The introduction of Lanthanum Bromide crystal, characterized by a fast and high light emission, offers the possibility to improve both imaging spatial resolution and energy resolution in SPECT in the 80-300 kev energy range, without compromising detection efficiency. The expected performances may be limited if the crystal is used with a multi-anode PMT with Position Sensitive response due to the wide differences in the segmented anode pad gains, ranging from 2:1 to 10:1,. These characteristics may strongly deteriorate the overall energy resolution and, consequently, impair the detector imaging capability. For this reason, a 256 independent channel electronic read out was developed, based on an FPGA control, to individually read the charge on each anode. The electronics features a very low electronic noise (< 1%) and a wide dynamic range. The readout electronics was used to build a gamma camera based on a single 100mm x 100mm continuous LaBr3:Ce crystal coupled to a 2x2 array SBA photocatode (38% QE) Hamamatsu H8500. An offline calibration procedure is also shown in order to compensate the anode gain variation and to exploit the LaBr3:Ce capabilities, obtaining on the whole detection area an 8.0-8.5% energy resolution at 140 kev. The high energy resolution performances of this gamma camera permitted to discriminate emissions from two different isotope (Tc-99m and Co-57) with very close photon energy (140 and 122 kev respectively). This capability can be used to provide the gamma image with references coming from Co-57 point sources (marker) fixed at known positions. These results confirm the LaBr3:Ce crystals as one of the most interesting for all single photon emission applications.

Dual isotope imaging with LaBr3:Ce crystal and H8500 PSPMT / Fabbri, Andrea; ORSOLINI CENCELLI, Valentino; Bennati, Paolo; Cinti, Maria Nerina; Pellegrini, Rosanna; DE VINCENTIS, Giuseppe; Pani, Roberto. - In: JOURNAL OF INSTRUMENTATION. - ISSN 1748-0221. - ELETTRONICO. - 8:2(2013), pp. Art. n. 580460-1-Art. n. 580460-6. ((Intervento presentato al convegno 14th International Workshop on Radiation Imaging Detectors tenutosi a Figueira da Foz, PORTUGAL nel JUL 01-05, 2012 [10.1088/1748-0221/8/02/c02022].

Dual isotope imaging with LaBr3:Ce crystal and H8500 PSPMT

FABBRI, ANDREA;ORSOLINI CENCELLI, VALENTINO;BENNATI, Paolo;CINTI, Maria Nerina;PELLEGRINI, Rosanna;DE VINCENTIS, Giuseppe;PANI, Roberto
2013

Abstract

The introduction of Lanthanum Bromide crystal, characterized by a fast and high light emission, offers the possibility to improve both imaging spatial resolution and energy resolution in SPECT in the 80-300 kev energy range, without compromising detection efficiency. The expected performances may be limited if the crystal is used with a multi-anode PMT with Position Sensitive response due to the wide differences in the segmented anode pad gains, ranging from 2:1 to 10:1,. These characteristics may strongly deteriorate the overall energy resolution and, consequently, impair the detector imaging capability. For this reason, a 256 independent channel electronic read out was developed, based on an FPGA control, to individually read the charge on each anode. The electronics features a very low electronic noise (< 1%) and a wide dynamic range. The readout electronics was used to build a gamma camera based on a single 100mm x 100mm continuous LaBr3:Ce crystal coupled to a 2x2 array SBA photocatode (38% QE) Hamamatsu H8500. An offline calibration procedure is also shown in order to compensate the anode gain variation and to exploit the LaBr3:Ce capabilities, obtaining on the whole detection area an 8.0-8.5% energy resolution at 140 kev. The high energy resolution performances of this gamma camera permitted to discriminate emissions from two different isotope (Tc-99m and Co-57) with very close photon energy (140 and 122 kev respectively). This capability can be used to provide the gamma image with references coming from Co-57 point sources (marker) fixed at known positions. These results confirm the LaBr3:Ce crystals as one of the most interesting for all single photon emission applications.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11573/562750
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