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Home > Issues > SearchUse of Beam Spoiler to Improve Build-up of Photon Beam Using Low Strength Magnetic Field
Journal of Magnetics, Volume 22, Number 4, 31 Dec 2017, Pages 709-714
Woo Sang Ahn (Department of Radiation Oncology, Gangneung Asan Hospital, University of Ulsan College of Medicine), Wonsik Choi (Department of Radiation Oncology, Gangneung Asan Hospital, University of Ulsan College of Medicine), Jungwon Kwak * 
(Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine), Young Ran Ka (Department of Radiological Technology, Jefferson State Community College), Cheol-soo Park (Department of Radiological Science, Hallym Polytechnic University), Seong Soo Shin (Department of Radiation Oncology, Gangneung Asan Hospital, University of Ulsan College of Medicine)
(Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine), Young Ran Ka (Department of Radiological Technology, Jefferson State Community College), Cheol-soo Park (Department of Radiological Science, Hallym Polytechnic University), Seong Soo Shin (Department of Radiation Oncology, Gangneung Asan Hospital, University of Ulsan College of Medicine)
Abstract
The purpose of this study is to propose the use of a beam spoiler for improving the build-up region of photon beam by using external magnetic field with a low strength of 0.5 T (Tesla) outside the human body. A homemade
magnet device which can apply a transverse magnetic field to photon beam was developed. The effect of dose enhancement on build-up region was investigated by the beam spoiler-to-magnet distance (BMD), the
magnet-to-magnet distance (MMD), and the magnet-to-surface distance (MSD). Build-up regions of 6 MV photon beam with and without the magnetic field were measured for the field size to 5 × 5 cm2. When applying the
low magnetic field with MMD of 10 cm, D0mm, D2mm, D5mm and D10mm at BSD of 13 cm and MSD of 5 cm were increased by approximately 3.2%, 3.9%, 1.7% and 0.4%, respectively, compared to the build-up of the existing 6 MV photon beam without the magnetic field. The dose reduction was 5.1% compared to skin dose for 4 MV photon beam without the magnetic field. It is expected that use of a beam spoiler in the magnet device
designed in this study could provide improved dose distributions in build-up regions while maintain similar surface dose to the existing 6 MV photon beam without the magnetic field.
magnet device which can apply a transverse magnetic field to photon beam was developed. The effect of dose enhancement on build-up region was investigated by the beam spoiler-to-magnet distance (BMD), the
magnet-to-magnet distance (MMD), and the magnet-to-surface distance (MSD). Build-up regions of 6 MV photon beam with and without the magnetic field were measured for the field size to 5 × 5 cm2. When applying the
low magnetic field with MMD of 10 cm, D0mm, D2mm, D5mm and D10mm at BSD of 13 cm and MSD of 5 cm were increased by approximately 3.2%, 3.9%, 1.7% and 0.4%, respectively, compared to the build-up of the existing 6 MV photon beam without the magnetic field. The dose reduction was 5.1% compared to skin dose for 4 MV photon beam without the magnetic field. It is expected that use of a beam spoiler in the magnet device
designed in this study could provide improved dose distributions in build-up regions while maintain similar surface dose to the existing 6 MV photon beam without the magnetic field.
Keywords: magnetic field; 6 MV photon beam; build-up region; beam spoiler
DOI: https://doi.org/10.4283/JMAG.2017.22.4.709
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