Variable Electron Applicator
Designing a component for the world´s leading electron beam machine
Original Electron Applicator
Objective:
The purpose of the electron applicator is to maintain a uniform field of electrons and direct them towards the treatment area on the patient. Currently, there are six different sizes of applicators with which to treat patients depending on the size of the treatment area. Since there are six different applicators, it is cumbersome to switch out the applicator each time a different size is required for treatment and the applicators take up precious space in the laboratory x-ray cleanrooms. The primary goal for our Senior Project Team is to complete a design of a variable electron applicator that is able to articulate into the different aperture sizes, while maintaining the same performance as the current electron applicator. Furthermore, the design must be backward-compatible with the current Varian oncology equipment, which requires several minor functions to assure compatibility with the machines.
Skills:
Design, machining, BOM, Project Management
How it Works:
We separated the applicator into 3 parts and made all 3 modular.
The middle and bottom shield has telescoping pieces (green) that slide into the large corner rails (blue), allowing quick and simple change of size. The telescoping pieces attach to each other by a small spring in order to retain rigidity. The wires holding onto the edge of the telescoping pieces lead up to the top shield, which has a different mechanism for changing sizes.
The top shield folds in and out to. Each of the inner segments is held together by hinges but propped up by the corner beam tracks. The top shield’s corner tracks are attached to the wire holding up the segments in the diagram above, which is what articulates the shrinking or increasing size of the middle and bottom shields.
Quick Maths
We wanted to make sure we covered our bases and checked specific weak spots to dynamic action, namely the cantilever beam action on the corner tracks of the top shield and the spring between the telescoping pieces. The track was thus designed to meet the criteria below based on user testing.
The springs had a simpler calculation but luckily we found off-the-shelf parts from Mcmaster. Based on their cyclical loading, we wanted the spring to be able to maintain their rigidity against gravity.
We Made it Too
A lot of machining. Assembly could use some improvements. Still beautiful.