PURPOSE: To compare possible neutron doses produced in scanning and scattering modes, with the latter assessed using a newly built passive-scattering proton beam line. METHODS AND MATERIALS: A 40 x 30.5 x 30-cm water phantom was irradiated with 230-MeV proton beams using a gantry angle of 270 degrees , a 10-cm-diameter snout, and a brass aperture with a diameter of 7 cm and a thickness of 6.5 cm. The secondary neutron doses during irradiation were measured at various points using CR-39 detectors, and these measurements were cross-checked using a neutron survey meter with a 22-cm range and a 5-cm spread-out Bragg peak. RESULTS: The maximum doses due to secondary neutrons produced by a scattering beam-delivery system were on the order of 0.152 mSv/Gy and 1.17 mSv/Gy at 50 cm from the beam isocenter in the longitudinal (0 degrees ) and perpendicular (90 degrees ) directions, respectively. The neutron dose equivalent to the proton absorbed dose, measured from 10 cm to 100 cm from the isocenter, ranged from 0.071 mSv/Gy to 1.96 mSv/Gy in the direction of the beam line (i.e., phi = 0 degrees ). The largest neutron dose, of 3.88 mSv/Gy, was observed at 135 degrees and 25 cm from the isocenter. CONCLUSIONS: Although the secondary neutron doses in proton therapy were higher when a scattering mode rather than a scanning mode was used, they did not exceed the scattered photon dose in typical photon treatments.
PURPOSE: To compare possible neutron doses produced in scanning and scattering modes, with the latter assessed using a newly built passive-scattering proton beam line. METHODS AND MATERIALS: A 40 x 30.5 x 30-cm water phantom was irradiated with 230-MeV proton beams using a gantry angle of 270 degrees , a 10-cm-diameter snout, and a brass aperture with a diameter of 7 cm and a thickness of 6.5 cm. The secondary neutron doses during irradiation were measured at various points using CR-39 detectors, and these measurements were cross-checked using a neutron survey meter with a 22-cm range and a 5-cm spread-out Bragg peak. RESULTS: The maximum doses due to secondary neutrons produced by a scattering beam-delivery system were on the order of 0.152 mSv/Gy and 1.17 mSv/Gy at 50 cm from the beam isocenter in the longitudinal (0 degrees ) and perpendicular (90 degrees ) directions, respectively. The neutron dose equivalent to the proton absorbed dose, measured from 10 cm to 100 cm from the isocenter, ranged from 0.071 mSv/Gy to 1.96 mSv/Gy in the direction of the beam line (i.e., phi = 0 degrees ). The largest neutron dose, of 3.88 mSv/Gy, was observed at 135 degrees and 25 cm from the isocenter. CONCLUSIONS: Although the secondary neutron doses in proton therapy were higher when a scattering mode rather than a scanning mode was used, they did not exceed the scattered photon dose in typical photon treatments.
Authors: Rui Zhang; Angélica Pérez-Andújar; Jonas D Fontenot; Phillip J Taddei; Wayne D Newhauser Journal: Phys Med Biol Date: 2010-11-12 Impact factor: 3.609
Authors: Whoon Jong Kil; Romaine C Nichols; Bradford S Hoppe; Christopher G Morris; Robert B Marcus; William Mendenhall; Nancy P Mendenhall; Zuofeng Li; Joseph A Costa; Christopher R Williams; Randal H Henderson Journal: Acta Oncol Date: 2013-04 Impact factor: 4.089
Authors: R Charles Nichols; Chen Hu; Jean-Paul Bahary; Kenneth L Zeitzer; Luis Souhami; Mark H Leibenhaut; Marvin Rotman; Elizabeth M Gore; Alexander G Balogh; David McGowan; Jeff Michalski; Adam Raben; Shari Rudoler; Christopher U Jones; Howard Sandler Journal: Adv Radiat Oncol Date: 2017-08-03