Applicability of Poly(styrene-butadiene-styrene) for Three-Dimensional Printing of Tissue-Equivalent Samples.

Several crucial and impactful three-dimensional (3D) printing applications have been developed within a broad range of fields. Among these, revolutionary changes in health care are highly anticipated. The use of 3D printing in medical applications indicates significant promise in terms of medical device personalization, drug delivery, and economical efficiency. However, despite recent significant advances in medicine inspired by 3D printing, scientific challenges and regulatory subtleties remain. This study considers additive technology application in radiotherapy. One of the main requirements for 3D-printed samples' use in radiotherapy is the tissue equivalence of the sample material. In this study, selected parameters of 3D-printed samples made of poly(styrene-butadiene-styrene) (SBS plastic) are obtained, that is, effective atomic number, mass and electron density, and Hounsfield units. The obtained parameters are compared with corresponding values for human tissue and organs. Experimental results demonstrate the tissue equivalency of the considered samples, which can be used in different applications in medical physics and radiotherapy. The obtained results have significant importance for the development, design, and production of samples for medical applications using 3D printing.

Feasibility of clinical electron beam formation using polymer materials produced by fused deposition modeling.

The main challenge in electron external beam radiation therapy with clinical accelerators is the absence of integrated systems to form irregular fields. The current approach to provide conformal irradiation is to use additional metallic shaping blocks, with inefficient and expensive workflows. This work presents a simple method to form therapeutic electron fields using 3D printed samples. These samples are manufactured by fused deposition modeling, which can affect crucial properties, such as material homogeneity, due to the presence of residual air-filled cavities. The applicability of this method was therefore investigated with a set of experiments and Monte Carlo simulations aimed at determining the electron depth dose distribution in polymer materials. The results show that therapeutic electron beams with energies 6-20 MeV can be effectively absorbed using these polymeric samples. The model developed in this study provides a way to assess the dose distribution in such materials and to calculate the appropriate thickness of polymer samples for therapeutic electron beam formation. It is shown that for total absorption of 6 MeV electron beams the material thickness should be at least 4 cm, while this value should be at least 8 cm for 12 MeV and 11 cm for 20 MeV, respectively. The results can be used to further develop 3D printing procedures for medical electron beam profile formation, allowing the creation of a collimator or absorber with patient-specific configuration using rapid prototyping systems, thus contributing to improve the accuracy of dose delivery in electron radiotherapy within a short manufacturing time.