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Basic dosimetry and beam-quality characterization
Published in Gavin Poludniowski, Artur Omar, Pedro Andreo, Calculating X-ray Tube Spectra, 2022
Gavin Poludniowski, Artur Omar, Pedro Andreo
The dosimetry of photons with energies up to about 300 keV is governed by the quantity kerma, which accounts for the transfer of the kinetic energy of photon-produced electrons to a volume of material. Kerma is the acronym for kinetic energy released per unit mass and has the unit of gray (Gy). It can be shown [65] that in a given medium, kerma is related to the field quantities fluence and energy fluence through
Principles and Basic Concepts in Radiation Dosimetry
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
This section relates quantities concerning energy transferred to (i.e. kerma) or deposited in (i.e. absorbed dose) a medium to the fluence that characterises the radiation field. This will first be done for uncharged particles (photons), starting with the relation between fluence and kerma (Section 5.4.1) before moving on to the relation between fluence and absorbed dose (Section 5.4.2) via the important concept of charged particle equilibrium (Section 5.5). Subsequently, the corresponding fluence–dose relation for charged particles will be derived (Section 5.6). Armed with these fluence–absorbed dose relationships, we will then be in a position to derive expressions describing detector or dosimeter response, generally known as cavity theory (Section 5.7).
Diagnostic Imaging Using X-rays
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Debbie Peet, Richard Farley, Elizabeth Davies
A measurement of an X-ray field obtained in air is a measure of the charge induced in an ionisation chamber, or solid-state detector calibrated to display a dose quantity known as “air KERMA”. KERMA stands for kinetic energy released per unit mass of air and has units of J.kg‒1 or Gy.
RENEB/EURADOS field exercise 2019: robust dose estimation under outdoor conditions based on the dicentric chromosome assay
Published in International Journal of Radiation Biology, 2021
David Endesfelder, Ursula Oestreicher, Ulrike Kulka, Elizabeth A. Ainsbury, Jayne Moquet, Stephen Barnard, Eric Gregoire, Juan S. Martinez, François Trompier, Yoann Ristic, Clemens Woda, Lovisa Waldner, Christina Beinke, Anne Vral, Joan-Francesc Barquinero, Alfredo Hernandez, Sylwester Sommer, Katalin Lumniczky, Rita Hargitai, Alegría Montoro, Mirta Milic, Octávia Monteiro Gil, Marco Valente, Laure Bobyk, Olga Sevriukova, Laure Sabatier, María Jesús Prieto, Mercedes Moreno Domene, Antonella Testa, Clarice Patrono, Georgia Terzoudi, Sotiria Triantopoulou, Rositsa Histova, Andrzej Wojcik
For the calibration of the RPL signal, RPL dosimeters of the same batch as used for the field exercise were irradiated at a known dose in a controlled facility. Two types of irradiations were performed to calibrate RPL in terms of absorbed dose in water and air kerma. Calibration in terms of absorbed dose in water was used to convert the RPL signal from GD placed in the thermos flasks and air kerma calibration for GD placed around the outside of the thermos flasks. The calibration of the RPL GDs in terms of absorbed dose in water was performed with 4 MV X-rays from LINAC (Elekta) at IRSN, France. RPL GDs irradiated at the LINAC facility were placed in a water tank, with water at 20 °C, according to the specification of IAEA TRS-398 protocol (IAEA 2001). Reference dosimetry was performed with a PTW 31010 ionization chamber calibrated in terms of absorbed dose in the water against 60Co gamma-rays. Dosimeters were also sealed in a vinyl bag. The delivered absorbed doses in water (Dw) ranged from 0.1 Gy to 3 Gy in order to provide a calibration curve. Uncertainty on the delivered Dw was estimated at 5% (k = 2). For calibration of kerma in air, irradiations were performed with gamma-rays of a 137Cs radioactive source at the IRSN reference facility. Dosimeters were irradiated in the air behind a 2 mm PMMA plate as specified in the new version of the ISO standard (ISO4037-3 2019) with doses ranging from 10 mGy to 3 Gy. Uncertainty on-air kerma values was estimated at 2.5% (k = 2). For these irradiations, two dosimeters were irradiated per dose and configuration.
Accelerator-based boron neutron capture therapy for malignant glioma: a pilot neutron irradiation study using boron phenylalanine, sodium borocaptate and liposomal borocaptate with a heterotopic U87 glioblastoma model in SCID mice
Published in International Journal of Radiation Biology, 2020
Evgenii Zavjalov, Alexander Zaboronok, Vladimir Kanygin, Anna Kasatova, Aleksandr Kichigin, Rinat Mukhamadiyarov, Ivan Razumov, Tatiana Sycheva, Bryan J. Mathis, Sakura Eri B. Maezono, Akira Matsumura, Sergey Taskaev
The experimental model was compiled and the doses were calculated using the NMC code to simulate the transport of particles by the Monte Carlo method (Brednikhin et al. 2012). When calculating the irradiation doses for each dose component, we used the kerma coefficients introduced by Goorley et al. (2002). The compound biological effectiveness (CBE) for healthy tissues was considered as 1.35 and −3.8 for the tumor tissue (Hiratsuka and Fukuda 2012). In the experimental model (Figure 2), the mice were set as a hollow cylinder of water with an outer and an inner radius of 11 and 3 cm, a height of 2 cm and an assumed mass of 26 g. The density of the cylinder that modeled the mice was calculated taking into account its mass and volume. Tumors were defined as water spheres with a radius of 0.3 cm at a distance of 2 cm from the center of the box.
Determination of spontaneous dicentric frequencies and establishment of dose-response curves after expose of human peripheral blood lymphocytes to low- and high-dose rate 60Co gamma rays – the basis for cytogenetic biodosimetry in Vietnam
Published in International Journal of Radiation Biology, 2019
Ngoc-Duy Pham, Minh-Hiep Nguyen, Que Tran, Quang-Tuan Che, Van-Hung Nguyen, Van-Toan Phan, Van-Dung Pham, Suen Ern Lee, Thi-Linh-Tien Vo
Gamma 60Co source: Gamma 60Co source (9.02 Ci, 9/2016) was used for irradiating at low-dose rate and blood samples were irradiated in vitro at 8 dose points (0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4 and 0.5 Gy) at 1.96 mGy/min. Gamma 60Co (Theratron Elite 80) was used for irradiating at high-dose rate and blood samples were irradiated in vitro at 11 dose points (0, 0.1, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4 and 5 Gy) at 275 mGy/min. The blood samples were placed in the center of a 15 × 15 cm radiation field and irradiated at room temperature. The set up exposures were calibrated by ionization chamber (Farmer Dosimeter) in air kerma and each irradiated sample was measured for the absorbed dose. The samples were kept at 37 °C for 2 h before they were cultured.