- Utilization of GEANT to calculation of production yield for89Zr by charge particles interaction on89Y,natZr andnatSr. [Journal Article]
- ARAppl Radiat Isot 2017; 127:161-165
- The89Zr, is one of the radionuclide with near-ideal properties for PET due to its suitable half-life and decay properties. The cross-section of89Zr via89Y(p,n)89Zr,89Y(d,2n)89Zr,natSr(α,xn)89Zr andna...
The89Zr, is one of the radionuclide with near-ideal properties for PET due to its suitable half-life and decay properties. The cross-section of89Zr via89Y(p,n)89Zr,89Y(d,2n)89Zr,natSr(α,xn)89Zr andnatZr(p,pxn)89Zr, were calculated by the TALYS-1.8 code to predict the optimum range of charge particle energy. The Monte Carlo code GEANT4 was used to simulate the formation of89Zr in the target body. The simulated89Zr yield was in good agreement with published experimental results in the optimum energy range. According to the calculations, the89Y(p,n)89Zr was superior to the other reactions useful to medical application.
- Boron Neutron Capture Therapy for Malignant Brain Tumors. [Review]
- NMNeurol Med Chir (Tokyo) 2016 Jul 15; 56(7):361-71
- Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of na...
Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Therefore, BNCT enables the application of a high dose of particle radiation selectively to tumor cells in which boron-10 compound has been accumulated. We applied BNCT using nuclear reactors for 167 cases of malignant brain tumors, including recurrent malignant gliomas, newly diagnosed malignant gliomas, and recurrent high-grade meningiomas from January 2002 to May 2014. Here, we review the principle and history of BNCT. In addition, we introduce fluoride-18-labeled boronophenylalanine positron emission tomography and the clinical results of BNCT for the above-mentioned malignant brain tumors. Finally, we discuss the recent development of accelerators producing epithermal neutron beams. This development could provide an alternative to the current use of specially modified nuclear reactors as a neutron source, and could allow BNCT to be performed in a hospital setting.
- Techniques to alleviate nuisance alarms observed by PCMs following 222Rn-progeny deposition on clothing. [Journal Article]
- HPHealth Phys 2015; 108(2 Suppl 2):S72-83
- This paper presents technically-based techniques to deal with nuisance personnel contamination monitor (PCM) alarms. The techniques derive from the fundamental physical characteristics of radon proge...
This paper presents technically-based techniques to deal with nuisance personnel contamination monitor (PCM) alarms. The techniques derive from the fundamental physical characteristics of radon progeny. Some PCM alarms, although valid alarms and not actually "false," could be due to nuisance naturally-occurring radionuclides (i.e., radon progeny). Based on certain observed characteristics of the radon progeny, several prompt techniques are discussed that could either remediate or at least mitigate the problem of nuisance alarms. Examples are provided which demonstrate the effective use of the techniques.
- The effectiveness of the high-LET radiations from the boron neutron capture [10B(n,α) 7Li] reaction determined for induction of chromosome aberrations and apoptosis in lymphocytes of human blood samples. [Journal Article]
- RERadiat Environ Biophys 2015; 54(1):91-102
- Provided that a selective accumulation of (10)B-containing compounds is introduced in tumor cells, following irradiation by thermal neutrons produces high-LET alpha-particles ((4)He) and recoiling li...
Provided that a selective accumulation of (10)B-containing compounds is introduced in tumor cells, following irradiation by thermal neutrons produces high-LET alpha-particles ((4)He) and recoiling lithium-7 ((7)Li) nuclei emitted during the capture of thermalized neutrons (0.025 eV) from (10)B. To estimate the biological effectiveness of this boron neutron capture [(10)B(n,α)(7)Li] reaction, the chromosome aberration assay and the flow cytometry apoptosis assay were applied. At the presence of the clinically used compounds BSH (sodium borocaptate) and BPA (p-boronophenylalanine), human lymphocytes were irradiated by sub-thermal neutrons. For analyzing chromosome aberrations, human lymphocytes were exposed to thermally equivalent neutron fluences of 1.82 × 10(11) cm(-2) or 7.30 × 10(11) cm(-2) (corresponding to thermal neutron doses of 0.062 and 0.248 Gy, respectively) in the presence of 0, 10, 20, and 30 ppm of BSH or BPA. Since the kerma coefficient of blood increased by 0.864 × 10(-12) Gy cm(2) per 10 ppm of (10)B, the kerma coefficients in blood increase from 0.34 × 10(-12) cm(2) (blood without BSH or BPA) up to 2.93 × 10(-12) Gy cm(2) in the presence of 30 ppm of (10)B. For the (10)B(n, α)(7)Li reaction, linear dose-response relations for dicentrics with coefficients α = 0.0546 ± 0.0081 Gy(-1) for BSH and α = 0.0654 ± 0.0075 Gy(-1) for BPA were obtained at 0.062 Gy as well as α = 0.0985 ± 0.0284 Gy(-1) for BSH and α = 0.1293 ± 0.0419 Gy(-1) for BPA at 0.248 Gy. At both doses, the corresponding (10)B(n, α)(7)Li reactions from BSH and BPA are not significantly different. A linear dose-response relation for dicentrics also was obtained for the induction of apoptosis by the (10)B(n, α)(7)Li reaction at 0.248 Gy. The linear coefficients α = 0.0249 ± 0.0119 Gy(-1) for BSH and α = 0.0334 ± 0.0064 Gy(-1) for BPA are not significantly different. Independently of the applied thermal neutron doses of 0.062 Gy or 0.248 Gy, the (10)B(n, α)(7)Li reaction from 30 ppm BSH or BPA induced an apparent RBE of about 2.2 for the production of dicentrics as compared to exposure to thermal neutrons alone. Since the apparent RBE value is defined as the product of the RBE of a thermal neutron dose alone times a boron localization factor which depends on the concentration of a (10)B-containing compound, this localization factor determines the biological effectiveness of the (10)B(n, α)(7)Li reaction.
- Direct photolysis of α-pinene ozonolysis secondary organic aerosol: effect on particle mass and peroxide content. [Journal Article]
- ESEnviron Sci Technol 2014 Oct 07; 48(19):11251-8
- Primary and secondary organic aerosols (POA and SOA) contain a complex mixture of multifunctional chemicals, many of which are photolabile. Much of the previous work that aimed to understand the chem...
Primary and secondary organic aerosols (POA and SOA) contain a complex mixture of multifunctional chemicals, many of which are photolabile. Much of the previous work that aimed to understand the chemical evolution (aging) of POA and SOA has focused on the reactive uptake of gas-phase oxidants by particles. By stripping volatile compounds and ozone from α-pinene ozonolysis SOA with three 1-m-long denuders, and exposing the residual particles in a flow cell to near-ultraviolet (λ>300 nm) radiation, we find that condensed-phase photochemistry can induce significant changes in SOA particle size and chemical composition. The particle-bound organic peroxides, which are highly abundant in α-pinene ozonolysis SOA (22 ± 5% by weight), have an atmospheric photolysis lifetime of about 6 days at a 24-h average solar zenith angle (SZA) of 65° experienced at 34° latitude (Los Angeles) in the summer. In addition, the particle diameter shrinks 0.56% per day under these irradiation conditions as a result of the loss of volatile photolysis products. Experiments with and without the denuders show similar results, suggesting that condensed-phase processes dominate over heterogeneous reactions of particles with organic vapors, excess ozone, and gas-phase free radicals. These condensed-phase photochemical processes occur on atmospherically relevant time scales and should be considered when modeling the evolution of organic aerosol in the atmosphere.
- Production of α-particle emitting ²¹¹At using 45 MeV α-beam. [Journal Article]
- PMPhys Med Biol 2014 Jun 07; 59(11):2849-60
- Among the α-particle emitting radionuclides, (211)At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the...
Among the α-particle emitting radionuclides, (211)At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of (211)At are less than 70 µm in water with a linear energy transfer between 100 and 130 keV µm(-1), which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce (211)At. The direct production method is based on the nuclear reactions (209)Bi(α,2n)(211)At. Production of the radionuclide (211)At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the α-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate α-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E(α, av) of 29.17 MeV, the very small contribution of (210)At confirms the right choice of the irradiation energy to obtain a pure production of (211)At isotope.
- Nuclear model analysis of excitation functions of proton, deuteron and α-particle induced reactions on nickel isotopes for production of the medically interesting copper-61. [Journal Article]
- ARAppl Radiat Isot 2014; 89:65-73
- Excitation functions of the (61)Ni(p,n)(61)Cu, (62)Ni(p,2n)(61)Cu, (60)Ni(d,n)(61)Cu and (58)Ni(α,p)(61)Cu reactions were analyzed with respect to the production of (61)Cu (T½=3.33 h), a promising ra...
Excitation functions of the (61)Ni(p,n)(61)Cu, (62)Ni(p,2n)(61)Cu, (60)Ni(d,n)(61)Cu and (58)Ni(α,p)(61)Cu reactions were analyzed with respect to the production of (61)Cu (T½=3.33 h), a promising radionuclide for PET imaging. The nuclear model codes EMPIRE and TALYS reproduced the experimental data of all reactions well, except those for the (d,n) process. The fitted excitation functions were employed to calculate the integral yield of (61)Cu in all reactions. The amounts of the possible impurities (62)Cu and (60)Cu were assessed. A validation of the evaluated (p,xn) data was attempted.
- High-adiabat high-foot inertial confinement fusion implosion experiments on the national ignition facility. [Journal Article]
- PRPhys Rev Lett 2014 Feb 07; 112(5):055001
- This Letter reports on a series of high-adiabat implosions of cryogenic layered deuterium-tritium (DT) capsules indirectly driven by a "high-foot" laser drive pulse at the National Ignition Facility....
This Letter reports on a series of high-adiabat implosions of cryogenic layered deuterium-tritium (DT) capsules indirectly driven by a "high-foot" laser drive pulse at the National Ignition Facility. High-foot implosions have high ablation velocities and large density gradient scale lengths and are more resistant to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot. Indeed, the observed hot spot mix in these implosions was low and the measured neutron yields were typically 50% (or higher) of the yields predicted by simulation. On one high performing shot (N130812), 1.7 MJ of laser energy at a peak power of 350 TW was used to obtain a peak hohlraum radiation temperature of ∼300 eV. The resulting experimental neutron yield was (2.4±0.05)×10(15) DT, the fuel ρR was (0.86±0.063) g/cm2, and the measured Tion was (4.2±0.16) keV, corresponding to 8 kJ of fusion yield, with ∼1/3 of the yield caused by self-heating of the fuel by α particles emitted in the initial reactions. The generalized Lawson criteria, an ignition metric, was 0.43 and the neutron yield was ∼70% of the value predicted by simulations that include α-particle self-heating.
- Anti-prostate-specific membrane antigen liposomes loaded with 225Ac for potential targeted antivascular α-particle therapy of cancer. [Journal Article]
- JNJ Nucl Med 2014; 55(1):107-14
- CONCLUSIONS: Our studies demonstrate that anti-PSMA-targeted liposomes loaded with (225)Ac selectively bind, become internalized, and kill PSMA-expressing cells including endothelial cells induced to express PSMA. These findings-combined with the unique ability of liposomes to be easily tuned, in terms of size and surface modification, for optimizing biodistributions-suggest the potential of PSMA-targeting liposomes encapsulating α-particle emitters for selective antivascular α radiotherapy.
New Search Next
- Activation of local and systemic anti-tumor immune responses by ablation of solid tumors with intratumoral electrochemical or alpha radiation treatments. [Review]
- CICancer Immunol Immunother 2014; 63(1):1-9
- Cancer, the most devastating chronic disease affecting humankind, is treated primarily by surgery, chemotherapy, and radiation therapy. Surgery and radiotherapy are mainly used for debulking the prim...
Cancer, the most devastating chronic disease affecting humankind, is treated primarily by surgery, chemotherapy, and radiation therapy. Surgery and radiotherapy are mainly used for debulking the primary tumor, while chemotherapy is the most efficient anti-metastatic treatment. To control better metastatic cancer, the host immune system should be stimulated. Yet, successful specific stimulation of the immune system against tumors was seldom achieved even in antigenic tumors. Our working hypothesis is that aggressive in situ tumor ablation can release tumor antigens and danger signals, which will enhance anti-tumor T cell responses resulting in the destruction of residual malignant cells in primary tumors and distant metastases. We developed two efficient in situ ablation treatments for solid cancer, which can be used to destroy the primary tumors and stimulate anti-tumor immune responses. The first treatment, electrochemical ablation, is applied through intratumoral electrodes, which deliver unipolar-pulsed electric currents. The second treatment, diffusing alpha-emitters radiation therapy (DaRT), is based on intratumoral (224)Ra-loaded wire(s) that release by recoil its daughter atoms. These short-lived alpha-emitting atoms spread in the tumor and spray it with lethal alpha particles. It was confirmed that these treatments effectively destroy various malignant animal and human primary solid tumors. As a consequence of such tumor ablation, tumor-derived antigenic material was released and provoked systemic T cell-dependent anti-tumor immunological reactions. These reactions conferred protection against a secondary tumor challenge and destroyed remaining malignant cells in the primary tumor as well as in distant metastases. Such anti-tumor immune responses could be further amplified by the immune adjuvant, CpG. Electrochemical ablation or DaRT together with chemotherapy and immunostimulatory agents can serve as treatment protocols for solid metastatic tumors and can be applied instead of or in combination with surgery.