title: Therapeutic potential of atmospheric neutrons.
abstract: BACKGROUND
  Glioblastoma multiform (GBM) is the most common and most aggressive type of primary brain tumour in humans. It has a very poor prognosis despite multi-modality treatments consisting of open craniotomy with surgical resection, followed by chemotherapy and/or radiotherapy. Recently, a new treatment has been proposed - Boron Neutron Capture Therapy (BNCT) - which exploits the interaction between Boron-10 atoms (introduced by vector molecules) and low energy neutrons produced by giant accelerators or nuclear reactors.
  
  
  METHODS
  The objective of the present study is to compute the deposited dose using a natural source of neutrons (atmospheric neutrons). For this purpose, Monte Carlo computer simulations were carried out to estimate the dosimetric effects of a natural source of neutrons in the matter, to establish if atmospheric neutrons interact with vector molecules containing Boron-10.
  
  
  RESULTS
  The doses produced (an average of 1 μGy in a 1 g tumour) are not sufficient for therapeutic treatment of in situ tumours. However, the non-localised yet specific dosimetric properties of 10B vector molecules could prove interesting for the treatment of micro-metastases or as (neo)adjuvant treatment. On a cellular scale, the deposited dose is approximately 0.5 Gy/neutron impact.
  
  
  CONCLUSIONS
  It has been shown that BNCT may be used with a natural source of neutrons, and may potentially be useful for the treatment of micro-metastases. The atmospheric neutron flux is much lower than that utilized during standard NBCT. However the purpose of the proposed study is not to replace the ordinary NBCT but to test if naturally occurring atmospheric neutrons, considered to be an ionizing pollution at the Earth's surface, can be used in the treatment of a disease such as cancer. To finalize this study, it is necessary to quantify the biological effects of the physically deposited dose, taking into account the characteristics of the incident particles (alpha particle and Lithium atom) and radio-induced effects (by-stander and low dose effect). One of the aims of the presented paper is to propose to experimental teams (which would be interested in studying the phenomena) a simple way to calculate the dose deposition (allometric fit of free path, transmission factor of brain).
authors.affiliation: University of Corsica, CNRS UMR SPE 6134, Campus Grimaldi, 20250 Corte, France ; Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Voyant
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Rudy
authors.initials: R
authors.lastname: Roustit
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tatje
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Katia
authors.initials: K
authors.lastname: Biffi
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Leschi
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Jérome
authors.initials: J
authors.lastname: Briançon
authors.affiliation: Castelluccio Hospital, Radiotherapy Unit, BP 85, 20177 Ajaccio, France.
authors.forename: Céline Lantieri
authors.initials: CL
authors.lastname: Marcovici
keywords: Atmospheric; Boron; Glioblastoma; NBCT; Neutron