(Saturday, 4/7/2018)
Room: Foyer
Purpose: To develop an optical guidance system which could be clinically implemented to increase the precision of seed placement, and thus limit the dosimetric uncertainty, on customizable I-125 eye plaques.
Methods: Following a study which demonstrated the substantial impact a slight deviation in seed placement can have on the total dose delivered by an eye plaque, a high precision optical guidance system was developed as an alternative to the purely caliper based seed placement technique which is currently in place at our institution. In this system, the plaque is secured in a fixed location using a stand to ensure that both of the physicist’s hands are free to assist with placement. A camera, located above this stand, takes live video of the seed placement and, on a nearby monitor, projects the planned seed location on the plaque. This provides real-time feedback with sub-millimeter resolution, to assist with limiting the uncertainty of this process. Once implemented, more consistent and predictable dosimetry should be achievable.
Results: A proof-of-concept design has been developed which verified the feasibility of our system. A MATLAB code was written which performs a spatial calibration of an image by relating the number of pixels to the dimensions of a known object. This code allows for measurements to be taken on a snapshot to verify proper calibration. It also projects a grid overlay or the user specified seed geometry on the video feed, allowing for real-time feedback on the accuracy of seed placement.
Conclusion: This project was based around the practical need to improve upon a system which is currently in use. The proof of concept has been developed, validated and shown to be useful in improving the accuracy of the eye plaque seed positioning process. A higher resolution system is currently in development for full clinical use.
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