Photon dose perturbations due to small inhomogeneities

X. Cedric; John W. Wong; James A. Purdy

doi:10.1118/1.596106

Photon dose perturbations due to small inhomogeneities

X. Cedric, John W. Wong, James A. Purdy

Department of Radiation Oncology

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

An apparatus capable of measuring small fractional changes in ionization current has been used to study the effect of small inhomogeneities on photon dose in water. Small ring shaped inhomogeneities were introduced into a water phantom and measurements have been made for 4, 6, and 18 MV x rays. The results show (1) beyond the range of secondary electrons, the dose perturbation is basically a photon transport phenomenon which becomes less important as the beam energy increases; (2) within the range of secondary electrons, dose perturbation also involves electron transport, which has a strong dependence on atomic number and could result in a substantially large effect on dose deposition.

Original language	English
Pages (from-to)	78-83
Number of pages	6
Journal	Medical physics
Volume	14
Issue number	1
DOIs	https://doi.org/10.1118/1.596106
State	Published - Jan 1987

Keywords

PHANTOMS
RADIATION DOSE DISTRIBUTIONS
WATER
X-RAY DOSIMETRY

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AB - An apparatus capable of measuring small fractional changes in ionization current has been used to study the effect of small inhomogeneities on photon dose in water. Small ring shaped inhomogeneities were introduced into a water phantom and measurements have been made for 4, 6, and 18 MV x rays. The results show (1) beyond the range of secondary electrons, the dose perturbation is basically a photon transport phenomenon which becomes less important as the beam energy increases; (2) within the range of secondary electrons, dose perturbation also involves electron transport, which has a strong dependence on atomic number and could result in a substantially large effect on dose deposition.

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KW - RADIATION DOSE DISTRIBUTIONS

KW - WATER

KW - X-RAY DOSIMETRY

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Photon dose perturbations due to small inhomogeneities

Abstract

Keywords

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