Modern models of s-process nucleosynthesis in stars require stellar reaction rates of high precision. Most neutron-capture cross-sections in the s-process have been measured, and for an increasing ...number of reactions the required precision is achieved. This does not necessarily mean, however, that the stellar rates are constrained equally well, because only the capture of the ground state of a target is measured in the laboratory. Captures of excited states can contribute considerably to stellar rates that are already at typical s-process temperatures. We show that the ground-state contribution X to a stellar rate is the relevant measure to identify reactions that are or could be well constrained by experiments and apply it to (n,{gamma}) reactions in the s-process. We further show that the maximum possible reduction in uncertainty of a rate via determination of the ground-state cross-section is given directly by X. An error analysis of X is presented, and it is found that X is a robust measure with mostly small uncertainties. Several specific examples (neutron capture of {sup 79}Se, {sup 95}Zr, {sup 121}Sn, {sup 187}Os, and {sup 193}Pt) are discussed in detail. The ground-state contributions for a set of 412 neutron-capture reactions around the s-process path are presented in a table. This allows identification of reactions that may be better constrained by experiments and that cannot be constrained solely by measuring ground-state cross-sections (and thus require supplementary studies). General trends and implications are discussed.
Eu has been standardized by three independent 4π β-γ coincidence counting systems with beta detectors as proportional counter, plastic scintillator and liquid scintillator along with the CIEMAT/NIST ...method. The average activity concentration by primary methods was linked to key comparison reference value (KCRV) by comparing it with that of 4π γ ionization chamber (GIC) whose calibration factor was determined from the KCRV (BIPM.RI(II)-K1.Eu-152 and CCRI(II)-K2.Eu-152) and deviates from GIC by ± 0.16% indicating good agreement within standard uncertainties.
Thehuman internal dosimetry of the radionuclidic impurities of samarium-153 in a new bone-seeking radiopharmaceutical,
Sm-1,4,7,10tetraazacyclododecanetetramethylenephosponic acid (
Sm-DOTMP), has ...been estimated from preclinical data. The effective dose from the impurities in lower-specific-activity
Sm is less than 17% of the effective dose from pure Sm-153. It has a background-equivalent radiation time for a dosage of 37 MBq/kg of less than one-half year.
Molecular imaging can report on the status of the tumor immune microenvironment and guide immunotherapeutic strategies to enhance the efficacy of immune modulation therapies. Imaging agents that can ...rapidly report on targets of immunomodulatory therapies are few. The programmed death ligand 1 (PD-L1) is an immune checkpoint protein over-expressed in several cancers and contributes to tumor immune suppression. Tumor PD-L1 expression is indicative of tumor response to PD-1 and PD-L1 targeted therapies. Herein, we report a highly specific peptide-based positron emission tomography (PET) imaging agent for PD-L1. We assessed the binding modes of the peptide WL12 to PD-L1 by docking studies, developed a copper-64 labeled WL12 (64CuWL12), and performed its evaluation in vitro, and in vivo by PET imaging, biodistribution and blocking studies. Our results show that 64CuWL12 can be used to detect tumor PD-L1 expression specifically and soon after injection of the radiotracer, to fit within the standard clinical workflow of imaging within 60 min of administration.
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•A highly specific PD-L1 binding peptide, WL12, was developed as a PET imaging agent.•64CuWL12 demonstrates specific binding to PD-L1 in vitro and in vivo.•64CuWL12-PET allows PD-L1 detection in cancers within 60 min of administration.•WL12 binding interactions with PD-L1 overlaps with that of PD-1.
Twenty surface sediment samples were gathered from Chasma Lake, deciding the radionuclides
137
Cs,
226
Ra,
228
Ra,
232
Th, and
40
K and their associated hazard indices. The deliberate radionuclide ...activities of present research have been contrasted with earlier research, and acquired outcomes in the present study are found below the results in the world. The radiation hazard indices following the presence of natural radionuclides in sediment samples were estimated, and the results assigned the values of all the determined radiological indices found inside the worldwide suggested limits. It was concluded from the current review that the sediment of Chashma Lake is safe for construction and agriculture and does not make radiation dangerous to the nearby local area of the lake.
Therapy with
Y-labeled fibroblast activation protein inhibitors (
Y-FAPIs) was recently introduced as a novel treatment concept for patients with solid tumors. Lesion and organ-at-risk dosimetry is ...part of assessing treatment efficacy and safety and requires reliable quantification of tissue uptake. As
Y quantification is limited by the low internal positron-electron pair conversion rate, the increased effective sensitivity of digital silicon photomultiplier-based PET/CT systems might increase quantification accuracy and, consequently, allow for dosimetry in
Y-FAPI therapy. The aim of this study was to explore the conditions for reliable lesion image quantification in
Y-FAPI radionuclide therapy using a digital PET/CT system.
Two tumor phantoms were filled with
Y solution using different sphere activity concentrations and a constant signal-to-background ratio of 40. The minimum detectable activity concentration was determined, and its dependence on acquisition time (15 vs. 30 min per bed position) and smoothing levels (all-pass vs. 5-mm gaussian filter) was investigated. Quantification accuracy was evaluated at various activity concentrations to estimate the minimum quantifiable activity concentration using contour-based and oversized volume-of-interest-based quantification approaches. A ±20% deviation range between image-derived and true activity concentrations was regarded as acceptable. Tumor dosimetry for 3 patients treated with
Y-FAPI is presented to project the phantom results to clinical scenarios.
For a lesion size of 40 mm and a clinical acquisition time of 15 min, both minimum detectable and minimum quantifiable activity concentrations were 0.12 MBq/mL. For lesion sizes of greater than or equal to 30 mm, accurate quantification was feasible for detectable lesions. Only for the smallest 10-mm sphere, the minimum detectable and minimum quantifiable activity concentrations differ substantially (0.43 vs. 1.97 MBq/mL). No notable differences between the 2 quantification approaches were observed. For the investigated tumors, absorbed dose estimates with reliable accuracy were achievable.
For lesion sizes and activity concentrations that are expected to be observed in patients treated with
Y-FAPI, quantification with reasonable accuracy is possible. Further dosimetry studies are needed to thoroughly investigate the efficacy and safety of
Y-FAPI therapy.
The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has ...increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their
behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.
Nanoparticle-based materials, such as drug delivery vehicles and diagnostic probes, currently under evaluation in oncology clinical trials are largely not tumor selective. To be clinically ...successful, the next generation of nanoparticle agents should be tumor selective, nontoxic, and exhibit favorable targeting and clearance profiles. Developing probes meeting these criteria is challenging, requiring comprehensive in vivo evaluations. Here, we describe our full characterization of an approximately 7-nm diameter multimodal silica nanoparticle, exhibiting what we believe to be a unique combination of structural, optical, and biological properties. This ultrasmall cancer-selective silica particle was recently approved for a first-in-human clinical trial. Optimized for efficient renal clearance, it concurrently achieved specific tumor targeting. Dye-encapsulating particles, surface functionalized with cyclic arginine-glycine-aspartic acid peptide ligands and radioiodine, exhibited high-affinity/avidity binding, favorable tumor-to-blood residence time ratios, and enhanced tumor-selective accumulation in αvβ3 integrin-expressing melanoma xenografts in mice. Further, the sensitive, real-time detection and imaging of lymphatic drainage patterns, particle clearance rates, nodal metastases, and differential tumor burden in a large-animal model of melanoma highlighted the distinct potential advantage of this multimodal platform for staging metastatic disease in the clinical setting.
Figure shows the clustering of radioactive variables. Display omitted
•The radiation hazard parameters were below the recommended values of safety limits.•Radiation hazard indices reflect study area ...become radiological safe to human beings.•Pearson correlation, PCA and HCA results are in good agreement with each other.
This paper reports on the distribution of three natural radionuclides 238U, 232Th and 40K in coastal sediments from Pattipulam to Devanampattinam along the East coast of Tamilnadu to establish baseline data for future environmental monitoring. Sediment samples were collected by a Peterson grab samples from 10m water depth parallel to the shore line. Concentration of natural radionuclides were determined using a NaI(Tl) detector based γ-spectrometry. The mean activity concentration is ⩽2.21, 14.29 and 360.23Bqkg−1 for 238U, 232Th and 40K, respectively. The average activity of 232Th, 238U and 40K is lower when compared to the world average value. Radiological hazard parameters were estimated based on the activity concentrations of 238U, 232Th and 40K to find out any radiation hazard associated with the sediments. The radiological hazard parameters such as radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), the annual gonadal dose equivalent (AGDE), annual effective dose equivalent (AEDE), external hazard index (Hex) internal hazard index (Hin), activity utilization index (AUI) and excess lifetime cancer (ELCR) associated with the radionuclides were calculated and compared with internationally approved values and the recommended safety limits. Pearson correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied in order to recognize and classify radiological parameters in sediments collected at 22 sites on East coast of Tamilnadu. The values of radiation hazard parameters were comparable to the world averages and below the recommended values. Therefore, coastal sediments do not to pose any significant radiological health risk to the people living in nearby areas along East coast of Tamilnadu. The data obtained in this study will serve as a baseline data in natural radionuclide concentration in sediments along the coastal East coast of Tamilnadu.
Natural and artificial radionuclide concentrations were determined and evaluated in 12 different medicinal plants used in Rize Province of Turkey. The levels of
226
Ra,
232
Th,
40
K and
137
Cs were ...specified in medicinal plants and a germanium detector with high-purity was used for these measurements. Mean activity values of
226
Ra,
232
Th,
40
K and
137
Cs in medicinal plants were obtained to be 4.48, 1.83, 259.2 and 0.70 Bq kg
‒1
, respectively. The obtained values were compared with the values reached in similar studies conducted in different countries. All activity values of
226
Ra,
232
Th and
40
K determined in the present study were found to be lower than the worldwide mean values. In addition, the following radiological parameters were determined in medicinal plants and compared with the recommended limits: radium equivalent activity (Ra
eq
), annual gonadal dose equivalent (AGDE), absorbed gamma dose rate (D), exposure rate (ER), gamma representative level index (RLI), annual effective dose (AED), and excess lifetime cancer risk (ELCR). Pearson correlation coefficients were determined to assess the correlations between radioactive variables in medicinal plants. The radiological values determined in this study are within the recommended safety limit and the medicinal plants do not pose any significant radiological risk to human health.
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