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 γ-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 systems 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 fieldof-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 systems energy resolution was measured as 36± 2% and the spatial resolution was 2.2mm at 2mm source-collimator distance. The values of the integral uniformity and differential uniformity in the useful field-ofview 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. Conclusion The γ-eye, used for sentinel lymph node mapping, provides a combination of high sensitivity (∼1.5 counts/s/kBq) and good spatial resolution (∼6mm full-width of the half-maximum at 20mm and ∼10mm fullwidth of the half-maximum at 50mm distance). Its compact size (40mm×40mm×70 mm) allows its use during surgery and/or for the detailed scan of a suspicious region. © 2016 Wolters Kluwer Health, Inc. All rights reserved.