Technical Note: A Monte Carlo study of magnetic-field-induced radiation dose effects in mice.

Autor: Rubinstein AE; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030., Liao Z; Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Melancon AD; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Guindani M; Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Followill DS; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Tailor RC; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Hazle JD; Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030., Court LE; Departments of Radiation Physics and Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030.
Jazyk: angličtina
Zdroj: Medical physics [Med Phys] 2015 Sep; Vol. 42 (9), pp. 5510-6.
DOI: 10.1118/1.4928600
Abstrakt: Purpose: Magnetic fields are known to alter radiation dose deposition. Before patients receive treatment using an MRI-linear accelerator (MRI-Linac), preclinical studies are needed to understand the biological consequences of magnetic-field-induced dose effects. In the present study, the authors sought to identify a beam energy and magnetic field strength combination suitable for preclinical murine experiments.
Methods: Magnetic field dose effects were simulated in a mouse lung phantom using various beam energies (225 kVp, 350 kVp, 662 keV [Cs-137], 2 MV, and 1.25 MeV [Co-60]) and magnetic field strengths (0.75, 1.5, and 3 T). The resulting dose distributions were compared with those in a simulated human lung phantom irradiated with a 6 or 8 MV beam and orthogonal 1.5 T magnetic field.
Results: In the human lung phantom, the authors observed a dose increase of 45% and 54% at the soft-tissue-to-lung interface and a dose decrease of 41% and 48% at the lung-to-soft-tissue interface for the 6 and 8 MV beams, respectively. In the mouse simulations, the magnetic fields had no measurable effect on the 225 or 350 kVp dose distribution. The dose increases with the Cs-137 beam for the 0.75, 1.5, and 3 T magnetic fields were 9%, 29%, and 42%, respectively. The dose decreases were 9%, 21%, and 37%. For the 2 MV beam, the dose increases were 16%, 33%, and 31% and the dose decreases were 9%, 19%, and 30%. For the Co-60 beam, the dose increases were 19%, 54%, and 44%, and the dose decreases were 19%, 42%, and 40%.
Conclusions: The magnetic field dose effects in the mouse phantom using a Cs-137, 3 T combination or a Co-60, 1.5 or 3 T combination most closely resemble those in simulated human treatments with a 6 MV, 1.5 T MRI-Linac. The effects with a Co-60, 1.5 T combination most closely resemble those in simulated human treatments with an 8 MV, 1.5 T MRI-Linac.
Databáze: MEDLINE
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