Alpha Decay Research Articles

Impact of cell geometry, cellular uptake region, and tumour morphology on 225Ac and 177Lu dose distributions in prostate cancer

BackgroundRadiopharmaceutical therapy with 225Ac- and 177Lu-PSMA has shown promising results for the treatment of prostate cancer. However, the distinct physical properties of alpha and beta radiation elicit varying cellular responses, which could be influenced by factors such as tumour morphology. In this study, we use simulations to examine how cell geometry, region of pharmaceutical uptake within the cell to model different internalization fractions, and the presence of tumour hypoxia and necrosis impact nucleus absorbed doses and dose heterogeneity with 225Ac and 177Lu. We also develop nucleus absorbed dose kernels for application to autoradiography images.MethodsWe used the GATE Monte Carlo software to simulate three geometries of LNCaP prostate cancer cells (spherical, cubic, and ovoid) with activity of 225Ac or 177Lu internalized in the cytoplasm or bound to the extracellular membrane. Nucleus S-values were calculated for each geometry, source region, and isotope. The cell models were used to create nucleus absorbed dose kernels for each source region describing the dose to each nucleus in a cell layer, which were applied to simulated tumours composed of normoxic, hypoxic, or necrotic cancer cells to obtain dose rate maps. Absorbed doses within the tumours and dose heterogeneity were analyzed for each tumour morphology and isotope. Cell geometry made a minimal impact on S-values to the nucleus, however internalization resulted in higher nucleus doses. Applying the kernels to the simulated tumour maps showed that doses to each cell type varied between 225Ac and 177Lu depending on tumour morphology. Dose heterogeneity within tumours was slightly higher with 225Ac, however the tumour morphology made a larger impact on dose heterogeneity compared to the choice of isotope, with hypoxic and necrotic tumours having very heterogeneous dose distributions.ConclusionsCell geometry simplifications may still allow robust results in simulation studies. Furthermore, the morphology of the tumour itself may make a larger impact on treatment response compared to other variables such as ratio of internalization. Finally, nucleus absorbed dose kernels were created that could enable microdosimetric studies with autoradiography.

Clinical Best Practices for Radiation Safety During an Alpha DaRT Treatment.

Alpha DaRT is a new alpha radiation treatment for treating solid tumors and is currently being evaluated through clinical trials worldwide. Being a novel radiation treatment, it is important to discuss the safety considerations and procedures that are needed to ensure safe use of this unique approach. The objective of this article is to provide a set of recommendations-radiation safety best practices that were developed based on operational and clinical experience.

Melanoma Cells from Different Patients Differ in Their Sensitivity to Alpha Radiation-Mediated Killing, Sensitivity Which Correlates with Cell Nuclei Area and Double Strand Breaks.

Background/Objective: In this study, for the first time, we examined and compared the sensitivity of four patient-derived cutaneous melanoma cell lines to alpha radiation in vitro and analyzed it in view of cell nucleus area and the formation of double-strand breaks (DSB). Melanoma cells sensitivity to alpha radiation was compared to photon radiation effects. Furthermore, we compared the sensitivity of the melanoma cells to squamous cell carcinoma. Methods: Human melanoma cell lines YDFR.C, DP.C, M12.C, and M16.C, and the squamous cell carcinoma cell line, CAL 27, were irradiated in vitro using Americium-241 as alpha-particle source. Cells were irradiated with doses of 0 to 2.8 gray (Gy). Cell viability, DNA DSB, and nuclear size were measured. Results: 1. Alpha radiation caused death and proliferation arrest of all four melanoma cell lines, but inter-tumor heterogeneity was observed. 2. The most sensitive cell line (DP.C) had a significantly larger nucleus area (408 µm2) and the highest mean number of DSB per cell (9.61) compared to more resistant cells. 3. The most resistant cell, M16.C, had a much lower nucleus area (236.99 µm2) and DSB per cell (6.9). 4. Alpha radiation was more lethal than photon radiation for all melanoma cells. 5. The SCC cell, CAL 27, was more sensitive to alpha radiation than all melanoma cells but had a similar number of DSB (6.67) and nucleus size (175.49 µm2) as the more resistant cells. 6. The cytotoxic effect of alpha radiation was not affected by proliferation arrest after serum starvation. 7. Killing of cells by alpha radiation was marginally elevated by ATR or topoisomerase 1 inhibition. Conclusions: This study demonstrates that various human melanoma cells can be killed by alpha radiation but exhibit variance in sensitivity to alpha radiation. Alpha radiation applied using the Intra-tumoral Diffusing alpha-emitters Radiation Therapy (Alpha DaRT) methodology may serve as an efficient treatment for human melanoma.

Chronic bronchitis and bronchial asthma: the impact of chronic occupational radiation exposure on incidence and mortality of Mayak nuclear workers.

The information about the radiation risk of non-cancer respiratory diseases is inconsistent and mainly corresponds to mortality. Previously, an increased risk of chronic bronchitis incidence was demonstrated in the cohort of workers employed at the first Russian nuclear facility Mayak Production Association who had been chronically exposed to gamma rays (externally) and to alpha-active plutonium aerosols (internally). Within this retrospective study, we performed analyses of incidence of and mortality from chronic bronchitis and bronchial asthma using improved estimates of radiation doses provided by the "Mayak Worker Dosimetry System (MWDS) - 2013". The cohort included 22,377 individuals hired in 1948-1982, and its follow-up was extended by 10 years (to the end of 2018). The excess relative risk of chronic bronchitis incidence per unit radiation dose (ERR/Gy) and the 95% confidence interval (95% CI) were: with the 0-year lag ERR/Gy=0.07 (95% CI -0.01, 0.17) for gamma exposure and ERR/Gy=0.36 (95% CI 0.13, 0.68) for alpha exposure; with the 10-year lag ERR/Gy=0.15 (95% CI 0.04, 0.30) for gamma exposure and ERR/Gy=0.54 (95% CI 0.19, 1.03) for alpha exposure. The chronic bronchitis mortality risk was significantly associated with internal alpha exposure only for certain worker categories: ERR/Gy=4.08 (95% CI 0.59, 14.3) in males; ERR/Gy=7.10 (95% CI 0.31, 70.44) in former smokers; ERR/Gy=7.94 (95% CI 1.71, 30.2) in workers with the smoking index above 20 pack×years. No association was observed in the chronic bronchitis mortality risk with external gamma exposure. No strong evidence was observed for the impact of gamma and alpha exposure on risk of mortality from chronic bronchitis. The study confirmed the significant positive linear association of the chronic bronchitis incidence risk with gamma and alpha radiation doses from occupational chronic external and internal exposure. However, the estimates of ERR/Gy of alpha particles from internal exposure appeared to be almost 2.4-3 times lower than those based on the MWDS-2008. The observed inconsistency requires further clarification. As for bronchial asthma in Mayak workers, no association was demonstrated in the incidence and mortality risks with occupational gamma and alpha radiation exposure.

Calculation of α-decay half-lives of 186−218Po isotopes and actinide nuclei using a new phenomenological potential

This paper is devoted to the calculations of alpha decay half-lives of [Formula: see text]Po [Formula: see text] isotopes and actinide nuclei between the atomic numbers Z = 90 and Z = 102, using an energy-dependent potential model. The [Formula: see text]-nucleus effective potential employed in this study includes a Coulomb potential, a centrifugal barrier potential, and a nuclear potential. The nuclear potential is chosen to be the energy-dependent singularized harmonic potential, typical of nuclear interactions. The role of the energy-dependent potential is very significant in this study. Indeed, when compared to the experimental data, our results are found to be improved when energy-dependent interaction potential is employed compared to when energy-independent interactions are used, especially for small values of the parameter [Formula: see text] as evidenced by the values of the root mean square deviation.

Study of Cluster Decays Including Those Leading to Doubly Magic Nucleus 298114 and Branching Ratios Relative to Alpha Decay

The study of superheavy nuclei (SHN) and their decay properties is one of the rapidly growing fields in nuclear physics. Using the CYE model, we have already studied the decay properties of the alpha decay, cluster decay, and spontaneous fission of the heavy and superheavy nuclei. In the present work, we will examine the effects by incorporating hexacontatetrapole (β6) parameter in the parent nucleus along with the quadrupole (β2), and hexadecapole (β4) deformations of the decaying parent nucleus emitting clusters 84Be and 126C. These deformations lower the half-life values, because they reduce the height and width of the potential barrier. Additionally, the creation of the doubly magic daughter 298114 from different decaying nuclei is computed. The calculated half-lives are compared with other models and are found to be in a good agreement. The branching ratios relative to the alpha-decay have also been calculated.

Gan Photonic Crystals: Spectral Dynamics in UV, X‐Ray, and Alpha Radiation

In this work, a comparative analysis of gallium nitride (GaN) thin films is conducted, both with and without photonic crystal (PhC) structures, focusing on their scintillation and photoluminescence properties. GaN's suitability for diverse optoelectronic and radiation detection applications is analyzed, and this study examines how PhC implementation can enhance these properties. Methodologically, the emission spectra is analyzed from 5.9 keV X‐ray sources, decay curves, pulse height spectra in response to 241Am 5.5 MeV alpha‐rays, and photoluminescence spectra induced by UV excitation. The findings demonstrate a substantial increase in quantum efficiency for PhC GaN, nearly tripling the light yield that of conventional plain GaN thin films under the UV excitation. The enhancement is predominantly attributed to the PhC GaN's proficiency in guiding light at 550 nm, a feature indicative of its spectral filtering capabilities, as detailed in the study. Furthermore, side‐band scintillations, stemming from inherent materials like Chromium that generate scintillations at diverse wavelengths, are effectively mitigated. A key finding of this study is the effective detection of light not only at the rear but also along the lateral sides of the films, offering new possibilities for radiation detector design and architecture.

Pathomorphological Features of Lung Fibrosis in Individuals Occupationally Exposed to Alpha Radiation

The aim of this study was to search for the specific morphological features of radiation-induced lung fibrosis compared to pulmonary fibrosis of another origin, using biological specimens of lung tissue collected from workers internally exposed to alpha radiation. The morphological features of lung fibrosis were defined using biological specimens of lung tissue that had been collected during autopsy examinations from 56 workers diagnosed with plutonium-induced lung fibrosis during life, from 34 workers with lung fibrosis of another origin (due to chronic inflammatory lung diseases) and from 35 workers without clinical pulmonary pathology (controls). The total lung-absorbed dose of gamma radiation from external exposure did not significantly differ among the studied groups, and the total lung-absorbed dose of alpha radiation from internal exposure was significantly higher in workers with plutonium-induced lung fibrosis. To investigate the extracellular matrix components, mono- and polyclonal labeled antibodies against type I, IV, and V collagens were used. In addition, to evaluate the system of extracellular matrix metabolism regulation, the antibodies against matrix metalloproteinases MMP-2, MMP-9, tissue inhibitors of matrix metalloproteinases TIMP-1 and TIMP-2 were used. The study revealed qualitative and quantitative morphological peculiarities of plutonium-induced lung fibrosis compared to lung fibrosis of another origin. This allows us to conclude that plutonium-induced lung fibrosis is a specific type of lung fibrosis, which is characterized with specific location and architectonics of fibrosis foci within the lung, and with changes in levels of collagen, elastic and reticular fibers in the pulmonary stroma. The analysis demonstrated that hyperproduction of type V collagen plays a key role in the development of plutonium-induced lung fibrosis. In addition, the imbalance between the expression of MMPs and their inhibitors plays an important role in the development of lung fibrosis.

Quasi-stationary alpha-states from non-Hermitian Hamiltonians of even-even heavy isotones

Three isotone groups (N=128,130,132) with alpha-decaying, short-lifetime even-even nuclei of large mass number are studied in order to show that the tunneling phase of the alpha decay process is appropriately describable by a specific non-hermitian mean-field model. In this model the mean-field lifetime of the alpha cluster is extracted directly by the complex diagonalization of the non-hermitian Hamiltonian of the system. In this paper, we demonstrate that by calculating the mean-field width of the alpha clusters, in each isotone groups, by non-perturbative complex spectral calculations, then, due to the distinct patterns the isotones are naturally organized into with respect to the half-life and proton number, the total width of the alpha-decay can be approximated by matching the calculated results to experimental data.

Measuring very low radiation doses in PTFE for nuclear forensic enrichment reconstruction

Every country that has made nuclear weapons has used uranium enrichment to do so. Despite the centrality of this technology to international security, there is still no reliable physical marker of past enrichment in the open literature that can be used to perform forensic verification of historically produced weapons on gas centrifuges. We show that the extremely low radioactivity from uranium alpha emissions during enrichment leaves detectable and irreversible calorimetric signatures in the common enrichment gasket material PTFE, allowing for historical reconstruction of past enrichment activities at a sensitivity better than one weapon's quantity of highly enriched uranium. Fast scanning calorimetry also enables the measurement of recrystallization enthalpies of sequentially microtomed slices, confirming the magnitude and the type of radiation exposure while also providing detection of tampering and a method for analyzing field samples useful for treaty verification. This work opens the door for common items to be turned into precise dosimeters to detect the past presence of radioactivity, nuclear materials, and related activities with high confidence.

Radiological characterization of materials used in the Italian heritage buildings

Building materials (BMs) can cause significant gamma dose indoors due to their natural radionuclide content. In 2013, the European Directive 59/2013/EURATOM introduced, in annex XIII, a list of types of BMs of interest for the content of gamma-emitting radionuclides among which materials or additives of natural igneous origin, such as granitoids, tuff and lava, are included. These materials have been largely employed for decorative and structural purposes in the course of centuries in the Italian heritage buildings. Aim of this study is to assess the contribute of BMs in terms of alpha exposure. Six samples of different materials, characterized in a previous study by the authors in terms of radiological content by means of a gamma spectrometry, have been analyzed in order to determine the specific exhalation rate of 222Rn, the radon emanation coefficient and excess in indoor radon concentration. Results confirm that BMs of natural igneous origin can play an important role in terms of alpha radiation dose and internal exposure due to the inhalation of the alpha particles emitted.

Fabrication of a cell irradiation technique by alpha-particles using allyl diglycol carbonate (ADC) detector and micro-capillary tubes.

To study the impact of micro-alpha irradiation collimator with a specific design to irradiate specific normal or up-normal cells using capillary tubes and nuclear track detector type CR-39. The in vitro experimental study was conducted at radiobiology Lab, of the Physics department, Salahaddin University, Erbil, Iraq from February to April 2022. Several alpha irradiation collimators were calibrated using allyl diglycol carbonate to fabricate a suitable blood cell irradiation technique. Time of irradiation and alpha particle energy were calibrated. Healthy blood samples of Albino rats and cancer blood samples were used to assess the applicability of the fabricated cell irradiation technique. The Rats were divided into intervention and control groups. Data was analysed using SPSS software version 28. Of the 15 healthy, male Albino rats having a mean weight of 230±12g each, there were 12(80%) in the intervention group and 3(20%) in the control group. Microcapillary tubes with suitable diameters had high stability for deposition of a sufficient density of alpha particles on the surface of allyl diglycol carbonate and blood samples. The optimum time of irradiation that had a significant (p<0.05) effect was 20 sec corresponding to alpha energy 4.5MeV. Low irradiation time had significant impact of alpha particles on the average percentage of lymphocyte and neutrophil cells.

In-situ observation of irradiation-induced amorphization on fluorapatites doped with REEs (REE = La, Nd, Sm, Tb, Er, and Lu) of various ionic radii

The immobilization of nuclear waste containing various actinides requires the actinide host phases to maintain long-term stability under alpha decay damage. In this study, the irradiation resistance to amorphization of fluorapatite compounds with the formula of Ca9REE(PO4)5(SiO4)F2 (REE: rare earth element, REE = La, Nd, Sm, Tb, Er, and Lu) were investigated, where REEs3+ with decreased ionic radii were used to simulate actinides in immobilization wastes. In-situ 800 keV Kr2+ irradiation was performed with varying temperatures. The critical amorphization temperature, Tc, for these apatites were found to be 513.8, 503.7, 494.1, 493.7, 483.1 and 460.9 K, respectively. Tc shows a distinct decreasing trend with the decrease of ionic radii of doped REEs3+, indicating enhanced irradiation resistance. The selected REEs exhibited increasing electronegativity, which correlated with an increase in bonding ionic properties. This trend is unfavourable for the formation of a covalent network, thereby enhancing irradiation resistance. Besides, the decreased ionic radii of doped REEs3+ enhanced the migration and diffusion rates of smaller REE3+ after the collision cascade process. Additionally, the dopant REEs3+ showed a significant preference for CaⅡ sites. This preference decreased as the ionic radius of doped REE3+ and reduced the average ionic radius of CaⅠ sites. Consequently, the one-dimensional channel in apatite became larger, facilitating the rearrangement of F− ion. This study investigated the irradiation-induced amorphization of REE-silicon doped fluorapatites and the results highlighted the importance of composition of immobilization materials on irradiation performance.

3D printed microcrystalline CsI:Tl composite scintillating thin films for X-ray imaging

The utilization of additive manufacturing techniques, especially Digital Light Printing (DLP), in fabricating CsI:Tl scintillator films demonstrates considerable potential for streamlining the production of scintillators tailored for X-ray imaging applications. This research focuses on the fabrication of CsI:Tl-based composite plastic scintillator thin films. In this study, circular films measuring 1-inch in diameter and 0.1 mm & 0.2 mm in thickness are being produced and tested for gamma photon counts under alpha and gamma radiation. To establish the stopping power range of the films, a Monte Carlo based GEANT4 simulation has been carried out. Additionally, investigations into their suitability for X-ray imaging applications are being conducted, revealing the spatial resolution of the films (0.2 and 0.1 mm) between 100 and 130 μm and 1.26 lp/mm with a contrast range of 4.0–12.3 %. The observed decrease in spatial resolution and contrast for the 0.2 mm thick film is attributed to the thickness increase exacerbating the scattering phenomenon while simultaneously enhancing the X-ray stopping power. This highlights the significance of inherent trade-off between maximizing spatial resolution and compromising light yield of 0.1 mm films compared to the 0.2 mm thick film. By utilizing 3D printing, this approach offers a cost-effective and time-efficient method for producing thin-film scintillators with enhanced flexibility and customization options compared to conventional methods.

Characterisation of radioactive decay series by digital autoradiography, part 1: A theoretical approach using time and space coincidence (TSC) analysis

The three natural decay chains have short-lived daughter elements, and the existence of these radioelements makes it possible for alpha and beta particle emissions to be generated at the same place and the same time. We show theoretically that such time and space coincidences (TSCs) can be detected efficiently by suitable autoradiographic systems using an algorithm that is six times more efficient than an approach based on the classical slicing of space-time. Two types of TSC coexist: true TSCs, resulting from the decay of short-lived daughter elements, and random TSCs. True TSCs are predictable and their numbers vary linearly with activity; the prediction of true α/α and α/α/α TSCs of the 235U chain is presented. Random coincidences are also predictable using Poisson's law. They vary quadratically as a function of activity. Examination of the case of an uranium ore at secular equilibrium shows that the observed α/α coincidences result from the sum of random and true TSCs. For high uranium contents, random coincidences predominate. For uranium at secular equilibrium, the theoretical calculation shows that true TSCs predominate for contents below ∼5000 ppm.

Forces, Hierarchy, Unification

Force or energy is both a relationship and a pulse between objects (relational physics). Based on this idea, I have succeeded in unifying the gravitational and electromagnetic forces, as well as the strong and weak forces, using the same framework. Through this verification work, I have also been able to determine the radius and mass of the neutrino. In my deep consideration of the background of the formation of the weak and strong forces, I also succeeded in unifying alpha and beta decay by combining radioactive decay with the vision of the pulse.

Detrital zircon in Pleistocene aeolianite of the Isipingo Formation at Cape Vidal, KwaZulu-Natal, South Africa, gives age and Hf isotope signatures without provenance significance

Abstract Pleistocene (50 to 70 ka) aeolianite of the Isipingo Formation (Maputaland Group) at Cape Vidal, northern KwaZulu-Natal province, South Africa, contains a combination of three detrital zircon age fractions (A: 940 to 1150 Ma, B: 470 to 720 Ma, C: 230 to 280 Ma) that are also known from Holocene sediments in eastern South Africa, Mesozoic – Cenozoic sandstones in southern Mozambique and from the Carboniferous to Jurassic Karoo Supergroup. Archaean and Palaeoproterozoic bedrock of the Kaapvaal Craton, which is exposed in the drainage basins of rivers that have provided detritus to coastal sedimentary basins, is represented by one single Archaean zircon. Combined laser Raman micro-spectroscopy and estimates of accumulated alpha radiation dose from U and Th concentrations indicate that the virtual absence of zircon older than late Mesoproterozoic cannot be attributed to selective removal of radiation-damaged zircon grains by abrasion during erosion and transport. The Isipingo Formation sandstone at Cape Vidal is a product of sedimentary recycling, potentially involving river transport from the continental hinterland, water- and wind-borne drift parallel to the coast and local recycling. Because of the similarity in detrital zircon distribution patterns of the sandstone and all of its potential Palaeozoic to Cretaceous sedimentary precursors, detrital zircon data cannot provide useful information on the relative importance of these processes, or on the routing of detritus to its final site of deposition.

Omniscinti™: Simultaneous detection of alpha/beta/gamma/fast and thermal neutron with a triple-layered phoswich detector

The aim of our study is to develop a material and associated detector that can provide a quantitative response when exposed to any kind of radionuclide decaying by the emission of alpha, beta, fast neutrons (thermalized by their environment or not) and/or gamma rays, accompanied with the categorization of such incoming radiation. To achieve this, only a single sensor is being used, composed of a three-layered, fully organic phoswich (a morphological stacking of different plastic scintillators) showing various thicknesses and decay times. The detection and sorting of fast, thermal neutrons and gamma-rays are obtained through a thick 6Li-doped scintillator. Beta and alpha detection and counting are performed respectively with thin and ultrathin films manufactured with dedicated thickness and decay times, optimized thanks to simulation studies. A Pulse Shape Discrimination method based on the charge comparison method is used to separate alpha, beta, neutrons and gamma rays contributions. We present the preparation and characterization of various configurations: quintuple discrimination, beta detection and alpha spectrometry (performed on a cocktail of alpha emitters). These experimental results are discussed and expended in the frame of complex multi-source scenarios. This all-purpose concept is trademarked as Omniscinti™.

Temporal assessment of Gross alpha emissions from the petroleum industry in Tenerife, Canary Islands (2001–2022)

A ca. 76% decrease in gross alpha activity levels, measured in surface aerosols collected in the city of Santa Cruz de Tenerife (Spain), has been explained in the present study in connection with the reduction of activities, and eventual closure, of an oil refinery in the city. Gross Alpha in surface aerosols, collected at weekly intervals over a period of 22 years (2001–2022), was used for the analysis. The dynamic behaviour of the gross alpha time series was studied using statistical wavelet, multifractal analysis, empirical decomposition method, multivariate analysis, principal component, and cluster analyses approaches. This was performed to separate the impact of other sources of alpha emitting radionuclides influencing the gross alpha levels at this site. These in-depth analyses revealed a noteworthy shift in the dynamic behaviour of the gross alpha levels following the refinery's closure in 2013. This analysis also attributed fluctuations and trends in the gross alpha levels to factors such as the 2008 global economic crisis and the refinery's gradual reduction of activity leading up to its closure. The mixed-model approach, incorporating multivariate regression and autoregressive integrated moving average methods, explained approximately 84% of the variance of the gross alpha levels. Finally, this work underscored the marked reduction in alpha activity levels following the refinery's closure, alongside the decline of other pollutants (CO, SO2, NO, NO2, Benzene, Toluene and Xylene) linked to the primary industrial activity in the municipality of Santa Cruz de Tenerife.

Demonstration of aneutronic p-11B reaction in a magnetic confinement device

Aneutronic fusion using commonly available fuel such as hydrogen and boron 11 (11B) is one of the most attractive potential energy sources. On the other hand, it requires 30 times higher temperature than deuterium–tritium fusion in a thermonuclear fusion reactor condition. Development of techniques to realize its potential for the experimental capability to produce proton-boron 11 (p-11B) fusion in the magnetically confined fusion device using neutral beam injection is desired. Here we report clear experimental exploration and measurements of p-11B fusion reactions supported by intense hydrogen beams and impurity powder dropper installed in the magnetic confinement plasma Large Helical Device. We measured a significant amount of fusion alpha particle emission using a custom designed alpha particle detector based on a passivated implanted planar silicon detector. Intense negative-ion-based hydrogen beam injectors created a large population of up to 160 keV energetic protons to react with the boron-injected plasma. The p-11B alpha particles having MeV energy were measured with the alpha particle detector which gave a fusion rate in a good agreement with the global p-11B alpha emission rate calculated based on classical confinement of energetic proton, using experimentally obtained plasma parameters.