title: Radiation quality investigations around a neutron therapy beam, using a high-pressure ionization chamber.
abstract: The mean quality factor (Q) and the dose mean linear energy transfer [LET (LD)] a few centimeters outside a neutron therapy beam have been measured using a high-pressure ionization chamber. Measurements have been carried out in air, 5 and 100 cm outside the treatment field edge on the patient plane for p(46)-Be neurons and are compared with the results obtained at the same points with a low-pressure proportional counter (Rossi counter) and a Bonner spheres system. General agreement is found between these independent methods. The dose equivalent at 5 and 100 cm distances outside the field edge is 2% and 0.4% of the dose equivalent at the isocenter. Measurements were also performed at the same points as a function of proton energy on the Be target. Proton energies of 25-46 MeV on Be were applied. The results indicate increase in the mean quality factor at proton energies below 30 MeV.
authors.affiliation: Department of Medical Physics, University of Athens, Greece.
authors.forename: G M
authors.initials: GM
authors.lastname: Makrigiorgos
authors.forename: J B
authors.initials: JB
authors.lastname: Smathers
authors.forename: L T
authors.initials: LT
authors.lastname: Myers
authors.forename: S H
authors.initials: SH
authors.lastname: Benedict
mesh_terms: D006801:Humans; D009502:Neutrons; D011874:Radiometry / Q000295:instrumentation*; D011882:Radiotherapy, High-Energy; D013679:Technology, Radiologic