Commissioning the neutron production of a Linac: Development of a simple tool for second cancer risk estimation

M. Romero-Expósito*, B. Sánchez-Nieto, J. A. Terrón, M. C. Lopes, B. C. Ferreira, D. Grishchuk, C. Sandín, S. Moral-Sánchez, M. Melchor, C. Domingo, F. Gómez, F. Sánchez-Doblado

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

20 Citations (Scopus)

Abstract

Purpose: Knowing the contribution of neutron to collateral effects in treatments is both a complex and a mandatory task. This work aims to present an operative procedure for neutron estimates in any facility using a neutron digital detector.

Methods: The authors previous work established a linear relationship between the total second cancer risk due to neutrons (TRn) and the number of MU of the treatment. Given that the digital detector also presents linearity with MU, its response can be used to determine the TRn per unit MU, denoted as m, normally ssociated to a generic Linac model and radiotherapy facility. Thus, from the number of MU of each patient treatment, the associated risk can be estimated. The feasibility of the procedure was tested by applying it in eight facilities; patients were evaluated as well.

Conclusions: The procedure presented here allows an easy estimation of the second cancer risk due to neutrons for any patient, given the number of MU of the treatment. It will enable the consideration of this information when selecting the optimal treatment for a patient by its implementation in the treatment planning system.

Results: From the reading of the detector under selected irradiation conditions, m values were obtained for different machines, ranging from 0.25×l10-4% per MU for an Elekta Axesse at 10 MV to 6.5×10-4% per MU for a Varian Clinac at 18 MV. Using these values, TRn of patients was estimated in each facility and compared to that from the individual evaluation. Differences were within the range of uncertainty of the authors methodology of equivalent dose and risk estimations.

Original languageEnglish
Pages (from-to)276-281
Number of pages6
JournalMedical Physics
Volume42
Issue number1
DOIs
Publication statusPublished - 1 Jan 2015

Keywords

  • neutrons
  • peripheral dose
  • second cancer risk
  • TPS algorithm

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