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Applied Radiation and Isotopes :... Jun 2022A computational simulation of alpha-particle expansion, emitted by Rn naturally diluted in the water of a spring located in the state of Puebla Mexico, is presented....
A computational simulation of alpha-particle expansion, emitted by Rn naturally diluted in the water of a spring located in the state of Puebla Mexico, is presented. This simulation provided information on the volume of expansion of the alpha particles in the vicinity of the spring and thus awareness if there was a radiological risk for the users or the population that lived near to it. Before performing the simulation, several measurements were made to water samples with a dynamic measurement system. This in order to know the level of radon concentration and compare the results obtained with the levels recommended by the United States Environmental Protection Agency (US-EPA) and the World Health Organization (WHO). In addition, to know if there was a radiological risk due to the presence of gamma emitting radionuclides, complementary water analyses were carried out using gamma-ray spectrometry techniques. The simulation was developed using the scientific software of particle interaction with matter, Geant4. The different variables declared for the software parameters are presented in this document. The results of the radon measurements in the water and the computational simulation, determined that there was no radiological risk due to alpha radiation. Furthermore, the results from the gamma-ray spectrometer showed that there was no presence of other hazardous radionuclides in the water.
Topics: Alpha Particles; Drinking Water; Mexico; Natural Springs; Radiation Monitoring; Radioisotopes; Radon; United States; Water Pollutants, Radioactive
PubMed: 35366603
DOI: 10.1016/j.apradiso.2022.110203 -
International Journal of Radiation... 2021The development of an exposure apparatus for in situ α-irradiation studies of cells. The construction of the apparatus is simple and the apparatus is maintenance free,...
PURPOSE
The development of an exposure apparatus for in situ α-irradiation studies of cells. The construction of the apparatus is simple and the apparatus is maintenance free, easy to use and of low cost. This small device can be placed in an incubator, where the exposure environment is controlled. Moreover the vapor saturated incubator protects the cells from drying out, allowing long irradiation intervals.
MATERIALS AND METHODS
The system includes a U alpha (α)-source of total activity 0.77 ± 0.03 MBq in the form of a thin disk deposited on an aluminum substrate. The α-particles emitted in the air have a mean energy of 4.9 MeV at the disk surface. Source homogeneity has been studied via Rutherford Backscattering Spectrometry. Using SRIM 2013 and Monte Carlo (MC) simulations via the MCNP6.1 code, LET and energy deposition values have been calculated for various filling gasses. Furthermore, based on these simulations, the assembly's dimensions and equivalent irradiation rate have been determined. With respect to the aforementioned dimensions, the experimental setup is constructed in a way to provide uniform irradiation of the sample. Using irradiation radial homogeneity has been studied. In order to evaluate biologically our apparatus, a well-established chromosomal aberration assay has been utilized, applied in exponentially growing hamster (CHO) cells. Furthermore, immunofluorescence gamma-H2AX/53BP1 foci assay has been performed as a 'biological detector', in order to validate α-particles surface density.
RESULTS
Source surface homogeneity: emission deviations do not exceed 10-15%. The optimal distance between the source and the cells for irradiation is determined to be 14.8 mm. Irradiation radial homogeneity: a deviation of 5% occurs at the first 8 mm from the center of the irradiation area, and a 10% deviation occurs after 12 mm. Chromosomal aberrations were found in good agreement with the corresponding in bibliography.
CONCLUSIONS
The current technical report describes analytically the development and evaluation stages of this experimental housing; from MC simulations to the irradiation of mammalian cells and data analysis. Moreover, guidance is provided as well as a report of the variables on which critical parameters are depended, so as to make this work useful to anyone who wants to construct a similar in-house α-irradiation apparatus for radiobiological studies using mammalian cells.
Topics: Alpha Particles; Animals; Chromosome Aberrations; Cricetinae; Monte Carlo Method; Radiobiology
PubMed: 34330206
DOI: 10.1080/09553002.2021.1962568 -
Current Radiopharmaceuticals 2024The low range of alpha particles provides an opportunity to better target cancer cells theoretically leading to the introduction of interesting alpha emitter... (Review)
Review
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 Ac, Pb, 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, At, 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 At production methods, chemical separation, radiolabeling procedures, At-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 Ac-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 Ac-based radiopharmaceuticals in the future.
Topics: Radiopharmaceuticals; Humans; Astatine; Alpha Particles; Animals; Neoplasms
PubMed: 37937552
DOI: 10.2174/0118744710262325231025075638 -
Current Radiopharmaceuticals Oct 2011The objectives in the application of targeted alpha therapy (TAT) for cancer therapy are reviewed. These relate to elimination of isolated cancer cells, cell clusters... (Review)
Review
The objectives in the application of targeted alpha therapy (TAT) for cancer therapy are reviewed. These relate to elimination of isolated cancer cells, cell clusters and tumors. Requirements for isolated cancer cells are good cellular targeting, high specific activity, and very short range. The regression of cell clusters in the peri-vascular space requires high capillary permeability and short range cross fire whereas for developed tumors, good bioavailabilty and anti- capillary activity are essential. Current sources of alpha radiation are reviewed and the prospects for commercial sources for clinical application are discussed. The Ac:Bi generator is the most practical alpha source, bringing therapy to Nuclear Medicine with the same practicality as the Mo:Tc generator has for imaging. The status quo of TAT is briefly reviewed with respect to dose normalization, real time microdosimetry and biological dosimetry for deterministic and stochastic effects and toxicity. The role of Monte Carlo calculations is emphasized. The strengths and weaknesses of TAT are examined and the way forward for clinical acceptance is discussed.
Topics: Alpha Particles; Clinical Trials as Topic; Humans; Monte Carlo Method; Neoplasms; Radiotherapy Dosage
PubMed: 22202156
DOI: 10.2174/1874471011104040336 -
Dalton Transactions (Cambridge, England... Oct 2017Identification of the appropriate combination of radionuclide, target and targeting vehicle is critical for successful radioimmunotherapy. For the treatment of... (Comparative Study)
Comparative Study
Identification of the appropriate combination of radionuclide, target and targeting vehicle is critical for successful radioimmunotherapy. For the treatment of disseminated peritoneal diseases such as pancreatic or ovarian cancer, α-emitting radionuclides have been proposed for targeted radiation therapy. This laboratory has taken a systematic approach investigating targeted α-radiation therapy, allowing comparisons to now be made between At, Th, Bi and Pb. Herein, trastuzumab radiolabeled with At and Th was evaluated for therapeutic efficacy in the LS-174T i.p. tumor model. A dose escalation study was conducted with each radioimmunoconjugate (RIC). Therapeutic benefit was realized with At-trastuzumab with doses of 20, 30 and 40 μCi. At doses >40 μCi, toxicity was observed with greater weight loss and 2-fold higher decrease in the platelet counts. Following a second study comparing the effect of 20, 30 and 40 μCi of At-trastuzumab, 30 μCi was selected as the dose for future studies. A parallel study was performed evaluating 0.25, 0.5, 1.0, 2.0 and 5.0 μCi of Th-trastuzumab. The 0.5 and 1.0 μCi injected dose resulted in a therapeutic response; a lower degree of weight loss was experienced by the mice in the 0.5 μCi cohort. When the data is normalized for comparing At, Th, Bi and Pb, the choice of radionuclide for RIT is perhaps not entirely based on simple therapeutic efficacy, other factors may play a role in choosing the "right" radionuclide.
Topics: Alpha Particles; Animals; Cell Line, Tumor; Colonic Neoplasms; Female; Humans; Mice; Radioimmunotherapy; Tissue Distribution; Trastuzumab
PubMed: 28675216
DOI: 10.1039/c7dt01819c -
Journal of Nuclear Medicine : Official... Nov 2017
Topics: Alpha Particles; Beta Particles; Humans; Male; Prostatic Neoplasms; Tumor Burden
PubMed: 28935836
DOI: 10.2967/jnumed.117.198333 -
Nuclear Medicine Communications Sep 2022Actinium-225 (225Ac) has emerged as a promising therapeutic radioisotope for targeted alpha therapy. It emits net four alpha particles during its decay to stable... (Review)
Review
Actinium-225 (225Ac) has emerged as a promising therapeutic radioisotope for targeted alpha therapy. It emits net four alpha particles during its decay to stable daughter bismuth-209, rightly called an in-vivo nano-generator. Compared to the worldwide demand of 225Ac, the amount produced via depleted thorium-229 sources is minimal, making it an expensive radionuclide. However, many research groups are working on optimizing the parameters for the production of 225Ac via different routes, including cyclotrons, reactors and high-energy linear accelerators. The present review article focuses on the various aspects associated with the development of 225Ac radiopharmaceuticals. It includes the challenges and opportunities associated with the production methods, labeling chemistry, in-vivo kinetics and dosimetry of 225Ac radiopharmaceuticals. A brief description is also given about the 225Ac radiopharmaceuticals at preclinical stages, clinical trials and used routinely.
Topics: Actinium; Alpha Particles; Radioisotopes; Radiopharmaceuticals
PubMed: 35950353
DOI: 10.1097/MNM.0000000000001594 -
Nuclear Medicine and Biology Mar 2017Alpha particles are radiation of high energy and short range, properties that can lead to radiolysis-mediated complications in labeling chemistry at the high...
INTRODUCTION
Alpha particles are radiation of high energy and short range, properties that can lead to radiolysis-mediated complications in labeling chemistry at the high radioactivity levels required for clinical application. In previous papers in this series, we have shown that radiation dose has a profound effect on the astatine species that are present in the labeling reaction and their suitability for the synthesis of N-succinimidyl 3-[At]astatobenzoate. The purpose of this study was to evaluate the effects of adding N-chlorosuccinimide (NCS) to the methanol solution used for initial isolation of At after distillation, a process referred to as At stabilization, on At chemistry after exposure to high radiation doses.
METHODS
High performance liquid chromatography was used to evaluate the distribution of At species present in methanol in the 500-65,000Gy radiation dose range and the synthesis of SAB from N-succinimidyl 3-(tri-n-butylstannyl)benzoate in the 500-120,000Gy radiation dose range using different At timeactivity combinations under conditions with/without At stabilization.
RESULTS
In the absence of NCS stabilization, a reduced form of astatine, At(2), increased with increasing radiation dose, accounting for about half the total activity by about 15,000Gy, while with stabilization, At(2) accounted for <10% of At activity even at doses >60,000Gy. SAB yields without stabilization rapidly declined with increasing dose, falling to ~20% at about 5000Gy while with stabilization, yields >80% were obtained with At solutions stored for more than 23h and receiving radiation doses >100,000Gy.
CONCLUSIONS
Adding NCS to the methanol solution used for initial isolation of At is a promising strategy for countering the deleterious effects of radiolysis on At chemistry.
ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE
This strategy could facilitate the ability to perform At labeling at sites remote from its production and at the high activity levels required for clinical applications.
Topics: Alpha Particles; Astatine; Isotope Labeling; Radiation Dosage; Radiochemistry; Radiopharmaceuticals
PubMed: 28013121
DOI: 10.1016/j.nucmedbio.2016.11.009 -
Reviews on Recent Clinical Trials Sep 2008Targeted alpha therapy is an advancing experimental therapy that holds promise to deliver high cytotoxicity to targeted cancer cells. Initially thought to be indicated... (Review)
Review
Targeted alpha therapy is an advancing experimental therapy that holds promise to deliver high cytotoxicity to targeted cancer cells. Initially thought to be indicated for leukaemia and micrometastases, there is now evidence that solid tumours can also be regressed. Alpha therapy may be molecular or physiological in its targeting. Alpha emitting radioisotopes such as Bi-212, Bi-213, At-211 and Ac-225 are used to label monoclonal antibodies or proteins that target specific cancer cells. Alternatively, radium-233 is used for palliative therapy of breast and prostate cancers as it is a bone seeking element. Progress in the development of clinical trials of alpha therapy is examined for leukaemia, lymphoma, melanoma, glioblastoma multiforme, bone metastases, ovarian cancer, pancreatic cancer and other cancers. Results of past and current trials are reviewed, and the bases of some proposed trials are presented.
Topics: Alpha Particles; Antibodies, Monoclonal; Clinical Trials as Topic; Humans; Neoplasms; Radioisotopes; Radiotherapy; Treatment Outcome
PubMed: 18782076
DOI: 10.2174/157488708785700339 -
Sozial- Und Praventivmedizin 1991The considerable radiosensitivity of the human lung together with the highly localized alpha-doses in the bronchial and pulmonary regions from naturally occurring and...
The considerable radiosensitivity of the human lung together with the highly localized alpha-doses in the bronchial and pulmonary regions from naturally occurring and man-enhanced radon decay products make the respiratory tract the most critical organ for cancer from exposure to ionizing radiation in our environment. From indoor radon, the tracheobronchial region of the lung generally receives radiation doses which are at least an order of magnitude above the total dose to any other organ. Excess lung cancer deaths found in epidemiological studies on heavily exposed populations of miners can be fitted reasonably well to a relative risk model, when declines in relative risk with both age at risk evaluation, and time since exposure, are incorporated. Smoking seems to act synergistically. A comparison of the major radon risk projections shows considerable discrepancies in the best estimates of risk, indicating that the uncertainties remain large.
Topics: Adolescent; Adult; Aged; Alpha Particles; Child; Environmental Exposure; Female; Humans; Lung; Lung Neoplasms; Male; Middle Aged; Models, Statistical; Neoplasms, Radiation-Induced; Radiation Tolerance; Radon; Risk; Time Factors
PubMed: 1750276
DOI: 10.1007/BF01359155