Cobalt (Co) doped zinc oxide (ZnO) microcrystals (MCs) are prepared by using the hydrothermal method from the precursor’s mixture of zinc chloride (ZnCl₂), cobalt-II chloride hexahydrate (CoCl₂·6H₂O), and potassium hydroxide (KOH). The smooth round cylindrical morphologies of the synthesized microcrystals of Co-doped ZnO show an increase in absorption with the cobalt doping. The antibacterial activity of the as-obtained Co-doped ZnO-MCs was tested against the bacterial strains of gram-negative (Escherichia coli, Klebsiella pneumonia) and gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes) via the agar well diffusion method. The zones of inhibition (ZOI) for Co-doped ZnO-MCs against E. coli and K. pneumoniae were found to be 17 and 19 mm, and 15 and 16 mm against S. Aureus and S. pyogenes, respectively. The prepared Co-doped ZnO-MCs were thus established as a probable antibacterial agent against gram-negative bacterial strains.

Tissue equivalent materials (TEM) are frequently used in research as a means to determine the delivered dose to patients undergoing various therapeutic procedures. They are used in routine quality assurance and quality control procedures in diagnostic and therapeutic physics. However, very few materials that are tissue equivalent have been developed for use in research at the low photon energies involved in diagnosis radiology. The objective of this study is to describe a series of TEMs designed to radiographically imitate human tissue at diagnostic photon energies. TEMs for adipose, cortical bone, fat, lung, and muscle tissues were investigated in terms of energy absorption and exposure buildup factors for photon energy range 15–150 keV and for penetration depths up to 40 mean free path. BUF was computed based on GP-fitting method. Moreover, we also compared some radiological properties, including the total attenuation and the energy-absorption attenuation, the effective atomic number, and the CT number at 30, 100, and 120 kVp. We found that SB3, Glycerol trioleate, and MS15 perfectly mimic cortical bone, fat, and muscle tissues, respectively. Additionally, AP6 and Stracey latex are good TEM for adipose and lung tissues, respectively. The results of this work should be useful in radiation diagnosis and dosimetry applications for the large physician researcher community.

This work concerns study of self-absorption factor (SAF) and dose rate constants of zirconium-89 (⁸⁹Zr) for the purpose of radiation protection in positron emission tomography (PET) and to compare them with those of ¹⁸F-deoxyglucose (¹⁸F-FDG). We analyzed the emitted energy spectra by ¹⁸F and ⁸⁹Zr through anthropomorphic phantom and calculated the absorbed energy using Monte Carlo method. The dose rate constants for both radionuclides were estimated with 2 different fluence-to-effective dose conversion coefficients. Our estimated SAF value of 0.65 for ¹⁸F agreed with the recommendation of the American Association of Physicists in Medicine (AAPM). The SAF for ⁸⁹Zr was in the range of 0.61-0.66 depending on the biodistribution. Using the fluence-to-effective dose conversion coefficients recommended jointly by the American National Standards Institute and the American Nuclear Society (ANSI/ANS), the dose rate at 1 m from the patient for ¹⁸F was 0.143 μSv·MBq⁻¹·hr⁻¹, which is consistent with the AAPM recommendation, while that for ⁸⁹Zr was 0.154 μSv·MBq⁻¹·hr⁻¹. With the conversion coefficients currently recommended by the International Committee on Radiological Protection (ICRP), the dose rate estimates were lowered by 2.8% and 2.6% for ⁸⁹Zr and ¹⁸F, respectively. Also, we observed that the AAPM derived dose is an overestimation near the patient, compared to our simulations, which can be explained by the biodistribution nature and the assumption of the point source. Thus, we proposed new radiation protection factors for ⁸⁹Zr radionuclide.