Computed Dose Distributions across Air-Tissue, Polythene-Tissue, and Graphite-Tissue Interfaces for 14-MeV Neutrons

• Published in: Radiation research 1977-02, Vol.69 (2), p.197-209, Article 197
• Main Authors: Bhatia, D. P., Nagarajan, P. S.
• Format: Article
• Language: English
• Subjects: Air; Alpha Particles; Angular distribution; Carbon; Charged particles; Culture Techniques; Dosimetry; Elastic scattering; Energy Transfer; Fast Neutrons; Graphite; Ground state; Mathematics; Models, Theoretical; Neutrons; Particle energy; Polyethylenes; Protons; Radiation Dosage; Radiotherapy; Scattering, Radiation
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3574427

This paper presents some details and the results of calculations of the depth-dose distributions for a 14-MeV neutron beam in a layer of tissue due to charged secondaries produced in (i) an overlying layer of either air, polythene, or graphite and (ii) the layer of tissue itself. The secondaries considered are: the α-particles and the recoiling nuclei from (n, α) events, and the recoils produced in elastic scattering events. The calculations show that for depths of up to about 100 μm, the largest part of the dose (rad) is from α's and heavy recoils. Heavy recoils from the overlying layers contribute significantly only up to about 10 μm. The dose due to these heavier particles is one order of magnitude higher than the proton dose up to about 30 μm, when the neutrons are incident on the air-tissue interface or the graphite-tissue interface. In the case of a polythene-tissue interface this is not so; however, the absolute magnitude of the heavy particle dose is the same for all the three interfaces.