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Manufacturing of Precision Aluminum Molds for Proton Therapy Microdosimetry Testing

Macartney Ewing

Authors:  Macartney Ewing, Camilo Correa Alfonso, Dr. Wesley Bolch

Faculty Mentor:  Dr. Wesley Bolch

College:  Herbert Wertheim College of Engineering

Abstract

This investigation aims to manufacture highly precise aluminum molds measuring 10 cm x 10 cm in varying thicknesses ranging from 0.5 mm to 2.5 cm. These molds were used to create slabs made of three proton tissue equivalent materials developed previously in our research group to behave as human bone, soft tissue, and lung tissue. These slabs will be used to perform microdosimetry measurements of the lineal energy along the Bragg Peak region and by using the microdosimetric kinetic model obtain the relative biological effectiveness (RBE) as a function of depth in these proton tissue-equivalent materials. To achieve an accuracy of 1 mm, the slabs need to be made with high tolerances to guarantee the desired dimensions and minimize the presence of air bubbles and indentations on the cast surfaces. Due to these requirements, the manufactured molds were created by assuring the internal surfaces are extremely flat and with the desired thickness. The molds constructed were able to create slabs as thin as 0.5 mm, while maintaining a near-constant thickness and very high surface finish. Microdosimetric measurements will be taken of these slabs after conducting proton therapy irradiations.

Poster Pitch

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Poster

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5 Responses
  1. Macartney Ewing

    Good afternoon! Feel free to type any questions here and I will be happy to answer them!

  3. Julia Withrow

    Hey Macartney! I love your project. In the CAD stage- did you have any redesigns throughout the process in order to fine-tune the structure? And how did you pick aluminum as the material?

  4. Lauren Rogers

    Hi Macartney! This is awesome! Did you have to go through any extra steps post-manufacturing to ensure that there was no non-visible debris that would endanger your testing?

  5. Macartney Ewing

    Hi Julia and Lauren,

    So sorry for the late response! Whenever I refresh the page, if I try to submit my comment before some kind of internal ‘timer’ is up, it tells me not to type too fast… but then I have to refresh the page to try again, so the timer restarts.

    Great question! There were lots of CAD redesigns and adjustments, mostly having to do with fasteners, hole size, and hole placement, all to make assembly by the user as quick and efficient as possible. We chose aluminum because it is relatively inexpensive, easy to machine, and doesn’t react with the materials being cured.

    Also great question, Lauren, that I maybe should have addressed in the poster! I did lightly sand the surfaces and wipe them out with alcohol and a clean rag before delivering them to Camilo for pouring, to ensure there was no leftover oil or debris.

    Thank you for the great question, both – I look forward to seeing your posters!