t the end of March, (and early april), I was under the impression that I had failed to build a convincing case that it's possible to design a low-cost mobile x-ray system capable of being used for human diagnostics.

At the time, it appeared further research was needed to build a more convincing argument.

So, being a university student at the time, what seemed like an acceptable option was to write a "thesis" of sorts, with a problem statement, research, and detailed designs of some x-ray system components which would be integrated in such a machine. For kicks, I decided to illustrate much of this document, such that it wouldn't be a boring read.

For about a month I worked all night on this, and at the end of may, had something quite detailed, with many illustrations.

For reasons of bandwidth, I can't host the 400Mb file for y'all.

However, here are some fantastic tidbits that are worth sharing!

  _   _                 _                                    
 | | | | _____      __ | |_ ___   __  __     _ __ __ _ _   _ 
 | |_| |/ _ \ \ /\ / / | __/ _ \  \ \/ /____| '__/ _` | | | |
 |  _  | (_) \ V  V /  | || (_) |  >  <_____| | | (_| | |_| |
 |_| |_|\___/ \_/\_/    \__\___/  /_/\_\    |_|  \__,_|\__, |
                                                       |___/ 

Below is a comic that describes how a project such as this x-ray source would proceed. To some, who have many engineering projects under their belt they may find it a bit humorous (and too true).

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Step 1: Engineering Stage 1 of the power train

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Step 2: Engineering stage 2 of the power train

Step 3: Engineering stage 3 of the power train

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Step 4: Engineering a modern austin ring transformer

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Step 4: Lithium-ion battery shenanigans

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Step 5: Digital controls design

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Step 6: X-ray dosimetry

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Step 7: Prototyping an x-ray tube designed for this purpose

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  _       _   _           _                 _     
 (_)___  | |_| |__   __ _| |_   _ __   ___ | |_   
 | / __| | __| '_ \ / _` | __| | '_ \ / _ \| __|  
 | \__ \ | |_| | | | (_| | |_  | | | | (_) | |_   
 |_|___/  \__|_| |_|\__,_|\__| |_| |_|\___/ \__|_ 
   __ ___      _____  ___  ___  _ __ ___   __|__ \
  / _` \ \ /\ / / _ \/ __|/ _ \| '_ ` _ \ / _ \/ /
 | (_| |\ V  V /  __/\__ \ (_) | | | | | |  __/_| 
  \__,_| \_/\_/ \___||___/\___/|_| |_| |_|\___(_) 
                                                  

Along with LOLrioKart speeding past the ivory tower, some parts of this are worth explaining further.

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Austin ring transformer:

When operating an x-ray tube, it's often the case that you do so in a manner that is "center grounded" so to speak. The anode receives +V, the cathode -V, and, any insulation used only needs to withstand V, and not 2V.

Unfortunately, this means you must provide an isolated 3V source for the tube's heated cathode, which must withstand -V plus some safety margin. Typically this is done with an "austin ring" transformer, but those are big and heavy, so, this is my switch-mode replacement. :-D

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High voltage source:

This would be the switch mode power supply topology used inside the x-ray source. It consists of a lithium ion battery stack, boosted to a few hundred volts by a polyphase boost converter, then boosted further using a series-resonant H bridge inverter. Note, the CDE capacitor in series with the H bridge's load, is chosen such that it cancels out the transformer's leakage indutctance, and provides an overall lower impedance for the power supply.

This is then fed into a voltage multiplier, which provides the extreme potentials needed for the x-ray tube.

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But, after showing this work to many folks in Rochester, NY, I soon realized that I wasn't going to get very far there. Despite being a healthcare powerhouse, ROC isn't quite the right place for people to talk about hardware technology, especially so, given Kodak and Xerox are both on their way out.

So... I dropped out of university, and bought a trailer.