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Radioisotopes in Biology and Medicine
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
This technique has been used extensively for the analysis of trace metal concentrations in various organs following X-irradiation, drug, or hormone treatment. The basic principle of neutron activation analysis is simple. The trace metals under investigation are made radioactive by bombarding the dry samples of liver, plasma, or spinal fluid with slow neutrons. During neutron irradiation, the stable trace metals, together with other elements, capture neutrons and become radioactive. By using a radiation detector, the amount of trace metal can be quantified. However, in organ samples, other elements (such as sodium, potassium, and chlorine, which have very high cross-sections for neutron capture) also become radioactive; this makes it impossible to quantify the radioactivity of a trace metal by single-channel analysis. Two techniques have been used to overcome the above difficulty. Use of multichannel analyzer: The multichannel analyzer separates the photopeak of radioisotopes of different energy. By stripping off the energy contribution from other radioisotopes with the help of a computer, one can get a single photopeak of the radioactive trace metal under investigation.Chemical separation of activated trace metals: Activated samples are digested in acid and mixed with a nonradioactive trace metal; the radioactive trace metal is precipitated chemically and then counted by a single-channel analyzer.
Neutron Dosimetry
Published in Gad Shani, Radiation Dosimetry, 2017
A dosimeter arrangement composed of a 40-μm-thick layer of polyethylene converter followed by a double-diode detector has been used. The double-diode detector (CD-NEUT-200-DBL) consists of two Canberra diodes, with an effective area of 2 cm and a bulk resistivity of about 500 Ω cm, located on the opposite sides of a single silicon block. The depleted zone of each of the two diodes is, in the actual configuration, 30 μm deep for a polarization tension of 10 V. These depleted zones are separated by 222 μm of Si. Ortec preamplifiers and a Canberra multichannel analyzer with amplifier are used and connected to a Toshiba T-180 portable computer for data acquisition, as indicated in Figure 10.54. Data analysis is performed using the Ortec Maestro II software.
How Much Diagnosis Can We Afford?
Published in Pat Croskerry, Karen S. Cosby, Mark L. Graber, Hardeep Singh, Diagnosis, 2017
The escalating costs of diagnosis reflect a host of factors, including the ever-increasing complexity of medical care, new and better tests, increased utilization of expensive imaging, better access to medical care, increased adherence to recommendations for screening tests, and inevitably, some waste. It all adds up. Consider the costs of a simple chemistry test, like measuring serum calcium. Run as part of a multi-channel analyzer on 5 microliters of blood, the cost for the reagent is about 10 cents. The autoanalyzer can run over 1000 tests per hour! The final charge might well be $25, the difference reflecting the lab’s overhead for its clinical and administrative staff, the amortized cost of the $5 million instrument, and a healthy “profit” for the clinical lab, one of the few departments in the hospital that actually makes money for the institution.
Acute and late effects of combined internal and external radiation exposures on the hematopoietic system
Published in International Journal of Radiation Biology, 2019
Laura M. Calvi, Benjamin J. Frisch, Paul D. Kingsley, Anne D. Koniski, Tanzy M. Love, Jacqueline P. Williams, James Palis
As previously described (Misra et al. 2015), radioactivity was measured in individual mice sequentially for the first 7 days and then at 7-day intervals until ∼28 days post-injection. Counts were made using a Canberra InSpector™ 1000 portable multichannel analyzer (MCA) (Meriden, CT) with a sodium iodide probe; daily background and source checks were also performed using the MCA. The check source was a 20 g liquid source in a glass vial containing 9.3 µCi of 137Cs. The counting chamber was shielded with ∼2 inches of lead, with additional lead sheeting of approximately one-half inch thickness to reduce background scatter. Individual mice were weighed and then immobilized in 50 ml conical tubes for insertion into the counting chamber (counts/2 min). While counts were underway, bedding and water was changed in each cage to remove excreted 137Cs and minimize surface and re-contamination from grooming. At the end of the assessment period, all activity data (Figure 1), together with each animal’s body weight, were supplied to Dr. Michael Stabin, Vanderbilt University (Nashville, TN), for calculation of the mean absorbed dose.
Characterization, kinetics and thermodynamics of biosynthesized uranium nanoparticles (UNPs)
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Mervate Aly Abostate, Youssry Saleh, Hamed Mira, Maysa Amin, Maha Al Kazindar, Basma Mahmoud Ahmed
The contents of the main radio elements; U, Th, Ra (ppm) and K (%) in the collected samples were radiometrically determined using high-efficiency multichannel analyzer of gamma-ray spectrometry with sodium iodine detector. The system consists of Bicron Scintillation detector, NaI (Tl) crystal 76 × 76 mm, hermatically sealed with a photomultiplier tube in aluminum housing, which manufactured by Saint-Gobain Crystals and Detectors. The detector is protected by a copper cylindrical protection (0.6 cm thickness) against induced X-ray and the chamber of lead bricks against the environmental radiations and then the detector is covered by a lead shield (5 cm thickness). It is connected with Nuclear Enterprises main shaping amplifier, Model NE-4658, and tennelec high-voltage power supply, Model, TC 952 with HV digital display. It is also connected with Nucleas PCA-8000 computer, 8192 multichannel analyzer with color graphical display of spectra and high-level technical operation features and Epson LX-80 printer. This technique of γ-ray spectrometry is characterized by high-efficiency but low resolving power relative to the HP-Ge detector. It is used for measurement of concentration of four radionuclides U, Th, Ra and K by measuring the activity of γ-rays emitted from these radionuclides and their daughters. Reference standard samples have been provided by International Atomic Energy Agency (IEAE) [15].
Bioaccumulation of natural radio-nuclides in aquatic, riparian and terrestrial animals along Suez-Azzafrana coastline, Egypt: insights from RESRAD-BIOTA
Published in International Journal of Radiation Biology, 2023
Mohamed Hegazy Mohamed Salama, Mohamed Safwat Mohamed Tawfik
Different statistical analyses were done such as; (Min, Max, Average and STDV, with uncertainty) for all the measured water and sediment samples. The quality assurance was done as the detector was coupled with multi-channel analyzer (16 k channels) and GENIE 2000 software. The minimum acquisition time was 22 h to reduce the statistical as well as area calculation errors. The gamma transition of 1460.7 keV was used for 40K. The MDA can also be reduced by increasing counting times and the sample size, as well as utilizing large volume HPGe detectors with higher relative efficiency. Given the specific radionuclide, the radiation yield per disintegration and the unit conversions are set values over which the investigator has no control, (Friedlander et al. 2005).