Dosimetric properties of neutron beams from the D-D reaction in the energy range from 6.8 to 11.1 MeV

• Published in: Physics in medicine & biology 1978-05, Vol.23 (3), p.397-404, Article 397
• Main Authors: Waterman, F M, Kuchnir, F T, Skaggs, L S, Hendry, G O, Tom, J L
• Format: Article
• Language: English
• Subjects: Atmosphere; Deuterium; Energy Transfer; Fast Neutrons - therapeutic use; Humans; Models, Structural; Neutrons - therapeutic use; Particle Accelerators; Radiation Dosage; Radiometry; Skin Neoplasms - radiotherapy
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/23/3/003

The tissue kerma in air, the tissue dose at maximum build-up, the relative depth dose on the central axis and the dose build-up characteristics were measured for neutrons produced by 6.8, 8.9 and 11.1 MeV deuterons on deuterium. The neutron beams were produced by a variable-energy cyclotron with a fully stopping deuterium gas target 20 cm long. Measurements were made in a 11.1cm x 11.1 cm field 126 cm from the target entrance window. The dose rate was found to increase rapidly with energy from 0.07 rad min-1 microamperemeter-1 at 6.8MeV to 0.35 rad min-1 muA-1 at 11.1 MeV. The entrance dose is about 50% of the dose maximum for each bombarding energy. The depth of the 95% dose level in the build-up region increased from 50 mg cm-2 at 6.8 MeV to 90 mg cm-2 at 11.1 MeV. The penetration was independent of the bombarding energy in the region investigated. Attenuation of the total dose to 50% of the maximum occurred at 10.2 +/- 0.1 g cm-2 for all three bombarding energies. The dose at the maximum is typically 14% higher than the tissue kerma in air.