The study investigates commercially available negative ion clothing, and evaluations are made using gamma-ray spectroscopy and Geant4 Monte Carlo simulations. Observed to contain naturally occurring radioactive material (NORM), evaluations are made of the radiological risk arising from the use of these as items of everyday wear, undergarments in particular. Organ doses from these were simulated using the MIRD5 mathematical female phantom, with the incorporation of dose conversion factors (DCFs). At 175 ± 26, 1732 ± 247, and 207 ± 38 Bq, for 238U, 232Th, and 40K respectively, item code S05 was found to possess the greatest activity, while item code S07 was shown to have the least activity, at 2 ± 0.5 and 15 ± 2 Bq, and again for 238U and 232Th, respectively. Sample code S11 recorded least activity, at 29 ± 5 Bq, for 40K. Among the clothing items, sample item code S05 offered the greatest concentrations of Th, U and Zr, with percentage means of 1.23 ± 0.1, 0.045 ± 0.001, and 1.29 ± 0.1, respectively, giving rise to an annual effective dose of 1.57 mSv/y assuming a nominal wearing period of 24 h per day. Accordingly, the annual public dose limit of 1 mSv can be exceeded by their use.

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Rhizophora spp. particleboards were prepared at approximately (20.0 × 20.0 × 1.0) cm3 and at 1.0 g·cm-3 target density. The mass attenuation coefficient of the soy-lignin bonded Rhizophora spp. particleboard was measured by Compton scattering using Ludlum configuration utilizing the Cesium-137 (137Cs). Monte Carlo (MC) GATE code was employed to simulate the scattering by using the same set-up. Compton scattering results from both experimental and simulation methods were compared with XCOM value of water. Half value layer (HVL) and mean free path (MFP) were calculated and analyzed. For Compton scattering method in comparison to XCOM value of water, both non-coated and coated samples showed a statistically non-significant value with p-value more than 0.05. The overall results suggested that the mass attenuation coefficient, HVL and MFP of soy-lignin bonded Rhizophora spp. particleboard based on Compton scattering study is within close agreement with XCOM value for water, exhibiting its potential as phantom materials.

Gadolinium-159 (159Gd) is a beta emitter with appropriate energy for therapeutic application. However, this radioisotope additionally emits gamma rays, enabling the distribution of 159Gd to be detected by a gamma camera after each therapeutic administration. The current research is innovative in the investigation of 159Gd as a theranostic radioisotope in the radioembolization of HCC using Monte Carlo (MC) simulation. For 159Gd therapeutic investigation, various patient scenarios including varying tumour involvement (TI), tumour-to-normal liver uptake ratio (T/N), and lung shunting (LS) were simulated using Geant4 MC to estimate the absorbed doses to organs at risk. For 159Gd planar imaging investigation, the SPECTHead example from GATEContrib (GitHub) was utilized, and inside a liver a tumour was created and placed inside a torso phantom and simulated using GATE MC simulation. The majority of 159Gd absorbed doses by normal liver and lungs were less than the maximum dose limitations of 70 Gy and 30 Gy, respectively. Absorbed doses to other organs were observed to be below 1 Gy. The utilization of 58 keV and 363.54 keV photopeaks in combination produced optimal planar imaging of 159Gd. This research gives new insights into the use of 159Gd as a theranostic radioisotope, with the potential to be used as an Yttrium-90 (90Y) alternative for liver radioembolization.

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