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1.
Glob Chang Biol ; 28(23): 6921-6943, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36117412

RESUMO

Forest models are instrumental for understanding and projecting the impact of climate change on forests. A considerable number of forest models have been developed in the last decades. However, few systematic and comprehensive model comparisons have been performed in Europe that combine an evaluation of modelled carbon and water fluxes and forest structure. We evaluate 13 widely used, state-of-the-art, stand-scale forest models against field measurements of forest structure and eddy-covariance data of carbon and water fluxes over multiple decades across an environmental gradient at nine typical European forest stands. We test the models' performance in three dimensions: accuracy of local predictions (agreement of modelled and observed annual data), realism of environmental responses (agreement of modelled and observed responses of daily gross primary productivity to temperature, radiation and vapour pressure deficit) and general applicability (proportion of European tree species covered). We find that multiple models are available that excel according to our three dimensions of model performance. For the accuracy of local predictions, variables related to forest structure have lower random and systematic errors than annual carbon and water flux variables. Moreover, the multi-model ensemble mean provided overall more realistic daily productivity responses to environmental drivers across all sites than any single individual model. The general applicability of the models is high, as almost all models are currently able to cover Europe's common tree species. We show that forest models complement each other in their response to environmental drivers and that there are several cases in which individual models outperform the model ensemble. Our framework provides a first step to capturing essential differences between forest models that go beyond the most commonly used accuracy of predictions. Overall, this study provides a point of reference for future model work aimed at predicting climate impacts and supporting climate mitigation and adaptation measures in forests.


Assuntos
Ciclo do Carbono , Mudança Climática , Carbono , Temperatura , Água
2.
J Obstet Gynaecol ; 42(5): 766-777, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35469530

RESUMO

Preeclampsia (PE) is characterised by the new onset of hypertension after the 20th week of pregnancy, with or without proteinuria or hypertension that leads to end-organ dysfunction. Since the only definitive treatment is delivery, PE still represents one of the leading causes of preterm birth and perinatal mobility and mortality. Therefore, any strategies that aim to reduce adverse outcomes are based on early primary prevention, prenatal surveillance and prophylactic interventions. In the last decade, intense research has been focussed on the study of predictive models in order to identify women at higher risk accurately. To date, the most effective screening model is based on the combination of anamnestic, demographic, biophysical and maternal biochemical factors. In this review, we provide a detailed discussion about the current and future perspectives in the field of PE. We will examine pathogenesis, risk factors and clinical features. Moreover, recent developments in screening and prevention strategies, novel therapies and healthcare management strategies will be discussed.


Assuntos
Hipertensão , Pré-Eclâmpsia , Nascimento Prematuro , Feminino , Humanos , Hipertensão/epidemiologia , Recém-Nascido , Pré-Eclâmpsia/epidemiologia , Gravidez , Nascimento Prematuro/epidemiologia , Nascimento Prematuro/etiologia , Nascimento Prematuro/prevenção & controle , Fatores de Risco
3.
Nat Commun ; 12(1): 2266, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33859182

RESUMO

Wetland methane (CH4) emissions ([Formula: see text]) are important in global carbon budgets and climate change assessments. Currently, [Formula: see text] projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent [Formula: see text] temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that [Formula: see text] are often controlled by factors beyond temperature. Here, we evaluate the relationship between [Formula: see text] and temperature using observations from the FLUXNET-CH4 database. Measurements collected across the globe show substantial seasonal hysteresis between [Formula: see text] and temperature, suggesting larger [Formula: see text] sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH4 production are thus needed to improve global CH4 budget assessments.

5.
Sci Data ; 7(1): 225, 2020 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-32647314

RESUMO

The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

6.
Sci Total Environ ; 672: 106-120, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30954809

RESUMO

Woody encroachment is a widespread phenomenon resulting from the abandonment of mountain agricultural and pastoral practices during the last century. As a result, forests have expanded, increasing biomass and necromass carbon (C) pools. However, the impact on soil organic carbon (SOC) is less clear. The main aim of this study was to investigate the effect of woody encroachment on SOC stocks and ecosystem C pools in six chronosequences located along the Italian peninsula, three in the Alps and three in the Apennines. Five stages along the chronosequences were identified in each site. Considering the topsoil (0-30 cm), subsoil (30 cm-bedrock) and whole soil profile, the temporal trend in SOC stocks was similar in all sites, with an initial increment and subsequent decrement in the intermediate phase. However, the final phase of the woody encroachment differed significantly between the Alps (mainly conifers) and the Apennines (broadleaf forests) sites, with a much more pronounced increment in the latter case. Compared to the previous pastures, after mature forest (>62 years old) establishment, SOC stocks increased by: 2.1(mean) ±â€¯18.1(sd) and 50.1 ±â€¯25.2 Mg C·ha-1 in the topsoil, 7.3 ±â€¯17.4 and 93.2 ±â€¯29.7 Mg C·ha-1 in the subsoil, and 9.4 ±â€¯24.4 and 143.3 ±â€¯51.0 Mg C·ha-1 in the whole soil profile in Alps and Apennines, respectively. Changes in SOC stocks increased with mean annual air temperature and average minimum winter temperature, and were negatively correlated with the sum of summer precipitation. At the same time, all other C pools (biomass and necromass) increased by 179.1 ±â€¯51.3 and 304.2 ±â€¯67.6 Mg C·ha-1 in the Alps and the Apennines sites, respectively. This study highlights the importance of considering both the subsoil, since deep soil layers contributed 38% to the observed variations in carbon stocks after land use change, and the possible repercussions for the carbon balance of large areas where forests are expanding, especially under pressing global warming scenarios.

7.
Ecol Appl ; 29(2): e01837, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30549378

RESUMO

The future trajectory of atmospheric CO2 concentration depends on the development of the terrestrial carbon sink, which in turn is influenced by forest dynamics under changing environmental conditions. An in-depth understanding of model sensitivities and uncertainties in non-steady-state conditions is necessary for reliable and robust projections of forest development and under scenarios of global warming and CO2 enrichment. Here, we systematically assessed if a biogeochemical process-based model (3D-CMCC-CNR), which embeds similarities with many other vegetation models, applied in simulating net primary productivity (NPP) and standing woody biomass (SWB), maintained a consistent sensitivity to its 55 input parameters through time, during forest ageing and structuring as well as under climate change scenarios. Overall, the model applied at three contrasting European forests showed low sensitivity to the majority of its parameters. Interestingly, model sensitivity to parameters varied through the course of >100 yr of simulations. In particular, the model showed a large responsiveness to the allometric parameters used for initialize forest carbon and nitrogen pools early in forest simulation (i.e., for NPP up to ~37%, 256 g C·m-2 ·yr-1 and for SWB up to ~90%, 65 Mg C/ha, when compared to standard simulation), with this sensitivity decreasing sharply during forest development. At medium to longer time scales, and under climate change scenarios, the model became increasingly more sensitive to additional and/or different parameters controlling biomass accumulation and autotrophic respiration (i.e., for NPP up to ~30%, 167 g C·m-2 ·yr-1 and for SWB up to ~24%, 64 Mg C/ha, when compared to standard simulation). Interestingly, model outputs were shown to be more sensitive to parameters and processes controlling stand development rather than to climate change (i.e., warming and changes in atmospheric CO2 concentration) itself although model sensitivities were generally higher under climate change scenarios. Our results suggest the need for sensitivity and uncertainty analyses that cover multiple temporal scales along forest developmental stages to better assess the potential of future forests to act as a global terrestrial carbon sink.


Assuntos
Carbono , Mudança Climática , Biomassa , Ciclo do Carbono , Florestas
8.
J Adv Model Earth Syst ; 10(10): 2427-2452, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31007835

RESUMO

Forest carbon use efficiency (CUE, the ratio of net to gross primary productivity) represents the fraction of photosynthesis that is not used for plant respiration. Although important, it is often neglected in climate change impact analyses. Here we assess the potential impact of thinning on projected carbon cycle dynamics and implications for forest CUE and its components (i.e., gross and net primary productivity and plant respiration), as well as on forest biomass production. Using a detailed process-based forest ecosystem model forced by climate outputs of five Earth System Models under four representative climate scenarios, we investigate the sensitivity of the projected future changes in the autotrophic carbon budget of three representative European forests. We focus on changes in CUE and carbon stocks as a result of warming, rising atmospheric CO2 concentration, and forest thinning. Results show that autotrophic carbon sequestration decreases with forest development, and the decrease is faster with warming and in unthinned forests. This suggests that the combined impacts of climate change and changing CO2 concentrations lead the forests to grow faster, mature earlier, and also die younger. In addition, we show that under future climate conditions, forest thinning could mitigate the decrease in CUE, increase carbon allocation into more recalcitrant woody pools, and reduce physiological-climate-induced mortality risks. Altogether, our results show that thinning can improve the efficacy of forest-based mitigation strategies and should be carefully considered within a portfolio of mitigation options.

9.
J Ovarian Res ; 8: 37, 2015 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-26067283

RESUMO

BACKGROUND: The overall incidence of poor ovarian response in IVF cycles has been reported to be between 9 and 24%. The management of these patients remains a significant challenge in assisted reproduction. The aim of the present study was to evaluate the effect of myo-inositol (MI) on ovarian function in poor responders undergoing ICSI. METHODS: The study is a prospective controlled observational trial, that involved 72 poor responders included in an ICSI program and divided into two groups; group A: 38 patients who have been assuming MI (4 g) + folic acid (FA) (400 µg) for the previous 3 months before the enrollment day; group B: 38 patients assuming FA (400 µg) alone for the same period. COH was carried out in the same manner in the two groups. The main goal was the assessment of oocytes retrieved number and quality; secondary endpoints were the Ovarian Sensitivity Index (OSI: n° oocytes retrieved/total Gonadotropins units × 1000), oestradiol levels on the day of hGC, fertilization rate, implantation rate, ongoing pregnancy rate. RESULTS: There was no significant difference between the two groups regarding oestradiol level, but total rec-FSH units were significantly lower (p = 0.004) and M2 oocytes rate significantly higer (p = 0.01) in group A. The ovarian sensitivity index was higher, reaching a statistical significance (p < 0.05), in the group of patients pre-treated with MI, showing an improvement in ovarian sensibility to gonadotropin. CONCLUSIONS: Our results suggest that MI therapy in poor responders results in an increased of the number of oocytes recovered in MII and of the gonadotropin Ovarian Sensitivity Index (OSI), suggesting a MI role in improving ovarian response to gonadotropins. Therefore MI seems to be helpful in "poor responders" undergoing IVF cycles.


Assuntos
Fertilização in vitro/efeitos dos fármacos , Inositol/administração & dosagem , Oócitos/efeitos dos fármacos , Indução da Ovulação/métodos , Adulto , Feminino , Ácido Fólico/administração & dosagem , Gonadotropinas/administração & dosagem , Humanos , Oócitos/crescimento & desenvolvimento , Gravidez , Taxa de Gravidez , Injeções de Esperma Intracitoplásmicas/métodos
10.
Gynecol Endocrinol ; 30(10): 730-3, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24948339

RESUMO

A stimulation protocol mimicking the physiological pattern of FSH release may improve IVF outcome in women of advanced age. Urinary-FSH delivers a wider range of isoforms including the most acidic produced during the early follicular phase when oestradiol level is low, a common condition in women of advanced reproductive age. We hypothesized that a stimulation protocol using urinary-FSH during the early follicular phase and then shifting toward recombinant-FSH may improve oocyte quality and pregnancy rate in 35-40 years old patients in IVF program. A retrospective study was performed: after a standard down-regulation with GnRH-analogue, 115 women underwent stimulation with urinary-FSH for 6 days according to a step-down approach and then shifting to recombinant-FSH (group A), 115 women underwent a stimulation protocol with only recombinant-FSH (group B). Days of stimulation were lower in group A than in group B, a higher proportion of MII oocytes and of grade 1 embryos, higher implantation rate and pregnancy rate were observed in group A versus group B. We conclude that a sequential protocol using urinary-FSH in the early days of stimulation and subsequently recombinant-FSH may improve the IVF outcome in patients of advanced reproductive age.


Assuntos
Protocolos Clínicos/normas , Fertilização in vitro/métodos , Hormônio Foliculoestimulante/administração & dosagem , Oócitos/efeitos dos fármacos , Resultado do Tratamento , Adulto , Feminino , Humanos
11.
J Androl ; 33(4): 588-93, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-21868752

RESUMO

A prospective randomized controlled study was designed to evaluate the effects of recombinant human follicle-stimulating hormone (rFSH) treatment on sperm DNA fragmentation in men with idiopathic oligoasthenoteratozoospermia (iOAT). One hundred twenty-nine men with sperm count less than 10 × 10(6) spermatozoa/mL and forward motility <25% were included; normal serum levels of FSH, luteinizing hormone (LH), and testosterone, and no other causes of infertility were enrolled. The patients were randomized into 2 groups: 65 men were treated on alternate days for 90 days with injections of 150 IU rFSH, and 64 subjects received nonantioxidant vitamin supplements. Main outcome measures were serum levels of FSH, LH, testosterone, and inhibin B and DNA fragmentation index (DFI) at baseline and after 90 days. No significant differences were observed between the 2 groups with regard to sperm parameters and hormone values. The DFI was similar between the 2 groups at the time of the enrollment but reduced significantly (P < .05) after rFSH therapy in study group, whereas no significant variation occurred in the control group. In the subgroup of patients with high basal DFI values (>15%), rFSH treatment significantly increased DFI (P < .01), whereas no significant variation occurred after 90 days of vitamin supplements. We conclude that rFSH administration improves sperm DNA integrity in iOAT men with increased DFI values. The degree of sperm DFI might be useful to identify those iOAT patients in which rFSH treatment can be advantageous.


Assuntos
Astenozoospermia/tratamento farmacológico , Fragmentação do DNA/efeitos dos fármacos , Hormônio Foliculoestimulante Humano/uso terapêutico , Oligospermia/tratamento farmacológico , Adulto , Hormônio Foliculoestimulante/sangue , Humanos , Hormônio Luteinizante/sangue , Masculino , Proteínas Recombinantes/uso terapêutico , Espermatozoides/efeitos dos fármacos , Espermatozoides/metabolismo , Testosterona/sangue
12.
J Nucl Med ; 50(10): 1683-91, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19759100

RESUMO

UNLABELLED: Visilizumab is an IgG(2) humanized monoclonal antibody (mAb) characterized by non-FcgammaR binding and specific to the CD3 antigen, expressed on more than 95% of circulating resting T-lymphocytes and on activated T-lymphocytes homing in inflamed tissues. We hypothesized that the use of a radiolabeled anti-CD3 antibody might serve as a diagnostic tool for imaging T-cell traffic and lymphocytic infiltration of tissues and organs affected by autoimmune diseases. Here we describe the results of in vitro and animal experiments with (99m)Tc-succinimidyl-6-hydrazinonicotinate hydrochloride (SHNH)-visilizumab. METHODS: For mAb labeling, we used a 2-step method with a heterobifunctional linker SHNH. Several titrations were performed to obtain the best labeling efficiency. In vitro quality controls included stability assay, cysteine challenge, sodium dodecyl sulfate polyacrylamide gel electrophoresis, binding assay, and immunoreactivity assay. In vivo studies by high-resolution images were performed at 6 and 24 h after the injection of (99m)Tc-SHNH-visilizumab. These included cell-targeting experiments in BALB/c mice xenografted subcutaneously with an increasing number of HuT78 cells in the leg and displaced with an excess of cold antibody. We also studied irradiated severe combined immunodeficient (SCID) mice reconstituted with human peripheral blood mononuclear cells (hPBMCs) and injected with (99m)Tc-labeled visilizumab or control mAb. After dynamic imaging for 3 h, major organs were removed, counted, and processed for immunohistologic examination. RESULTS: Visilizumab was labeled with HYNIC with high labeling efficiency (>90%) and high specific activity (SA; 10,360-11,100 MBq/mg), with retained biochemical integrity and in vitro binding activity to CD3-positive cells. The in vivo targeting experiment showed a proportional increase of specific uptake with the number of injected cells, both at 6 and at 24 h, and the in vivo competition study demonstrated more than 60% decreased uptake after an excess of unlabeled antibody. In SCID mice, hPBMCs in different tissues were detected by (99m)Tc-labeled visilizumab and confirmed by histology. CONCLUSION: Visilizumab can be efficiently labeled with (99m)Tc with high efficiency and SA and could be a valuable tool for the study of human T-lymphocyte trafficking and lymphocytic infiltration of tissues and organs.


Assuntos
Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Complexo CD3/imunologia , Radioimunodetecção , Linfócitos T/metabolismo , Animais , Anticorpos Monoclonais/farmacocinética , Anticorpos Monoclonais Humanizados , Ligação Competitiva , Linhagem Celular , Movimento Celular , Feminino , Humanos , Técnicas Imunoenzimáticas , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Camundongos , Técnicas de Sonda Molecular , Niacinamida/análogos & derivados , Niacinamida/química , Compostos de Organotecnécio/química , Controle de Qualidade , Especificidade por Substrato , Succinimidas/química , Linfócitos T/citologia , Linfócitos T/imunologia , Distribuição Tecidual
13.
PLoS One ; 3(11): e3768, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19020658

RESUMO

BACKGROUND: The prevalence of thyroid nodules increases with age, average 4-7% for the U.S.A. adult population, but it is much higher (19-67%) when sub-clinical nodules are considered. About 90% of these lesions are benign and a reliable approach to their preoperative characterization is necessary. Unfortunately conventional thyroid scintigraphy does not allow the distinction among benign and malignant thyroid proliferations but it provides only functional information (cold or hot nodules). The expression of the anti-apoptotic molecule galectin-3 is restricted to cancer cells and this feature has potential diagnostic and therapeutic implications. We show here the possibility to obtain thyroid cancer imaging in vivo by targeting galectin-3. METHODS: The galectin-3 based thyroid immuno-scintigraphy uses as radiotracer a specific (99m)Tc-radiolabeled mAb. A position-sensitive high-resolution mini-gamma camera was used as imaging capture device. Human galectin-3 positive thyroid cancer xenografts (ARO) and galectin-3 knockout tumors were used as targets in different experiments in vivo. 38 mice with tumor mass of about 1 gm were injected in the tail vein with 100 microCi of (99m)Tc-labeled mAb to galectin-3 (30 microg protein/in 100 microl saline solution). Tumor images were acquired at 1 hr, 3 hrs, 6 hrs, 9 hrs and 24 hrs post injection by using the mini-gamma camera. FINDINGS: Results from different consecutive experiments show an optimal visualization of thyroid cancer xenografts between 6 and 9 hours from injection of the radiotracer. Galectin-3 negative tumors were not detected at all. At 6 hrs post-injection galectin-3 expressing tumors were correctly visualized, while the whole-body activity had essentially cleared. CONCLUSIONS: These results demonstrate the possibility to distinguish preoperatively benign from malignant thyroid nodules by using a specific galectin-3 radio-immunotargeting. In vivo imaging of thyroid cancer may allow a better selection of patients referred to surgery. The possibility to apply this method for imaging and treatment of other galectin-3 expressing tumors is also discussed.


Assuntos
Apoptose , Galectina 3/metabolismo , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/patologia , Animais , Anticorpos Monoclonais/química , Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Câmaras gama , Humanos , Imuno-Histoquímica/métodos , Camundongos , Camundongos Knockout , Camundongos Nus , Transplante de Neoplasias , Interferência de RNA , Cintilografia , Neoplasias da Glândula Tireoide/metabolismo
14.
Cancer Biother Radiopharm ; 23(1): 43-52, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18298328

RESUMO

BACKGROUND: The imaging probe (IP) is a high-resolution (HR), 1-in(2) field-of-view hand-held gamma camera. We used it to detect breast cancer sentinel node (SN). PATIENTS AND METHODS: We divided 120 T1 breast cancer patients, who underwent Anger camera lymphoscintigraphy (ACL), in two subgroups of 60 patients who were age, body mass index, and cancer size matched: subgroup A (SA) and B (SB). SN was detected with a common gamma probe (GP) in SA, with IP plus GP in SB. RESULTS: Surgeons removed radioactive nodes without exceeding four nodes. Eighty-two (82) SNs were taken off in SA and 105 in SB (p<0.01). Of SA, 22 of 60 patients and 36 of 60 patients of SB showed more than 1 node, and 3 of them showed 3 nodes and 1 showed 4 nodes. Thirteen (13) patients resulted N(+) (21.6%) in SA. Ten (10) patients of SA showed an invasion on the hottest nodes and 3 on the second nodes. In the SB, 18 patients (25%) showed invasion. Sixteen (16) invasions were on hot, 4 on second, and 1 on the third node. Withdrawal time of SN was 11.25+/-4.7 minutes for SA and 7.4+/-2.8 minutes for SB (p<0.025). CONCLUSIONS: SN biopsy with IP is fast and discovers more SNs and more invasions than ACL.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Câmaras gama , Linfonodos/diagnóstico por imagem , Biópsia de Linfonodo Sentinela , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/diagnóstico , Carcinoma Ductal de Mama/secundário , Feminino , Humanos , Linfonodos/patologia , Metástase Linfática/diagnóstico por imagem , Metástase Linfática/patologia , Pessoa de Meia-Idade , Cintilografia , Coloide de Enxofre Marcado com Tecnécio Tc 99m
15.
Cancer Biother Radiopharm ; 19(1): 121-8, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15068620

RESUMO

Pinhole gamma camera imaging offers the ability to obtain high resolution images from single gamma ray emitting radiotracers playing a reasonable tradeoff between very small field of view (FoV) and sensitivity. On the other hand the total spatial resolution of a pinhole imaging device is predominantly affected by the detector intrinsic spatial resolution for reduced magnification factors. To design very compact pinhole SPET scanners with very high intrinsic spatial resolution, authors investigated a miniature gamma camera based on the newly developed Hamamatsu H8500 flat panel photomultiplier. The PSPMT was coupled to the following scintillation arrays: CsI(Tl) array with 0.2-mm, 1-mm, 1.4-mm pixel size and NaI (Tl) with 1-mm pixel size. The imaging performances were evaluated by 57Co spot and flood irradiations. NaI(Tl) array shows a better pixel identification for 1 mm pixel size, proving to be a good candidate to make a large area photodetector based on multi PSPMTs closely packed. Although CsI(Tl) array had the smallest pixel size, the low light output limited the best intrinsic spatial resolution to about 0.5 mm.


Assuntos
Medicina Nuclear/instrumentação , Medicina Nuclear/métodos , Câmaras gama , Raios gama , Intensificação de Imagem Radiográfica , Tomografia Computadorizada de Emissão de Fóton Único
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