Final Design
Housing Unit
The x-ray housing unit was 3D printed and was designed with the presence of conductive and high voltage elements in mind. Thus the design isolates components from each other such that probability of electrical arcing between components would be reduced. The x-ray source is at the bottom of the housing unit. Two stepper motors actuate a dual axis rotating mechanism which in turn moves the device's collimator and output x-ray beam. The design allows for a working resolution of 20 data points per centimeter squared, resulting in 400 data points in a four centimeter by four centimeter area.
The scanning mechanism is controlled via an Arduino compatible microcontroller. Each stepper motor requires 5V power input to function. Power input for low voltage applications is provided via batteries.
X-ray source
The x-ray source incorporated into the device is Superior X-Ray Tube Co. SXR 80-14-1.0 4P X-ray tube, which can operate up to 80kV. This x-ray tube also included a built in shield made of leaded plastic which helped focus the output beam and limit leakage radiation.
High Voltage Power Supply
The high voltage required for x-ray operation was provided through a battery powered flyback transformer. This combination was found to provide voltage increases of 1667 times, correlating to an output of 20 kV when an input of 12 volts was provided.
Container Unit
A container with dimensions of 25 cm wide by 30 cm tall was created in order to store and isolate all the necessary components of the device to prevent damage to device and increase user safety. Auxiliary radiation shielding made of 1/32 inch lead lined poster board was added to reduce leakage radiation by 99.99% when device operates below 40kV.
Performance
Safety testing of the prototype was conducted at 20kVp, the upper limit of power provided by the flyback transformer. Testing demonstrated leakage radiation of between 3 and 16 millirads, at the highest being barely over the 12 millirad average of expectable background radiation value given by the testing UCSD safety personnel. Based on reported values the effectiveness of radiation shielding was considered to be satisfactory. Radiation values at the scanning area read around 45 millirads.