RESUMO
The performance of a light sharing and recirculation mechanism that allows the extraction of depth of interaction (DOI) are investigated in this paper, with a particular focus on timing. In parallel, a method to optimize the coincidence time resolution (CTR) of PET detectors by use of the DOI information is proposed and tested. For these purposes, a dedicated 64-channels readout setup has been developed with intrinsic timing resolution of 16 ps FWHM. Several PET modules have been produced, based on LYSO:Ce scintillators and commercial silicon photomultiplier (SiPM) arrays, with [Formula: see text] mm2 individual SiPM size. The results show the possibility to achieve a timing resolution of 157 ps FWHM, combined with the already demonstrated spatial resolution of 1.5 mm FWHM, DOI resolution of 3 mm FWHM, and energy resolution of 9% FWHM at 511 keV, with 15 mm long crystals of section [Formula: see text] mm2 and [Formula: see text] mm2. At the same time, the extraction of the DOI coordinate has been demonstrated not to deteriorate the timing performance of the PET module.
Assuntos
Tomografia por Emissão de Pósitrons/métodos , Algoritmos , Fótons , Tomografia por Emissão de Pósitrons/instrumentação , Tomografia por Emissão de Pósitrons/normasRESUMO
A new method for obtaining depth of interaction (DOI) information in PET detectors is presented in this study, based on sharing and redirection of scintillation light among multiple detectors, together with attenuation of light over the length of the crystals. The aim is to obtain continuous DOI encoding with single side readout, and at the same time without the need for one-to-one coupling between scintillators and detectors, allowing the development of a PET scanner with good spatial, energy and timing resolutions while keeping the complexity of the system low. A prototype module has been produced and characterized to test the proposed method, coupling a LYSO scintillator matrix to a commercial SiPMs array. Excellent crystal separation is obtained for all the scintillators in the array, light loss due to depolishing is found to be negligible, energy resolution is shown to be on average 12.7% FWHM. The mean DOI resolution achieved is 4.1 mm FWHM on a 15 mm long crystal and preliminary coincidence time resolution was estimated in 353 ps FWHM.
Assuntos
Contagem de Cintilação/métodos , Tomógrafos Computadorizados/normas , Tomografia Computadorizada por Raios X/métodos , Fótons , Contagem de Cintilação/instrumentação , Tomografia Computadorizada por Raios X/instrumentaçãoRESUMO
A liquid phase blocking ELISA (LPB-ELISA) was developed for the detection and measurement of antibodies against infectious bronchitis virus (IBV). The purified and nonpurified virus used as antigen, the capture and detector antibodies, and the chicken hyperimmune sera were prepared and standardized for this purpose. A total of 156 sera from vaccinated and 100 from specific pathogen-free chickens with no recorded contact with the virus were tested. The respective serum titers obtained in the serum neutralization test (SNT) were compared with those obtained in the LPB-ELISA. There was a high correlation (r2 = 0.8926) between the two tests. The LPB-ELISA represents a single test suitable for the rapid detection of antibodies against bronchitis virus in chicken sera, with good sensitivity (88%), specificity (100%) and agreement (95.31%).
Assuntos
Anticorpos Antivirais/isolamento & purificação , Vírus da Bronquite Infecciosa/imunologia , Animais , Galinhas , Ensaio de Imunoadsorção Enzimática/métodos , Doenças das Aves Domésticas/imunologia , Sensibilidade e EspecificidadeRESUMO
A liquid phase blocking ELISA (LPB-ELISA) was developed for the detection and measurement of antibodies against infectious bronchitis virus (IBV). The purified and nonpurified virus used as antigen, the capture and detector antibodies, and the chicken hyperimmune sera were prepared and standardized for this purpose. A total of 156 sera from vaccinated and 100 from specific pathogen-free chickens with no recorded contact with the virus were tested. The respective serum titers obtained in the serum neutralization test (SNT) were compared with those obtained in the LPB-ELISA. There was a high correlation (r2 = 0.8926) between the two tests. The LPB-ELISA represents a single test suitable for the rapid detection of antibodies against bronchitis virus in chicken sera, with good sensitivity (88 per cent), specificity (100 per cent) and agreement (95.31 per cent).