title: λ-Eye: a high-sensitivity γ imaging probe for axillary sentinel lymph node mapping.
abstract: OBJECTIVE
  The aim of this study is the construction and performance evaluation of 'λ-eye', a γ imaging probe, optimized in terms of sensitivity for sentinel lymph node mapping. The optimization of the probe is based on theoretical models and simulation results that were presented in a previous study of our group. In this work, the construction of the probe, the experimental confirmation of the simulation results, and the evaluation of its performance with phantoms and lymph node imaging in small animals are presented.
  
  
  METHODS
  The system's spatial and energy resolution, sensitivity, and count rate performance were measured using phantoms. The values of the integral and differential uniformity in the useful field-of-view and in the central field-of-view were also calculated. Finally, a proof-of-concept animal experiment was conducted for the imaging of the lymph nodes of normal mice.
  
  
  RESULTS
  The system's energy resolution was measured as 36±2% and the spatial resolution was 2.2 mm at 2 mm source-collimator distance. The values of the integral uniformity and differential uniformity in the useful field-of-view and in the central field-of-view were found to be 5.2, 2.1, 1.7, and 0.75%, respectively. Finally, the lymph nodes of normal mice were clearly imaged with a 10 s acquisition time.
  
  
  CONCLUSIONS
  The 'λ-eye', used for sentinel lymph node mapping, provides a combination of high sensitivity (∼1.5 counts/s/kBq) and good spatial resolution (∼6 mm full-width of the half-maximum at 20 mm and ∼10 mm full-width of the half-maximum at 50 mm distance). Its compact size (40 mm×40 mm×70 mm) allows its use during surgery and/or for the detailed scan of a suspicious region.
authors.affiliation: aDepartment of Nuclear Medicine, Medical School, University of Thessaly, Larissa bR&D, BioEmission Technology Solutions cDepartment of Biomedical Technology, Technological Educational Institute of Athens dInstitute of Radioisotopes and Radiodiagnostic Products, NCSR 'Demokritos', Athens eDepartment of Medical Physics, Medical School, University of Patras, Patra, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Georgiou
authors.forename: George
authors.initials: G
authors.lastname: Loudos
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Fysikopoulos
authors.forename: Efthimis
authors.initials: E
authors.lastname: Lamprou
authors.forename: Kwnstantinos
authors.initials: K
authors.lastname: Mikropoulos
authors.forename: Antonio
authors.initials: A
authors.lastname: Shegani
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Georgoulias
mesh_terms: D000818:Animals; D005720:Gamma Rays; D051379:Mice; D019047:Phantoms, Imaging; D011877:Radionuclide Imaging / Q000295:instrumentation*; D021701:Sentinel Lymph Node Biopsy / Q000295:instrumentation*