Accidental neutron exposure in a medical setting: a case study

Elizabeth Ainsbury, Jonathan Eakins, Inci Güclü, Ciǧdem Kirbaşoǧlu, Debbie Peet, Idris Tosun

Research output: Contribution to journalArticlepeer-review


In May 2016, a new linear accelerator (Linac) was installed at a hospital oncology department. A team of individuals supervised the installation, including a Radiation Oncologist who acted as an independent observer to the installation, calibration, beam data collection and shielding measurements. In order to ensure the shielding was correct, a licensed representative of the Turkish Atomic Energy Authority carried out formal measurements of the gamma and neutron dose rates at a variety of locations in and around the Linac facility. At 18 MV, the maximum neutron dose rate was 172 μSv h-1 and the maximum gamma dose rate was approximately 2 μSv h-1 (ambient dose equivalent in both cases), significantly higher than the expected and local background doses. As the neutron dose rates in particular were so high, it was concluded that the shielding was not sufficient, potentially due to an inadequate design. In order to rule out overexposure during the installation, biological dosimetry was carried out for a number of the individuals involved. The estimated doses were closely aligned with the doses measured using commercially available neutron dosemeters and were also within the tolerance dose ranges estimated using Monte Carlo simulations, which also supported the investigation. The results underline the need for careful planning before and after installation of new radiation exposure facilities, especially high MV Linac operation for which photo-neutrons might need to be mitigated. The results clearly indicate the importance of such checks, in addition to demonstrating the relevance of biological dosimetry supported by modelling strategies complex or unclear exposure scenarios.

Original languageEnglish
Pages (from-to)1444-1456
Number of pages13
JournalJournal of Radiological Protection
Issue number4
Publication statusPublished - 20 Nov 2020

Bibliographical note

Funding Information: Not available.

Open Access: No Open Access licence.

Publisher Copyright: © 2020 Crown copyright. Reproduced with the permission of the Controller of Her Majesty's Stationery Office.

Citation: Ainsbury, Elizabeth A., et al. "Accidental neutron exposure in a medical setting: a case study." Journal of Radiological Protection 40.4 (2020): 1444.



  • Monte Carlo modelling
  • biological dosimetry
  • gamma
  • medical physics
  • neutron


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