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- Biological dose (1)
- Dose distribution (1)
- Heavy ion (1)
- Heavy ion therapy (1)
- Heavy ion track (1)
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- Ion-kill (1)
- Katz Model (1)
- Late effects (1)
- Lithium fluoride (1)
- Particle track (1)
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- Stopping power (1)
- Track registration (1)
- Tracks; radiobiology; dosimetry; fractionation; radiation therapy (1)
Articles 61 - 90 of 191
Full-Text Articles in Physical Sciences and Mathematics
Radiosensitivity Parameters For Neoplastic Transformations In C3h10t1/2 Cells, M. P. R. Waligorski, G. L. Sinclair, Robert Katz
Radiosensitivity Parameters For Neoplastic Transformations In C3h10t1/2 Cells, M. P. R. Waligorski, G. L. Sinclair, Robert Katz
Robert Katz Publications
We have evaluated radiosensitivity parameters for cellular transformation from published experimental data on neoplastic transformations induced in C3H10T1/2 cells by BEVALAC ions. The measured RBE values are well reproduced by a track theory calculation using sets of m-target parameters with either m = 2 or m = 3, suggesting a quadratic or cubic extrapolation to low doses of γ rays. Using track theory one is thus able to predict transformation frequencies in those cells after an arbitrary radiation field, under known or assumed conditions of exposure, in a manner shown earlier for cellular survival. Extension of these calculations to interpret …
Inactivation Of Dry Enzymes And Viruses By Energetic Heavy Ions, M. P. R. Waligorski, Kim Sun Loh, Robert Katz
Inactivation Of Dry Enzymes And Viruses By Energetic Heavy Ions, M. P. R. Waligorski, Kim Sun Loh, Robert Katz
Robert Katz Publications
A newly developed corrected formula for the radial distribution of dose (RDD) has been used to calculate cross sections for the inactivation of dry enzymes and viruses by heavy ions ranging from 42He to 4018 Ar of energies ca. 10 MeV/a.m.u., spanning a range of LET of ca. 5–2,000 Me V cm2 g–1. In comparison with earlier “point-target” calculations of Butts and Katz where a linear range-energy relationship for electrons (δ-rays) was used, and with “extended-target” calculations of Zhang, Dunn, and Katz, where a power range-energy law and an “uncorrected” RDD formula …
The Fricke Dosimeter As A 1-Hit Detector, Robert Katz, G. L. Sinclair, M. P. R. Waligorski
The Fricke Dosimeter As A 1-Hit Detector, Robert Katz, G. L. Sinclair, M. P. R. Waligorski
Robert Katz Publications
A fit to the experimental data for the response of the Fricke dosimeter to energetic heavy ions is obtained using a calculation of the relative effectiveness of a 1-hit detector, from track theory. We use 2 fitted parameters, the target size, a0, which may be thought to represent a “diffusion length,” and E0, the dose of gamma-rays at which there is an average of one hit per target (the D-37 dose), and a new algorithm for the average radial distribution of dose in liquid water from the passing ion. The G value for ions is then …
The Radial Distribution Of Dose Around The Path Of A Heavy Ion In Liquid Water, M. P. R. Waligorski, R. N. Hamm, Robert Katz
The Radial Distribution Of Dose Around The Path Of A Heavy Ion In Liquid Water, M. P. R. Waligorski, R. N. Hamm, Robert Katz
Robert Katz Publications
Monte Carlo calculations of the radial distribution of dose in liquid water, incorporating energy deposition due to primary excitations and ionizations, have been performed for protons of energy 1, 10, 20, 50, and 100 MeV. By combining these results with earlier semi-empirical formulae used in track structure theory calculations, a corrected analytic formulation has been developed which on radial integration closely reproduces the value of stopping power for protons in the energy range 0.1–1000 MeV. After including a β-dependent ‘effective charge’ formula, this corrected formulation is tested against all published measurements of radial distribution of dose from energetic ions in …
Lung Cancer Risk At Low Doses Of Α Particles, Werner Hofmann, Robert Katz, Zhang Chunxiang
Lung Cancer Risk At Low Doses Of Α Particles, Werner Hofmann, Robert Katz, Zhang Chunxiang
Robert Katz Publications
A survey of inhabitant exposures arising from the inhalation of 222Rn and 220Rn progeny, and lung cancer mortality has been carried out in two adjacent areas in Guangdong Province, People’s Republic of China, designated as the “high background” and the “control” area. Annual exposure rates are 0.38 working level months (WLM) per year in the high background, and 0.16 WLM/yr in the control area. In 14 yr of continuous study, from 1970 to 1983, age-adjusted mortality rates were found to be 2.7 per 105 living persons of all ages in the high background area, and 2.9 per …
Biological Effects Of Heavy Ions From The Standpoint Of Target Theory, Robert Katz
Biological Effects Of Heavy Ions From The Standpoint Of Target Theory, Robert Katz
Robert Katz Publications
The biological effect of heavy ions is best described through the action cross section, as a function of the end-point of interest and the charge and speed of the ion. In track theory this is called the “ion-kill" cross section, for it is the effect produced by a single heavy ion and its delta rays. As with nuclear emulsions the biological track structure passes from the grain count regime to the track width regime to the thindown region with an increase in LET. With biological cells, as with any detector capable of storing sub-lethal damage, with low LET irradiation the …
Thindown In Radiobiology, Robert Katz, D. E. Dunn, G. L. Sinclair
Thindown In Radiobiology, Robert Katz, D. E. Dunn, G. L. Sinclair
Robert Katz Publications
A new expression for the radial dose distribution, tested against available data, and yielding good agreement with enzyme and virus cross sections, is used to calculate cellular inactivation cross sections from track theory models and parameters. We use a cellular model and radiosensitivity parameters, fitted to HILAC data 15 years ago, to represent mammalian cells irradiated at the UNILAC. The observed branching with Z and the decline in cellular action cross sections with an increase in ion LET are attributed to thindown; that is, to the limits imposed by the maximum radial penetration of delta rays. Target size and structure …
Lung Cancer Incidence In A Chinese High Background Area — Epidemiological Results And Theoretical Interpretation, Werner Hofmann, Robert Katz, Chunxiang Zhang
Lung Cancer Incidence In A Chinese High Background Area — Epidemiological Results And Theoretical Interpretation, Werner Hofmann, Robert Katz, Chunxiang Zhang
Robert Katz Publications
A survey of inhabitant exposures arising from the inhalation of radon and thoron daughters, and lung cancer mortality has been carried out in two adjacent areas in Guangdong province, China, designated as the "high background" and the "control" area. Annual exposure rates are 0.38 WLM/yr in the high background, and 0.16 WLM/yr in the control area, while age-adjusted mortality rates are 2.7 per 105 living people of all ages in the high background, and 2.9 per 105 in the control area. From this data we conclude that we are unable to determine the excess lung cancer rate over normal fluctuations …
Radial Distribution Of Dose And Cross-Sections For The Inactivation Of Dry Enzymes And Viruses, Zhang Chunxiang, D. E. Dunn, Robert Katz
Radial Distribution Of Dose And Cross-Sections For The Inactivation Of Dry Enzymes And Viruses, Zhang Chunxiang, D. E. Dunn, Robert Katz
Robert Katz Publications
A new semi-empirical algorithm for the radial distribution of dose is compared with available data. The algorithm is used to calculate the inactivation cross section for dry enzymes and viruses using an extended target model of a 1-hit detector. Agreement with data is at about the 15% level, approximating the precision of the data itself.
Some Comments On The Concepts Of Dose And Dose Equivalent, Robert Katz, Werner Hofmann
Some Comments On The Concepts Of Dose And Dose Equivalent, Robert Katz, Werner Hofmann
Robert Katz Publications
Although dose is the simplest and most widely used measurement of a radiation field, it does not always lead to an unambiguous estimate of response. This is reflected in the very wide range of relative biologic effectiveness (RBE) values for biological systems. The ambiguity arises from the focus on energy deposition as the source of biological effect, whether in macroscopic or microscopic volumes. The properties of the biological detector play a role equally important to the properties of the radiation field in their interaction. To predict even the most experimentally accessible biological response, cell killing, we must know the probability …
Quality Factor For Low Doses Of High-Let Radiations, Werner Hofmann, Robert Katz
Quality Factor For Low Doses Of High-Let Radiations, Werner Hofmann, Robert Katz
Robert Katz Publications
The International Commission on Radiological Protection (ICRP77) and the International Commision on Radiation Units and Measurements (ICRU70) have recommended that the evaluation of radiation hazards be based on the “dose equivalent” defined as the product of the absorbed dose and some modifying factors, the most important of which is the quality factor (Q). The quality factor is intended to allow for the effect on the resulting detriment of the microscopic distribution of the absorbed energy. It is therefore defined as a function of the collision stopping power (L∞) in water at the point of interest. Thus Q rises …
Track Formation In Plastics, Robert Katz
Track Formation In Plastics, Robert Katz
Robert Katz Publications
It is proposed that the “threshold for etchable track formation” in plastics is associated with the linear density of activated polymeric clusters along the path of an ion, in the “grain-count regime.” Existing data for CR-39 reveal a change in etching rate in the neighborhood of z/β having the value of about 15-20. We infer that this defines the transition from the grain count regime to the track width regime, as the activation cross-section exceeds the cross-sectional area of the cluster. This interpretation is consistent with available data for the G value for polymer scission and the dose of gamma-rays …
Thresholds In Radiobiology, Robert Katz, Werner Hofmann
Thresholds In Radiobiology, Robert Katz, Werner Hofmann
Robert Katz Publications
Interpretations of radiation effects frequently call upon the word “threshold.” In this letter we wish to explore the meaning of this word, its relationship to the fundamental character of radiation effects, and to the question of perception. We make no distinction between “stochastic effects” and “non-stochastic effects” (ICRU 1971, ICRP 1977). As conceived here, all interactions of radiation with matter are probabilistic. At the cellular or molecular level, where most radiation effects originate, the statistical nature of ionization and excitation events gives rise to considerable fluctuation in the number of these primary events in sensitive sites. Whatever the array of …
Biological Effects Of Low Doses Of Ionizing Radiations: Particle Tracks In Radiobiology, Robert Katz, Werner Hofmann
Biological Effects Of Low Doses Of Ionizing Radiations: Particle Tracks In Radiobiology, Robert Katz, Werner Hofmann
Robert Katz Publications
A radiation field is made up of a tangle of particle tracks, from the primary particle and secondary and higher generation electron interactions, well isolated at low doses and with multiple intersections in cell nuclei at high doses. Low dose effects in multicellular systems are therefore the sum of individual track structures. Until we can state with confidence the structure of a particle track in biological matter for all end-points of interest, at least as well as we can for nuclear emulsions, our knowledge of low dose effects should be regarded as uncertain and inadequate. In this context “track structure” …
Heavy Ion Beam Model For Radiobiology, Rose Ann Roth, Robert Katz
Heavy Ion Beam Model For Radiobiology, Rose Ann Roth, Robert Katz
Robert Katz Publications
An ad hoc model of energetic heavy ion beams, including secondary and tertiary particles, has been constructed for predicting radiobiological experiments. While the beam model is relatively primitive, it yields depth-dose and depth-radiobiological calculations in good agreement with experiment upstream of the Bragg peak. Beyond the peak, the model is somewhat coarse grained and seems to underestimate low-LET fragment production. These defects can be repaired at some cost in computer time. Presently a complete set of depth-dose and radiobiological results (RBE, OER, aerobic and hypoxic survival) is obtained in 4–8 min, for a single beam, at a cost of $10. …
Supralinearity Of Peak 5 And Peak 6 In Tld-700, Michael P. R. Waligórski, Robert Katz
Supralinearity Of Peak 5 And Peak 6 In Tld-700, Michael P. R. Waligórski, Robert Katz
Robert Katz Publications
Track theory has been applied to an earlier suggestion, that the supralinearity of TLDs at high gamma-ray doses is due to pre-existing 1-hit and 2-hit trap structures, to calculate high-LET response. Measured 60Co dose responses for peaks 5 and 6 in LiF (TLD- 700) were decomposed to yield parameters characterizing each peak as a two-component c-hit mixture. One value of “trap radius” was assigned to each two-component representation, different for peak 5 and for peak 6, to calculate their responses for H, He, C, O, and Ne bombardments. Calculations reproduce experimental features of the heavy ion response of TLD-700, and …
Photometric Measurements Of Thin Tracks In Nuclear Emulsion, Robert Katz
Photometric Measurements Of Thin Tracks In Nuclear Emulsion, Robert Katz
Robert Katz Publications
Difficulties observed in the application of track theory to CNO particles are attributed to problems in the application of a light scattering correction in microphotometry.
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 …
Supralinearity Of Thermoluminescent Dosimeters, Leif Larsson, Robert Katz
Supralinearity Of Thermoluminescent Dosimeters, Leif Larsson, Robert Katz
Robert Katz Publications
The supralinear response of thermoluminescent dosimeters (TLDs) after irradiation with gamma- or beta-rays can be decomposed by use of the cumulative Poisson distribution into a sum of 1-or-more and 2-or-more hit components, suggesting the coexistence of both types of trap structures. Following the response of other 1-hit detectors, and of biological cells to energetic heavy ions, we expect and find that the supralinear response tends to disappear with alpha particle, and with neutron irradiation, and that the supralinear, or 2-hit, component tends to be more responsive to high LET (Linear Energy Transfer) radiations. Since the response of biological cells to …
Systematic Evaluation Of Cellular Radiosensitivity Parameters, R. A. Roth, S. C. Sharma, Robert Katz
Systematic Evaluation Of Cellular Radiosensitivity Parameters, R. A. Roth, S. C. Sharma, Robert Katz
Robert Katz Publications
Cellular radiosensitivity parameters of the track structure theory of Katz and co-workers are evaluated from a sum of squares minimizing computer program for nonlinear models. Based on these observations, suggestions are presented for efficient experiment design for the determination of these parameters from track-segment bombardments of high LET radiations.
Simplified Rbe-Dose Calculations For Mixed Radiation Fields, Robert Katz, B. G. Fullerton Jr., R. A. Roth, S. C. Sharma
Simplified Rbe-Dose Calculations For Mixed Radiation Fields, Robert Katz, B. G. Fullerton Jr., R. A. Roth, S. C. Sharma
Robert Katz Publications
A problem for radiobiology, radiation protection and treatment planning is the calculation of RBE as a function of the delivered dose when this dose is a result of a mixture of low and high LET radiations, as for neutron and pion beams. Track structure theory (Katz and Sharma, 1975) has recently been used to produce an algorithm for calculating survival, RBE, and OER as a function of dose in such environments. This simple formulation is based on the concept of irradiation equivalence (Katz et al., 1972) through which the effect of a mixed radiation environment is calculated as if it …
Rbe-Dose Relations For Neutrons And Pions, Robert Katz, S. C. Sharma
Rbe-Dose Relations For Neutrons And Pions, Robert Katz, S. C. Sharma
Robert Katz Publications
RBE-Dose relations have been calculated from cellular radiosensitivity parameters and theoretical particle-energy spectra in tissue, of the secondary particles from neutron and negative pion irradiations. The theoretical results are compared with clinical and radiobiological data for normal tissue, tumors, and cells in culture. Formulae for calculation, cellular parameters, and the needed properties of equivalent “track-segment bombardments” are given, for several mammalian cells irradiated with pions and with neutrons of several energies.
Résumé
Rapports EBR-dose pour neutrons et pions
A partir des paramètres de la radiosensitivité cellulaire et du spectre théorique, dens le tissu, de l’énergie d’atomes secondaires provenant d’irradiations de …
Response Of Nuclear Emulsions To Ionizing Radiations, Robert Katz, F. E. Pinkerton
Response Of Nuclear Emulsions To Ionizing Radiations, Robert Katz, F. E. Pinkerton
Robert Katz Publications
Heavy ion tracks in Ilford K-2 emulsion are simulated with a computer program that makes use of the delta-ray theory of track structure, and the special assumption that the response of the emulsion to gamma-rays is 8-or-more hit. The Ilford K-series of nuclear emulsions is produced from a parent stock called K.0 emulsion, sensitized to become K.1 to K.5, and desensitized to become K–1 to K–3. Our simulations demonstrate that the emulsions K.5 through K.0 to K-1 are 1-or-more hit detectors, while K-2 is an 8-or-more hit detector. We have no data for K-3 emulsion. It would appear that emulsions …
Oer For Mixed Neutrons And Γ Rays, Robert Katz, S. C. Sharma
Oer For Mixed Neutrons And Γ Rays, Robert Katz, S. C. Sharma
Robert Katz Publications
A formula for the OER in a mixed field of neutrons and gamma rays (Hall, 1972a; 1972b) is given .... Our results, calculated from track structure theory (Katz and Sharma, 1973) and secondary particle-energy spectra in tissue from these neutrons (Caswell and Coyne, 1973; Dennis, 1972) are within 5 per cent of the values of Omix found from the Hall formula, when that formula is supplied with calculated values of Rn, On, and Oγ, at appropriate survival levels. Our calculations suggest that the Hall formula may be used with confidence for neutrons of …
Cellular Survival In A Mixed Radiation Environment, Robert Katz, S. C. Sharma
Cellular Survival In A Mixed Radiation Environment, Robert Katz, S. C. Sharma
Robert Katz Publications
Calculations of the survival, r.b.e., and o.e.r. of human kidney cells, after sequential irradiation with gamma-rays and 14 MeV neutrons, agree well with the experiments of Railton et al., with CHO cells in these radiation environments.
Les calculs de survie, de EBR et de FAO concernant les cellules du rein humain, après des séquences d’irradiation avec des rayons gamma et des neutrons 14 MeV, concordent bien avec les expériences de Railton et ses collègues sur des cellules CHO dans des milieux comportant les mêmes radiations.
Berechnungen des Überlebens, des RBW und des OER von menschlichen Nierenzellen nach aufeinanderfolgender Bestrahlung mit …
Heavy Particles In Therapy: An Application Of Track Theory, Robert Katz, S. C. Sharma
Heavy Particles In Therapy: An Application Of Track Theory, Robert Katz, S. C. Sharma
Robert Katz Publications
The survival, OER, and RBE for HeLa, leukemia, and kidney cells after irradiation with 14 MeV neutrons, pion beams, and heavy ion beams dispersed by ridge filters are calculated. Simple beam models and the delta-ray theory of cellular survival are used in the calculations, which refer to a mixed radiation environment and the potential application of these irradiation systems in radiotherapy.
Résumé
Particules lourdes en thérapie; une application de la théorie de trace
On a calculé la survie, l’OER et le RBE (efficacité biologique relative) pour les cellules de HeLa, de leucémie et rénales, après l’irradiation aux neutrons de 14 …
Irradiation Equivalence, Robert Katz, S. C. Sharma, M. Homayoonfar
Irradiation Equivalence, Robert Katz, S. C. Sharma, M. Homayoonfar
Robert Katz Publications
Recent analyses of track structure show that the parameters describing a radiation field are not separable from those describing a detecting system; that is, it is impossible to write an expression describing the effect of irradiation as a product of 2 factors, one of which contains only parameters describing the detecting system, while the other contains parameters describing only the radiation field. From this perspective it is difficult to understand the use of a “quality factor,” applicable to all biological substances and given as a function of the “effective LET,” for the conversion of rads to rems. One cannot define, …
Detection Of Energetic Heavy Ions, Robert Katz, S. C. Sharma, Mehdi Homayoonfar
Detection Of Energetic Heavy Ions, Robert Katz, S. C. Sharma, Mehdi Homayoonfar
Robert Katz Publications
The delta-ray theory of track structure, applied earlier to such 1-or-more hit detection systems as the inactivation of dry enzymes and viruses, the NaI(Tl) scintillation counter, and nuclear emulsion, is extended to the silver activated phosphate glass dosimeter, the LiF thermoluminescent dosimeter, the creation of free radicals in solid biological substances, solid and liquid organic scintillators, and the ferrous sulfate (Fricke) dosimeter. The response of these systems to both gamma-rays and heavy ions is characterized by two parameters: 1) Dγ37, the dose of gamma-rays at which 37% of the sensitive elements remain unaffected by the radiation, and …