More than meets the eye: The ingredients for a DIY medical marvel
This is what the insides of a CT scanner look like. (Click for full size.)
Stripped of its clinical white casing, the scanner's frame seems as if it'd be more at home on the Death Star than in a hospital. A surface inspection suggests it needs at least seven fans to keep it cool, what must be miles of wiring, and enough metal to build a small boat.
As complex a device as this may look, though, a CT scanner is really made up of just four or five major components. With the right mix of pluck and equipment, anybody could turn this into a weekend project. Want to build your own? Here's what you'll need:
- An X-ray tube consisting of an anode and a cathode. The tube is vacuum sealed, placed inside a housing, and mounted into the scanner's rotating frame.
- Collimators, which are devices that allow the X-ray photons to be targeted at a specific part of the body. Other collimators in the CT scanner block stray X-ray photons from reaching the detector.
- A detector array. One of the most common kinds of X-ray detectors involve xenon gas sandwiched between tungsten metal plates. When the detector is bombarded with X-ray photons, they react with the xenon to produce collectible images.
- A power source. X-ray tubes run on high voltages, so you'll need what's called an autotransformer, or a large loop of wire wound around a core. With the transformer, you can get about twice the energy that you put in.
- Copper or aluminum filters to remove low-energy X-ray photons.