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A high loading of high‐density and high‐atomic‐number fillers are necessary to obtain desirable X‐ray attenuation characteristics from radiation shields. However, at high filler loadings, the mechanical and viscoelastic properties of polymers are severely impaired, posing a long‐term threat to the mechanical integrity and radiation protection, and the radiation shield temperature may increase after prolonged exposure to ionizing radiation, accelerating the aging of the polymer matrix. In addition, inadequate thermal conduction can make the user uncomfortable while using radiation shields for personal protection. Unfortunately, little attention has been paid to the viscoelastic, stress relaxation, and thermal conductivity‐related features of these densely loaded systems, despite the significant effect of these parameters on long‐term applications and user compliance. In the present work, two different styrene butadiene styrene (SBS) copolymers were used to develop SBS‐tungsten (W) composites. At 500 phr W loading, significant attenuation of X‐rays was achieved along with good tensile strength and elongation at break. The results indicate that the concentration of styrene in the SBS and W loading substantially affected the attenuation, mechanical and rheological properties, and tensile stress relaxation rates. The thermal conductivity increased by >100%, and after gamma irradiation, faster cooling was observed in the W‐loaded composites beyond 300 phr of W loading. The 40% styrene composite demonstrated superior heat transfer at high W loadings owing to the better dispersion and distribution of the W filler in the SBS matrix. Rheological results showed that SBS‐W composites with 30% styrene had a more pronounced Payne effect than those with 40% styrene. Stress relaxation and morphological analyses also revealed changes in the W dispersion in the SBS matrix depending on the styrene content. [ABSTRACT FROM AUTHOR]

Aim: This article aimed to present the salient features of the in-house developed Java program for the determination of inflection point and dosimetric parameters of flattening filter-free (FFF) photon beam. Reference levels for the dosimetric parameters of the FFF photon beams were also presented. Materials and Methods: Beam profiles of 6 MV FFF and 10 MV FFF photon beams for a collimator setting of 20 cm × 20 cm measured at 10 cm depth in an isocentric setup acquired from various institutions were analyzed using an in-house developed Java program and manual method. The values of reference dose value (RDV), field size, penumbra, and degree of un-flatness (defined as the lateral separation between 90% [X90%], 75% [X75%], and 60% [X60%] dose points on the profile) were calculated and compared. The reference values of field size, penumbra, and degree of un-flatness were also determined for Varian and Elekta medical electron linear accelerators (LINACs). Results: The maximum differences for RDV determined using the Java method and manual method are 2.4% and 2.7% for 6 and 10 MV FFF photon beams, respectively. The maximum difference between the values of field size, penumbra, and degree of un-flatness determined using Java and manual methods is within 1.3 mm. The reference values of field size and penumbra for Varian LINACs are 19.94 ± 0.10 cm and 0.83 ± 0.08 cm (6 MV FFF) and 19.95 ± 0.10 cm and 0.83 ± 0.08 cm (10 MV FFF). Similarly, the reference values of field size and penumbra for Elekta LINACs are 20.02 ± 0.09 cm and 0.94 ± 0.12 cm (6 MV FFF) and 20.03 ± 0.11 cm and 0.97 ± 0.16 cm (10 MV FFF). Conclusions: A software program was developed in Java for analyzing the beam profiles of FFF photon beams. The results of Java-derived values of dosimetric parameters of FFF photon beams were found in good agreement with the values determined using the manual method. The reference values of these parameters were also derived and quoted using a large cohort of the data. [ABSTRACT FROM AUTHOR]

Aim: In nanoparticles-aided radiotherapy, the radiation sensitivity of tumor is increased with the infusion of nanoparticles in tumor. This therapeutic modality is capable of delivering enhanced dose to tumor, without exceeding the normal tissue tolerance dose. Further, the quantification of the enhanced dose using suitable dosimeter is important. The present study is aimed at measuring the dose enhancement factors (DEFs) using the combination of nanoparticles-embedded alginate (Alg) film and unlaminated Gafchromic EBT3 film. Materials and Methods: Gold nanoparticles (AuNPs)- and silver nanoparticles (AgNPs)-embedded Alg polymer films were synthesized and characterized using standard techniques. Further, a customized version of the Gafchromic EBT3 film, i.e., unlaminated EBT3 film, was specially fabricated. The DEFs were measured using Xoft Axxent electronic brachytherapy device. Results: The surface plasmon resonance (SPR) and particle size of AuNPs were found to be 550 and 15 ± 2 nm, respectively. In the case of AgNPs, the SPR and particle size were recorded as 400 and 13 ± 2 nm, respectively. The DEFs measured, using unlaminated EBT3 film, for Xoft Axxent electronic brachytherapy using AuNPs and AgNPs were 1.35 ± 0.02 and 1.20 ± 0.01, respectively. Conclusion: The increase in dose enhancement during nanoparticles-aided electronic brachytherapy can be attributed to dominance of photoelectric effect, due to the presence of low-energy X-rays. The investigation indicates that the Xoft Axxent electronic brachytherapy device is suitable for nanoparticles-aided brachytherapy. [ABSTRACT FROM AUTHOR]