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If you’ve ever had a doctor order internal imaging, there is a very good chance that you had a CT (computed tomography)/CAT (computed axial tomography) scan. CT scans let doctors see a comprehensive view of your anatomy and they work by combining several X-ray images. In the standard configuration, an X-ray emitter tube spins around the patient while capturing images every few degrees. That results in anywhere from dozens to thousands of images (depending on the desired resolution) that form a kind of 3D view. Pyrotechnical was able to replicate that effect using inexpensive parts to build his own CT scan machine.
Medical CT scan machines, like the kind you’ve seen if you’ve had a scan, cost millions of dollars because they utilize the best components available in order to create high-quality scans. But it is possible to perform CT scans with much more affordable equipment if one isn’t concerned with getting the best quality. In this case, Pyrotechnical achieved this using an old used X-ray emitter tube from a mammography machine. To get an X-ray image, you need a special screen with a coating that emits light when excited by the colliding X-rays. Pyrotechnical was able to find a used X-ray screen, as well. The X-ray image shows up on that screen after passing through the scanned object and the machine takes a conventional photo of the image.
As with a medical CT scan machine, Pyrotechnical needed to capture many photos from angles all around the object. He used an Arduino Uno board to rotate a small turntable with a stepper motor and the scanned object rests on that turntable. The Arduino also activates relays to power the X-ray emitter tube and to trigger a Bluetooth remote. That Bluetooth remote tells Pyrotechnical’s smartphone to take a picture of the X-ray screen. It performs that process every eight degrees to capture a total of 45 X-ray photos.
Converting those 45 photos yields a short video that looks really neat, but it is also possible to create a 3D model. Using a process similar to photogrammetry, software developed for this purpose stitches the photos into a 3D model that the user can then view. That model is pretty rough, due to the poor quality of the X-ray images, but it is still very cool to see inside of everyday objects.