Evaluation of radiation attenuation properties on a various composition of polydimethylsiloxane (PDMS) for fabrication of kidney phantom

Chemical compounds such as polydimethylsiloxane (PDMS) and hydrogen silicone (HS) have been extensively used for fabricating medical phantoms due to its human tissue equivalency. This study aimed to evaluate the mass attenuation coefficient, effective atomic number, and other radiation attenuation properties of various polydimethylsiloxane samples and to verify the best material that can be used to simulate the kidney tissue. There are six samples of polymers in total, which are denoted as S0, S1, S2, S3, S4 and S5; these were 20/0/0, 16/4/0, 16/0/4, 12/4/4, 10/4/6 and 8/4/8, respectively with the composition of PDMS, HS and water. The Photon Shielding and Dosimetry (Phy-X/PSD) software (Phy-x.net) were used to estimate the attenuation properties, and the results were compared with the theoretical values obtained from the XCOM platform. The values of effective atomic number, mass attenuation coefficient, and linear attenuation coefficient, for PDMS S0 are reported to be the highest compared to all other samples, as S0 is based on 100% PDMS without any water and HS. The S1 sample, which only contained 20% of HS, was found to be higher than S2 sample, which had 20% water but without any HS. Hence, the water in samples significantly influences the radiation attenuation properties for photon energy. The Zeff for soft tissue and PDMS are different; their respective atomic numbers differ due to a presence of higher elements such as Si. This study reveals that the modified material, S1 samples constructed from 80% PDMS and 20% hydrophilic can be used to simulate the kidney in terms of the total mass attenuation coefficient, CT number and effective atomic number

Strain-induced cesium bismuth bromide perovskite/bismuth oxide bromide composite with enhanced optical properties

Perovskite halides are well suited for optoelectronic applications because of their excellent optical properties. Among them, cesium bismuth bromide (Cs3Bi2Br9) has emerged as a promising lead-free optical material to replace lead-based perovskite halides. This can be achieved by introducing a hydrated perovskite passivation layer, BiOBr. However, previous work was solely limited to bismuth oxide bromide (BiOBr) passivation on the Cs3Bi2Br9 surface layer and did not address composite synthesis from two different phases. Herein, we report the discovery and characterization of Cs3Bi2Br9/BiOBr composite via a pre-precipitation method using isopropanol (IPA) and hydrous ethanol (EtOH). Williamson-Hall plot analysis of the X-ray diffraction (XRD) results showed the successful formation of a Cs3Bi2Br9/BiOBr composite with an induced-strain effect when EtOH was introduced. The ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectra showed that the absorption and emission peaks of Cs3Bi2Br9 were located at 340 nm and 410 nm, respectively. A redshift in the absorption onset and energy bandgap generates a 190% increase in PL emission for the EtOH-synthesized perovskite sample. The enhancement is correlated to the induced effect in the Cs3Bi2Br9 phase, where BiOBr could act as an agent to improve the optical properties of Cs3Bi2Br9 by inducing strains other than the surface passivation layer

Investigation of CsBr:BiBr3 precursor ratio concentration on cesium bismuth bromide perovskite formation

The effect of precursor ratios on the formation of Cs3Bi2Br9 via a re-precipitation synthesis method has been studied thoroughly. X-ray diffraction analysis showed that the precursor ratio was critical for the Cs3Bi2Br9 phase formation. The Cs-rich or Bi-rich precursor ratio resulted in diverse perovskite structure formation of Cs3BiBr6 and Cs3Bi2Br6 with micron size platelet and semi-micron size crystal morphology respectively. Unreacted BiBr3 precursor remains in the supernatant solution under Bi-rich conditions. The synthesized powder dispersed in toluene shows the degradation of the Cs3Bi2Br9 phase at Cs-rich conditions. Photoluminescence quantum yield (PLQY) of 0.73 % was identified in Cs3Bi2Br9 with a large contribution to the exciton-related recombination process. A precursor ratio CsBr:BiBr3 of 3.0:2.0 is proposed to form a single-phase Cs3Bi2Br9 structure, as the deviation in precursor ratio would promote the Cs3BiBr6 structure growth and affect the material’s optical performance

Mechanical and Imaging Properties of a Clinical-Grade Kidney Phantom Based on Polydimethylsiloxane and Elastomer

Medical imaging phantoms are considered critical in mimicking the properties of human tissue for calibration, training, surgical planning, and simulation purposes. Hence, the stability and accuracy of the imaging phantom play a significant role in diagnostic imaging. This study aimed to evaluate the influence of hydrogen silicone (HS) and water (H2O) on the compression strength, radiation attenuation properties, and computed tomography (CT) number of the blended Polydimethylsiloxane (PDMS) samples, and to verify the best material to simulate kidney tissue. Four samples with different compositions were studied, including samples S1, S2, S3, and S4, which consisted of PDMS 100%, HS/PDMS 20:80, H2O/PDMS 20:80, and HS/H2O/PDMS 20:40:40, respectively. The stability of the samples was assessed using compression testing, and the attenuation properties of sample S2 were evaluated. The effective atomic number of S2 showed a similar pattern to the human kidney tissue at 1.50 × 10−1 to 1 MeV. With the use of a 120 kVp X-ray beam, the CT number quantified for S2, as well measured 40 HU, and had the highest contrast-to-noise ratio (CNR) value. Therefore, the S2 sample formulation exhibited the potential to mimic the human kidney, as it has a similar dynamic and is higher in terms of stability as a medical phantom