title: Quantitative investigation of a novel small field of view hybrid gamma camera (HGC) capability for sentinel lymph node detection.
abstract: OBJECTIVE
  The hybrid gamma camera (HGC) has been developed to enhance the localization of radiopharmaceutical uptake in targeted tissues during surgical procedures such as sentinel lymph node (SLN) biopsy. To assess the capability of the HGC, a lymph node contrast (LNC) phantom was constructed to simulate medical scenarios of varying radioactivity concentrations and SLN size.
  
  
  METHODS
  The phantom was constructed using two clear acrylic glass plates. The SLNs were simulated by circular wells of diameters ranging from 10 to 2.5 mm (16 wells in total) in 1 plate. The second plate contains four larger rectangular wells to simulate tissue background activity surrounding the SLNs. The activity used to simulate each SLN ranged between 4 and 0.025 MBq. The activity concentration ratio between the background and the activity injected in the SLNs was 1 : 10. The LNC phantom was placed at different depths of scattering material ranging between 5 and 40 mm. The collimator-to-source distance was 120 mm. Image acquisition times ranged from 60 to 240 s.
  
  
  RESULTS
  Contrast-to-noise ratio analysis and full-width-at-half-maximum (FWHM) measurements of the simulated SLNs were carried out for the images obtained. Over the range of activities used, the HGC detected between 87.5 and 100% of the SLNs through 20 mm of scattering material and 75-93.75% of the SLNs through 40 mm of scattering material. The FWHM of the detected SLNs ranged between 11.93 and 14.70 mm.
  
  
  CONCLUSIONS
  The HGC is capable of detecting low accumulation of activity in small SLNs, indicating its usefulness as an intraoperative imaging system during surgical SLN procedures.
  
  
  CONCLUSIONS
  This study investigates the capability of a novel small-field-of-view (SFOV) HGC to detect low activity uptake in small SLNs. The phantom and procedure described are inexpensive and could be easily replicated and applied to any SFOV camera, to provide a comparison between systems with clinically relevant results.
authors.affiliation: 1 Space Research Centre, Department of Physics and Astronomy, University of Leicester, Leicester, UK.|2 Radiological Sciences Department, College of Applied Medical Sciences, King Khalid University, Abha, Saudi Arabia.
authors.forename: Mohammed S
authors.initials: MS
authors.lastname: Alqahtani
authors.affiliation: 1 Space Research Centre, Department of Physics and Astronomy, University of Leicester, Leicester, UK.
authors.forename: John E
authors.initials: JE
authors.lastname: Lees
authors.affiliation: 1 Space Research Centre, Department of Physics and Astronomy, University of Leicester, Leicester, UK.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Bugby
authors.affiliation: 1 Space Research Centre, Department of Physics and Astronomy, University of Leicester, Leicester, UK.|3 Radiological Sciences Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Layal K
authors.initials: LK
authors.lastname: Jambi
authors.affiliation: 4 Radiological Sciences, School of Medicine, University of Nottingham, Nottingham, UK.
authors.forename: Alan C
authors.initials: AC
authors.lastname: Perkins
mesh_terms: D004867:Equipment Design; D015902:Gamma Cameras; D006801:Humans; D019047:Phantoms, Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D000071036:Sentinel Lymph Node / Q000000981:diagnostic imaging*; D021701:Sentinel Lymph Node Biopsy
chemical_list: D019275:Radiopharmaceuticals