Restricted LET Remains a Good Parameter of Radiation Quality

Harder, Dietrich; Blohm, R.; Kessler, M.

doi:10.1093/oxfordjournals.rpd.a080134

Cited by 13 publications

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“…The present data alone do not allow judgement as to whether alternative radiation quality parameters, such a lineal energy in a particular volume (ICRU 1983), Z2/Q2 (Katz et al . 1971), or energy-restricted LET (Harder et al 1988) would give more satisfactory agreement over the full spectrum of relevant particle energies .…”

Section: Discussionmentioning

confidence: 99%

Direct Comparison between Protons and Alpha-particles of the Same LET: I. Irradiation Methods and Inactivation of Asynchronous V79, HeLa and C3H 10T½ Cells

Goodhead

Belli

Mill³

et al. 1992

International Journal of Radiation Biology

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A direct comparison was carried out of the biological effectiveness of protons and alpha-particles of the same linear energy transfer (LET) under identical conditions with a variety of in vitro biological systems. Monolayers of mammalian cells were irradiated with accelerated beams of protons (1.2 and 1.4 MeV) and alpha-particles (30 and 35 MeV) corresponding to LETs of 23 and 20 keV microns-1 for each particle type. For V79-4 cells it was observed that the linear term of the dose-response for cell inactivation by protons was significantly greater than that for alpha-particles of the same LET. For HeLa and HeLa S3 cells, also, the linear term appeared to be greater for protons, but this was not observed with more limited data for C3H 10T1/2 cells. The result for V79 cells is in agreement with the report of Belli et al. (1989) who observed that the biological effectiveness of protons rose sharply between 17 and 30 keV microns-1 in strong contrast to alpha-particles which reached a peak effectiveness at greater than 100 keV microns-1. These results place new constraints on the biologically relevant features of the microscopic structure of radiation tracks, and have implications for the mechanistic and practical comparison between radiations.

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Section: Discussionmentioning

confidence: 99%

Direct Comparison between Protons and Alpha-particles of the Same LET: I. Irradiation Methods and Inactivation of Asynchronous V79, HeLa and C3H 10T½ Cells

Goodhead

Belli

Mill³

et al. 1992

International Journal of Radiation Biology

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Physical quantification of the biological effectiveness of ionizing radiations

Watt

Kadiri

1990

Int J of Quantum Chemistry

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The role, and limitations, of the fundamental physical quantities used in our current system of dosimetry for the protection of individuals against the hazardous effects of ionizing radiation is discussed briefly. A major limitation is the inability to correlate biological data, in a unified way, as a function of linear energy transfer with the consequent necessity for quality factors.From consideration of the various interaction processes undergone by charged particles in the equilibrium slowing down spectra generated by the incident radiation field, it is shown that good correlation of biological effects, for all radiation types, can be achieved in terms of linear primary ionization. The implication is that delta-ray effects play at most a very minor role, at moderate fluences, and that, consequently, the absorbed dose is an unsuitable parameter for describing radiation effects. Structure in the radiosensitive targets is observed to have a critical dimension of about 2 nrn. It occurs only when double-stranded DNA is present and the magnitude of the inactivation probability is consistent with double-stranded breaks being the significant lesion. Calculation is made of the yield of lesions as a function of the mean free path for primary ionization.Differential spectra of radiation quality are obtained for monoenergetic electrons (0.2 keV to 30 MeV); for characteristic X-rays from carbon, aluminium, neon, potassium, copper, silver, and tungsten; for 50 kV X-rays, 250 kV X-rays,. 24'Am, "'Cs, and %o gamma rays; and for neutrons with energies between 0.1 and 50 MeV. Damage by electrons is shown to be predominant at the ends of their tracks between 50 and 200 eV, whereas this is not so for the proton recoil spectrum generated by neutrons above 1 MeV.Proposals are made for a unified system of dosimetry that is independent of radiation type and that obviates the need for quality factors. The method is thought to be of general applicability to irradiations by nuclides incorporated into mammalian cells, by ingested emitters, and by external sources.

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The Track Structure of Photons, Electrons and α-Particles from the Point of View of the Formation of Ionization Clusters

Großwendt

2001

Advanced Monte Carlo for Radiation Physics, Particle Transport Simulation and Applications

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Restricted LET Remains a Good Parameter of Radiation Quality

Cited by 13 publications

References 0 publications

Direct Comparison between Protons and Alpha-particles of the Same LET: I. Irradiation Methods and Inactivation of Asynchronous V79, HeLa and C3H 10T½ Cells

Direct Comparison between Protons and Alpha-particles of the Same LET: I. Irradiation Methods and Inactivation of Asynchronous V79, HeLa and C3H 10T½ Cells

Physical quantification of the biological effectiveness of ionizing radiations

The Track Structure of Photons, Electrons and α-Particles from the Point of View of the Formation of Ionization Clusters

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