In brachytherapy, or internal radiation therapy, cancer is treated by inserting radioactive implants in or close to the tumors. These implants, such as episcleral plaques for the treatment of uveal melanoma, are designed according to generic population approximations. However, implants more personalized to the anatomy and to the precise geometry of each patient's tumor, could enhance treatment precision by allowing better adjustment of dose profiles to the contours of cancerous tissues. This work describes an original approach integrating biomedical imaging, 3D printing, radioactivity painting, and anatomical measurement of biomedical imaging, as a workflow for the development of tumor shape‐specific brachytherapy implants. A case study is carried out on the fabrication of radioactive episcleral plaques (EP) for the treatment of uveal melanoma. First, computer‐aided design (CAD) plans of EP are prepared according to guidelines prescribed by the Collaborative Ocular Melanoma Study (COMS) protocol. Polyetheretherketone (PEEK), a high‐performance polymer suitable for permanent implants, is used to 3D‐print plaques (10‐, 14‐ or 22‐mm diameter EPs) according to these CAD plans and the geometrical accuracy of the printed design is evaluated. The possibility to modulate the dose distribution is demonstrated by painting the inner surfaces of the EPs with radioactive 103Pd in different patterns, followed by dose profile measurements. The approach confirms the possibility to modulate the dose distribution generated by 3D‐printed plaques through radioactivity painting. Lastly, the suitability of the 3D‐printed plaques for surgical manipulations is demonstrated by performing ex vivo surgical tests on human eyeballs. This new workflow for the fabrication of tumor‐specific radioactive implants may improve the precision of a range of different brachytherapy procedures that require more personalized anatomical adjustments with the geometry of tumors and organs at risk
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