title: Validation of a dose-point kernel convolution technique for internal dosimetry.
abstract: The objective of this study was to validate a dose-point kernel convolution technique that provides a three-dimensional (3D) distribution of absorbed dose from a 3D distribution of the radionuclide 131I. A dose-point kernel for the penetrating radiations was calculated by a Monte Carlo simulation and cast in a 3D rectangular matrix. This matrix was convolved with the 3D activity map furnished by quantitative single-photon-emission computed tomography (SPECT) to provide a 3D distribution of absorbed dose. The convolution calculation was performed using a 3D fast Fourier transform (FFT) technique, which takes less than 40 s for a 128 x 128 x 16 matrix on an Intel 486 DX2 (66 MHz) personal computer. The calculated photon absorbed dose was compared with values measured by thermoluminescent dosimeters (TLDS) inserted along the diameter of a 22 cm diameter annular source of 131I. The mean and standard deviation of the percentage difference between the measurements and the calculations were equal to -1% and 3.6%, respectively. This convolution method was also used to calculate the 3D dose distribution in an Alderson abdominal phantom containing a liver, a spleen, and a spherical tumour volume loaded with various concentrations of 131I. By averaging the dose calculated throughout the liver, spleen, and tumour the dose-point kernel approach was compared with values derived using the MIRD formalism, and found to agree to better than 15%.
authors.affiliation: Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston 77030.
authors.forename: H B
authors.initials: HB
authors.lastname: Giap
authors.forename: D J
authors.initials: DJ
authors.lastname: Macey
authors.forename: J E
authors.initials: JE
authors.lastname: Bayouth
authors.forename: A L
authors.initials: AL
authors.lastname: Boyer
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D003198:Computer Simulation; D005583:Fourier Analysis; D006801:Humans; D007457:Iodine Radioisotopes; D008961:Models, Structural; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy; D016499:Radioimmunotherapy; D011874:Radiometry / Q000379:methods* / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage; D012985:Software Design; D013819:Thermoluminescent Dosimetry
chemical_list: D007457:Iodine Radioisotopes