title: Prompt gamma ray imaging for verification of proton boron fusion therapy: A Monte Carlo study.
abstract: OBJECTIVE
  The purpose of this study was to verify acquisition feasibility of a single photon emission computed tomography image using prompt gamma rays for proton boron fusion therapy (PBFT) and to confirm an enhanced therapeutic effect of PBFT by comparison with conventional proton therapy without use of boron.
  
  
  METHODS
  Monte Carlo simulation was performed to acquire reconstructed image during PBFT. We acquired percentage depth dose (PDD) of the proton beams in a water phantom, energy spectrum of the prompt gamma rays, and tomographic images, including the boron uptake region (BUR; target). The prompt gamma ray image was reconstructed using maximum likelihood expectation maximisation (MLEM) with 64 projection raw data. To verify the reconstructed image, both an image profile and contrast analysis according to the iteration number were conducted. In addition, the physical distance between two BURs in the region of interest of each BUR was measured.
  
  
  RESULTS
  The PDD of the proton beam from the water phantom including the BURs shows more efficient than that of conventional proton therapy on tumour region. A 719keV prompt gamma ray peak was clearly observed in the prompt gamma ray energy spectrum. The prompt gamma ray image was reconstructed successfully using 64 projections. Different image profiles including two BURs were acquired from the reconstructed image according to the iteration number.
  
  
  CONCLUSIONS
  We confirmed successful acquisition of a prompt gamma ray image during PBFT. In addition, the quantitative image analysis results showed relatively good performance for further study.
authors.affiliation: Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505, South Korea.
authors.forename: Han-Back
authors.initials: HB
authors.lastname: Shin
authors.affiliation: Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505, South Korea.
authors.forename: Do-Kun
authors.initials: DK
authors.lastname: Yoon
authors.affiliation: Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505, South Korea.
authors.forename: Joo-Young
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505, South Korea.
authors.forename: Moo-Sub
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505, South Korea. Electronic address: suhsanta@catholic.ac.kr.
authors.forename: Tae Suk
authors.initials: TS
authors.lastname: Suh
mesh_terms: D055592:Biophysical Phenomena; D001895:Boron / Q000528:radiation effects* / Q000627:therapeutic use*; D003198:Computer Simulation; D005240:Feasibility Studies; D005720:Gamma Rays; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009010:Monte Carlo Method; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D019047:Phantoms, Imaging; D061766:Proton Therapy / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data*; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data*
chemical_list: D001895:Boron
keywords: Prompt gamma ray; Proton boron fusion therapy; SPECT; Tumour monitoring