Range Of Alpha Particles Research Articles

A study of particle detectors based on single crystal diamond substrate

The diamond radiation detector was prepared using a high-quality monocrystalline substrate. A square contact of 3.6 × 3.6 mm2 was fabricated on one side of the substrate, while the other side has a full area metallized contact. The current-voltage characteristics were measured up to 1 kV in both directions. The fabricated diamond detector shows very low current below 2 pA in whole voltage ranges. The detector was then used for alpha particle detection. The triple radiation source was used with different monoenergetic particles with energies varying from 5.1 MeV to 5.8 MeV. The range of alpha particles used was no more than 15 μm according to SRIM simulations. The diamond detector shows a high resolution for alpha particle spectroscopy below 0.43% at 5.5 MeV energy.

Abstract 6034: PSMA targeted alpha radiopharmaceutical [211At]PSAt-3 inhibits tumor growth in a preclinical model of prostate cancer

Abstract Introduction: Prostate cancer continues to be a highly prevalent cancer diagnosis among men and a leading cause of cancer related deaths worldwide. With the introduction[177Lu]Lu-PSMA-617, targeted radionuclide therapy has proven successful in increasing survival time for patients with metastasized castration resistant prostate cancer. However, despite encouraging results, such patients tend to develop progressive disease, and thus, enhanced efficacy is warranted. To this end, the use of radiopharmaceuticals harnessing alpha-emitters is a promising venue due to the potent energy deposition and short range of alpha particles in tissue. Here, we employ the PSMA targeting vector, [211At]PSAt-3, for targeted alpha radionuclide therapy in a preclinical prostate cancer model. Methods: [211At]PSAt-3, a structural derivative of PSMA-617, in which the L-2-naphtylalanine was replaced by L-3-[211At]astato-phenylalanine, was obtained by electrophilic [211At]astatodesilylation. Evaluation of [211At]PSAt-3 was conducted in male inbred nude mice of Balb/c background xenografted subcutaneously with human prostate cancer cells (LNCaP). Prior biodistribution studies were carried out with approximately 100 kBq intravenous injections, and subsequent biodistribution 2, 6 and 24h post injection (P.I.). For establishment of therapeutic effect, a single intravenous dose of [211At]PSAt-3 was administered. To asses hematological toxicity, blood cell composition was assessed weekly. Results: Favorable tumor uptake of 15.2±6 %ID/g was observed 2h after injection of [211At]PSAt-3 in LNCaP xenografted nude mice, with subsequent 9±5.1% ID/g and 6.4±2.4% ID/g 6 and 24h P.I., respectively. [211At]PSAt-3 cleared mainly by the kidneys, in which uptake was 72, 38 and 6% ID/g at 2, 6 and 24h P.I., respectively. Thyroid/throat uptake remained low at ~0.1% ID for all timepoints investigated, indicating a low degree of de-astatination. Initial efficacy studies using a single intravenous dose of 0.5 MBq (~20 MBq/kg) demonstrated significant growth delay and tumor volume reduction compared with control mice (saline). Blood platelet count was reduced after administration of [211At]PSAt-3 and subsequently recovered. No signs of severe toxicity, and no significant weight loss between control and treated mice was observed, suggesting that the treatment is well tolerated. Conclusion: 0.5 MBq [211At]PSAt-3 was well tolerated in mice and demonstrated tumor volume reduction and significant delay of tumor growth. These findings suggest [211At]PSAt-3 as a promising candidate for clinical translation. Citation Format: Lars Hvass, Marius Müller, Anne Clausen, Matthias Herth, Andreas Kjaer. PSMA targeted alpha radiopharmaceutical [211At]PSAt-3 inhibits tumor growth in a preclinical model of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6034.

Astatine-211 Radiopharmaceuticals; Status, Trends, and the Future.

The low range of alpha particles provides an opportunity to better target cancer cells theoretically leading to the introduction of interesting alpha emitter radiopharmaceuticals including 225Ac, 212Pb, etc. The combination of high energy and short range of alpha emitters differentiates targeted radiotherapy from other methods and reduces unwanted cytotoxicity of the cells around the tumoral tissue. Among interesting alpha emitters candidates for targeted therapy, 211At, one of the radioisotopes with the best optimal decay properties, shows great promise for targeted radiotherapy in some animal prostate cancer xenograft studies and bone micro tumors with significant effects compared to other beta and alpha emitters and also demonstrates interesting properties for clinical applications. However, production and application of this alpha emitter in the development of actinium-based radiopharmaceuticals is hampered by many obstacles. This mini-review demonstrates 211At production methods, chemical separation, radiolabeling procedures, 211At-radiopharmaceuticals and their clinical trials, transport, logistics, and costs and future trends in the field for ultimate clinical applications. This review showed that there are limited clinical trials on 211Ac-based radiopharmaceuticals, which is due to the low accessibility of this radioisotope and other limitations. However, the development programs of major industries indicate the development of 211Ac-based radiopharmaceuticals in the future.

The Mapping of Alpha-Emitting Radionuclides in the Environment Using an Unmanned Aircraft System

The protection of first responders from radioactive contamination with alpha emitters that may result from a radiological accident is of great complexity due to the short range of alpha particles in the air of a few centimeters. To overcome this issue, for the first time, a system mounted on a UAS for the near-real-time remote measurement of alpha particles has been developed, tested, and calibrated. The new system, based on an optical system adapted to be installed on a UAS in order to measure the UV-C fluorescence emitted by alpha particles in the air, has been tested and calibrated, carried out in the laboratory and in field experiments using UV-C LEDs and 241Am sources. In experimental flights, the probability of detecting a point source was determined to be approximately 60%. In the case of a surface extended source, a detection efficiency per unit surface activity of 10 counts per second per MBq cm−2 was calculated. A background count rate of UV-C of around 26 ± 28 s−1 for an integration time of 0.1 s was measured during flights, which led to a decision threshold surface activity of 5 MBq cm−2.

Investigation of charged particles interaction with CeBr3 scintillator by Monte Carlo simulation programs

This work aims to investigate the interaction of charged particles (alpha and proton) with the CeBr3 scintillator by using Monte Carlo simulation. The total mass stopping power (TMSP), projected range, ion distributions, and ion ranges in the CeBr3 at an energy range of 0.01 - 10,000 , were computed by SRIM and FLUKA programs. The simulation results show that the TMSP of CeBr3 obtained by both programs is in good agreement. The alpha particle has a higher TMSP of the CeBr3 than the proton. The projected range of alpha and proton particles increases with increasing energy. The projected range of the proton is higher than that of the alpha particle when compared at the same energy. Finally, the 2D visualization of ion distributions and ion ranges for alpha and proton particles was reported.
 
 

Mass Stopping Power and Range of Alpha Particles in Biological Human Body (Water and Eye Lens Tissue)

Mass Stopping Power and Range of Alpha Particles in Biological Human Body (Water and Eye Lens Tissue)

Modeling of the non-Maxwellian response of DT plasmas to alpha particle transport in inertial confinement fusion (ICF) hotspot

In the alpha particle transport in ICF hotspot, previous models focus mainly on how the incident particles lose their energy but lost sight of how the target particles will respond to this lost energy. In this paper, we developed a novel single-scattering model based on the Monte Carlo method, which abandons the stopping-power and models every single-scattering event in the alpha particle life. It enables to describe both the energy stopping of the incident alpha particle and the target particles response to the collisions. With this model, it shows that the target DT-ions at the ICF hotspot boundary will be non-Maxwellian distributed after colliding with the high-energy alpha particles, which refers to a much higher fusion reactivity compared with a Maxwellian one. At the same time, this model gives a longer and dispersed alpha particle range in hotspot plasmas and suggests that the traditionally used stopping power models would overestimate the stopping ability of the target particles.

Stopping Power of Alpha Particles in Some Human Body Tissues Using Density Functional Theory

In this research, the stopping power, range, and stop time of alpha particle (He+2) in lung, bladder, intestine, and ovary human tissues are calculated using density functional theory and Beth's relativistic equation in range of alpha particle energy (0.01-1000 MeV). The experimental data of alpha particles extracted from SRIM-2013 program was used for the same human tissues applied in the MATLAB-2021 program, The Mean ionization potential of studied tissues is calculated using Gaussian 09W program. A good agreement has been found between our calculations for stopping power, range, and stopping time of alpha particle in studied human body tissues and SRIM-2013 program calculations

The Fundamental Gamma Rays and Charge Particle Interactions of the CeBr3 Scintillator

The research aims to study the primary interaction between gamma radiation in CeBr3 crystal. The analysis of mass attenuation coefficient (MAC), effective atomic number (Z eff), electron density (N eff), mean free path (MFP), and energy absorption buildup factor (EABF) was evaluated using the using the WinXCom software. Also, the interaction with charged particles as the total mass stopping power (TMSP), projected range (PR) of proton () and alpha () particles were evaluated by SRIM programming. The results found that the MAC depends on the energy ranges, the photoelectric effect is the main interaction at low energy ranges, Compton scattering phenomena illustrate and evidents at intermediate energy ranges, and pair production characteristics dominate over on 1.022 MeV in high energy ranges. Moreover, absorption edges appear on energy’s discontinuity at low energy. The Z eff and N eff show similar trends and correspond to the energy ranges. The MFP of the CeBr3 compared with some standard scintillators such as NaI and BGO crystal and found that the BGO responds to faster interaction than CeBr3 and NaI crystals. The EABF shows scattering energies followed by atomic equivalent (Z eq), and they also increase with increasing penetration depth (mfp). The TMSP and PR depend on charged particles, density, and the unit path distance of a material.

Development and evaluation of a standard for absorbed dose to water from alpha-particle-emitting radionuclides

Targeted radionuclide therapy and brachytherapy with alpha particles has gained significant clinical relevance recently. Absorbed dose traceability to a standard is currently lacking in the dosimetry chain. The short range of alpha particles in water of <100 μm complicates the absorbed dose measurements in the form of significant attenuation and perturbation effects. The aim of this work was to develop and validate a standard for absorbed dose to water from alpha-particle-emitting radionuclides. A dosimetric formalism to realize surface absorbed dose to water per unit activity using a windowless cylindrical parallel-plate ion chamber (IC) was introduced. IC-based and Monte Carlo (MC)-based correction factors were calculated for a planar circular 210Po alpha-particle emitter. The measured absorbed dose to air was compared to the MC-calculated absorbed dose. A parallel-plate IC with a nominal 4 mm collector diameter composed of polystyrene-equivalent material was utilized as a standard. MC simulations were performed using the TOPAS MC code and finite source size, backscatter, and emission angle divergence correction factors were calculated by modeling the IC and the source. Multiple measurement trials were performed to measure ionization current at air gaps in the 0.3 mm to 0.525 mm range. The proposed dosimetric formalism was employed to calculate the surface absorbed dose to water from a point-like 210Po source. The recombination and polarity correction factors were measured to be <0.50% when a 150 V mm−1 electric field strength was applied. The MC-calculated and measured absorbed dose to air agreed within 2.05%. The finite source size and backscatter corrections were <10% with the emission angle divergence correction being in the 93%–239% range. The surface absorbed dose to water was measured to be 2.8913 × 10−6 Gy s−1 Bq−1 with a combined uncertainty of 4.23% at k = 1. This work demonstrated the ability of a windowless parallel-plate IC as a standard for absorbed dose from alpha-particle-emitting radionuclides.

Effect of reverse voltage on alpha spectra of pre-conditioned Si PIN diodes deployed in vacuum/ambient environment

Semiconductor-based Si PIN diodes are employed for radiation detection owing to their many advantages. However, their performance and reliability heavily rely on their pre-conditioning and the environment in which they are deployed. In this article, the response of Si PIN diodes that are subjected to two different pre-conditions [heat-treated at 100 °C (HT) and exposed to 85% relative humidity (HUM)] and two deployment environments [vacuum and ambient] to alpha particles emanating from triple-alpha source (239Pu-5155 keV, 241Am-5486 keV, and 244Cm-5805 keV) are investigated. Prior to alpha spectroscopy measurements, a meticulous electrical characterization, in terms of reverse current-voltage (IR-VR) and reverse capacitance-voltage (CR-VR) measurements are carried out. The IR-VR characteristics revealed that the leakage current (IR) is higher for measurements performed in ambient as compared to vacuum, while CR-VR characteristics are utilized to set the minimum reverse voltage (VR) that resulted in depletion width commensurate with the range of alpha particles. In order to confirm the optimum VR for maximum charge collection, alpha spectra are obtained in vacuum conditions for different values of VR ranging from 0 to 48.6 V, which showed a left-exponential Gaussian convoluted lineshape. A systematic analysis of the lineshape in terms of the fitting parameters viz, peak position, FWHM, area under the peak, and tailing parameter, revealed that the most robust data is obtained at an optimum VR of 4.6 V, where saturation is observed in peak position, area under the peak and tailing parameter. It is to be added that in the present experiment, 4.6 V is the optimum VR for obtaining robust measurements even for pre-conditioned diodes in different deployment conditions and is thus suitable for field condition measurements.

Development of [225Ac]Ac-DOTA-C595 as radioimmunotherapy of pancreatic cancer: in vitro evaluation, dosimetric assessment and detector calibration

BackgroundPancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy which may benefit from radioimmunotherapy. Previously, [177Lu]Lu-DOTA-C595 has been developed as a beta-emitting radioimmunoconjugate to target cancer-specific mucin 1 epitopes (MUC1-CE) overexpressed on PDAC. However, the therapeutic effect may be enhanced by using an alpha-emitting radionuclide such as Actinium-225 (Ac-225). The short range and high linear energy transfer of alpha particles provides dense cellular damage and can overcome typical barriers related to PDAC treatment such as hypoxia. Despite the added cytotoxicity of alpha-emitters, their clinical implementation can be complicated by their complex decay chains, recoil energy and short-range impeding radiation detection. In this study, we developed and evaluated [225Ac]Ac-DOTA-C595 as an alpha-emitting radioimmunotherapy against PDAC using a series of in vitro experiments and conducted a preliminary dosimetric assessment and cross-calibration of detectors for the clinical implementation of Ac-225.ResultsCell binding and internalisation of [225Ac]Ac-DOTA-C595 was rapid and greatest in cells with strong MUC1-CE expression. Over 99% of PDAC cells had positive yH2AX expression within 1 h of [225Ac]Ac-DOTA-C595 exposure, suggesting a high level of DNA damage. Clonogenic assays further illustrated the cytotoxicity of [225Ac]Ac-DOTA-C595 in a concentration-dependent manner. At low concentrations of [225Ac]Ac-DOTA-C595, cells with strong MUC1-CE expression had lower cell survival than cells with weak MUC1-CE expression, yet survival was similar between cell lines at high concentrations irrespective of MUC1-CE expression. A dosimetric assessment was performed to estimate the dose-rate of 1 kBq of [225Ac]Ac-DOTA-C595 with consideration to alpha particles. Total absorption of 1 kBq of Ac-225 was estimated to provide a dose rate of 17.5 mGy/h, confirmed via both detector measurements and calculations.Conclusion[225Ac]Ac-DOTA-C595 was shown to target and induce a therapeutic effect in MUC1-CE expressing PDAC cells.

Simulation of the indirect reaction 92Mo(α, 2n)94Ru→m94Tc using TALYS and GEANT4 nuclear codes

Radioisotope 94mTc is a favorable positron emitter radioisotope in nuclear medicine that can be used for PET. Production of 94mTc via indirect reaction 92Mo(α, 2n)94Ru → 94mTc was predicted by SRIM, TALYS,and GEANT4 codes. SRIM and GEANT4 codes were employed to calculate the range of alpha particles into enriched 92Mo and to estimate the thickness of the target. Further, the GEANT4 and the TALYS codes were used to investigate the cross-section and production yield of the 92Mo(α, 2n)94Ru reaction. Four model methods were utilized to compute the cross-section by TALYS-1.95 code. The simulated results were compared with experimental values that reported by F.O. Denzler and found to be in good agreement between them. This observation indicates that the SRIM, the GEANT4 and the TALYS codes are suitable tools for prediction of producing radioisotopes via various reactions.

Influence of the mixing of Au with D and T upon alpha heating in hot dense plasmas

AbstractThe influence of the mixing of Au with D and T (DT) upon alpha heating is studied in the wide ranges of plasma temperatures from 0.1 to 100.0 keV, under the assumption that all the charged particles in the mixture are in the same temperature. Two cases of mixture densities 4.15 and 415 g/cc are discussed, where the average ionization degree of Au ions and the partial densities of different ions in the mixture are determined by the average atom model. It is found that the mixing decreases the energy partition fraction for DT ions significantly even if the number of Au ions is 1.0% of that for DT ions. The mixing also lengthens the range of alpha particles in the plasmas, which is more prominent when Au ion is in a low ionized state. Moreover, the heating of Au ions by alpha particles is found much easier than that of DT ion All these are very harmful to the controlled fusion. All the results about energy partition fractions are mainly because that the heavy Au ion is usually in a highly charged state in the plasmas. This makes the nuclear stopping due to Au ions much bigger than that due to DT ions and cover the incident energy range for the heating of DT ions by alpha particles. The similar work in Phys. Plasmas 21,102,307 (2014) is found doubtful since its nuclear stopping due to high Z ions was obtained by means of perturbation theory.

Role of TiO2 addition on recycling of TV screen waste glasses: Experimental and theoretical studies on structure and radiation attenuation properties

Using the powder metallurgy, TiO2-doped TV screen glass ceramic samples were prepared with TiO2 concentrations of 0 (S-TV), 10 (S-TV/Ti10), and 20 (S-TV/Ti20) wt%. The TV screen glass was collected from a damaged TV's CRT. The fabricated materials were investigated for their physical, structural, and radiation-shielding attributes. The chemical composition of the prepared glasses was analysed with the aid of the X-ray fluorescence (XRF) method. The crystalline phase and microstructure of the glass ceramics were studied through the X-ray diffraction (XRD) method and scanning electron microscope (SEM), respectively. The density and Vickers hardness of the sample were determined by the Archimedes method and a micro hardness tester, respectively. The absorption parameters of electrons, protons, alpha particles, carbon ions, fast neutrons, and thermal neutron were calculated from various software and analytic expressions. The XRD spectra of the samples showed the presence of distinct crystalline peaks associated with TiO2, SiO2, and Ba2SiO4. The SEM images revealed that crystalline structures nucleated and increased with coarser crystalline grains when the amount of TiO2 was increased. The densities of the glass ceramics were 2.525, 2.546, and 2.285 g/cm3 for the S-TV, S-TV/Ti10, and S-TV/Ti20 samples, respectively while the corresponding Vickers hardness values were 495, 540, and 578 HV. The projected range of electrons, protons, alpha particles, and heavy carbon ions were within the limits 2.78–32182.18 μm, 0.215–1400 μm, 0.154–130.54 μm, and 0.053–14.10 μm in S-TV, 2.76–31991.36 μm, 0.205–1320 μm, 0.147–122.05 μm, and 0.049–13.11 μm in S-TV/Ti10, and 2.84–32824.95 μm, 0.212–1360 μm, 0.151–125.55 μm, and 0.051–13.45 μm in S-TV/Ti20, respectively. Among the three samples, S-TV was the best thermal neutron absorber, while S-TV/Ti10 is most effective in slowing down fast neutrons. The optimum TiO2 doping content for enhancing the charged particle and fast neutron moderating abilities of TV screens is 10 wt%.

Bistatic RCS reduction caused by radionuclide layer for spherical object

Radar cross section (RCS) is one of the important research topics in recent decades and the use of Radionuclide Layer (RNL) is one of the methods for radar cross section reduction. In this paper, the RNL of Americium-241 is considered on the surface of the spherical body with a radius of 5 cm. The range of alpha particles emitted from RNL and the electron density of air at standard temperature and pressure (STP) conditions have been extracted by the SRIM and Geant4 computational codes. Finally using CST software and RF module, the radar cross-section of the conductive spherical body, without and with plasma induced by RNL are obtained in different activities. The radar cross-section reduction of about for the spherical body in the frequency range of 2 to 12 GHz is observed for the activity of .

141Pr(α,x): New Cross-Section Data With Special Reference to 140Nd Production for Medicine

Cross sections for the 141Pr(α,x) 144,143,141Pm, 138mPr, 141cum,140cumNd, and 139cumCe reactions were measured by the stacked foil technique at an alpha-particle range of 60 to 20 MeV. Most of the data were obtained for the first time. Experimental data were compared with earlier research and theoretical values from the TENDL-2021 database. Thick target yields of activation products were calculated. The reaction 141Pr(α,5n)140Pm (9.2 s)→140Nd was compared with other 140Nd production routes.

Effect of Ce-dopant on photon interaction parameters of zirconolite-based borosilicate glass ceramics

In the present investigation, 70 wt% of zirconolite (CaZr1-xCexTi2O7, x = 0, 0.2, 0.4, 0.6, 0.8 and 1) and 30 wt% of sodium borosilicate glass (NaB0.5Al0.5Si2O6) (sample C0 to C10) have been synthesized. The photon interaction parameters viz. mass attenuation coefficient, effective atomic number, effective electron density, mean free path, and half value layer have been investigated for glass-ceramic samples at incident photon energies of 59.58 keV, 81.2 keV, 356 keV, 662 keV, 1173 keV and 1333 keV. Furthermore, effective neutron removal cross-section values, mass stopping power (MSP) and range of alpha particles and proton, were also calculated using SRIM codes. Moreover, gamma-ray energy absorption buildup factor (EABF) and exposure buildup factor (EBF) were also estimated. The experimental results are in agreement with the theoretically calculated values using WinXCOM program. Among the given prepared samples, C10 shows the best shielding properties, and C0 shows the best capability for neutron absorption. The MSP and projected range of α-particles and protons in all the prepared samples show very small variation with the change of Ce content in zirconolite in the energy range upto 15 MeV. The measured values are extensively desirable in fission and fusion reactors, medical applications, shielding researchers, and radiation physics.

Comparing absorbed doses and radiation risk of the α-emitting bone-seekers [223Ra]RaCl2 and [224Ra]RaCl2.

[223Ra]RaCl2 and [224Ra]RaCl2 are bone seekers, emitting high LET, and short range (< 100 μm) alpha-particles. Both radionuclides show similar decay properties; the total alpha energies are comparable (223Ra: ≈28 MeV, 224Ra: ≈26 MeV). [224Ra]RaCl2 has been used from the mid-1940s until 1990 for treating different bone and joint diseases with activities of up to approximately 50 MBq [224Ra]RaCl2. In 2013 [223Ra]RaCl2 obtained marketing authorization by the FDA and by the European Union for the treatment of metastatic prostate cancer with an activity to administer of 0.055 MBq per kg body weight for six cycles. For intravenous injections in humans a model calculation using the biokinetic model of ICRP67 shows a ratio of organ absorbed dose coefficients (224Ra:223Ra) between 0.37 (liver) and 0.97 except for the kidneys (2.27) and blood (1.57). For the red marrow as primary organ-at-risk, the ratio is 0.57. The differences are mainly caused be the differing half-lives of the decay products of both radium isotopes. Both radionuclides show comparable DNA damage patterns in peripheral blood mononuclear cells after internal ex-vivo irradiation. Data on the long-term radiation-associated side effects are only available for treatment with [224Ra]RaCl2. Two epidemiological studies followed two patient groups treated with [224Ra]RaCl2 for more than 25 years. One of them was the "Spiess study", a cohort of 899 juvenile patients who received several injections of [224Ra]RaCl2 with a mean specific activity of 0.66 MBq/kg. Another patient group of ankylosing spondylitis patients was treated with 10 repeated intravenous injections of [224Ra]RaCl2, 1 MBq each, 1 week apart. In total 1,471 of these patients were followed-up in the "Wick study". In both studies, an increased cancer mortality by leukemia and solid cancers was observed. Similar considerations on long-term effects likely apply to [223Ra]RaCl2 as well since the biokinetics are similar and the absorbed doses in the same range. However, this increased risk will most likely not be observed due to the much shorter life expectancy of prostate cancer patients treated with [223Ra]RaCl2.

Mass Stopping Power and Range of Alpha Particles in Biological Human Body Tissues (Blood, Brain, Adipose and Bone)

Mass Stopping Power and Range of Alpha Particles in Biological Human Body Tissues (Blood, Brain, Adipose and Bone)