Kerma Factors for Neutron Energies below 30 MeV

Caswell, Randall S.; Coyne, J.; Randolph, M. L.

doi:10.2307/3575276

Cited by 228 publications

(98 citation statements)

References 15 publications

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“…where K͑E͒ represents the neutron kerma factors 21 and Q n ͑E͒ represents the neutron quality factors. 22 The average neutron quality factor was also calculated according to the following equation:…”

Section: Methodsmentioning

confidence: 99%

Neutron spectra and dose equivalents calculated in tissue for high‐energy radiation therapy

et al. 2009

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Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient's risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances ͑SSD͒. We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depthdose equivalent curve should be used to correct the dose equivalent at the patient surface.

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Section: Methodsmentioning

confidence: 99%

Neutron spectra and dose equivalents calculated in tissue for high‐energy radiation therapy

et al. 2009

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“…Finally, Caswell et al [23] extended the evaluated ENDF libraries from 20 MeV to 30 MeV, using optical model results to obtain the total, elastic, and reaction cross sections. But extrapolations of partial cross sections beyond 20 MeV with this method are not always reliable.…”

Section: Evaluation Methodsmentioning

confidence: 99%

Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N

Chadwick¹,

Young²

1995

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“…For neutron kerma coefficients, the present work can be viewed as an update on the work of Caswell, Coyne, and Randolph [6], which provided tabulations of total kerma coefficients up to 30 MeV. A comprehensive description of our calculated kerma coefficients up to 150 MeV for elements and mixtures/compounds important in dosimetry is given in Ref.…”

mentioning

confidence: 97%

Neutron, proton, and photonuclear cross-sections for radiation therapy and radiation protection

Chadwick¹

1998

Radiation and Environmental Biophysics

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Les Afamos Natlonsl Moratory, an affirmative astiedequal oppertun"kyempleyer, is operated by the Unheraiiy of CMomia for the U.S. Deparbnent of Ene&y under mntract W-740MNG-36. By accaptanca of this article, the publisher rewgnfzes that the U.S. Gwemment retafns a nonexslustie, reya~free license to pubfii or repreduce the pubfried form of thii scmtributien, or to allow others 10 do SO,for U.S. Government purposes. The k Afamos National Laberatmy requests that the pubfkher identify this article aa wxk perfonnad under the auspicas of the U.S. AbstractWe review recent work at Los Alamos to evaluate neutron, proton, and photonuclear cross sections up to 150 MeV (to 250 MeV for protons), based on experimental data and nucIear model calculations. These data are represented in the ENDF format and can be used in computer codes to simulate radiation transport. They permit calculations of absorbed dose in the body from therapy beams, and through use of kerma coefficients allow absorbed dose to be estimated for a given neutron energy distribution. For radiation protection, these data can be used to determine shielding requirements in accelerator environments, and to calculate neutron, proton,~-ray, and radionuclide production. Illui%rative comparisons of the evaluated cross section and kerma coefficient data with measurements are given.

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Kerma Factors for Neutron Energies below 30 MeV

Cited by 228 publications

References 15 publications

Neutron spectra and dose equivalents calculated in tissue for high‐energy radiation therapy

Neutron spectra and dose equivalents calculated in tissue for high‐energy radiation therapy

Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N

Neutron, proton, and photonuclear cross-sections for radiation therapy and radiation protection

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