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.

MRI is truly the cutting edge of human achievement. Watch this video to see
the forces involved:

[http://www.youtube.com/watch?v=6BBx8BwLhqg](http://www.youtube.com/watch?v=6BBx8BwLhqg)

And this for a detailed explanation of MRI principles:

[http://www.youtube.com/watch?v=pGcZvSG805Y](http://www.youtube.com/watch?v=pGcZvSG805Y)

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.

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j8hn
Off topic but what would you recommend for brain imaging, a CT scan or MRI?

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Shinkei
CT is a great screening exam because it is cheap, quick and more readily
available. MRI is much more specific in diagnosing problems in the brain and
has a lot more 'features' that can be added to aid in diagnosis. So generally,
everyone gets a CT and then moves on to an MRI if there is an abnormality...
or if they fail to find an abnormality when the clinical exam remains
abnormal/severe. There are a lot of exceptions... like in little kids, you
should always avoid radiation when possible and people will go straight to
MRI.

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j8hn
Why is there such a big difference in patient price between a CT and MRI scan?

My doctor told me to have a CT scan done but I am worried about the radiation.
I feel that if an MRI was cheaper, then I would have been prescribed an MRI.

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ris
Ask them about the radiation dose in banana-equivalent, then be less worried.

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nate_meurer
You're confusing CT scans with conventional x-ray images. CT scans deliver the
radiation equivalent of hundreds of conventional x-ray images. The radiation
dose is high enough to epidemiologically significant (meaning higher cancer
rates in people who have been scanned, especially children).

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ris
Believe me, I'm not confusing them - I just think it's significantly less
risky than the parent does. And yes, there can be higher cancer rates in
people who have a _lot_ of CT scans done e.g. because of a serious illness.

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jonknee
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.

[http://www.osirix-viewer.com/Downloads.html](http://www.osirix-
viewer.com/Downloads.html) OsiriX is a DICOM viewer and PACS for Macs and iOS

[http://www.dcm4che.org/](http://www.dcm4che.org/) 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.

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randlet
I use pydicom[1] quite a lot. It is an open source, pure Python module for
reading & writing DICOM files. Works very well by essentially transforming the
whole DICOM file into a big dictionary.

[1][https://code.google.com/p/pydicom/](https://code.google.com/p/pydicom/)

~~~
orting
pydicom is nice but it lacks network functionality: find, send, store and so
on. And it cannot decompress jpegs. Two large open source toolkits are
dcmtk[1] and gdcm[2]. Both comes with commandline applications for viewing
dicom files and querying pacs servers. gdcm is bundled with itk[3].

[1] [http://dicom.offis.de/dcmtk.php.en](http://dicom.offis.de/dcmtk.php.en)

[2]
[http://sourceforge.net/projects/gdcm/](http://sourceforge.net/projects/gdcm/)

[3] [http://www.itk.org/](http://www.itk.org/)

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orting
It is a beautiful little machine, looking forward to seeing it in action.

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.

For reconstruction from the projections the Cph CT Toolbox
[https://code.google.com/p/cphcttoolbox/](https://code.google.com/p/cphcttoolbox/)
contains open source implementations of several reconstruction algorithms. It
is written in python.

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.

~~~
ris
(from following link...) Ah, an old CRT screen as a detector - hadn't thought
of that.

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algorias
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.

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.

~~~
NatW
Just fyi, in Paris you can get an MRI (they call it an IRM)(or a CT Scan) at a
private clinic with fairly-modern e.g: GE machines (don't know how old) for
180 euros (including an assessment by a radiologist). Ahead of an MRI, you
additionally pay a pharmacy 20-50 euros for injections they'll administer to
you during the MRI, depending on which type of scan you're getting (your
weight), etc. You leave with a DVD that summarizes your results and a report.
I imagine the fees are subsidized by the government, but I actually don't know
if it is since it is a private clinic I'm talking about. I imagine the
technicians, doctors, and assistants are likely paid less in France.

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fluidcruft
FYI, in the US, the thousands-of-dollars list price for an MRI turns in to a
few hundred if Medicare or an insurance company are paying (and no, I'm not
talking about what the patient gets charged out of pocket--the actual total
amount charged is reduced that much).

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yummyfajitas
It also turns into a few hundred if you tell them you can't pay thousands of
dollars, but are willing to take any free slot.

MRI is a classic example of high fixed cost, negligible variable cost. Once
they buy the machine, it pays to make sure it never runs idle.

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ris
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...)

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.

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quux
Here's another home made CT scanner project someone did, not as polished, but
he does a great job explaining the principles involved.

[http://www.youtube.com/watch?v=hF3V-GHiJ78](http://www.youtube.com/watch?v=hF3V-GHiJ78)

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spartango
> 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.

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.

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yread
related:
[http://www.ru.nl/hfml/research/levitation/diamagnetic/](http://www.ru.nl/hfml/research/levitation/diamagnetic/)

Frog levitating in 10 Tesla

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skbohra123
Off topic question: What kind of cardboard is that used in the prototype? I
have been searching for such a material for some time.

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turgidElderly
It's not cardboard. It's laser-cut wood.

...and BTW, is anyone going to point out the obvious hazards of DIY x-ray
dosing? Like, okay, sure, you can perform CT scans on inanimate objects in the
privacy of your own home, without subjecting living creatures to x-rays, but
still... open source x-ray machines?

Consider the infamous Therac-25:

[https://en.wikipedia.org/wiki/Therac-25](https://en.wikipedia.org/wiki/Therac-25)

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Beltiras
There's a big difference between imaging and treatment radiation.

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jwr
An impressive project, truly some Hacker News!

