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Radiation Detection and Measurement
Published in Shaheen A. Dewji, Nolan E. Hertel, Advanced Radiation Protection Dosimetry, 2019
A proportional counter is essentially an ionization chamber, operated at a higher potential, wherein pulses are detected rather than charge measured. Pulse heights produced in an ionization chamber are small, but when the potential is increased, there is a region of operation where pulse heights increase with applied potential. This type of operation can provide additional information that is useful for characterizing the radiation being measured (Knoll 2010).
Radiation Detectors for Area (Ambient) Monitoring
Published in K. N. Govinda Rajan, Radiation Safety in Radiation Oncology, 2017
If N is the number of primary ion pairs produced and M is the amplification factor, the total ion pairs produced is given by M × N. M (and hence the pulse height) increases with the applied voltage, as can seen from the curve in the proportional region. So, a stable voltage source is an important requirement for detectors operating in this region. The detector is also known as a proportional counter (PC).
Dictionary
Published in Mario P. Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990
Counter. A detector of radiation which gives an instantaneous, discrete, electrical signal upon passage of a single-charged particle through it. Counters may be of various types, the most important being the pulse ionization chamber, proportional counter, Geiger counter, and scintillation counter.
Design and dosimetry of a facility to study health effects following exposures to fission neutrons at low dose rates for long durations
Published in International Journal of Radiation Biology, 2021
Thomas B. Borak, Laurence H. Heilbronn, Nathan Krumland, Michael M. Weil
We used a LET-½ chamber manufactured by Far West Technology Inc., shown in the bottom of Figure 5. This has a spherical cavity 12.7 mm (½ inch) in diameter surrounded with 2.5 mm wall of A-150 tissue equivalent plastic. These detectors are based on a design by Rossi (Rossi and Rosenzweig 1955) in which the central anode is surrounded by a helical grid. The plastic sphere is surrounded by an aluminum shell that provides electrostatic shielding and serves as a vacuum-tight container. The system was filled with propane-based tissue-equivalent gas to an absolute pressure of 34 Torr, to simulate a sphere of tissue with a diameter of 1 µm. The detector contained a gravity activated source of 244Cm that emits alpha particles at 5.8 MeV. When activated, the alpha particles are collimated along a trajectory through the center of the gas cavity. The fixed stopping power of monoenergetic alpha traversing the cavity provides an unambiguous calibration for the gain of the proportional counter.
Polymer drug conjugates containing memantine, tacrine and cinnamic acid: promising nanotherapeutics for the treatment of Alzheimer’s disease
Published in Journal of Microencapsulation, 2023
Tobeka Naki, William Morwa Reagile Matshe, Mohammed Olusegun Balogun, Suprakas Sinha Ray, Samuel Ayodele Egieyeh, Blessing Atim Aderibigbe
X-ray powder diffraction patterns were recorded on a Bruker D8 Discover equipped with a proportional counter, using Cu-Kα radiation (λ = 1.5405 Å, nickel filter). Data were collected in the range of 2θ = 10–100°, scanning at 1.5° min−1 with a filter time constant of 0.38 s per step and a slit width of 6.0 mm. The samples were placed on a silicon wafer slide. The X-ray diffraction data were evaluated using the Eva (evaluation curve fitting) software. Baseline correction was performed on each diffraction pattern by subtracting a spline function fitted to the curved background. It was used to confirm the incorporation of the drugs in the prepared conjugates.
Assessment of the dicentric chromosome assay as a biodosimetry tool for more personalized medicine in a case of a high risk neuroblastoma 131I-mIBG treatment
Published in International Journal of Radiation Biology, 2019
Jose Maria Chimeno, Natividad Sebastià, Irene Torres-Espallardo, Julia Balaguer, Cristian Candela-Juan, Jose Luis Loaiza, Mar Adria, Blanca Ibanez-Rosello, Adela Cañete, Luis Martí-Bonmatí, Alegría Montoro
Equivalent dose rate measurements were acquired at a distance of 2 meters from the patient with a proportional counter tube (Berthold LB1236) in order to estimate the physical WBD. The measurements were done immediately after the administration of 131I-mIBG as well as before and after the first urination. A set of measurements were taken every 2 hours during the first day and then every 4–6 hours after 48 hours. The patient urinated before each set of measurements. The WBD was calculated following the standard MIRD procedure with a bi- , tri- and penta- exponential fit of the measurements (Snyder et al. 1975).