Compact gamma-ray probe for breast imaging based on a 5-inch PSPMT and a single NaI crystal scintillator

摘要

Abstract: Scintimammography is a promising technique for breast cancer detection. Scintimammography uses radiotracer containing $+99m$/Tc that emits 140 keV gamma photons. We developed a small field of view gamma ray imaging probe called IRIS. A possible application of this probe is scintimammography. IRIS is composed by a single NaI(Tl) scintillator coupled to a 5 inch round PSPMT. In order to optimize compromise between resolution and detection efficiency, we developed a Monte Carlo code modeling light transport in NaI crystals. The thickness of the scintillator (4 mm) was optimized for $+99m$/Tc imaging. We also designed a high-resolution collimator with a 35 mm thickness and 1.7 mm hole diameter. Detection efficiency of the crystal is 65% at 140 keV. IRIS shows a 2.5 mm global spatial resolution in contact. Energy and spatial corrections allow a $POM 5% uniformity and an energy resolution better than 10% at 140 keV. IRIS has a 10 cm field of view and a 13 cm external diameter at the entrance face. The small size of the detector head allows placing the detector close to the breast, improving global spatial resolution. The high-resolution gamma ray imaging probe IRIS shows physical characteristics well suited for $+99m$/Tc breast imaging. !21