Tutorial on neutron physics in dosimetry

Abstract

Almost since the time of the discovery of the neutron more than 70 years ago, efforts have been made to understand the effects of neutron radiation on tissue and, eventually, to use neutrons for cancer treatment. In contrast to charged particle or photon radiations which directly lead to release of electrons, neutrons interact with the nucleus and induce emission of several different types of charged particles such as protons, alpha particles or heavier ions. Therefore, a fundamental understanding of the neutron-nucleus interaction is necessary for dose calculations and treatment planning with the needed accuracy. We will discuss the concepts of dose and kerma, neutron-nucleus interactions and have a brief look at nuclear data needs and experimental facilities and set-ups where such data are measured. Figure 1: Cross section for the 16 O(n,γ) reaction (top) and 235U(n,fission) reaction (bottom) plotted as function of the incident neutron energy. The data are from the ENDF/B-VII evaluation and have been retrieved using Janis 3.0 (Soppera et al., 2008).

A Monte Carlo model of the Dingo thermal neutron imaging beamline

“…Nuclear reactions within a biological target can lead to the production of secondary high linear energy transfer (LET) charged particles. The magnitude of this effect, and therefore the relative biological effectiveness (RBE), depends on the neutron energy and the reaction channels being open 44,45 . Moreover, fast neutrons may cause damage to the instrumentation and historical samples.…”

Synapse. A Neutron Spectrum Unfolding Code Based on Generalized Regression Artificial Neural Networks

“…Neutrons are produced by different ways and can be found in nature or produced artificially [23]. In general, neutrons are more difficult to detect than gamma rays because of their weak interaction with matter and their large dynamic range in energy, extending from few thousandths of eV to several hundreds of MeV [24].…”

“…Once the neutron spectrum, θ E (E), has been obtained, the dose ∆, can be calculated using the fluence-to-dose conversion coefficients δ θ E, as shown in equation 3, [23][24][25][26][27].…”

“…The dose is also important mainly due it is the variation of the intensity of neutron radiation as a function of angle of incidence on a body situated in the radiation field, however, the determination of neutron dose in nuclear facilities, generally requires to know the neutron energy spectrum incident on the body [23][24][25][26][27][28][29][30].…”

Dosimetria TL em campos mistos no reator IPEN/MB-01

“…O progresso que se tem atingido é enorme, porém, muito ainda resta a ser feito. Devido à necessidade de compreensão dos efeitos da radiação de nêutrons em eletrônicos e em seres humanos, bem como o renovado interesse mundial em relação às usinas nucleares, o campo de pesquisa em nêutrons oferece um excelente campo de pesquisa e oportunidades para muitos estudos nas próximas décadas (Pomp, 2010). Dentre as áreas mais importantes para a dosimetria de nêutrons pode-se citar a dosimetria ocupacional em reatores e aceleradores (Králík e Vykydal, 2016), dosimetria em pacientes em procedimentos médicos como protonterapia (Trinkl et al, 2017) e na Terapia de Captura de Nêutrons (NCT -Neutron Capture Therapy) (Barth et al, 2012;Nedunchezhian et al, 2016).…”