Measurement of thermal neutron fluence distribution with use of 23Na radioactivation around a medical compact cyclotron

Toshioh Fujibuchi, Ichiro Yamaguchi, Tetsuharu Kasahara, Takashi Iimori, Yoshitada Masuda, Ken Ichi Kimura, Hiroshi Watanabe, Tomonori Isobe, Takeji Sakae

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


A medical compact cyclotron produces about 1015 neutrons per day along with 100 GBq of 18F. Therefore, it is important to establish radiation safety guidelines on residual radioactivity for routine operation, maintenance work, and decommissioning. Thus, we developed a simple method for measuring the thermal neutrons in a cyclotron room. In order to verify the feasibility of our proposed method, we measured the thermal neutron distribution around a cyclotron by using the activation of 23Na in salt. We installed 78 salt dosimeters in the cyclotron room with a 50 cm mesh. The photopeak of 24Na was measured, and the neutron flux distribution was estimated. Monitoring the neutron flux distribution in a cyclotron room appears to be useful for not only obtaining an accurate estimate of the distribution of induced radioactivity, but also optimizing the shield design for radiation safety in preparation for the decommissioning process.

Original languageEnglish
Pages (from-to)159-165
Number of pages7
JournalRadiological physics and technology
Issue number2
Publication statusPublished - Jul 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Radiation
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Radiology Nuclear Medicine and imaging


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