Volume 12, Issue 4 p. 405-412

Calculation of radiation doses for nonuniformly distributed β and γ radionuclides in soft tissue

Cheuk S. Kwok

Cheuk S. Kwok

McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5

Ontario Cancer Treatment and Research Foundation, 711 Concession Street, Hamilton, Ontario, Canada L8V 1C3

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William V. Prestwich

William V. Prestwich

McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5

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Brian C. Wilson

Brian C. Wilson

McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5

Ontario Cancer Treatment and Research Foundation, 711 Concession Street, Hamilton, Ontario, Canada L8V 1C3

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First published: July 1985
Citations: 35

Abstract

In cancer radioimmunotherapy nonuniform distributions of radionuclides in geometrically irregular tumor volumes will be encountered. If the tumor is surrounded by a homogeneous layer of soft tissue, the radiation dose distribution in the tumor due to a beta-emitting nuclide can be calculated by convolution of the appropriate Loevinger's point source dose function, J, with the nuclide concentration distribution. Computer programs using fast Fourier transform techniques have been developed to evaluate the three-dimensional spatial convolution accurately and efficiently. Equivalent techniques have also been applied to gamma-emitting nuclides by replacing J in the convolution by the photon point isotropic specific absorbed fraction. Illustractive results are presented for the radiation dose distribution in a 1-ml target volume with activity distribution which is (i) uniform, (ii) limited by diffusion into the target volume, or (iii) limited by diffusion and shedding of radionuclide in the peripheral layers of the target volume. Calculations for the three cases are presented for 32P,131I, and 15-, 30-, and 100-keV photon emitters.