open access

Vol 17, No 6 (2012)
Original research articles
Published online: 2012-11-01
Submitted: 2011-10-05
Get Citation

Thermal and resonance neutrons generated by various electron and X-ray therapeutic beams from medical linacs installed in polish oncological centers

Adam Konefał, Andrzej Orlef, Marcin Łaciak, Aleksander Ciba, Marek Szewczuk
DOI: 10.1016/j.rpor.2012.06.004
·
Rep Pract Oncol Radiother 2012;17(6):339-346.

open access

Vol 17, No 6 (2012)
Original research articles
Published online: 2012-11-01
Submitted: 2011-10-05

Abstract

Background

High-energy photon and electron therapeutic beams generated in medical linear accelerators can cause the electronuclear and photonuclear reactions in which neutrons with a broad energy spectrum are produced. A low-energy component of this neutron radiation induces simple capture reactions from which various radioisotopes originate and in which the radioactivity of a linac head and various objects in the treatment room appear.

Aim

The aim of this paper is to present the results of the thermal/resonance neutron fluence measurements during therapeutic beam emission and exemplary spectra of gamma radiation emitted by medical linac components activated in neutron reactions for four X-ray beams and for four electron beams generated by various manufacturers’ accelerators installed in typical concrete bunkers in Polish oncological centers.

Materials and methods

The measurements of neutron fluence were performed with the use of the induced activity method, whereas the spectra of gamma radiation from decays of the resulting radioisotopes were measured by means of a portable high-purity germanium detector set for field spectroscopy.

Results

The fluence of thermal neutrons as well as resonance neutrons connected with the emission of a 20[[ce:hsp sp="0.25"/]]MV X-ray beam is ∼106[[ce:hsp sp="0.25"/]]neutrons/cm2 per 1[[ce:hsp sp="0.25"/]]Gy of a dose in water at a reference depth. It is about one order of magnitude greater than that for the 15[[ce:hsp sp="0.25"/]]MV X-ray beams and about two orders of magnitude greater than for the 18–22[[ce:hsp sp="0.25"/]]MeV electron beams regardless of the type of an accelerator.

Conclusion

The thermal as well as resonance neutron fluence depends strongly on the type and the nominal potential of a therapeutic beam. It is greater for X-ray beams than for electrons. The accelerator accessories and other large objects should not be stored in a treatment room during high-energy therapeutic beam emission to avoid their activation caused by thermal and resonance neutrons. Half-lives of the radioisotopes originating from the simple capture reaction (n,γ) (from minutes to hours) are long enough to accumulate radioactivity of components of the accelerator head. The radiation emitted by induced radioisotopes causes the additional doses to staff operating the accelerators.

Abstract

Background

High-energy photon and electron therapeutic beams generated in medical linear accelerators can cause the electronuclear and photonuclear reactions in which neutrons with a broad energy spectrum are produced. A low-energy component of this neutron radiation induces simple capture reactions from which various radioisotopes originate and in which the radioactivity of a linac head and various objects in the treatment room appear.

Aim

The aim of this paper is to present the results of the thermal/resonance neutron fluence measurements during therapeutic beam emission and exemplary spectra of gamma radiation emitted by medical linac components activated in neutron reactions for four X-ray beams and for four electron beams generated by various manufacturers’ accelerators installed in typical concrete bunkers in Polish oncological centers.

Materials and methods

The measurements of neutron fluence were performed with the use of the induced activity method, whereas the spectra of gamma radiation from decays of the resulting radioisotopes were measured by means of a portable high-purity germanium detector set for field spectroscopy.

Results

The fluence of thermal neutrons as well as resonance neutrons connected with the emission of a 20[[ce:hsp sp="0.25"/]]MV X-ray beam is ∼106[[ce:hsp sp="0.25"/]]neutrons/cm2 per 1[[ce:hsp sp="0.25"/]]Gy of a dose in water at a reference depth. It is about one order of magnitude greater than that for the 15[[ce:hsp sp="0.25"/]]MV X-ray beams and about two orders of magnitude greater than for the 18–22[[ce:hsp sp="0.25"/]]MeV electron beams regardless of the type of an accelerator.

Conclusion

The thermal as well as resonance neutron fluence depends strongly on the type and the nominal potential of a therapeutic beam. It is greater for X-ray beams than for electrons. The accelerator accessories and other large objects should not be stored in a treatment room during high-energy therapeutic beam emission to avoid their activation caused by thermal and resonance neutrons. Half-lives of the radioisotopes originating from the simple capture reaction (n,γ) (from minutes to hours) are long enough to accumulate radioactivity of components of the accelerator head. The radiation emitted by induced radioisotopes causes the additional doses to staff operating the accelerators.

Get Citation

Keywords

Thermal/resonance neutrons; Induce radioactivity; Medical linacs

About this article
Title

Thermal and resonance neutrons generated by various electron and X-ray therapeutic beams from medical linacs installed in polish oncological centers

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 17, No 6 (2012)

Pages

339-346

Published online

2012-11-01

DOI

10.1016/j.rpor.2012.06.004

Bibliographic record

Rep Pract Oncol Radiother 2012;17(6):339-346.

Keywords

Thermal/resonance neutrons
Induce radioactivity
Medical linacs

Authors

Adam Konefał
Andrzej Orlef
Marcin Łaciak
Aleksander Ciba
Marek Szewczuk

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl