Design and Development of a 3D-Printed Tissue Equivalent Phantom for Cobalt-60 HDR Brachytherapy

Abstract

The use of 3D phantoms represents patient anatomy, enabling more effective treatment planning optimization. This study aims to develop a tissue-equivalent 3D-printed phantom as a dosimetry application for the HDR-BT Cobalt-60 source. Polylactic Acid (PLA) with a single infill density of 85% was used to achieve tissue-equivalent characteristics. The phantom features a 200 mm diameter spherical structure composed of three distinct components, including an applicator channel and cavities in each layer to accommodate the HDR-BT source dose measurement detector. The characteristics of the 3D-PLA phantom were analyzed and compared with soft tissue, muscle, and water based on ICRU-44 reports, as well as with the RW3 phantom (PTW, Germany) as a standard phantom. The resulting 3D-PLA phantom density of 1.05 g/cm3 was in good agreement with muscle, RW3 phantom, soft tissue, and water, respectively. The linear attenuation coefficient of the 3D-PLA phantom at energies >0.1 MeV and its effective atomic number (Z_eff) ≈ 8.26 closely resemble soft tissue properties. The HU value of the 3D-PLA phantom is −116.6 ± 7.5 HU, also within the soft tissue HU values range. These findings confirm that the developed 3D-PLA phantom exhibits the necessary characteristics for dosimetry applications.