Radioactivity Concentration Research Articles

Effect of sampling face velocity on the ultrafine particle surface collection efficiency of a cellulose membrane filter and a cellulose-glass fiber filter for environmental airborne radioactivity monitoring.

Surface collection efficiency (SCE) of a cellulose membrane filter (CMF) and a cellulose-glass fiber filter used in environmental monitoring for alpha-emitting radionuclides from nuclear facilities and natural radioactivity sources was evaluated for particles in the size range of 0.03-0.1μm at different levels of face velocity. The SCE of the CMF was higher than that of the cellulose-glass fiber filter, and only the membrane filter showed the dependence of SCE on the particle size at higher face velocity. The use of the CMF at higher face velocity in environmental radioactivity monitoring leads to measurements of the background alpha spectrum with more degradation under the changing particle size condition in the atmosphere. Consequently, that fact needs to be taken into account, along with the expected particle size distribution and concentration of the airborne radioactivity being sampled, when selecting a face velocity to achieve the best possible detection limit.

Behavior of radioactive cesium concentration for 13 years after FDNPP accident at Koriyama campus of Nihon University, Fukushima, Japan.

The concentration of the radioactive cesium (134Cs and 137Cs) in soils and in atmospheric fallouts has been measured at the Koriyama campus, Nihon University, after the Fukushima Dai-ichi Nuclear Power Plant accident for 13y, from October 2011 till September 2023 and now ongoing. The concentration of them decreased very rapidly due to decontamination activities and weathering effects, with an environmental half-life of 1.21 and 2.82y in soils, with those of 1.58 and 2.08y in atmospheric fallouts for 134Cs and 137Cs, respectively. The behavior of the decrease was not simple, due to particles raised from the surface soil in wooded areas that had not been thoroughly decontaminated or that had been accumulated due to the re-release of radioactive cesium by trees after decontaminated activity.

Assessment of Natural Radioactive Nuclides in Different Herbal Remedies Consumed in Katsina Metropolis

The use of herbal remedies to treat various ailments is common practice in developing countries, but the formulation of these products is usually complex, hence, the need for thorough quality checks especially with possible health risks these could pose. The research aimed to assess the natural radioactive nuclides concentrations of herbal formulations sold in Katsina Metropolis and ascertain the radiological implications for humans. The activity concentration of natural radionuclides in the fifteen (15) herbal remedies commonly consumed in the Katsina metropolis. Results from the above table show the activity of natural radionuclides in 15 herbal remedy samples found in the Katsina metropolis. The activity concentration of 40K ranges from 1027.76+51.30, which was found to have the highest radioactivity in the G, and 51.77+2.60 was found to be lowest in K. In 238U which ranges from 72.78+7.67 in O and the lowest concentration of 1.65+0.23 in E then lastly followed by the activity concentration of 232Th activity concentration varies from 20.18+1.13 as the highest and the lowest in B with 1.26+-0.07.

Ocular Tissue Distribution of Omidenepag Isopropyl in Rabbits and Cynomolgus Monkeys.

To evaluate the ocular distribution of omidenepag isopropyl (OMDI) and its active form omidenepag (OMD), an EP2 receptor agonist, after topical administration of OMDI into rabbit and monkey eyes, and to determine whether OMDI and OMD interact with target receptors or enzymes of other antiglaucoma agents. Both eyes of six rabbits and of 14 monkeys were topically instilled with 0.03% [14C]-OMDI. Rabbits were sacrificed after one to four hours, and ocular tissues were collected. Monkeys were sacrificed after 0.25 to 24 hours, and blood and ocular tissues were collected. Radioactivity was measured in each sample. The interactions of OMDI and OMD with the receptors and enzymes associated with the mechanisms of action of other antiglaucoma agents were evaluated. Most radioactivity applied to rabbit eyes was recovered as OMD from the cornea, aqueous humor, and iris-ciliary body. Similarly, high concentrations of radioactivity were observed in monkey cornea, bulbar/palpebral conjunctiva, and trabecular meshwork. OMD bound to EP2 receptors, but neither OMD nor OMDI bound to α2A, β1, and β2 adrenergic receptors or inhibited enzymatic activities of CA1 and CA2. OMD and OMDI had little or no effect on ROCK1 and ROCK2. OMDI rapidly permeates rabbit and monkey corneas and is converted to OMD, which distributes into anterior ocular tissues. Neither OMD nor OMDI interacted with the target receptors or enzymes of other antiglaucoma agents, suggesting that OMD interacts highly selectively with EP2 receptors. OMDI is a specific antiglaucoma agent that interacts selectively with ocular EP2 receptors.

Assessment of radioactivity concentration levels in soil samples around some quarry sites in Akamkpa, Cross River State, Nigeria

Assessment of radioactivity concentration levels in soil samples around some quarry sites in Akamkpa, Cross River State, Nigeria

Measurements of Heavy Elements and Radioactivity Concentration Levels in Types of Fertilizers and Pesticides Commonly Used in Sana’a Yemen

This study aims to measure heavy metals (HMs) concentration and radioactivity concentration levels in fertilizer and pesticide samples collected from local markets in Sana’a, Yemen. Gamma spectroscopy employing a Survey Sodium Iodide NaI (TI) RIIDEYM-G detector was used for radiation and dose assessments. As for heavy metal analyses, this study used Inductively Coupled Optical Emission Spectroscopy (ICP-OES). Thirty samples were collected from local markets in Sana’a, Yemen. Radioactivity measurements show low levels of radioactivity concentration. The average dose rates due to fertilizer and pesticide samples were 1.14 and 1.07 mSv/y, respectively. These values are nearly equal to the recommended annual radiation dose rate limit (1mSv/y) recommended by the International Commission on Radiological Protection (ICRP). For heavy metal analysis, it was found that the average concentrations of heavy metals (HMs) (cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn)) in the fertilizer samples were 1.08 mg/kg, 4.944 mg/kg, 13.8495 mg/kg, 274.371 mg/kg, 3.30446 mg/kg, 15.35686 mg/kg, and 24.4547 mg/kg, respectively. Heavy metal concentrations in fertilizer samples were mainly less than European (EU) guideline limits, with the exception of a few samples. The average concentrations of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) in the pesticide samples were 0.8 mg/kg, 0.5784 mg/kg, 52.280 mg/kg, 73.4651 mg/kg, 2.4482 mg/kg, 3.199 mg/kg, and 1.1309 mg/kg, respectively. The heavy metal concentrations in pesticide samples were less than the corresponding values in fertilizer samples.

Assessment of natural radioactivity in the Higher and Tethys Himalayan Rocks along Manali-Leh Highway, India.

The Higher and Tethys Himalayan region of NW-Himalaya is less explored from the natural radioactivity mapping assessment, though geologically and tectonically, this region is still active. The concentration of primordial radionuclides (226Ra, 232Th, and 40K) in rock samples of the Manali-Leh Highway region of the Himalayas is determined in the present study using the HPGe detector. The radiological hazard parameters are also estimated in terms of radium equivalent activity (Raeq), annual effective dose (Ein and Eout), hazard indices (Hin, Hex, Hα, and Hγ), and gamma absorbed dose rate. SEM-EDS analysis was used to understand the mineralogical composition of the rocks. The activity concentration of 226Ra, 232Th, and 40K radionuclides varies from 1.4 ± 0.9 to 25.3 ± 1.2, 0.7 ± 0.5 to 59.6 ± 1.6, and BDL (below detection limit) to 830.3 ± 45.7Bqkg-1, with an average value of 13.0 ± 1.0, 21.7 ± 1.0, and 243.7 ± 25.2Bqkg-1, respectively. The average of Raeq in the study region lies within the safe limit of 370Bqkg-1. The hazard indices have values < 1, indicating no radiological hazards to the population from the rocks. The annual effective dose also has values less than the global average value. This study revealed that the rocks of the Higher Himalayan region have a higher concentration of natural radioactivity, while the Tethys Himalayan rocks have lower concentrations of 226Ra, 232Th, and 40K radionuclides. The origin of rocks from different lithologies may be the reason for the natural radioactivity variation. The average concentrations of primordial radionuclides in the region are within the world average indicating that the rocks of the region are safe to be used for different purposes.

Flood risk assessment of the Narmada Basin, India, under climate change scenarios

ABSTRACT Climate change has led to a significant rise in the occurrence of extreme events such as floods and droughts. It is essential to accurately assess the hazards linked to climate change to effectively tackle flood risks in the future. This study investigates the risk of flooding in the Narmada Basin under climate change scenarios. Future precipitation data of global climate models are used to create intensity–duration–frequency curves and peak flows are estimated using a hydrological model. These peak flows serve as inputs for the hydraulic model to simulate floods across various return periods. The fuzzy inference system (FIS) is employed to optimize releases and reduce peak flows to mitigate flood impacts. The findings indicate that the extent of flooding and maximum water depths increase with higher return periods and future scenarios, and optimizing the reservoir releases, decreases the extent of flooding. This decrease in inundation area ranges from approximately 9 to 10% in the Bargi-to-Indira Sagar section to 20–23% in the Indira Sagar-to-Omkareshwar Sagar segment. In the Omkareshwar Sagar-to-Sardar Sarovar segment, the flooded area diminishes by 17–18% under the Radioactive Concentration Pathway (RCP) 4.5 and by 12–14% under the RCP 8.5 scenarios.

Estimation of the Effective Radiation Dose in Nuclear Medicine Workers from Dhaka by Measuring Radioactivity in Urine Sample Resulting from Internal Exposure

This study estimates the effective doses and activity concentration from 151 urine samples which are collected from 15 (Fifteen) occupational workers at National Institute of Nuclear Medicine and Allied Science (NINMAS) in Dhaka, Bangladesh. The radioactivity concentration in urine sample is due to intake of I-131, Tc-99m and F-18. The samples have been analyzed using High Purity Germanium (HPGe) detector. The radioactivity of I-131 and Tc-99m was found 0.91 ± 0.26 BqL-1 to 504.49 ± 6.03 BqL-1 and 0.15 ± 0.21 BqL-1 to 191.19 ± 6.98 BqL-1 respectively. Radioactivity of F-18 was found from 0.031 ± 0.022 BqL-1 to 0.282 ± 0.065 BqL-1. The effective doses of occupational workers have been also calculated using the radioactivity concentration and the dose coefficient according to ICRP publication 78. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 64−80

Metabolism and disposition of zamicastat in rats

The metabolism and disposition of zamicastat, a reversible dopamine β-hydroxylase (DβH) inhibitor, developed for treatment of Pulmonary Arterial Hypertension (PAH), were investigated in rats after oral and intravenous administration of [14C]-zamicastat. Zamicastat was rapidly absorbed and widely distributed to peripheral tissues, with total radioactivity almost completely recovered 168 h post-dose. Its main route of excretion was via faeces, whilst urine and expired air had minor roles. Maximum plasma concentration of zamicastat-related radioactivity occurred in the first hours, remaining quantifiable up to 144 h. The unchanged zamicastat plasma peak was 2 h post-dose and declined to low levels over 24 h. Zamicastat metabolism occurs largely during the first 8 h with only one metabolite identified in the latest time-point (96 h), the isocyanic acid/thiocyanic acid (tautomeric forms). Zamicastat metabolic pathway involved multiple reactions comprising desulphurisation, oxidative desulphurisation, N-debenzylation followed by further oxidation or N-acetylation, and the unexpected multistep metabolic pathway leading to isocyanic acid/thiocyanic acid.

Pharmacokinetic analysis and simplified uptake measures for tumour lesion [18F]F-AraG PET imaging in patients with non-small cell lung cancer.

The novel positron emission tomography (PET) imaging tracer, [18F]F-AraG, targets activated T-cells, offering a potential means to improve our understanding of immune-oncological processes. The aim of this study was to determine the optimal pharmacokinetic model to quantify tumour lesion [18F]F-AraG uptake in patients with non-small cell lung cancer (NSCLC), and to validate simplified measures at different time intervals against the pharmacokinetic uptake parameter. Ten patients with early-stage NSCLC and three patients with advanced NSCLC underwent a dynamic PET scan of minimal 60min. Venous and/or arterial blood sampling was obtained at maximum seven time points. Tumour lesion time activity curves and metabolite-corrected input functions were analysed using single-tissue reversible (1T2k), two-tissue irreversible (2T3k) and two-tissue reversible (2T4k) plasma input models. Simplified uptake measures, such as standardised uptake value (SUV) and tumour-to-blood (TBR) or tumour-to-plasma ratio (TPR), were evaluated for different time intervals. Whole-blood and plasma radioactivity concentrations showed rapid clearance of [18F]F-AraG. Metabolite analysis revealed a low rate of metabolism, at 70min p.i., on average, 79% (SD = 9.8%) of the total radioactivity found in blood corresponded to intact [18F]F-AraG. The time activity curves were best fitted by the 2T3k model. Strong positive correlations were found for SUV (body weight (BW), lean body mass (LBM) or body surface area (BSA) corrected), TBR and TPR for any time interval between 20 and 70min p.i. against the 2T3k-derived Ki. The correlation of TBR at 60-70min p.i. with 2T3K-derived Ki (r (df = 20) = 0.87, p < 0.01), was stronger than for SUVBW (r (df = 20) = 0.80, p < 0.01). Tumour lesion [18F]F-AraG uptake in patients with NSCLC is characterised by a 2T3k model. TBR and TPR show most potential for simplified quantification of tumour lesion [18F]F-AraG uptake in patients with NSCLC.

Evaluation of Radioactivity Concentration and Hazard Indices in ash Some Hospitals Incinerators in Baghdad / Al Resafa

Due to their harmful effects on human health and their tendency to cause cancer, radionuclide concentrations and risk indicators have been measured in hospital incinerator ash. This was done by collecting samples ash of Hospitals Incinerators, examining them, and identifying the risks that emerged from the examination. Three samples Only taken for the study from certain hospitals affiliated with the Baghdad Al-Rusafa Health Department. High purity germanium gamma spectrometer (HPGe) were used to analyze the samples. The concentrations of potassium isotopes (K-40) range from (147.1±16.5 to 214.4±21.1 Bq/kg), While the range of concentrations for Ra-226 isotopes is (7.52±1 to 19±1.8 Bq/kg), and lead (Pb-212) isotope concentrations ranged from (10.1±1.1 to 11.1±1.5 Bq/kg). In addition, the isotope concentration of actinium (Ac-228) is 8.05±1. Radium equivalent (), risk index , annual effective dose equivalent radioactivity level index ), absorbed dose rate D, and lifetime cancer risk were calculated. The results showed that no radiation risk Only indicated by any of the risk indicators. This indicates that the ash from the hospital incinerator does not pose any radioactive danger.

Determination the concentration for uranium in phosphrous fertilizers by using nuclear track detector CR-39

The aim of this research was to study the concentrations of Uranium in the phosphorus fertilizers using Nuclear track detector (CR-39). Our present investigation is based on the study of 10 types samples for different kinds of phosphorus fertilizers which were available in the local market Some of them were Iraqi made and the others from different countries like, (Iran, Italy, Holland, Lebanon and Jordan) .. The result obtained shows that the Uranium concentration in phosphorus fertilizers samples varies from (3.59ppm) to(2.59ppm). Based on the radioactive concentration of Uranium in the samples all the results obtained between(3.59ppm) in the Iraqi super phosphate to (2.59ppm) in the mixture Iraqi phosphate fertilizer are within the international levels as given by IAEA (International atomic Energy Agency) date if compares that equal by 12ppm .

Long-Term Effects of 90Sr and 239+240Pu Contaminated on the Seafloor Sediment on the Transfer through Marine Food Web: Sensitivity to the Physical Property- and Sediment-Related Parameters

This study, as a follow-up to the &lt;sup&gt;137&lt;/sup&gt;Cs study of Kim et al. (2023), performs a set of sensitivity experiments on ocean physical properties and sediment-related parameters based on initial bottom contamination of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in the upper sediment layer. Both studies utilizes the Extended BURN model proposed by Bezhenar et al. (2016). The initial contamination levels were set to 3 and 0.4 Bq/kg, respectively, based on observations off the coast of Fukushima. The sensitivity experiments were divided into EXP-WOHAD, which examined the effects of the vertical diffusion coefficient and vertical sediment flux, and EXP-WHAD, which investigated the effects of ocean currents. The results of the EXP-WOHAD experiments showed that both radionuclides are more sensitive to sediment fluxes than to vertical diffusion coefficients. For both &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport was dominated by transport to the intermediate sediment layer rather than to seawater. Specifically, for &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport to seawater was insignificant due to its strong sorption properties in sediments. In terms of bioaccumulation, &lt;sup&gt;90&lt;/sup&gt;Sr accumulated most in fish and invertebrates, while &lt;sup&gt;239+240&lt;/sup&gt;Pu accumulated most in invertebrates, followed by zooplankton. Notably, &lt;sup&gt;239+240&lt;/sup&gt;Pu showed high bioaccumulation despite its low initial sediment contamination. The changes in radioactivity concentrations in the EXP-WHAD experiments were similar to those in the EXP-WOHAD experiments, and the bioaccumulation trends in biota were also comparable. This study confirms that the accumulation of radionuclides in seawater, intermediate sediments, and biota is sensitive to the marine physical environment and varies by nuclide. When the sediment flux increased by a factor of 100, the remaining radioactivity levels of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in biota after 100 years showed a significant reduction, decreasing by more than 900 and 30,000 times, respectively; it highlighting the importance of parameterization according to the physical environment of the area of interest.

Intensive agriculture, a pesticide pathway to >100 m deep groundwater below dryland agriculture, Cordoba Pampas, Argentina

Groundwater pesticide pollution in shallow groundwater is a well-established global phenomenon. However, deep aquifers are widely thought to be naturally protected from such modern contaminants, by confining geological barriers and upwards hydraulic gradients. Here we document pervasive pesticide pollution in >100 m deep artesian wells in a sedimentary aquifer below dryland agriculture. The vertical distribution of key groundwater markers, including numbers and concentrations of pesticides, stable (δ18O & δ2H) and radioactive (3H &14C) isotopes and ion concentrations were used to develop a conceptual model of pollutant transport to deep groundwater. Tritium, stable isotope and pesticide distributions in unconfined groundwater indicate that water table rise to <1 m below the surface (due to anthropogenic landscape modification and periodic flooding), has created a rapid pollutant ‘doorway’ to groundwater. Despite a lack of deep borehole pumping for irrigation, these rising water tables have permanently inverted previously upward hydraulic gradients towards the underlying semi-confined aquifer in some areas. Physical heterogeneities and/or leaky domestic boreholes then act as preferential transport avenues for surface pollutants to both unconfined and semi-confined groundwater. These pathways allow small aliquots of highly contaminated surface water and modern unconfined groundwater to mix with the pre-existing pre-modern deep groundwater, resulting in mixed isotopic signatures in deep wells (e.g., radiocarbon <5 pMC but detectable tritium) and detections of multiple synthetic pesticides in the deep aquifer, including AMPA at concentrations up to 4.93 µg/L and Metolachlor up to 0.015 µg/L. Our results demonstrate how semi-confined deep groundwaters may be contaminated by current agricultural techniques even where deep groundwater exploitation is limited. We urge measures to eliminate these pollutant pathways.

GROSS ALPHA/BETA ACTIVITY DETERMINATIONIN DRINKING WATER PROFICIENCY TESTS

Water intended for drinking purposes has to be analyzed first for gross alpha/beta activity according to national and international standards and recommendations. According to Albanian legislation, Article 6, the gross alpha/beta radioactivity concentration in water, should be below the level of 0.1 Bq/L and 1 Bq/L respectively for human consumption. Our laboratory participated in an interlaboratory comparison organized by IAEA Terrestrial Environmental Laboratory under suggestion of ALMERA members. Proficiency Test among environmental radioactivity monitoring laboratories for the determination of gross alpha/beta activity concentration in drinking water and contaminated surfaces (2018, 2020). Independent standard methods were used for the reference value determination. Each sample was pretreated on site with nitric acid until reaching a pH level below 2. By creating relatively non-polar surfaces, this procedure avoids a loss of radionuclide fractions due to absorption into the walls of the containers.The Gross alpha/beta activity measurements were done using gas-flow proportional counter (GPC) method. The total dissolved solids should not exceed a surface density of 5 mg/cm2 for gross alpha determination and 10 mg/cm2 for gross beta determination The performance of participating laboratories was evaluated with respect to the reference values using relative deviations. The results presented from our laboratory in both inter comparisons (IAEA-TEL-2018-03) and (IAEA-TEL-2020-03) were all acceptable. The laboratory for the measurement of gross alpha/beta radioactivity and our Institute as a part of Tirana University is in the process of accreditation, so far the participation in the inter comparisons exercise is very important.

Interlaboratory comparison of gross alpha/beta activity of drinking water over a decade

Interlaboratory comparison exercises for determining the gross alpha and beta activity concentrations in drinking water, organized by the National Institute for Radiological Protection (NIRP), China CDC, have been carried out since 2012. The purpose of this study is to assess the accuracy and precision of gross alpha and beta analyses of low-level radioactivity concentrations. Natural water samples were used for the comparison, and the performance of the participating laboratories was evaluated with respect to the reference values using the Z-score performance indicator. The comparison data from 2012 to 2022 were analyzed, where the percentage of laboratories with acceptable results was 80–92%, and the dispersion of the measurement results across laboratories became smaller over time. The results demonstrate that these exercises can help laboratories to resolve issues in gross α/β analysis and improve the consistency of the measurement results.

Total Radiological Dose and Safety Assessment of Workers in Radioactive Liquid Waste Storage Location in Al Tuwaitha Site

This study aims to determine the total effective dose (external and internal) in the radioactive liquid Waste Hall (WH) in the Radiochemistry Laboratories building (RCL) in Al- Tuwaitha site in order to estimate the radiation risk for workers in this place. The external effective dose was calculated by an indirect method using ThermoLuminescent Dosimeters (LiF: Mg, Ti (TLD-100)) by placing them in the waste hall for one month. The internal effective dose was estimated by collecting eight air samples (environmental samples) from different locations in WH using an air sampler pump (Sniffer) to collect air samples loaded with particles or dust which are deposited on cellulose filter papers (φ 125mm). This was done for two flow rates the lowest and the highest values of the air sampler pump of 5CFM and 20CFM, respectively.The filter papers were chemically treated using the digestion method. The radionuclides in these samples were measured using a gamma spectrometry system equipped with a high-purity germanium detector (HPGe), and the radioactivity concentration was measured using a gross alpha beta gamma system. The results showed 137Cs of low concentration was deposited on the filter paper. The total annual effective dose rate (external and internal) results showed that the highest in WH was (6358.97μSv/year) for the low probability scenario and (1589.74 μSv/year) for the realistic scenario.

Association between 99mTc-PSMA SPECT/CT imaging and prostate-specific antigen (PSA) and alkaline phosphatase (ALP) levels post-endocrine therapy in patients with prostate cancer and bone metastases

AimTo investigate the association between positive lesions detected by 99mTc-PSMA SPECT/CT and blood levels of prostate-specific antigen (PSA) and alkaline phosphatase (ALP) in patients with prostate cancer (PCa) and bone metastasis undergoing endocrine therapy. MethodsA retrospective analysis was performed on 43 patients diagnosed with PCa bone metastasis who underwent endocrine therapy. PSA, ALP, whole body bone imaging and 99mTc-PSMA SPECT/CT imaging were collected from all patients (Among them, 17 cases were re-examined 99mTc-PSMA SPECT/CT imaging). According to the results of the first 99mTc-PSMA SPECT/CT imaging for detecting bone metastasis, all cases were divided into two groups: positive group and negative group. The relationship between 99mTc-PSMA imaging and PSA and ALP was analyzed by ROC curve. Fisher exact probability method was used to examine the changes in imaging radioactivity uptake, PSA, and ALP levels in 17 patients after treatment, and P < 0.05 was statistically significant. ResultsAll 43 patients had different degrees of radioactive concentrations on whole-body bone imaging. The first 99mTc-PSMA SPECT/CT imaging showed positive bone metastases in 31 cases and negative bone metastases in 12 cases. ROC curve analysis of PSA and ALP, AUC were 0.778 and 0.770, respectively. When PSA > 1.13 ng/mL, 99mTc-PSMA SPECT/CT imaging diagnostic sensitivity was 93.55%, and specificity was 66.67%. When ALP was >86U/L, the diagnostic sensitivity of 99mTc-PSMA SPECT/CT imaging was 64.52%, and the specificity was 83.33%. In 17 cases, the PSA level decreased in 7 and increased in 10. There were 10 cases of increased ALP and 7 cases of decreased ALP levels. In the second 99mTc-PSMA imaging lesion, there were 9 cases with decreased or no uptake, and 8 cases with increased uptake or number of lesions. The changes in 99mTc-PSMA uptake by Fisher’s exact probability method were statistically significant (P < 0.05, P = 0.006, and P = 0.006, respectively), and ALP level was not statistically significant (P = 0.563). Conclusion99mTc-PSMA SPECT/CT imaging can detect PCa bone metastases, which are related to PSA levels. When PSA > 1.13 ng/mL, the sensitivity of diagnosis and detection of positive bone metastases is higher, and when ALP is >86U/L, 99mTc-PSMA imaging has higher specificity.

THE CONCENTRATION OF NATURAL RADIATION SOURCES (NRS), MAINLY 238U, 232Th, and 40K, IN BUILDING MATERIALS (SAND, CLAY BRICKS, AND CONCRETE BLOCKS) USED ALONG KANGUNDO ROAD, NAIROBI KENYA

This research aimed at assessing the concentration of Natural Radiation Sources (NRS), mainly 238U, 232Th, and 40K, in building materials (sand, clay bricks, and concrete blocks) used along Kangundo Road in Nairobi City County. Human exposure to ionising radiation is largely due to Natural Radiation Sources (NRS). These radioactive elements with long half-lives are found in the Earths lithosphere and in construction materials with radiation levels varying due to their geology. A purposive random sampling method was deployed in this work to collect samples of building materials for analysis. The radioactivity concentration levels in the sampled building materials were determined using a NaI (TI) spectrometer at Kenyatta University laboratory. The activity concentration of 40K varied from 151 ± 8 to 2392 ± 120 Bq/kg, 238U varied from 27 ± 2 to 412 ± 21 Bq/kg and 232Th ranged from 54 ± 3 to 612 ± 31Bq/kg. More than 70 per cent of the samples analysed had activity concentration surpassing the world permissible limits of 420 Bq/kg, 33 Bq/kg, 45 Bq/kg for 40K, 238U and 232Th respectively. The study therefore recommended that assessment of radioactivity concentration for samples with high radioactivity values.