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Full-Text Articles in Physics
Radiobiological Aspects Of Supralinear Photographic Emulsions, Robert Katz, Edward C. Pennington
Radiobiological Aspects Of Supralinear Photographic Emulsions, Robert Katz, Edward C. Pennington
Robert Katz Publications
Abstract Nuclear emulsions of the Ilford K series, exposed to X-rays from 15 to 150 kVp and systematically underdeveloped, exhibit supralinear blackness-exposure curves ranging from 1- to 4-hit in character, and whose shape is the same at all excitation voltages. Processing can be so adjusted that the curve shape is well represented by the model, and matches an experimental dose-response curve obtained with hamster cells after irradiation with gamma rays. The effective grain size of these emulsions is 1.3 μm when normalized to unit density material for comparison with the radiation-sensitive elements of biological cells. With fractionated exposures, response …
High Let Constraints On Low Let Survival, Robert Katz
High Let Constraints On Low Let Survival, Robert Katz
Robert Katz Publications
Survival curves for biological cells irradiated with gamma rays (and other low LET radiations) cannot be properly interpreted without examining the implications of these interpretations for high LET radiations. The theory of RBE demands that the RBE of any high LET radiation field is at most one when the probability for cell killing as a function of the absorbed dose of gamma rays is linear or sublinear, for homogeneous samples whose radiosensitivity parameters are not altered during the irradiation. A contrary experimental finding strongly suggests that the experimental sample is heterogeneous. Violation of this constraint is not unusual where the …
Calculated Yields And Slowing-Down Spectra For Electrons In Liquid Water: Implications For Electron And Photon Rbe, R. N. Hamm, H. A. Wright, Robert Katz, J. E. Turner, R. H. Ritchie
Calculated Yields And Slowing-Down Spectra For Electrons In Liquid Water: Implications For Electron And Photon Rbe, R. N. Hamm, H. A. Wright, Robert Katz, J. E. Turner, R. H. Ritchie
Robert Katz Publications
Detailed Monte Carlo calculations have been carried out of slowing-down spectra and yields for a number of end-points for electrons in liquid water. These investigations were made to study differences in physical effects of different low-LET radiations and implications for RBE. Initial electron energies from 1 keV to 1 MeV were used, and all secondary electrons were followed in the computations until their energies fell below 10 eV. Though there are substantial differences in the slowing-down spectra at energies near and above the K-shell ionization potential of oxygen, the energy spectrum of electrons at lower energies is found to be …