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Abstract Background Continuously monitored external dose-rate signals from remote dose-rate meters (DRMs) were analyzed to determine the effective half-life (Teff) of 131I in differentiated thyroid cancer (DTC) patients. The aim is to gain novel understanding of the excretion of radioactive iodine (RAI) in DTC patients and to demonstrate that a remote DRM system can be reliably used for real-time monitoring of external dose-rates of DTC patients. Methods 110 DTC patients who received postoperative RAI therapy between September 2018 and February 2023 in Turku University Hospital were studied retrospectively. The external dose-rates of the patients were continuously monitored during their hospitalization with a remote DRM fixed in the ceiling of the isolation room. Generalized linear mixed model (GLMM) was used to analyse the association between logarithmical Teff and patient characteristics. Results The median Teff for all patients was 12.60 h (Q1: 10.35; Q3: 14.75 h). Longer Teffs were associated with higher BMI (p = 0.004), lower GFR (p

Background: Continuously monitored external dose-rate signals from remote dose-rate meters (DRMs) were analyzed to determine the effective half-life (Teff) of 131I in differentiated thyroid cancer (DTC) patients. The aim is to gain novel understanding of the excretion of radioactive iodine (RAI) in DTC patients and to demonstrate that a remote DRM system can be reliably used for real-time monitoring of external dose-rates of DTC patients. Methods: 110 DTC patients who received postoperative RAI therapy between September 2018 and February 2023 in Turku University Hospital were studied retrospectively. The external dose-rates of the patients were continuously monitored during their hospitalization with a remote DRM fixed in the ceiling of the isolation room. Generalized linear mixed model (GLMM) was used to analyse the association between logarithmical Teff and patient characteristics. Results: The median Teff for all patients was 12.60 h (Q1: 10.35; Q3: 14.75 h). Longer Teffs were associated with higher BMI (p = 0.004), lower GFR (p < 0.001), and diabetes (p = 0.007). Our study also revealed that neither age nor subsequent RAI therapies have a significant impact on the whole body Teff (p = 0.522 and p = 0.414, respectively). Conclusion: Patients with higher BMI, decreased GFR, or diabetes have a longer whole-body Teff of 131I. Ceiling-mounted remote DMRs can reliably be used to determine patient's Teff. Since Teff values vary among patients, ceiling-mounted meters can be used to optimize the length of radiation isolation period at the hospital while improving patient comfort and staff efficiency. [ABSTRACT FROM AUTHOR]

Objective: Radioiodine (I-131) therapy for hyperthyroidism is a well-established and safe treatment option. This study aimed to investigate the relationship between the computed tomography (CT) value and the function and volume of the thyroid gland by identifying the factors that induce changes in the CT value of patients with hyperthyroidism. Methods: This retrospective study evaluated 38 patients with Graves' disease and 10 patients with Plummer disease. To obtain the mean CT value and volume of the thyroid gland, the entire thyroid gland was set as the region of interest. A test dose of 3.7 MBq I-131 was administered before initiating I-131 therapy, and the radioiodine uptake (RIU) rate was assessed after 3, 24, 96, and 168 h. An approximate curve was plotted based on the RIU values obtained, and the effective half-life (EHL) was calculated. The correlation between the mean CT value and the volume of the thyroid gland, 24-h RIU, EHL, and the free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), and TSH receptor antibody (TRAb) levels was evaluated. Results: The CT value exhibited a significant positive correlation with EHL in patients with Graves' disease (r = 0.62, p < 0.0001) as well as patients with Plummer disease (r = 0.74, p < 0.05). However, it did not display any correlation with the remaining parameters. Conclusion: The CT value is significantly correlated with EHL, suggesting that it reflects thyroid function and is mainly related to the factors associated with iodine discharge. [ABSTRACT FROM AUTHOR]

Current patient release criteria established in NRB-99/2009 relate to four radionuclides used in Russia that period of the document preparation. These criteria were calculated only considering the radionuclide decay. Thus, these criteria give conservative assessments which require the patient to stay in dedicated protected room (“hot” room) of the radiotherapy department for several days and do not allow to radionuclide therapy to be given in the outpatient hospital which certainly reduces the availability of this type of treatment. Consideration of the biological excretion of the radiopharmaceutical will be able to make the patient release criteria after radionuclide therapy significantly softer. Recently, new promising radionuclides and radiopharmaceuticals for therapy have appeared, the introduction of which into medical practice is obstructed by the lack of the patient release criteria. Current study is devoted to justification of improvement the approach to definition of patient release criteria after radionuclide therapy with promising and applied radiopharmaceuticals considering biological excretion of radiopharmaceutical. As examples, calculations of patient release criteria were performed for 177Lu-PSMA, 177Lu-DOTA-TATE, 131I-mIBG и Na131I. The dosimetric model used for calculation is based on the model which was used for definition of the current patient release criteria in NRB-99/2009. Additionally, the biological excretion of the radionuclide in radiopharmaceutical, which was assessed according to the published data, was considered. Two phases of biological excretion were evaluated for considered radiopharmaceuticals (fast and slow fractions). The main contribution of the radionuclide decrease in the patient’s body during the first hours after the injection is made by the fast-eliminated fraction. During 4-6 hours after the administration about 50% of these radiopharmaceuticals eliminated via urine. The calculation of patient release criteria were performed for slow-elimination fractions which characterize the decrease of radionuclide activity in the body after the patient release. The following effective half-lives were used: 177Lu-PSMA – 60 hours, 177Lu-DOTA-TATE – 100 hours, 131I-mIBG – 45 hours, Na131I – 7.5 days. The calculations demonstrate when planning a course of radionuclide therapy with four administrations of 177Lu-PSMA, the release of a patient is allowed at the dose rate of 20 μSv/h from the patient at the distance of 1 m; in case of radionuclide therapy with 177Lu-DOTA-TATE, release of a patient is allowed at the dose rate of 12 μSv/h. Considering the fast-eliminated fraction in the first hours after the administration, it can be assumed that more patients with normal renal function can undergo radionuclide therapy with 177Lu-PSMA in the outpatient hospital. Some patients after the 177Lu-PSMA administration and patients in the therapy with 177Lu-DOTA-TATE may be held in the department in the “hot” rooms for 1-2 days until the dose rate decrease to the acceptable levels. The consideration of biological excretion of radiopharmaceutical makes it possible to soften patient release criterion for 131I-mIBG by four times and for Na131I – by 10%. It will allow to release patients after radionuclide therapy earlier without reduce of radiation safety of people around the patient and will increase the capacity of radionuclide therapy department.

Simple Summary: 166Ho-based transarterial radioembolization (TARE) procedures for liver cancer treatment can be safely applied in a hospital setting. It has been shown that a fraction of the injected radioactivity is excreted. Knowledge of the amount and nature of these excretions is vital for dosimetry, radiation protection, record keeping, and compliance with national and international regulations regarding waste disposal. Radioprotection measures should be taken, with particular attention to the urine of patients after treatment procedures. Regulations regarding radioactive waste must be considered. After transarterial radioembolization (TARE) with microspheres loaded with holmium-166, radioactivity is excreted from the body. The aim of this study was to evaluate radioactive renal and intestinal excretions after TARE planning and treatment procedures with holmium-166-loaded microspheres and to correlate the findings with the intratherapeutic effective half-life. Urinary and intestinal excretions of patients who underwent TARE procedures were collected during postinterventional intervals of 24 h (TARE planning) and 48 h (TARE treatment). Whole-body effective half-life measurements were performed. Calibrations of the 166Ho measuring system showed evidence of long-living nuclides. For excretion determination, 22 TARE planning procedures and 29 TARE treatment procedures were evaluated. Mean/maximum total excretion proportions of the injected 166Ho were 0.0038%/0.0096% for TARE planning procedures and 0.0061%/0.0184% for TARE treatment procedures. The mean renal fractions of all measured excretions were 97.1% and 98.1%, respectively. Weak correlations were apparent between the injected and excreted activities (R2 planning/treatment: 0.11/0.32). Mean effective 166Ho half-lives of 24.03 h (planning) and 25.62 h (treatment) confirmed low excretions. Radioactive waste disposal regulations of selected jurisdictions can be met but must be reviewed before implementing this method into clinical practice. Inherent long-living nuclide impurities should be considered. [ABSTRACT FROM AUTHOR]

Summary: An investigation on the nuclear transmutations of elemental long‐lived fission products (LLFPs) in a fast reactor is being conducted in Japan, focusing on the Se‐79, Zr‐93, Tc‐99, Pd‐107, I‐129, and Cs‐135, to reduce the environmental burden. With their high neutron flux and adequate excessive neutrons, fast reactors are considered strong candidates for transmuting those LLFPs into stable isotopes or shorter effective half‐lives under the partition and transmutation (P/T) strategy. In this investigation, the LLFP subassembly is assumed to be loaded into the radial blanket region of a Japanese MONJU class sodium‐cooled fast reactor (710 MWth). This work focuses on two LLFPs, namely, I‐129 and Tc‐99. The LLFPs are mixed with YD2 or YH2 moderator material to enhance the LLFP transmutation rate. The results include the optimal position of the LLFP assembly in the radial blanket and the optimal moderator volume fraction to optimize the transmutation performance indices, that is, the transmutation rate (TR, %/year), the support factor (SF is defined as the ratio of transmuted to produced LLFP), and the effective half‐life (T‐half) of the LLFPs. A countermeasure is also devised to resolve the expected higher power peak at the fuel assembly adjacent to the LLFP assembly. The neutronics and burnup analyses are conducted using the continuous‐energy Monte Carlo SERPENT2 code with the JENDL‐4.0 nuclear data library. [ABSTRACT FROM AUTHOR]

Aim: Radioiodine therapy (RIT) may trigger the development of Graves' ophthalmopathy (GO) or exacerbate pre-existing subclinical GO. Therefore, glucocorticoid administration is recommended for patients with pre-existing GO. Aim of this study was to analyze the influence of glucocorticoid therapy with methylprednisolone on intratherapeutic effective half-life (EHL) of radioiodine-131 in patients with Graves' disease (GD) as recent studies showed an effect for prednisolone. Methods: In a retrospective study, 264 patients with GD who underwent RIT without any additional antithyroid medication were evaluated. Intrathyroidal EHL was determined pre- and intratherapeutically. Patients with co-existing GO (n = 43) received methylprednisolone according to a fixed scheme starting 1 day prior to RIT, patients without GO (n = 221) did not receive any protective glucocorticoid medication. The ratios of EHL during RIT and during radioiodine uptake test (RIUT) were compared. Results: Patients receiving methylprednisolone showed a slight decrease of the mean EHL from 5.63 d (RIUT) to 5.39 d (RIT) (p > 0.05). A comparable result was obtained in patients without glucocorticoids (5.71 d (RIUT) to 5.47 d (RIT); p > 0.05). The ratios of the EHL between RIT and RIUT failed to show a significant difference between the two groups. EHL is therefore not significantly influenced by an additional protective treatment with methylprednisolone. Conclusions: In the present study a decreased intrathyroidal EHL under glucocorticoid medication with methylprednisolone could not be detected. Therefore, co-medication with methylprednisolone in patients with GO may be preferred to avoid an intratherapeutic decrease of EHL by accompanying protective glucocorticoides. [ABSTRACT FROM AUTHOR]

When planning treatment for Graves' disease with 131I, the effective half-life (Teff) should be estimated individually as it depends on biological characteristics such as iodine uptake and excretion, which differ from an individual to another (Berg et al. 1996). All the methods to quantify Teff described in the literature are quite complex and are difficult to be used in clinical routine. With the aim of optimizing this process, a simplified method is proposed here to evaluate Teff of 131I during treatment of Graves' disease. The present study suggests improving the method of determining Teff based on thermoluminescence dosimetry. This involves implementing a new method and includes reduction of TLD (Thermoluminescent Dosimeter) measurements. The proposed method was validated on patients with Graves' disease. The radiation dose delivered to the patients was determined using the MIRD (Medical Internal Radiation Dosimetry) formalism. The relative difference between Teff obtained based on seven measurement intervals at [0–24 h, 24–48 h, 48–72 h, 72–96 h, 96–120 h, 120–144 h, 144–168 h] and based on three measurement intervals at [0–24 h, 72–96 h, 144–168 h] and [0–24 h, 120–144 h, 144–168 h] was 1.9% and 3.81%, respectively. Comparison of doses obtained based on a general Teff and on a personalized Teff gave a statistically significant difference with a correlation coefficient R2of 0.44. The Teff obtained from just three measurements was found to be sufficiently accurate and easily applicable. The results obtained demonstrate the need to determine and use personalized Teff values instead of using a fixed value of 7 days. [ABSTRACT FROM AUTHOR]

The environmental monitoring survey using this organisms was called “Caddisfly Watch” and this activity has involved both scientists and local people for collecting them.A simple method is needed for the continuous monitoring of radiocesium (137Cs) contamination in riverine environments after the 2011 accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in Japan. In a program called “Caddisfly Watch”, we used larvae of the caddisfly Stenopsyche marmorata (Trichoptera: Stenopsychidae) to monitor the spatial distribution and estimate effective half-life (Teff) of 137Cs pollution in riverine environments. Caddisfly larvae showed that the highest concentration of 137Cs among several aquatic organisms and no apparent variation between growth stage. In addition, caddisfly larvae reflected 137Cs concentrations in suspended particulate matter in their gut, and that showed no seasonal variation, better reproducibility, and significant correlation with those in sediment. Results indicate that caddisfly larvae can be used as a biological sampler of suspended particulate matters. The Teff values of 137Cs concentrations in caddisfly larvae estimated by single component decay function model showed significant fit. The Teff values in Kuma, Maeda, downstream Niida, upstream Niida, Ohkawa, and Ukedo river showed 2.8, 5.7, 3.1, 6.7, 0.6, and 4.8 years (34, 68, 38, 80, 6.9, and 58 months), respectively. The results of declining trend in this study were similar to those in previous reported in Fukushima. Further continuous observations using this simple approach of “Caddisfly Watch” make it possible to predict the future of the contamination with radioactive Cs in the river environment.

This work is devoted to a comparative study of pharmacokinetic properties of complex compounds labeled with gallium-68 aminoglucose (68Ga-NODA-AG) or thioglucose (68Ga-NODA-TG) in BALB/c mice after intravenous administration. Statistical significance of activity accumulation in most organs and tissues was observed only at 5 min post-injection. At the following terms, these values didn't have any statistical significance in most organs and tissues. Activity was eliminated from organs and tissues with high rate. The biological and effective half-lives of 68Ga-NODA-AG and 68Ga-NODA-TG from organs and tissues were less than 1 hour. [ABSTRACT FROM AUTHOR]

This paper presents the results of long-term investigations of 137Cs activity concentrations in chicken meat and eggs from northwest Croatia for the period 1987–2018. The research has been done as a part of monitoring program of radioactive contamination in Croatia. The highest activity concentrations in both of these foodstuffs were measured in 1987 and have been decreasing exponentially ever since. The Fukushima-Daiichi accident in 2011 did not cause any increase of 137Cs activity concentrations. The ecological half-life for 137Cs was estimated to be 8.0 and 8.4 years for chicken meat and eggs respectively. The correlation between 137Cs in fallout and chicken meat as well as between 137Cs in fallout and eggs is very good, the respective correlation coefficients being 0.79 and 0.72, indicating that fallout was the main source of 137Cs contamination in both foodstuffs. The estimated effective doses received by adult members of the Croatian population due to the intake of radiocaesium by chicken meat and egg consumption for the overall observed period are very small, 2.0 and 0.6 µSv respectively. Therefore, chicken meat and chicken egg consumption was not a critical pathway for the transfer of radiocaesium to humans. [ABSTRACT FROM AUTHOR]

137Cs concentrations were measured in mushrooms in an area affected by radioactive discharges of the Mining-and-Chemical Combine (MCC) (Rosatom, Russia) in 2002–2017. The sources of radionuclides in the study sites were global fallouts and waterborne and airborne radioactive discharges of the MCC. The mushroom species Suillus granulatus and S. luteus showed the highest 137Cs concentrations (140–7100 Bq kg−1) for this area. Over the entire monitoring period, no significant change in 137Cs concentration was observed in the Suillus spp. samples collected from the sites with the aerial deposition of radionuclides. In the floodplain site with the radionuclide deposition from water and air, a significant decrease in the average 137Cs concentration was observed in the period between 2004 and 2017: a three-fold decrease in Suillus spp. and a nine-fold decrease in Lactarius deliciosus. The effective half-lives of 137Cs in fruiting bodies of the mushrooms L. deliciosus and Suillus spp. in this site were 3.6 ± 0.6 and 9.2 ± 2.7 years, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The effective half-life of radioiodine is an important parameter for dosimetry in differentiated thyroid cancer patients, particularly in children. We determined the pre-therapy and post-therapy effective half-life in different types of lesions, i.e., remnant, node, or lung metastases. Methods: Of 84 patients recruited, 27 were < 18 years (group 1) and the remaining 57 were between 18 and 21 years (group 2). A total of 114 studies were conducted and 253 lesions were analyzed. Serial whole-body scans were acquired at 24, 48, and ≥ 72 h after administration of iodine-131. Region of interests was drawn over lesions to determine counts in the lesion. Time versus counts graphs were plotted and mono-exponentially fitted to determine effective half-life. Results: The post-therapy effective half-life was found to be lesser than pre-therapy effective half-life in all types of lesions and in all groups. Median effective half-life was found maximum in intact lobe, minimum in the lung, and intermediate in remnant and nodes. In the assessment of all lesions together, pre- and post-therapy median and interquartile range (IQR) effective half-life were 59.8 (37–112) h and 48.6 (35.2–70.8) h (p < 0.0001) in group 1, 73.9 (46.2–112.7) h and 60 (57.4–85.9) h (p < 0.0001) in group 2, and 68.6 (41.53–112.36) h and 54.7 (36–80.6) h (p < 0.0001) in combined group, respectively. Importantly, the pre- and post-therapy median effective half-life serially dropped after each successive cycles of iodine-131. Conclusions: There was a significant difference in pre-therapy and post-therapy effective half-life in all types of lesions. These results may have implications in calculating the correct therapeutic dose in children and in young adults. [ABSTRACT FROM AUTHOR]

Purpose: Renal function and effective half-life (t1/2,eff) of I-131 have not been fully elucidated in patients undergoing radioiodine therapy (RAIT) for differentiated thyroid cancer (DTC). Aim of the present analysis was to evaluate the potential of cystatin C-based estimated glomerular filtration rate (eGFRCysC) in comparison to conventional creatinine (eGFRCrea) and to verify which methods to determine t1/2,eff are most accurate to predict t1/2,eff.Methods: Forty-eight patients receiving whole-body I-131-scintigraphy were included. eGFRCysC was compared to eGFRCrea with regard to accuracy of t1/2,eff prediction. Three different methods (i.e. blood-based, gamma camera-based and probe-based) and two protocols with either three (short period,SP; up to 42 h) or four (long period,LP; up to 114 h) time points were compared using the Akaike's information criterion.Results: The eGFRCysC measurement is more likely than eGFRCrea in predicting the t1/2,eff. High correlation coefficients were found between t1/2,eff assessed by gamma camera and probe measurements and blood-based determination revealed lower values. Patients with normal eGFR showed higher values of t1/2,eff of LP compared to SP.Conclusions: eGFRCysC should be included in further study protocols. As camera and probe measurements lead to almost superimposable results, one of the methods is expendable. Blood-based results of t1/2,eff were lower, presumably due to unspecific iodine retention, whereas the lower correlation with renal function may be caused by individual differences in intestinal iodine resorption. SP-protocols up to 42 h after I-131 administration are sufficient to determine t1/2,eff. Further studies are necessary for specific recommendations regarding I-131 activity reduction during RAIT in patients with DTC and renal insufficiency. [ABSTRACT FROM AUTHOR]

Purpose: The main goal of this study was to determine the dose rate constant of radionuclides used in Nuclear Medicine when they are biodistributed in humans. The secondary goal was to calculate the effective half‐life for the same radionuclides in order to determine the realistic dose due to the incorporation of these nuclides for a variety of reasons. Methods: Anthropomorphic voxel phantoms, with characteristics based on ICRP‐110 were considered and the biodistributions of radionuclides were simulated using the Monte Carlo code MCNPX. In addition, the effective half‐lives for all simulated radionuclides were calculated. Results: The results for the dose rate constant, taking into account the patient body attenuation, showed no correlation between the biodistribution of the radionuclide and the energy of the radiation emitted. Body attenuation ranged between 6.7% and 94.1%. Also, the priority angle of radiation emission was determined. The values found for the body attenuation agree with the literature, corroborating the calculation of the body dose rate constant. Conclusions: The results for the body dose rate constant calculated in this work, for 30 radionuclides and 57 radiopharmaceuticals, and their effective half‐lives, may be used to estimate the dose emitted by a person who has incorporated a radionuclide in the Nuclear Medicine activity range. This dose will be optimized when the body dose rate constant and the effective half‐life determined in this study are used together with dose reduction factors. [ABSTRACT FROM AUTHOR]

Featured Application: Rapid decrease of radiocesium contamination through the rivers was observed but high accumulation of radiocesium over floodplains in the downstream areas should be noted for future river decontamination. Radiocesium monitoring in sediments and river water has been conducted along five rivers in Minami-Soma City during 2012–2016 to clarify the temporal changes of radiocesium contamination in these rivers. Sampling has been performed annually under normal flow conditions. Sediment and river water samples were collected from four or five sampling sites along each river. Gamma-ray measurements of sediments were performed using a low-background Ge detector and unfiltered river water was utilized to determine radiocesium concentration using a well-type Ge detector. The 137Cs concentration in sediments was highest at upstream sites and slowly decreased to downstream sites for all rivers reflecting the high radioactive contamination in the upstream area. Temporal decrease of the 137Cs concentration was observed in sediments and river water for each river. The effective half-lives were 1.3–2.1 y for sediments, and 0.9–2.1 y for river water from rivers with upstream dams. On the undammed river, the effective half-lives were 4.7 y and 3.7 y for sediment and river water, respectively. Much longer effective-half-lives might reflect the direct transfer of radiocesium from forests and plains to the river. The 137Cs concentration in riverbed was low in downstream areas, however, accumulation of 137Cs over the floodplain was observed. Rapid decrease of 137Cs contamination through rivers will put residents at ease, but high accumulation of radiocesium over floodplains should be noted for future river decontamination. [ABSTRACT FROM AUTHOR]

We measured cesium-137 concentrations from June 2011 to May 2016 in three wild edible herbaceous species, i.e. giant butterbur ( Petasites japonicus ), knotweed ( Trifolium pratense ), and mugwort ( Artemisia indica var. maximowiczii ), that were grown on the same sampling field in Chiba Prefecture, Japan. The pattern of plant 137 Cs concentrations versus time could be described well with the two-component exponential decline (short-term and long-term components), and the half-lives of these three plant species were between 103 and 230 d for the short component and 970–3830 d for the long component. During April 2014 to May 2016, due to the slow decline in the 137 Cs concentrations in these three plant species, we assumed that the bioavailable 137 Cs fraction in the observation ground soil was almost the same in this period. Then, values of the aggregated transfer factor from soil to plant ( T ag ) were calculated for these plant species, and the values ranged from 5.3 × 10 −5 to 1.6 × 10 −4 m 2 kg −1 -fresh. We also calculated T ag values for wild edible herbaceous plants in Fukushima Prefecture using open data sources that were reported from January 2014 to June 2016. The five plant species included were giant butterbur ( P. japonicus ), western bracken fern ( Pteridium aquilinum ), Japanese royal fern ( Osmunda japonica ), ostrich fern ( Matteuccia struthiopteris ) and momijigasa ( Parasenecio delphiniifolius ). The T ag values ranged from 1.4 × 10 −4 to 7.0 × 10 −4 m 2 kg −1 -fresh and were similar to those measured in our Chiba field study. [ABSTRACT FROM AUTHOR]

Radionuclides deposited on land by global fallouts and nuclear power station accidents spread over coastal environments through estuarine areas connecting land to ocean. In this study, we monitored activity concentration of radiocaesium in surface sediment and re-suspended particles in Matsukawa-ura lagoon, the largest lagoon in Fukushima, after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident. Radiocaesium distribution in surface sediment varied spatiotemporally and irregularly due to the effect of tidal waves. The effective half-life was significantly shorter than physical half-life, suggesting some system of radiocaesium discharge in the lagoon. Sediment trap observation revealed re-suspended particles from sediment were transported to the ocean. For these reasons, it is suggested that re-suspension of particles in the lagoon and their transportation to the ocean by the seawater exchange process are important processes of radiocaesium discharge. Moreover, our results show that seawater exchange process contributes to the dispersion of radiocaesium in the ocean. [ABSTRACT FROM AUTHOR]

The activity concentration of 137 Cs in samples of coniferous forest humus collected across the territory of the Czech Republic in 1995 and 2005 was analysed, and it was found significantly correlated with the surface deposition caused by the Chernobyl accident. The effective (12.8 y) and environmental (22.3 y) half-lives of radiocaesium in humus were calculated and compared with those in spruce bark. The impact of important forest stand factors, that is, precipitation, content of organic matter, age of trees and pH, on the behaviour of 137 Cs in humus was studied. It was observed that humus samples with a higher proportion of organic matter, higher pH(H2O) and pH(CaCl2) contained higher amounts of 137 Cs. Conversely, with the age of trees, the activity concentration of 137 Cs in humus is decreasing. Higher precipitation and humus acidity decrease the reduction rate of the 137 Cs in humus. These stand factors increase bioavailability of 137 Cs in humus. The transfer and retention of available 137 Cs in biomass of organisms living in humus for a long time can satisfactorily explain the longer residence time of 137 Cs in humus affected by the studied factors. [ABSTRACT FROM AUTHOR]

It has been widely shown that nuclear fallout includes substances, which accumulate in organisms such as crustaceans, fish, mushrooms and lichens, helping to evaluate the activity concentration of contaminants accumulated on a long time. In this context, radiocaesium deposited in soil following the Chernobyl accident on 26 April 1986 is known to have remained persistently available for plant uptake in many areas of Europe. Studies on the lichen Stereocaulon vesuvianum show the plant's high capacity to retain radionuclides from the substrate and the air. After the Chernobyl accident, starting from September 1986, at the Radioactivity Laboratory (LaRa) of the University of Naples Federico II, four monitoring campaigns to evaluate the activity concentration of four isotopes of the two elements caesium and ruthenium ( 134 Cs, 137 Cs, 103 Ru and 106 Ru) were carried out until 1999. This study allowed the effective half-life of 134 Cs and 137 Cs to be estimated. Twenty-eight years after the accident, in December 2014, a further sampling was carried out; only 137 Cs was revealed beyond the detection limits, measuring activity concentrations ranging from 20 to 40 Bq/kg, while the other radionuclides were no longer observed due to their shorter half-life. The last sampling allowed more precise determination of the effective half-life of 137 Cs (6.2 ± 0.1 year), due to the larger dataset on a large time period. [ABSTRACT FROM AUTHOR]

Purpose To determine the thyroid clearance effective half-life [ABSTRACT FROM AUTHOR]

Radiocesium monitoring in sediments and river water has been conducted along five rivers in Minami-Soma City during 2012–2016 to clarify the temporal changes of radiocesium contamination in these rivers. Sampling has been performed annually under normal flow conditions. Sediment and river water samples were collected from four or five sampling sites along each river. Gamma-ray measurements of sediments were performed using a low-background Ge detector and unfiltered river water was utilized to determine radiocesium concentration using a well-type Ge detector. The 137Cs concentration in sediments was highest at upstream sites and slowly decreased to downstream sites for all rivers reflecting the high radioactive contamination in the upstream area. Temporal decrease of the 137Cs concentration was observed in sediments and river water for each river. The effective half-lives were 1.3–2.1 y for sediments, and 0.9–2.1 y for river water from rivers with upstream dams. On the undammed river, the effective half-lives were 4.7 y and 3.7 y for sediment and river water, respectively. Much longer effective-half-lives might reflect the direct transfer of radiocesium from forests and plains to the river. The 137Cs concentration in riverbed was low in downstream areas, however, accumulation of 137Cs over the floodplain was observed. Rapid decrease of 137Cs contamination through rivers will put residents at ease, but high accumulation of radiocesium over floodplains should be noted for future river decontamination.

Alpine regions in the federal state of Salzburg (Austria) have been intensively contaminated by Chernobyl fallout, necessitating long-term monitoring programs. The sites predominately affected are those in areas with soil developed on silicate bedrock, as these soils tend to be acidic, favouring high transfer factors for 137Cs. In addition, nutrient deficiency, low mineral and high organic matter content, and tough climatic conditions are causing the slow migration of 137Cs in the soil, which are associated with long effective half-lives in the biosphere. As a quantitative measure for effective half-lives, milk has been collected at nine alpine seasonal stock farming sites since 1988; at four sites, the monitoring is still ongoing (2020). For the period between 1999 and 2020, the decrease of 137Cs can be reasonably fitted with one effective half-life describing the time-trend. The effective half-lives obtained by this procedure vary between 9.3 ± 0.9 years and 18.8 ± 3.4 years. The effective half-lives show a weak negative correlation with the half-value depth of 137Cs, defined as the depth of the upper soil layer containing half of the deposited fallout inventory. The majority of the inventory is bound in the rooting zone of 0–10 cm, which is reflected by the small half value depths in the range between 3.2 and 4.4 cm. The soils investigated are acidic with pH values between 3.78 and 4.88, showing a pronounced negative correlation with the effective half-lives of 137Cs in milk. The data indicate that in these soils rich in organic matter, which are also almost totally devoid of clay minerals and have a very low clay size fraction, pH may be the dominating factor influencing the effective half-lives of 137Cs plant uptake and the subsequent contamination of milk. • Depth distribution of 137Cs in alpine soils. • Effective half-life of 137Cs contamination in milk from alpine production sites. • Correlation of soil pH with effective half-life of 137Cs in milk from alpine production sites. • Dependence of effective half-life of 137Cs in milk on soil parameters. [ABSTRACT FROM AUTHOR]

Published pre-Fukushima food monitoring data from 1963 to 1995 were used to study the long-term presence of Cs and Sr in rice and wheat. Effective half-lives ( T) were calculated for rice (Cs: 5.6 years; Sr: 6.7 years) and wheat (Cs: 3.5 years; Sr: 6.2 years), respectively. In rice, Cs exhibits a longer T because putrefaction processes will lead to the formation of NH ions that are efficient ion exchangers for mineral-adsorbed cesium ions, hence making it more readily available to the plant. Knowledge on the long-term behavior of radiocesium and radiostrontium will be important for Japanese food-safety campaigns after the Fukushima nuclear accident. [ABSTRACT FROM AUTHOR]

Radiocaesium ( 134 Cs and 137 Cs) release following the accident at the Fukushima Dai-ichi Nuclear Power Plant, belonging to the Tokyo Electric Power Company caused severe contamination of new tea plant ( Camellia sinensis (L.)) shoots by radiocaesium in many prefectures in eastern Japan. Because tea plants are perennial crops, there is the fear that the contamination might last for a long time. The objectives of this study were to reveal time series changes in the distribution of radiocaesium in tea plants after radioactive fallout and to evaluate the effect of pruning on reduction of radiocaesium concentrations in new shoots growing next year. The experimental tea field was located in Shizuoka, Japan, approximately 400 km away from the Fukushima Dai-ichi Nuclear Power Plant in a southwest direction. Time series changes in radiocaesium concentrations in unrefined tea, a tea product primarily produced for making Japanese green tea, from May 2011 to June 2013 and distribution of radiocaesium in tea plants from May 2011 to May 2012 were monitored. The radiocaesium concentrations in unrefined tea exponentially decreased; the effective half-lives for 134 Cs and 137 Cs were 0.30 and 0.36 y during the first 2 y after the accident, respectively. With time, the highest concentrations of 137 Cs moved from the upper to the lower parts of plants. Medium pruning 2–3 months after the accident reduced the concentration of 137 Cs in new shoots harvested in the first crop season of the following year by 56% compared with unpruned tea plants; thus, pruning is an effective measure for reducing radiocaesium concentration in tea. [ABSTRACT FROM AUTHOR]

Anthropogenic 137 Cs activity concentration, in surface sea water along the western and eastern coast of India has been estimated using the in-situ pre-concentration approach. Activity levels of 137 Cs ranges from 0.09–1.30 Bq m − 3 with an overall mean of 0.69 ± 0.29 Bq m − 3 . Latitudinal variation and higher depletion in activity concentration of 137 Cs at few locations were observed. Temporal change of 137 Cs in sea water along Indian coast unveils a lower effective half-life of 13.8 ± 0.7 y in comparison to Asia Pacific regional sea water. The results prevailed that the spatial distribution confers no fresh input of 137 Cs in Indian coastal region. [ABSTRACT FROM AUTHOR]

The Fukushima NPP accident caused a small but detectable cesium fallout in northern Finland, of the order of 1 Bq/m 2 . This fallout transferred further to soil, water, flora and fauna. By using modern HPGe detector systems traces of 134 Cs from the Fukushima fallout were observed in various samples of biota. In northern Finland different types of environmental samples such as reindeer meat, berries, fish, lichens and wolf were collected during 2011–2013. The observed 134 Cs concentrations varied from 0.1 Bq/kg to a few Bq/kg. By using the known 134 Cs/ 137 Cs ratio observed in Fukushima fallout the increase of the Fukushima accident to the 137 Cs concentrations was found to vary from 0.06 % to 6.9 % depending on the sample type. The aggregated transfer factors (T ag ) and effective half-lives (T eff ) for 134 Cs and 137 Cs were also determined and then compared with known values found from earlier studies which are calculated based on the fallout from the Chernobyl accident. Generally, the T ag and T eff values determined in this study were found to agree with the values found in the earlier studies. The T eff values were sample-type specific and were found to vary from 0.91 to 2.1 years for 134 Cs and the estimates for 137 Cs ranged between 1.6 and 19 years. Interestingly, the ground lichens had the longest T eff whereas the beard lichen had the shortest. In fauna, highest T ag values were determined for wolf meat ranging between 1.0 and 2.2 m 2 /kg. In flora, the highest T ag values were determined for beard lichens, ranging from 1.9 m 2 /kg to 3.5 m 2 /kg. [ABSTRACT FROM AUTHOR]

Introduction Preparation for postoperative radioiodine ablation for differentiated thyroid carcinoma is performed by either thyroid hormone withdrawal or recombinant human thyroid-stimulating hormone ( rhTSH) administration. There is little information on the impact of the method of preparation with respect to whole-body effective I-131 half-life and its potential clinical implications in the Australian setting. Methods A retrospective study was performed on patients admitted for adjuvant radioiodine ablation for non-metastatic differentiated thyroid carcinoma at the Royal Adelaide Hospital over a 4½-year period from 2009. Dose rate measurements were analysed for 19 rhTSH and 31 thyroid hormone withdrawal patients. Results The mean effective I-131 half-lives were 11.51 and 13.29 h for the rhTSH and thyroid hormone withdrawal groups, respectively, with no statistically significant difference between the two groups ( P = 0.761). This result differs from previously published data where withdrawal periods were typically longer, resulting in slower renal clearance and longer half-lives for withdrawal patients. Conclusions Our study did not demonstrate a significant difference in whole-body effective half-life of I-131 between the two methods of preparation for radioiodine ablation. This suggests that putative advantages of rhTSH over withdrawal in terms of whole-body radiation dose, duration of hospital admission and quality of life may be sensitive to duration of withdrawal. [ABSTRACT FROM AUTHOR]

To estimate the radiocesium decreasing rates from persimmon trees during a period of about 3 y following the accident at Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP), we conducted measurements of tree tissue parts collected in 2011–2013. The sampling was carried out in Chiba, 220 km south of FDNPP; radioactive fallouts discharged from FDNPP had mainly been observed in March–April 2011 on the sampling site. We measured 137 Cs concentrations in the tree tissue parts, i.e., fruits (flesh, skin and seeds), leaves and newly emerged branches, and then the effective half-lives ( T eff ) of 137 Cs were calculated. Leaf samples were classified into two types by sampling months according to the growing stages, that is, immature (April–May) and mature (June–November) leaves. All these parts showed exponential declines in 137 Cs concentration with good adjusted contribution ratios of higher than ca. 0.7. The calculated T eff values from all tissue parts were similar with the average of 229 d (range: 216–243 d). From these results, we concluded that each tree tissue was representative for the calculation of T eff . For comparison to these observation results, open source food monitoring data from 2011 to 2013 including 137 Cs data for persimmon fruits collected in Fukushima Prefecture were used to calculate T eff for persimmon trees. Values of T eff were obtained for persimmon fruits grown in each local government area in Fukushima Prefecture and they ranged from 303 to 475 d. [ABSTRACT FROM AUTHOR]

Purpose: Recombinant human thyroid-stimulating hormone (rhTSH)-based protocol is a promising recent development in the management of differentiated thyroid carcinoma (DTC). The objectives of this prospective study were: (1) to assess the feasibility and efficacy of the rhTSH primed I therapy protocol in patients with DTC with distant metastatic disease, (2) to perform lesional dosimetry in this group of patients compared to the traditional protocol, (3) to document the practical advantages (patient symptoms and hospital stay) of the rhTSH protocol compared to the traditional thyroid hormone withdrawal protocol, (4) to document and record any adverse effect of this strategy, (5) to compare the renal function parameters, and (6) to compare the serum TSH values achieved in either of the protocols in this group of patients. Methods: The study included 37 patients with metastatic DTC having lung or skeletal metastases or both. A comparison of lesional radiation absorbed dose, hospital stay, renal function tests, and symptom profile was undertaken between the traditional thyroid hormone withdrawal protocol and rhTSH-based therapy protocol. Dosimetric calculations of metastatic lesions were performed using lesion uptake and survey meter readings for calculation of effective half-life. Non-contrast-enhanced CT was used for assessment of tumor volume. Quality of life was assessed using the European Organization for Research and Treatment of Cancer (EORTC) QOL forms. A comparison of pretreatment withdrawal thyroglobulin (TG) was done with the withdrawal TG level 3 months after treatment. Results: The mean effective half-life of I in metastatic lesions was less during the rhTSH protocol (29.49 h) compared to the thyroid hormone withdrawal protocol (35.48 h), but the difference was not statistically significant ( p = 0.056). The mean 24-h % uptake of the lesions during the traditional protocol (4.84 %) was slightly higher than the 24-h % uptake during the rhTSH protocol (3.56 %), but the difference was not found to be statistically significant ( p = 0.301). The mean tumor radiation absorbed dose per mCi was less during the rhTSH protocol (6.04 rad/mCi) than during the thyroid hormone withdrawal protocol (8.68 rad/mCi), and the difference was statistically significant ( p = 0.049), though visual analysis of the rhTSH posttherapy scans showed avid concentration of I in the metastatic sites and revealed more lesions in 30 % of the patients compared to the traditional large dose scan and equal number of lesions in 65 % of the patients. Visual analysis of the traditional large dose scan, rhTSH pretreatment scan, and rhTSH posttherapy scans showed that the traditional large dose scan is better compared to the rhTSH 1 mCi scan as it showed more lesions in 19 of 37 patients (51.35 %). rhTSH posttherapy scans were better compared to the traditional large dose scans and rhTSH pretreatment scans. More lesions were seen on rhTSH posttherapy scans in 11 of 37 patients (29.7 %) compared to the traditional large dose scans and in 24 of 37 (64.86 %) patients compared to the rhTSH 1 mCi scans. Our findings demonstrate that the rhTSH primed pretreatment scan undertaken at 24 h after diagnostic dose is suboptimal to evaluate whether a metastatic lesion concentrates I. The majority of these lesions demonstrated radioiodine accumulation in the posttreatment scan. Quality of life as assessed using EORTC QOL-3 forms clearly showed that rhTSH improved the quality of life of patients compared to the thyroid hormone withdrawal protocol. Functional scale and global health status were significantly better in the rhTSH protocol compared to the thyroid hormone withdrawal protocol ( p < 0.001). The mean symptom scale score was significantly higher in the thyroid hormone withdrawal protocol (45.25) compared to the rhTSH protocol (13.59) ( p < 0.001). Of the 20 patients, 4 (20 %) had more than 25 % increase in the TG value on follow-up. The median hospital stay of patients receiving I therapy with the rhTSH protocol was shorter (2 days, range 2-8 days) compared to the thyroid hormone withdrawal protocol (3 days, range 1-8 days) and the difference was found to be statistically significant ( p = 0.007). The mean serum creatinine level was significantly lower in the rhTSH protocol (0.826 mg/dl) than the thyroid hormone withdrawal protocol (0.95 mg/dl) ( p = 0.013), though the mean blood urea level of patients during the rhTSH therapy protocol was slightly higher (22.81 mg/dl) than during the thyroid hormone withdrawal protocol (21.91 mg/dl) without statistical significance ( p = 0.55). The mean serum TSH on day 2 of the rhTSH protocol was 140.99 μIU/ml (range 71-176 μIU/ml) compared to 72.62 μIU/ml (range 2.05-154 μIU/ml) in the traditional protocol after around 4-6 weeks of thyroid hormone withdrawal ( p < 0.05). Conclusion: Overall, the rhTSH primed I therapy protocol was found to be feasible and a good alternative to the thyroid hormone withdrawal protocol in patients with metastatic DTC. The lesional dosimetry findings need to be further examined in subsequent studies. The rhTSH primed pretreatment scan at 24 h after diagnostic dose is suboptimal to determine whether a metastatic lesion concentrates I and the posttreatment scan is important for the correct impression. [ABSTRACT FROM AUTHOR]

Abstract: During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly 137Cs in fish and deer, have contributed significantly to doses and risks to the public. The “effective” half-lives (T e ) of 137Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974–2011, the T e s of 137Cs in Savannah River floodplain soil and vegetation were 17.0 years (95% CI = 14.2–19.9) and 13.4 years (95% CI = 10.8–16.0), respectively. These T e s were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of 137Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall T e of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the T e for 1990–2011 was significantly shorter (11.8 years, 95% CI = 4.8–18.8) due to an increase in the rate of 137Cs removal. The shortest T e s were for fish in SRS streams and the Savannah River (3.5–9.0 years), where dilution and dispersal resulted in rapid 137Cs removal. Long-term data show that T e s are significantly shorter than the physical half-life of 137Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating T e s and risky to extrapolate T e s beyond this period unless the processes governing 137Cs removal are clearly understood. [Copyright &y& Elsevier]