Maximum Beta Energy Research Articles

Optimal production and purification of n.c.a.143Pr as a promising palliative agent for the treatment of metastatic bone pain

This study proposes the beta-emitting radioisotope 143Pr as a promising candidate for palliative treatment of metastatic bone pain due to its desirable physical decay characteristics. An optimized process was developed for the production and purification of non-carrier-added 143Pr using a medium flux research reactor. Calculations were performed to determine the optimal irradiation time and cooling period for irradiating 1 mg of natural cerium oxide to indirectly produce 143Pr through the decay of 143Ce. Following irradiation and cooling, extraction chromatography was employed to efficiently isolate 143Pr from the irradiated target material. A column containing Ln-resin was used along with nitric acid as the mobile phase and an optional oxidation step with NaBrO3/ascorbic acid to separate 143Pr from impurities such as 143Ce and 141Ce. Radionuclidic purity of over 99.995% was achieved as confirmed through gamma spectroscopy, demonstrating effective separation of 143Pr. Additional quality control analyses established the chemical and radiochemical purity of the purified 143Pr nitrate product. With a half-life of 13.6 days and maximum beta energy of 0.937 MeV, 143Pr exhibits favorable properties for palliative bone pain therapy. This study therefore provides a viable method for producing high-purity 143Pr through the optimized irradiation and purification processes described. Further investigation is warranted to explore potential clinical applications of 143Pr for palliation of metastatic bone cancer pain.

Green synthesis of highly functionalized heterocyclic bearing pyrazole moiety for cancer-targeted chemo/radioisotope therapy

New derivatives of heterocyclic bearing pyrazole moiety were synthesized (eight new compounds from 2 to 9) via green synthesis methods (microwave-assisted and grinding techniques). 4,6-Diamino-1,3-diphenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (2) shows high anti-cancer activity against both HepG2 and HCT-116 with IC50 of 9.2 ± 2.8 and 7.7 ± 1.8 µM, respectively, which referenced to 5-Fu which is showing activity of 7.86 ± 0.5 and 5.35 ± 0.3 against both HepG2 and HCT-116, respectively. The cytotoxic activity against HCT-116 and HepG2 was slightly decreased and slightly increased, respectively, by a different pyrazole moiety (compound 5). Pharmacokinetics of compound 2 was carried out using the radioiodination technique in tumour-bearing Albino mice which shows good uptake at the tumour site. The biodistribution showed high accumulation in tumour tissues with a ratio of 13.7% ID/g organ after one hour in comparison with 2.97% ID/g organ at normal muscle at the same time point. As I-131 has maximum beta and gamma energies of 606.3 and 364.5 keV, respectively, therefore the newly synthesized compound 2 may be used for chemotherapy and TRT.

Pristine/folate-functionalized graphene oxide as two intrinsically radioiodinated nano-theranostics: self/dual in vivo targeting comparative study

BackgroundNanomedicine offers great potentials for theranostic studies via providing higher efficacy and safety levels. This work aimed to develop and evaluate a new nanoplatform as a tumor theranostic probe.ResultsCarboxyl-functionalized graphene oxide nanosheets (FGO) was well synthesized from graphite powder and then conjugated with folic acid to act as a targeted nano-probe. Full characterization and in vitro cytotoxicity evaluation were conducted; besides, in vivo bio-evaluation was attained via intrinsic radioiodination approach in both normal and tumor-bearing Albino mice. The results indicated that FGO as well as conjugated graphene oxide nanosheets (CGO) are comparatively non-toxic to normal cells even at higher concentrations. Pharmacokinetics of FGO and CGO showed intensive and selective uptake in the tumor sites where CGO showed high T/NT of 7.27 that was 4 folds of FGO at 1 h post injection. Additionally, radioiodinated-CGO (ICGO) had declared a superior prominence over the previously published tumor targeted GO radiotracers regarding the physicochemical properties pertaining ability and tumor accumulation behavior.ConclusionsIn conclusion, ICGO can be used as a selective tumor targeting agent for cancer theranosis with aid of I-131 that has a maximum beta and gamma energies of 606.3 and 364.5 keV, respectively.

High precision measurement of the 151Sm beta decay by means of a metallic magnetic calorimeter

The beta decay of 151Sm was measured by means of a metallic magnetic calorimeter. The measurement and subsequent analysis yielded a beta spectrum with an outstanding high-energy resolution of about 70 eV (FWHM) at 22 keV and a very low energy threshold well below 400 eV. The spectrum exhibited unexpectedly elevated beta emission probabilities at very low energy that we have not been able to reproduce in our theoretical study. The data analysis was thus scrutinized and an independent analysis of the same data set carried out. All new approaches have confirmed the previously found shape of the beta spectrum. The measured spectrum was compared to predictions from an advanced theoretical modeling that includes the atomic exchange effect, precise radiative corrections as well as the realistic nuclear structure that usually plays an important role in first forbidden non-unique transitions.The measured spectrum was then carefully analyzed to determine the maximum beta energy, which was found to be Q = 76.430(68) keV. The dominant beta decay of 151Sm populates the ground state of 151Eu, and a weak beta branch populates the first excited state of 151Eu. From our measurements, the probabilities of these two branches were determined to be 99.31(11)% and 0.69(11)%, respectively.

Computational evaluation of a novel beta radiation probe design using integrated circuits

Researchers at Texas A&M University (TAMU) have designed the radiation integrated circuit (RIC) for deployment as a new radiation detection system. Most integrated circuits are susceptible to radiation-induced failures, and decades of research have gone into solving this problem. Research at TAMU has led to a novel integrated circuit design that utilizes both radiation-hardened areas (RHAs) and radiation-sensitive areas (RSAs) to take advantage of these failures. The RSAs are susceptible to charged particle interactions, allowing the RIC to detect alpha and beta particles. However, beta particles are more penetrating compared to alpha particles, resulting in a lower interaction probability for beta particles incident on a bare RIC. In any material, the higher the beta energy, the deeper the beta particle can penetrate; therefore, the use of a wedge-shaped attenuator for beta particle detection not only increases interaction probability, but also provides the capability to perform maximum beta energy discrimination in the field. The objective of this research was to optimize the design of the RIC. Monte Carlo N-particle radiation transport code (MCNP) simulations assessed the beta particle detection and maximum energy discrimination performance of plate glass, borosilicate (Pyrex®) glass, acrylic (Lucite®), and natural rubber attenuators. In this proof-of-concept analysis, natural rubber was observed to be the optimal attenuating material for the beta probe with respect to maximum energy discrimination capability and weight, but all materials considered proved to be good candidates. The results of this study are promising and indicate the potential to achieve maximum beta particle energy discrimination of 50 keV using a wedged, natural rubber attenuator on the RIC.

Development of gamma-photon/Cerenkov-light hybrid system for simultaneous imaging of I-131 radionuclide

Although iodine 131 (I-131) is used for radionuclide therapy, high resolution images are difficult to obtain with conventional gamma cameras because of the high energy of I-131 gamma photons (364keV). Cerenkov-light imaging is a possible method for beta emitting radionuclides, and I-131 (606MeV maximum beta energy) is a candidate to obtain high resolution images. We developed a high energy gamma camera system for I-131 radionuclide and combined it with a Cerenkov-light imaging system to form a gamma-photon/Cerenkov-light hybrid imaging system to compare the simultaneously measured images of these two modalities. The high energy gamma imaging detector used 0.85-mm×0.85-mm×10-mm thick GAGG scintillator pixels arranged in a 44×44 matrix with a 0.1-mm thick reflector and optical coupled to a Hamamatsu 2 in. square position sensitive photomultiplier tube (PSPMT: H12700 MOD). The gamma imaging detector was encased in a 2cm thick tungsten shield, and a pinhole collimator was mounted on its top to form a gamma camera system. The Cerenkov-light imaging system was made of a high sensitivity cooled CCD camera. The Cerenkov-light imaging system was combined with the gamma camera using optical mirrors to image the same area of the subject. With this configuration, we simultaneously imaged the gamma photons and the Cerenkov-light from I-131 in the subjects. The spatial resolution and sensitivity of the gamma camera system for I-131 were respectively ~3mm FWHM and ~10cps/MBq for the high sensitivity collimator at 10cm from the collimator surface. The spatial resolution of the Cerenkov-light imaging system was 0.64mm FWHM at 10cm from the system surface. Thyroid phantom and rat images were successfully obtained with the developed gamma-photon/Cerenkov-light hybrid imaging system, allowing direct comparison of these two modalities. Our developed gamma-photon/Cerenkov-light hybrid imaging system will be useful to evaluate the advantages and disadvantages of these two modalities.

Dose assessment of bremsstrahlung induced by beta-emitting radioisotopes of uranium-238 series and lead in human tissues

In the natural uranium-238 decay series, pure beta isotopes such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb and 210Bi are released. The few lead isotopes such as 211Pb, 212Pb, 213Pb and 215Pb are good beta emitters. In certain nuclear reactions of reactor these isotopes are released. These beta isotopes have maximum beta energies, which induce the bremsstrahlung radiation. The bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. The shapes of bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. The bremsstrahlung spectra produced by these high-energy isotopes such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb, 210Bi, 211Pb, 212Pb, 213Pb and 215Pb in bone, muscle and teeth are studied, and the computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth–dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The evaluated beta bremsstrahlung dose as a function distance for the studied nuclides is also presented. The efficiency, intensity and dose rate of bremsstrahlung induced by beta isotopes of natural uranium-238 decay series and beta-emitting lead isotopes in human tissues such as brain, breast, heart, kidney, liver, muscle, pancreas and bone have also been studied in the present investigation. The values of bremsstrahlung dosimetric parameters are low for pancreas, but they are high for bone. For all studied tissues these parameters are high for 234Pa, but low for 210Pb.

Calibration of the Method for Measuring 14C in Combustion Gases

Much recent effort has been focused on the development of monitoring methods to calculate the percentage of biomass in the fuel used for energy generation in power plants. One possible method is based on measurements of radiocarbon concentration in combustion gases by liquid scintillation (LS) spectrometry. Fossil fuels contain no 14C due to their age. Therefore, after the combustion of such fuels, the resulting CO2 contains no 14C as well. The only source of 14C comes from the admixture of biomass containing modern carbon. 14C is a beta-emitting radionuclide with a maximum beta energy of 156 keV. There is no emission of gamma rays during decay; therefore, no possibility of gamma spectrometry exists. A difficult task thus is to validate the method and to calibrate it in agreement with the known amount of biomass in the fuel. For this purpose, a set of samples was prepared that were mixtures of hard coal and biomass with a known percentage of carbon. The oxycombustion method was applied for sample preparation in which the combustion of the fuel is done in pure oxygen; therefore, the combustion gas contains mostly CO2 and steam. The CO2 from the gas sample is then adsorbed by 3-methoxypropylamine. A known amount of this absorbent was mixed with a scintillation cocktail and measured in the LS spectrometer. In this way, a calibration curve has been obtained, allowing quantitative measurements of biomass content in the fuel.

Decay scheme study of 126Sn and 126Sb

To study the decay scheme of (126)Sn, two samples of a purified solution were measured by gamma-ray spectrometry and the relative photon emission intensities were determined. The (126)Sb(m) isomeric branching ratio was derived to be 18.6 (6) %. The maximum beta energy of the (126)Sn decay was checked by liquid scintillation. The Kbeta/Kalpha intensity ratio of Sb was determined being 0.226 (11). These new experimental results were used to re-examine the whole decay scheme of (126)Sn and its daughters.

Characteristics of a 85Kr beta-particle source applied in Series 1 reference irradiations of TMDIS-1 direct ion storage dosemeters

Characteristics necessary to specify an ISO 6980 Series 1 reference radiation field were determined for a commercially available 85Kr beta-particle source, using a BEAM EGS4 Monte Carlo code. The characteristics include residual maximum beta energy, E(res), and the uniformity of the dose rate over the calibration area. The E(res) and the uniformity were also determined experimentally, using an extrapolation ionization chamber (EC) and a 0.2 cm3 parallel plate ionization chamber, respectively. The depth-dose curve measured with the EC gave a value 0.62 MeV for the E(res). Series 2 90Sr + 90Y and Series 1(85) Kr beta-particle sources calibrated for H(p)(0.07) at the secondary standard dosimetry laboratory (SSDL) of STUK were used to determine the energy and angular responses of DIS-1 direct ion storage dosemeters. The averaged zero angle H(p)(0.07) responses to the 90Sr + 90Y and 85Kr reference radiations were 135 and 80%, respectively. The responses were normalized to 100%, H(p)(0.07) response to 137Cs photon radiation.

Self-absorption correction for beta radioactivity measurements in water samples

Two methods were used to apply self-absorption corrections for the determination of beta radioactivity in water samples (either for an identified radionuclide or for monitoring trends). One method was performed by estimating the absorption coefficient by assuming an exponential behaviour of absorption using external absorbers, while the other method was performed by preparing empirical curves using standards of different mass. In the first method, a relationship between absorption coefficient and maximum beta energy was also derived. In the second method, self-absorption curves for 90Sr/ 90Y standard were prepared with several sodium salts (carbonate, nitrate and sulphate salts) and, for 40K standard using a potassium salt. Both beta emitters are usually necessary to calibrate detectors for beta radioactivity measurements. This study showed that, for 90Sr/ 90Y, results using standards of different mass were more accurate than using external absorbers. Furthermore, it is highly recommended to melt sodium nitrate salts in order to perform a self-absorption curve for 90Sr/ 90Y because standards were stable in time and homogeneously distributed. For 40K, a self-absorption curve may be easily derived using paper absorbers of different thickness, instead of performing a time consuming self-absorption curve using a set of varying thickness of 40K standards. In order to test the two methods, the gross beta activity of several environmental water samples was analysed.

A comparison of intravascular source designs based on the beta particle emitter 114mIn/ 114In : Line source versus stepping source

Background: Catheter-based intravascular brachytherapy (IVB) sources of the next generation will have to meet high demands in terms of miniaturization, flexibility, safety, reliability, costs and versatility. The radionuclide pair 114mIn/ 114In (half-life 49.51 days, maximum beta energy 2.0 MeV, average beta energy 0.78 MeV) is an attractive beta emitter for application in such a source. Methods: Since metallic indium is unfit for the manufacture of a brachytherapy source, the feasibility, safety and dosimetric properties of a design concept comprising a linear array of ceramic In 2O 3 spheres within a thin-walled, superelastic Ni/Ti capsule are investigated. Results: Neutron activation of enriched In 2O 3 spheres yields a specific activity sufficiently high for the manufacture of a stepping source, keeping treatment times limited to a few minutes. Although 114mIn/ 114In also emits some gamma radiation, the effective doses received by members of the medical staff are an order of magnitude lower than those received from fluoroscopy. The dose distributions about a 40-mm line source and a 5-mm stepping source (outer diameter 0.36 mm) are calculated using MCNP4C. Dose–volume histograms (DVHs) are calculated for the line source (centered and noncentered) and the stepping source (centered) using the geometry of a human coronary artery. Conclusion: The results show that a centered stepping source with optimized dwell times delivers the most homogenous dose within the target volume.

188Re-Direct Labeling of Monoclonal Antibodies for Radioimmunotherapy of Solid Tumors: Biodistribution, Normal Organ Dosimetry, and Toxicology

The increased interest in the availability of radionuclides for therapy has resulted from the recent success and potential importance of radiolabeled antibodies for both diagnosis and therapy. There is a widespread interest in the availability of 188Re for various therapeutic applications, particularly for attachment to tumor-specific monoclonal antibodies for radioimmunotherapy. This review provides a perspective of 188Re-direct labeled MAbs for radioimmunotherapy of solid tumors, normal organ biodistribution, absorbed radiation doses to normal organs and tumors, and the toxicity to bone marrow and normal tissues. Methods for calculation of mean absorbed radiation doses to the whole body, various normal organs, and tumors have been developed using source-organ residence times and the methods developed by the Medical Internal Radiation Dose (MIRD) committee. The toxicity for 188Re-labeled antibodies is predominantly hematopoietic, with platelets and white blood cells being most sensitive to the effects of radiation. Rhenium-188 would be the isotope of choice for radioimmunotherapeutic applications because of cost, availability, and favorable radiation characteristics. Rhenium-188 has a half-life of 16.9 h and maximum beta energy of 2.118 MeV. This isotope is particularly attractive because it can be supplied conveniently from 188W/ 188Re-radionuclide generator system.

Empirical Expressions for Beta Ray Point Source Dose Distributions

Loevinger's well-known analytic expression, plus a constant 'end-of-'range' term, has been fitted to dose distributions, calculated by Monte Carlo methods, from point sources of beta rays in an infinite water medium. Optimum parameters are given for fits to 60 individual nuclides. Addition of the end-of-range term extends the range of good fits from about 0.4Rmax to 0.65Rmax, where Rmax is the maximum beta range. For low energy emitters or those having conversion electrons, the fit is often poor at distances, rmin, less than a few mg.cm-2. The RMA error of the fit at 25 points between rmin and 0.65Rmax ranges from 1.6 to 3.3% for 41 single-component spectra, and from 1.9 to 6% for 19 multi-component spectra. This is considerably smaller than is usually assumed for Loevinger's expression or given by nearly all other expressions for point source distributions. Values of the parameters are given as functions of maximum beta energy.

Dosimetry of radionuclide therapy using radiophosphonated antisense oligodeoxynucleotide phosphorothioates based on animal pharmacokinetic and tissue distribution data.

The aim of this study was to evaluate the therapeutic possibilities of radiolabeled antisense oligodeoxynucleotides. The internal radiation dose from known cellular and animal data was calculated, and the suitability of different phosphorus isotopes as labels for oligonucleotides was assessed. We calculated the pharmacokinetics and tissue distribution in vivo of short oligodeoxynucleotide phosphorothioates by using the data from two different radionuclides: phosphorus-33 (t1/2 = 24.4 days, maximum beta-energy = 250 ke V) and phosphorus-32 (t1/2 = 14.3 days, maximum beta-energy = 2270 ke V). The absorbed doses of 32P-labeled and 33P-labeled oligonucleotides were estimated using the published biodistribution data for several oligonucleotides in animal models for both tumor xenografts and AIDS. The local absorption of 33P was higher than that of 32P if the radius of the spherical distribution of activity was smaller than approximately 500 microns. In a mouse tumor xenograft model, an intravenously injected activity of 1 MBq achieved sufficient radiation doses in the tumor; 11 Gy for 32P and 1.5 Gy for 33P were obtained. In normal organs in the same model, the liver doses were 5.0 Gy (32P) and 0.7 Gy (33P), and the kidney doses were 14 Gy (32P) and 2.0 Gy (33P). We conclude that 33P may have more beneficial radiotherapeutic characteristics for oligonucleotides than 32P. This method could be applied on the macroscopic, cellular, and subcellular levels and help to design further experimental studies for the use of oligonucleotide radiotherapy and phosphorothioate probes.

Deconvolution of 204Tl/ 36Cl and 147Pm/ 45Ca dual mixtures

Technical characteristics of liquid scintillation counting include high counting efficiency, well-defined sample preparation procedures and a high capacity to measure a large number of samples. However, poor resolution and quenching limit the capability of measuring double-labeled samples when the maximum beta-ray energies are close. The simultaneous standardization of 35S and 14C was described in a previous paper, involving an improved spectrum unfolding method. This procedure has been tested with two other types of close maximum beta-energy nuclides: 204Tl and 36Cl have 710 and 763 keV maximum beta-energies respectively, and cannot be standardized simultaneously by double window methods. However, spectral shape differences permit their deconvolution with great accuracy. Both 147Pm and 45Ca (224 and 255 keV maximum beta-energies) have also been standardized. Samples with different quench values and activity ratios have been assayed, and the limitations have been determined.

Treatment of hepatocellular carcinoma (HCC) with radiolabeled Lipiodol: a preliminary report.

Fatty acid esters such as Lipiodol or Ethiodol (Savage Laboratories, Melville, New York) are known to selectively localize in vascular hepatocellular carcinomas (HCC), following intra-arterial hepatic administration. Lipiodol was labeled with radioactive 131I and administered in 47 patients with HCC for both imaging and therapy. The short term preliminary results suggest radiolabeled Lipiodol is effective in eliminating ascites, shrinking the tumor by a high internal radiation dose, and in improving symptomatology of these tumors. In the future, 90Y, which is a stronger pure beta-emitter (maximum beta energy of 2.27 MeV, a half life of 64 h, and a maximum penetration or beta range of 11mm), than 131I will be used for more effective treatment of HCC.

Responses of Thermoluminescent Materials to Beta Radiation and Low Energy Photons

The responses in terms of the individual dose equivalent, superficial, Hs(d), of a number of commercially available thermoluminescent materials to beta radiation were investigated and compared with the responses of the same materials to low energy photons. The maximum beta energies used ranged from 0.067 to 2.27 MeV and the photon energies ranged from 0.033 to 0.662 MeV. All irradiations were carried out on appropriate tissue-equivalent phantoms. The results of these studies serve to identify materials and configurations suitable for personal dosimetry in mixed beta-photon fields.

Responses of Thermoluminescent Materials to Beta Radiation and Low Energy Photons

Abstract The responses in terms of the individual dose equivalent, superficial, Hs(d), of a number of commercially available thermoluminescent materials to beta radiation were investigated and compared with the responses of the same materials to low energy photons. The maximum beta energies used ranged from 0.067 to 2.27 MeV and the photon energies ranged from 0.033 to 0.662 MeV. All irradiations were carried out on appropriate tissue-equivalent phantoms. The results of these studies serve to identify materials and configurations suitable for personal dosimetry in mixed beta-photon fields.

Detection of hard β-emitting radionuclides in aqueous solutions using Cerenkov radiation: A review article

Cerenkov counting of solutions is advocated as a useful means of detecting hard β-emitters; the present work is dedicated to the practical aspects of Cerenkov detection with commercially available liquid scintillation spectrometers. The variations of count rates with the type of vials and the volume of solutions are pointed out. With a spectrometer equipped with S 11 phototubes, detection efficiencies from 16 calibrated sources are found to be 23–50 per cent for emitters of E β maximum in the range 1·3−2·3 MeV and 50–70 per cent up to 3·5 MeV. The results of experiments with various optical filters suggest a direct relationship between the β energy of the isotope and the fraction of Cerenkov light emitted in the ultra-violet region. Pulse height analysis either by calculation of the channel ratio obtained from the spectrometer or by direct oscilloscopic display of spectra enables the energy of any unknown β-emitter to be evaluated. Color quenching of biological solutions inhibits more widespread use of Cerenkov counting while solute quenching is shown not to be a problem. Changes induced by 31 wavelength shifters are assessed; we single out Esculin as one of the most effective. Stress is being put on the advantages of Cerenkov counting of 42K, 32P, 86Rb and 24Na and the applicability of the method to more than 40 β-emitters having maximum beta energies above 1 MeV.