Article

Radiological Physics and Technology

, Volume 1, Issue 1, pp 44-54

First online:

Experimental verification of proton beam monitoring in a human body by use of activity image of positron-emitting nuclei generated by nuclear fragmentation reaction

  • Teiji NishioAffiliated withParticle Therapy Division, Research Center for Innovative Oncology, National Cancer CenterDepartment of Nuclear Engineering and Management, Graduate School of Engineering, University of TokyoDepartment of Radiology, Graduate School of Medicine, University of Tokyo Email author 
  • , Aya MiyatakeAffiliated withDepartment of Nuclear Engineering and Management, Graduate School of Engineering, University of Tokyo
  • , Kazumasa InoueAffiliated withDepartment of Radiology, National Cancer CenterFunctional Imaging Division, Research Center for Innovative Oncology, National Cancer CenterGraduate School of Health Science, Tokyo Metropolitan University
  • , Tomoko Gomi-MiyagishiAffiliated withParticle Therapy Division, Research Center for Innovative Oncology, National Cancer Center
  • , Ryosuke KohnoAffiliated withParticle Therapy Division, Research Center for Innovative Oncology, National Cancer Center
  • , Satoru KameokaAffiliated withParticle Therapy Division, Research Center for Innovative Oncology, National Cancer Center
  • , Keiichi NakagawaAffiliated withDepartment of Radiology, Graduate School of Medicine, University of Tokyo
  • , Takashi OginoAffiliated withParticle Therapy Division, Research Center for Innovative Oncology, National Cancer Center

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Abstract

Proton therapy is a form of radiotherapy that enables concentration of dose on a tumor by use of a scanned or modulated Bragg peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can be confirmed by detection of pair-annihilation gamma rays from positron-emitting nuclei generated by the nuclear fragmentation reaction of the incident protons on target nuclei using a PET apparatus. The activity of the positron-emitting nuclei generated in a patient was measured with a PET-CT apparatus after proton beam irradiation of the patient. Activity measurement was performed in patients with tumors of the brain, head and neck, liver, lungs, and sacrum. The 3-D PET image obtained on the CT image showed the visual correspondence with the irradiation area of the proton beam. Moreover, it was confirmed that there were differences in the strength of activity from the PET-CT images obtained at each irradiation site. The values of activity obtained from both measurement and calculation based on the reaction cross section were compared, and it was confirmed that the intensity and the distribution of the activity changed with the start time of the PET imaging after proton beam irradiation. The clinical use of this information about the positron-emitting nuclei will be important for promoting proton treatment with higher accuracy in the future.

Keywords

Proton therapy Proton beam monitoring Beam OFF-LINE PET system PET-CT imaging