ESR investigations of gamma irradiated medical devices

Monte Carlo Simulation of Gamma and Neutron Shielding with High-performance Ultra-heavy Cement Composite

Purpose

As the applications of nuclear technology increase in today's world, radiation protection becomes even more important. Radiation protection is important in medical imaging applications and radiotherapy rooms. Therefore, in this research, we have investigated features of the ionizing radiation shielding of the modified cement composite with iron, strontium, zinc, and zirconium elements in the photon energy range of 15 keV to 10 MeV.

Materials and Methods

To extract such features, it is necessary to use a computational method. In this research, we have done all our calculations based on the Geant4 tool based on the Monte Carlo method. This tool is a multipurpose tool that can be used for particle transport calculations such as electrons, protons, neutrons, heavy charged particles, and photons in different environments such as human tissues.

Results

The mass attenuation coefficient of the samples was calculated using the Geant4 Monte Carlo simulation tool and compared with the results of the Phy-X program, which was in good agreement. To evaluate the radiation shielding capabilities, other quantities such as the linear attenuation coefficient, the thickness of the tenth value layer, the thermal neutron cross-section, absorption rate of thermal neutrons, and the cross-section of the fast neutron removal are determined.

Conclusions

According to the quantitative results, cement composite is more effective in absorbing and weakening gamma and neutrons. Calculations of radiation shielding quantities show that cement composites containing tungsten carbide and thallium oxide waste powder are a suitable combination and a practical material for radiation control. In addition, by returning industrial waste to the production sector, they will also be effective in reducing environmental pollution. In general, the cement composite sample containing iron, thallium, zinc, zirconium, tungsten, and carbon elements shows a high potential for radiation protection applications. This study highlights the effective radiation shielding potential of cementitious composites and demonstrates the importance of advancing safety measures in medical and industrial radiation applications.

Use of 3D-printed polylactic acid/bioceramic composite scaffolds for bone tissue engineering in preclinical in vivo studies: A systematic review

3D-printed composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. The aim of the study was to systematically review the feasibility of using PLA/bioceramic composite scaffolds manufactured by 3D-printing technologies as bone grafting materials in preclinical in vivo studies. Electronic databases were searched using specific search terms, and thirteen manuscripts were selected after screening. The synthesis of the scaffolds was carried out using mainly extrusion-based techniques. Likewise, hydroxyapatite was the most used bioceramic for synthesizing composites with a PLA matrix. Among the selected studies, seven were conducted in rats and six in rabbits, but the high variability that exists regarding the experimental process made it difficult to compare them. Regarding the results, PLA/Bioceramic composite scaffolds have shown to be biocompatible and mechanically resistant. Preclinical studies elucidated the ability of the scaffolds to be used as bone grafts, allowing bone growing without adverse reactions. In conclusion, PLA/Bioceramics scaffolds have been demonstrated to be a promising alternative for treating bone defects. Nevertheless, more care should be taken when designing and performing in vivo trials, since the lack of standardization of the processes, which prevents the comparison of the results and reduces the quality of the information. STATEMENT OF SIGNIFICANCE: 3D-printed polylactic acid/bioceramic composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. Since preclinical in vivo studies with animal models represent a mandatory step for clinical translation, the present manuscript analyzed and discussed not only those aspects related to the selection of the bioceramic material, the synthesis of the implants and their characterization. But provides a new approach to understand how the design and perform of clinical trials, as well as the selection of the analysis methods, may affect the obtained results, by covering authors' knowledgebase from veterinary medicine to biomaterial science. Thus, this study aims to systematically review the feasibility of using polylactic acid/bioceramic scaffolds as grafting materials in preclinical trials.

Additive Manufacturing of Material Scaffolds for Bone Regeneration: Toward Application in the Clinics

Additive manufacturing (AM) allows the fabrication of customized bone scaffolds in terms of shape, pore size, material type and mechanical properties. Combined with the possibility to obtain a precise 3D image of the bone defects using computed tomography or magnetic resonance imaging, it is now possible to manufacture implants for patient-specific bone regeneration. This paper reviews the state-of-the-art of the different materials and AM techniques used for the fabrication of 3D-printed scaffolds in the field of bone tissue engineering. Their advantages and drawbacks are highlighted. For materials, specific criteria, were extracted from a literature study: biomimetism to native bone, mechanical properties, biodegradability, ability to be imaged (implantation and follow-up period), histological performances and sterilization process. AM techniques can be classified in three major categories: extrusion-based, powder-based and liquid-base. Their price, ease of use and space requirement are analyzed. Different combinations of materials/AM techniques appear to be the most relevant depending on the targeted clinical applications (implantation site, presence of mechanical constraints, temporary or permanent implant). Finally, some barriers impeding the translation to human clinics are identified, notably the sterilization process.