LaBr₃:Ce small FOV gamma camera with excellent energy resolution for multi-isotope imaging

Abstract

The simultaneous administration of radiopharmaceuticals labeled with more than one radioisotope is becoming of increasing interest in clinical practice. Because the photon energies of the utilized radioisotopes could be very close (less than 15% difference), a gamma camera with adequate energy resolution is required. The availability of scintillation crystals with high light yield, as lanthanum tri-bromide (LaBr 3 :Ce), is particularly appealing for these applications.In this work, a new small field of view gamma camera prototype is presented, based on a planar LaBr 3 :Ce scintillation crystal with surfaces treatment typical of spectrometric devices, in order to enhance energy resolution performances. The crystal has round shape and has been optically coupled with a position sensitive photomultiplier tube with high quantum efficiency. The presented gamma camera shows outstanding energy resolution results in the investigated energy range (32-662 keV). These relevant performances have been obtained through the application of uniformity correction on the raw data, necessary due to the presence of position sensitive phototube, characterized by a spread of anodic gain values. In spite of position linearity degradation at crystal edges, due to reflective treatment of surfaces, intrinsic spatial resolution values are satisfactory on the useful field of view.The characterization of the presented gamma camera, based on a continuous LaBr 3 :Ce scintillation crystal with reflective surfaces, indicates good performances in multi-isotope imaging due to the excellent energy resolution results, also in comparison with similar detectors.

Comparison of the imaging performances for recently developed monolithic scintillators: CRY018 and CRY019 for dual isotope gamma ray imaging applications

“…With the standard Anger method (that correspond to the power = 1) the Field of View (FoV) is limited, because of the light tails that are reflected inwards causing a degradation in the reconstruction of the scintillation event positions. By increasing the power in RTP algorithm, the FoV size is almost recovered reaching a satisfactory result comparable with the ones obtained with similar detectors [7]. Images in figure 2 show a halo due to the presence in CRY019 of a self activity background of 176 Lu [4].…”

“…Usually, the clinical practice involves two radioisotopes characterized by photon emissions very close in energy (i.e. 81 keV and 122 keV) [6,7]. As a consequence, a high energy resolution is needed in order to reach a good discrimination of the information coming from the different radioisotope contributions in the overall spectrum.…”

A Novel Method for Spectrometry Based on Imaging Systems

“…All surfaces, except the one in contact with the photocathode, were polished and covered with white painting (0.2 mm of TiO 2 ). White painting is a typical feature for spectrometrical application increasing light collection [12,13].…”

“…In this work, the efficiency of a simple DoI estimator has been studied and verified using a round shape and white painted surfaces CRY018 monolithic crystal coupled to a MAPMT. The full reflective optical treatment enhances the spectrometric properties, as known in the literature [12,13] and affects the shape of the scintillation light distribution. In monolithic detectors, the DoI information is achieved by modelling the scintillation light distribution with analytical functions [14][15][16].…”

CdTe compact gamma camera for coded aperture imaging in radioguided surgery

“…Detection of bone tumors and parathyroid adenoma, radioimmunoguided surgery for colon cancer, sentinel-node mapping for breast tumor or melanoma tumor therapy, are typical applications of RGS [3]. In RGS, though gamma-ray radiotracers are typically adopted [4][5][6][7], also βradioisotopes can be used [8][9][10] as well as β + sources [11][12][13][14]. The success of RGS depends on the progress of the research on radiopharmaceuticals and intraoperative probes.…”