title: Basic Study for the Purpose of Developing a Quantitative67Ga-SPECT Measurement Method.
abstract: 67Ga-single photon emission computed tomography (SPECT) images vary according to the imaging time and image display methods. The calculation of an index, such as the standardized uptake value used in positron emission tomography, from67Ga-SPECT images would enable the accurate evaluation of the region of accumulation. The purpose of this study was to elucidate the conversion formula, the lower detection limit (LDL), and recovery coefficient (RC) for quantifying the radiation concentration in the67Ga accumulation site.
  
  
  
  After chronologically obtaining SPECT/CT images at a radiation concentration of 1.0-442.4 kBq/mL with 27 bottles (diameter: 48 mm, 100 mL), the radiation concentration conversion formula was calculated using the successive approximation reconstruction method. The conversion coefficient was then calculated from the relationship between the count rate and the radiation concentration, and the LDL was determined. To compensate for the partial volume effect, the recovery curve was calculated using the mean SPECT count for six bottles (diameter: 9, 18, 29, 38, 48, and 94 mm).
  
  
  
  There was a linear relationship between the radiation concentration and the count rate with a good correlation (r=0.99). The LDL was 1.0 kBq/mL. The recovery curve reached a plateau at a diameter of at least 48 mm.
  
  
  
  The calculation of the absorbed dose index was possible using the radiation concentration conversion formula and the RC.
authors.affiliation: Department of Radiological Technology, Kumamoto General Hospital.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Reiki
authors.initials: R
authors.lastname: Sakata
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakasone
authors.forename: Masataka
authors.initials: M
authors.lastname: Kadota
authors.forename: Shigeki
authors.initials: S
authors.lastname: Ito
mesh_terms: D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D013679:Technology, Radiologic; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*