Serpentinites are metamorphic rocks that are widely applied as aggregates in the production of radiation-shielding concrete. Different varieties of massive serpentinite mountains located in Egypt exist without real investment. Hence, this study aims to evaluate the radiation shielding efficacy of three varieties of serpentinite rocks from different geological perspectives: mineralogical, geochemical, and morphological characteristics. X-ray diffraction, transmitted-light microscopy, and thermal analysis were required to characterize their mineralogical composition, while X-ray fluorescence was necessary to investigate their geochemical features. Moreover, scanning electron microscopy was used to detect their morphological characteristics. On the other hand, the PuBe source and stilbene detector were employed for the experimental determination of fast neutrons and γ-ray attenuations, which were conducted at energy ranges of 0.8–11 and 0.4–8.3 MeV, respectively. Based on the mineralogical, geochemical, and morphological characteristics of these rocks, the radiation attenuation capacity of lizardite > antigorite > chrysotile. However, these serpentinites can be applied as a natural alternative to some radiation-shielding concrete in radiotherapy centers and other counterpart facilities.

The purpose of this study was to assess the magnitude of radiation exposure during paediatric CT in Sudanese hospitals. Doses were determined from CT acquisition parameters using CT-Expo 2.1 dosimetry software. Doses were evaluated for three patient ages (0-1, 1-5 and 5-10 y) and two common procedures (head and abdomen). For children aged 0-1 y, volume CT air kerma index (Cvol), air Kerma-length product and effective dose (E) values were 19.1 mGy, 265 mGy.cm and 3.1 mSv, respectively, at head CT and those at abdominal CT were 8.8 mGy, 242 mGy.cm and 7.7 mSv, respectively. Those for children aged 1-5 y were 22.5 mGy, 305 mGy.cm and 1.1 mSv, respectively, at head CT and 12.6 mGy, 317 mGy.cm, and 5.1 mSv, respectively, at abdominal CT. Dose values and variations were comparable with those reported in the literature. Organ equivalent doses vary from 7.5 to 11.6 mSv for testes, from 9.0 to 10.0 mSv for ovaries and from 11.1 to 14.3 mSv for uterus in abdominal CT. The results are useful for dose optimisation and derivation of national diagnostic reference levels.

Natural and ¹³⁷Cs radioactivity in coastal marine sediment samples was measured using gamma spectrometry. Samples were collected at 16 locations from four beaches along the coastal area of Muscat City, Gulf of Oman. Radioactivity in beach sand was used to estimate the radiological risk parameters to humans, whereas the radioactivity in marine sediments was used to assess the radiological risk parameters to non-human biota, using the ERICA Tool. The average radioactivity concentrations (Bqkg⁻¹) of ²²⁶Ra, ²³²Th, ⁴⁰K, ²¹⁰Pb and ¹³⁷Cs in sediments (sand) were as follows: 16.2 (16.3), 34.5(27.8), 54.7 (45.6), 46.8 (44.9) and 0.08 (0.10), respectively. In sand samples, the estimated average indoor (${\mathrm{D}}_{\mathrm{in}}$) and outdoor (${\mathrm{D}}_{\mathrm{out}}$) air absorbed dose rates due to natural radioactivity were 49.26 and 27.4 and the total effective dose (${\mathrm{AED}}_{\mathrm{Total}}$; µSvy⁻¹) ranged from 150.2 to 498.9 (average: 275.2). The measured radioactivity resulted in an excess lifetime cancer risk (ELCR) in the range of 58–203 (average: 111) in and an average gonadal dose (AGD; µGy.y⁻¹) ranged from 97.3 to 329.5 (average: 181.1). Total dose rate per marine organism ranged from 0.035 µGy h⁻¹ (in zooplankton) to 0.564 µGy h⁻¹ (in phytoplankton). The results showed marine sediments as an important source of radiation exposure to biota in the aquatic environment. Regular monitoring of radioactivity levels is vital for radiation risk confinement. The results provide an important radiological risk profile parameter to which future radioactivity levels in marine environments can be compared.

This study was performed to measure the entrance surface air kerma (ESAK) for optimisation of chest X-ray examination of children in general radiography hospitals in Khartoum. ESAK was estimated using the X-ray tube output exposure and patient-specific exposure parameters collected during routine examinations. The estimated ESAK values per radiography ranged from 17 to 89 μGy, 32 to 161, 67 to 242, 77 to 278; and from 95 to 389 μGy for Newborn, 1, 5, 10 and 15 y children, respectively. Doses are comparable with a previous study and are somewhat higher than the UK reference dose levels. The study demonstrated the necessity to follow guidelines for quality radiograph as a key element in the optimisation of X-ray examination of children. Frequent dose measurements are of particular importance for the optimisation of X-ray examination of children in general radiography hospitals.