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1.
J Digit Imaging ; 36(5): 1987-1994, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37349619

RESUMO

The purpose of this short report is to illustrate the implementation of a RIS function for balancing radiological activities and workloads between two different teams of radiologists from the same Diagnostic Department during emergency nights and holiday shifts. One group is from the main hospital, Arcispedale S.Maria Nuova di Reggio Emilia, and the other group belongs to the five minor hospitals in the district of Reggio Emilia.The implementation of a dedicated balancing function in the RIS system successfully allows the balancing of the radiological activity between two or more teams of different radiologists, while preserving the care continuity of care and the involved workers' experience and confidence in reporting.


Assuntos
Serviço Hospitalar de Emergência , Carga de Trabalho , Humanos , Diagnóstico por Imagem
2.
Phys Med Biol ; 65(11): 11NT02, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32311679

RESUMO

This work aims to characterize the novel DRX Plus 3543C detector in terms of detective quantum efficiency (DQE) using both a mobile x-ray system called Carestream DRX Revolution Nano and a traditional x-ray system (Carestream DRX Evolution). We used the commercial system DRX Revolution Nano, equipped with a new x-ray source based on CNT technology and field emission (FE) as the electron emitter (cathode). An innovative aspect of this device is its intrinsic selection of the focal spot size. We tested the system using three IEC-specified beam qualities (RQA3, 5 and 7) in terms of modulation transfer function (MTF), normalized noise power spectra (NNPS) and DQE as defined in the IEC 62220-1-1:2015. We compared the results obtained using DRX Revolution Nano and DRX Evolution with correlation and with Bland-Altman plots to study their agreement. RQA3 MTF is slightly lower than the RQA5 and 7 curves between 0.5 and 2.5 cycles mm-1. We measured MTF values of about 0.6 at 1 lp mm-1 and about 0.28 lp mm-1 at 2 lp mm-1. The NNPS curves show a decreasing trend with the energy regarding the DRX Revolution Nano. On the other hand, the DRX Evolution NNPS curve at RQA3 is greater than the one at RQA5, but the one at RQA5 is less than the one at RQA7. The DQE(0) ranged between about 0.82 (DRX Evolution at RQA3) and 0.54 (DRX Evolution at RQA7). As expected, the squared Pearson's correlation coefficients between the two x-ray tubes were always in an optimal agreement, and Bland-Altman plots confirmed a substantial equivalence between the two physical characterizations of the wireless detector. In conclusion, we can show that the dynamic focal selection of the system equipped with CNT does not play a substantial role in image quality compared to a traditional system in terms of physical characterisation of the detector in our measurement conditions.


Assuntos
Nanotubos de Carbono/química , Dosímetros de Radiação/normas , Radiografia/métodos , Radiografia/instrumentação , Tecnologia sem Fio/instrumentação , Raios X
3.
Biomed Phys Eng Express ; 6(2): 025008, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33438634

RESUMO

The goal of this paper was the comparison of radiation dose and imaging quality before and after the Clarity IQ technology installation in a Philips AlluraXper FD20/20 angiography system using a Channelized Hotelling Observer model (CHO). The core characteristics of the Allura Clarity IQ technology are its real-time noise reduction algorithms (NRT) combined with state-of-the-art hardware; this technology allows to implement acquisition protocols able to significantly reduce patient entrance dose. To measure the system performances in terms of image quality we used a contrast detail phantom in a clinical scatter condition. A Leeds TO10 phantom has been imaged between two 10 cm thick homogeneous solid water slabs. Fluoroscopy images were acquired using a cerebral protocol at 3 dose levels (low, medium and high) with a field- of view (FOV) of 31 cm. Cineangiography images were acquired using a cerebral protocol at 2 fps. Thus, 4 acquisitions were obtained for the conventional technology and 4 acquisitions were taken after the Clarity IQ upgrade, for a total of 8 different image sets. A validated 40 Gabor channels CHO with an internal noise model compared the image sets. Human observers' studies were carried out to tune the internal noise parameter. We showed that the CHO did not detect any significant difference between any of the image sets acquired using the two technologies. Consequently, this x-ray imaging technology provides a non-inferior image quality with an average patient dose reduction of 57% and 28% respectively in cineangiography and fluoroscopy. The Clarity IQ installation has certainly allowed a considerable improvement in patient and staff safety, while maintaining the same image quality.


Assuntos
Algoritmos , Angiografia/normas , Processamento de Imagem Assistida por Computador/normas , Variações Dependentes do Observador , Imagens de Fantasmas , Controle de Qualidade , Tomografia Computadorizada por Raios X/métodos , Cineangiografia/métodos , Fluoroscopia/métodos , Humanos , Doses de Radiação
4.
Contrast Media Mol Imaging ; 2018: 3574310, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30363632

RESUMO

Background and Purpose: The accurate prediction of prognosis and pattern of failure is crucial for optimizing treatment strategies for patients with cancer, and early evidence suggests that image texture analysis has great potential in predicting outcome both in terms of local control and treatment toxicity. The aim of this study was to assess the value of pretreatment 18F-FDG PET texture analysis for the prediction of treatment failure in primary head and neck squamous cell carcinoma (HNSCC) treated with concurrent chemoradiation therapy. Methods: We performed a retrospective analysis of 90 patients diagnosed with primary HNSCC treated between January 2010 and June 2017 with concurrent chemo-radiotherapy. All patients underwent 18F-FDG PET/CT before treatment. 18F-FDG PET/CT texture features of the whole primary tumor were measured using an open-source texture analysis package. Least absolute shrinkage and selection operator (LASSO) was employed to select the features that are associated the most with clinical outcome, as progression-free survival and overall survival. We performed a univariate and multivariate analysis between all the relevant texture parameters and local failure, adjusting for age, sex, smoking, primary tumor site, and primary tumor stage. Harrell c-index was employed to score the predictive power of the multivariate cox regression models. Results: Twenty patients (22.2%) developed local failure, whereas the remaining 70 (77.8%) achieved durable local control. Multivariate analysis revealed that one feature, defined as low-intensity long-run emphasis (LILRE), was a significant predictor of outcome regardless of clinical variables (hazard ratio < 0.001, P=0.001).The multivariate model based on imaging biomarkers resulted superior in predicting local failure with a c-index of 0.76 against 0.65 of the model based on clinical variables alone. Conclusion: LILRE, evaluated on pretreatment 18F-FDG PET/CT, is associated with higher local failure in patients with HNSCC treated with chemoradiotherapy. Using texture analysis in addition to clinical variables may be useful in predicting local control.


Assuntos
Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Quimiorradioterapia , Feminino , Fluordesoxiglucose F18 , Neoplasias de Cabeça e Pescoço/mortalidade , Neoplasias de Cabeça e Pescoço/terapia , Humanos , Interpretação de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Prognóstico , Cintilografia/métodos , Estudos Retrospectivos , Análise de Sobrevida , Adulto Jovem
5.
Phys Med ; 32(12): 1651-1658, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27989415

RESUMO

PURPOSE: Glioblastoma Multiforme (GBM) is the most common malignant brain tumor and frequently recurs in the same location after radiotherapy. Intensive treatment targeting localized lesion is required to improve GBM outcome, but dose escalation using conventional methods is limited by healthy tissue tolerance. Helical Tomotherapy (HT) Dose Painting (DP) treatments were simulated to safely deliver high doses in the recurrent regions. MATERIALS AND METHODS: Apparent Diffusion Coefficient (ADC) data from five recurrent GBM were retrospectively considered for planning. Hypo-fractionated (25-50Gy, 5 fractions) voxel-based prescriptions were opportunely converted to personalized structured-based dose maps to create DP plans with a commercial Treatment Planning System. Optimized plans were generated and analyzed in terms of plan conformity to dose prescription (Q0.90-1.10), tolerance of the healthy tissues (DMAX), and dosimetry accuracy of the deliverable plans (γ-index). RESULTS: Only three of the five cases could receive a safe retreatment without violating the maximum critical organs dose constraints. The conformity of the simulated plans was between 40.9% and 79.9% (Q0.90-1.10), their delivery time was in the range of 38.3-63.6min, while the dosimetry showed γ-index of 82.4-92.4%. CONCLUSIONS: This study proved the ability of our method to simulate personalized, deliverable and dosimetrically accurate DPBN plans. HT hypo-fractionated treatments guided by ADC maps can be realized and applied to deliver high doses in the GBM recurrent regions, although there are some critical issues related to low Q0.90-1.10 values, to exceeding of healthy-tissue dose constraints for some patients and long delivery times.


Assuntos
Glioblastoma/diagnóstico por imagem , Glioblastoma/radioterapia , Doses de Radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada , Difusão , Estudos de Viabilidade , Humanos , Dosagem Radioterapêutica , Recidiva
6.
Phys Med ; 31(1): 72-9, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25457430

RESUMO

BACKGROUND: Targeted radionuclide therapy is a rapidly growing modality. A few commercial treatment planning systems are entering the market. However, some in-house systems are currently developed for a more flexible and customized dosimetry calculation at voxel-level. For this purpose, we developed a novel software, VoxelMed, and performed a comparison with the software STRATOS. METHODS: The validation of both of them was undertaken using radioactive phantoms with different volume inserts. A cohort of 10 patients was also studied after a therapeutic administration of (177)Lu-labelled radiopeptides. The activity, number of disintegrations, absorbed dose and dose-volume histogram (DVH) were calculated for the phantoms and the kidneys in patients, which were the main critical organs at risk in this study. RESULTS: In phantoms the absorbed doses computed with VoxelMed and STRATOS agree within 5%. In patients at the voxel-level the absorbed dose to kidneys (VoxelMed: mean 0.66 Gy/GBq) showed a limited difference of 5%, but with a remarkable range (-40%, +60%) between the two software packages. Voxel-dosimetry allows to estimate the dose non-homogeneities in volumes, which may be evaluated through DVHs. CONCLUSION: This study demonstrates that a fully 3D voxel-dosimetry with multiple SPECT images is feasible by using home-made or commercial software package and absorbed dose results obtained are similar. The main difference between the studied tools was observed in the activity integration method (effective vs physical half-time to time activity curve tail). We believe that an effective half-time integration method produces a more accurate approximation of clinical uptake and resultant dosimetry.


Assuntos
Octreotida/análogos & derivados , Compostos Organometálicos/uso terapêutico , Radiometria/métodos , Software , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Octreotida/uso terapêutico , Imagens de Fantasmas , Dosagem Radioterapêutica
7.
Minerva Cardioangiol ; 62(4): 305-9, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25012099

RESUMO

AIM: Clinical experience shows that about 2 out of 3 patients with indication to resynchronization therapy (CRT) may have improvements in NYHA class, echocardiographic parameters and survival. However, specific clinical or technical parameters that identify responder patients have not yet been found. Aim of the present study was to assess the efficacy of CRT and to estimate the predictive value of specific echocardiographic parameters. METHODS: All patients who underwent CRT from January 2004 till June 2009, at our Institution, were clinically examined and evaluated by echo and ECG before implant. Between January and February 2010, among a population of 55 patients (41 M, 14F, mean age 66.3±5.9), 42 patients (33 M) were considered in the final multiparametric analysis. Of the 13 excluded patients, 6 died, 2 underwent cardiac transplantation and 5 were lost to follow-up. Basal characteristics of the study population were: ischemic etiology in 15 out of 42 patients, back-up defibrillation in 39 patients. The mean follow-up period was 26.2±13.0 months. Patients had been classified as CRT responders if they showed an inverse left ventricle (LV) remodeling, defined as a 10% reduction of end-diastolic diameter (LVEDD) compared to the basal measure. RESULTS: Echo parameters significantly improved after CRT: LVEDD was significantly (P<0.05) reduced (basal vs. CRT: 76±7 mm vs. 64±10 mm, P=0.00004); basal ejection fraction (EF) was 21±5% vs. 37±14% after CRT (P=0.00001); mitral regurgitation (MR) (grading from 1 to 4) was 2.8±0.6 vs. 2.3±0.9 (P=0.00998); QRS duration was 157±25 ms vs. 135±23 ms (P=0.00036), and NYHA class 2.6±0.5 vs. 2.1±0.4, P=0.00006). Only a positive trend of the E/A ratio was observed (P=0.088). Among 42 patients, 24 (57%) had an inverse LV remodeling and were defined as CRT responders. By comparing responder with no-responder patients, the basal values of echo parameters like EF, LVEDD, MR, QRS, NYHA class were similar in the two groups; while E/A was statistically different between the two groups (P=0.02), being less severe in responder patients. CONCLUSION: Our experience confirms that about 2 out of 3 patients are responder to CRT and their clinical improvements remain stable in a long term follow-up. Patients with a less severe E/A ratio are more likely to improve their clinical condition as shown by the reverse remodeling measured through the LVEDD.


Assuntos
Terapia de Ressincronização Cardíaca/métodos , Ecocardiografia , Insuficiência Cardíaca/terapia , Remodelação Ventricular/fisiologia , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Retrospectivos , Resultado do Tratamento
8.
J Digit Imaging ; 27(6): 786-93, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24965275

RESUMO

On X-ray modalities, the information concerning the dose delivered to the patient is usually available in image headers or in structured reports stored in the picture archiving and communication system (PACS). Sometimes this information is sent in the Modality Performed Procedure Step message. By saving the information inside the Radiological Information System, it can be linked to the patient and to his/her episode/request. A software, "Gray Detector," implementing different and complementary extraction methods was developed. Query/retrieve on images header, Modality Performed Procedure Step message analysis, or the combination of the two methods were used. In order to avoid erroneous dose-protocol association, every accession number is linked to its unique report code, allowing multiple-protocols exam recognition. The adoption of different methods to extract dosimetric information makes it possible to integrate any kind of modality in a vendor/version neutral way. Linking the dosimetric information received from a modality to the patient and to the unique report code solves, for example, common problems in computed tomography exams, where the dosimetric value related to multiple segments/studies on the modality can be associated by the technician who performs the exam only to one accession number corresponding to a single study/segment. Analyses of dosimetric indexes' dependence on modality type, patient age, technician, and radiologist were performed. Linking dosimetric information to radiological information system data allows a contextualization of the former and helps to optimize the image-quality/dose ratio, thereby making it possible to take a clinical decision that is "patient-centered."


Assuntos
Registros Eletrônicos de Saúde/estatística & dados numéricos , Doses de Radiação , Sistemas de Informação em Radiologia/estatística & dados numéricos , Software/estatística & dados numéricos , Integração de Sistemas , Humanos
9.
Minerva Cardioangiol ; 62(3): 283-6, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24831764

RESUMO

AIM: Both ablation catheters with irrigated system and 8mm tip-catheters have shown to be more effective for typical atrial flutter radiofrequency (RF) ablation when compared to conventional 4 mm tip catheter. The purpose of this prospective study was to compare the efficiency of radiofrequency catheter ablation (RFA) of the cavotricuspid isthmus using a new type of open irrigation-tip catheter versus 8 mm tip-catheters to eliminate atrial flutter (AFL). METHODS: Sixty consecutive patients, matched for age, presence of cardiopathy, atrial dimensions and comorbidity, underwent RF ablation of cavotricuspid isthmus (CTI) for the treatment of typical atrial flutter, using an open irrigated tip catheter - Surround Flow™ - (N.=30) or an 8-mm-tip catheter (N.=30). The RF pulses were applied point-by-point for 30 seconds, with power limited at 35 w for the irrigated catheter and by temperature control (60/70 w) for the 8-mm catheter. RESULTS: The CTI block was successfully performed in 100% of cases. There was no significant difference with regard to ablation parameters, such as total time of RF ablation (608±324 vs. 556±244 s, P=0.79), number of RF applications (12±8 vs. 10±5, P=0.56), total procedure duration (86.4±23.6 vs. 78.1±22.5 min, P=0.58) and time of fluoroscopy (12±6 vs. 14±6 min, P=0.25) and periprocedural complications (1 groin hematoma in the 8 mm group). During follow-up of 11.6 months on average, one patient in the 8 mm group had recurrence of typical atrial flutter. CONCLUSION: Efficacy and safety of CTI ablation was comparable between both techniques (open irrigated catheter and 8mm tip catheter). The ablation parameters were comparable and homogeneous between the two groups.


Assuntos
Flutter Atrial/cirurgia , Ablação por Cateter/métodos , Catéteres , Idoso , Ablação por Cateter/efeitos adversos , Ablação por Cateter/instrumentação , Desenho de Equipamento , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Recidiva , Fatores de Tempo , Resultado do Tratamento
10.
Biomed Res Int ; 2013: 935351, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23865075

RESUMO

Kidney dosimetry in (177)Lu and (90)Y PRRT requires 3 to 6 whole-body/SPECT scans to extrapolate the peptide kinetics, and it is considered time and resource consuming. We investigated the most adequate timing for imaging and time-activity interpolating curve, as well as the performance of a simplified dosimetry, by means of just 1-2 scans. Finally the influence of risk factors and of the peptide (DOTATOC versus DOTATATE) is considered. 28 patients treated at first cycle with (177)Lu DOTATATE and 30 with (177)Lu DOTATOC underwent SPECT scans at 2 and 6 hours, 1, 2, and 3 days after the radiopharmaceutical injection. Dose was calculated with our simplified method, as well as the ones most used in the clinic, that is, trapezoids, monoexponential, and biexponential functions. The same was done skipping the 6 h and the 3 d points. We found that data should be collected until 100 h for (177)Lu therapy and 70 h for (90)Y therapy, otherwise the dose calculation is strongly influenced by the curve interpolating the data and should be carefully chosen. Risk factors (hypertension, diabetes) cause a rather statistically significant 20% increase in dose (t-test, P < 0.10), with DOTATATE affecting an increase of 25% compared to DOTATOC (t-test, P < 0.05).


Assuntos
Rim/diagnóstico por imagem , Octreotida/análogos & derivados , Compostos Organometálicos/farmacocinética , Radiometria , Receptores de Peptídeos/metabolismo , Idoso , Idoso de 80 Anos ou mais , Calibragem , Estudos de Coortes , Humanos , Cinética , Pessoa de Meia-Idade , Octreotida/farmacocinética , Fatores de Risco , Fatores de Tempo , Tomografia Computadorizada de Emissão de Fóton Único , Tomografia Computadorizada por Raios X
11.
Radiol Med ; 116(7): 1039-49, 2011 Oct.
Artigo em Inglês, Italiano | MEDLINE | ID: mdl-21424564

RESUMO

PURPOSE: The aim of this study was to investigate the efficacy of a dedicated software tool for automated volume measurement of breast lesions in contrast-enhanced (CE) magnetic resonance mammography (MRM). MATERIAL AND METHODS: The size of 52 breast lesions with a known histopathological diagnosis (three benign, 49 malignant) was automatically evaluated using different techniques. The volume of all lesions was measured automatically (AVM) from CE 3D MRM examinations by means of a computer-aided detection (CAD) system and compared with the size estimates based on maximum diameter measurement (MDM) on MRM, ultrasonography (US), mammography and histopathology. RESULTS: Compared with histopathology as the reference method, AVM understimated lesion size by 4% on average. This result was similar to MDM (3% understimation, not significantly different) but significantly better than US and mammographic lesion measurements (24% and 33% size underestimation, respectively). CONCLUSIONS: AVM is as accurate as MDM but faster. Both methods are more accurate for size assessment of breast lesions compared with US and mammography.


Assuntos
Neoplasias da Mama/diagnóstico , Carcinoma Intraductal não Infiltrante/diagnóstico , Carcinoma Lobular/diagnóstico , Diagnóstico por Computador , Imageamento por Ressonância Magnética , Mamografia , Adulto , Idoso , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/diagnóstico , Carcinoma Intraductal não Infiltrante/diagnóstico por imagem , Carcinoma Intraductal não Infiltrante/patologia , Carcinoma Lobular/diagnóstico por imagem , Carcinoma Lobular/patologia , Meios de Contraste , Feminino , Humanos , Mamografia/métodos , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , Ultrassonografia
12.
Q J Nucl Med Mol Imaging ; 54(5): 476-89, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20927015

RESUMO

The development of new technologies in radiation therapy has made it possible to introduce more sophisticated techniques that can deliver the prescribed dose with more conformation and accuracy and to apply dose escalation protocols without increasing the risk of healthy tissue damage. This has consented the simultaneous delivery of different dose levels to different parts of the target, making it possible to boost those tumour sub-volumes that are considered more radio resistant. The use of PET for radiotherapy planning purposes has become increasingly important in the last few years, because of its ability to provide valuable biologic and functional data. PET imaging can affect the treatment strategy definition and improve the target delineation and the assessment of therapy response. The most attractive aspect is the perspective to deliver differential doses inside target volumes for areas of different biologic behaviour based on functional imaging, moving closer to the goals of biologically conformal radiation therapy. Each single step of PET/CT-guided radiotherapy workflow, needs to be performed following high standard procedures, within a rigorous and appropriate quality assurance protocol to minimize the sources of errors and to maximize the efficacy of PET imaging in radiation therapy, ensuring safe and effective use of the technology. The present paper focuses on aspects concerning the use of PET/CT in radiation treatment process, with the aim to delineate different possible approaches to its clinical application and to highlight the critical aspects of the various subprocesses.


Assuntos
Tomografia por Emissão de Pósitrons/métodos , Radioterapia/métodos , Tomografia Computadorizada por Raios X/métodos , Fluxo de Trabalho , Humanos , Controle de Qualidade , Planejamento da Radioterapia Assistida por Computador
13.
Phys Rev Lett ; 93(24): 242001, 2004 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-15697795

RESUMO

We report the first observation of a charm-strange meson D(+)(sJ)(2632) at a mass of 2632.5+/-1.7 MeV/c(2) in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, D(+)(s)eta and D0K+. In the D(+)(s)eta decay mode we observe a peak with 101 events over a combinatoric background of 54.9 events at a mass of 2635.4+/-3.3 MeV/c(2). There is a corresponding peak of 21 events over a background of 6.9 at 2631.5+/-2.0 MeV/c(2) in the decay mode D0K+. The decay width of this state is <17 MeV/c(2) at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(D(+)(s)eta) is 0.14+/-0.06. The mechanism that keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the D(+)(s)eta decay mode.

14.
Phys Rev Lett ; 89(11): 112001, 2002 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-12225136

RESUMO

We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.

15.
Phys Rev Lett ; 86(23): 5243-6, 2001 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-11384468

RESUMO

We report new precision measurements of the lifetimes of the Lambda(+)(c) and D0 from SELEX, the charm hadroproduction experiment at Fermilab. Based upon 1630 Lambda(+)(c) and 10 210 D0 decays we observe lifetimes of tau[Lambda(+)(c)] = 198.1+/-7.0+/-5.6 fs and tau[D0] = 407.9+/-6.0+/-4.3 fs.

16.
Phys Rev Lett ; 84(9): 1857-61, 2000 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-21923211

RESUMO

We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ_{c}^{+}→pK^{-}π^{+}. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Σ^{-} beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ_{c}^{+}→Σ^{+}K^{-}π^{+} and Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} are measured to be B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Σ^{+}K^{-}π^{+})=0.22±0.06±0.03 and B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+})=0.20±0.04±0.02, respectively.

17.
Radiother Oncol ; 52(1): 69-77, 1999 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10577689

RESUMO

BACKGROUND AND PURPOSE: A relevant part of radiotherapy treatment planning system QA concerns dose calculation verification. Report 55 by AAPM TG-23 is an instrument for performing dosimetric evaluation of treatment planning systems in case of external photon beams. It was employed by different groups in three radiotherapy departments for controlling performances of RTPS CadPlan Varian-Dosetek, versions 2.7.9, 3.0.6 and 3.1.1. MATERIALS AND METHODS: Once the basic data of the AAPM 4 MV and 18 MV X-ray units had been converted into the CadPlan format and the AAPM units configured, the whole set of TG23 tests were carried out on three different systems. According to Report 55, comparisons between values measured by TG-23 and calculated by RTPS were made in terms of dose at selected points and radiological field width at different depths. RESULTS: As far as dose is concerned, 266 data were compared for 4 MV and 297 for 18 MV. Ninety-five-point-nine percent of dose deviations for 4 MV and 92.6% for 18 MV are less than 2%. Most of the relevant discrepancies for both energies occur in a test case where dose has to be calculated under a long narrow block centred on the beam axis. Deviations as much as 6.1% for 4 MV and -7.5% for 18 MV were observed in points at 1 cm depth under the block. Poor results were also observed in the rectangular field 25 x 5, in points outside the field edges under collimators. As regards radiological field width, 58 out of 64 comparisons for 4 MV occurred in the range +/- 2 mm. For 18 MV the biggest deviation was -2.2 mm. CONCLUSIONS: The TG-23 tests demonstrated that the accuracy of the RTPS in dose calculation is good in most of the typical radiotherapy applications. Our results are better than those recently published for other RTPS. The TG-23 package turned out to be an effective instrument for QA and calculation verification, as well as being a powerful method for training purpose in configuring and using a RTPS.


Assuntos
Planejamento da Radioterapia Assistida por Computador , Radiometria , Dosagem Radioterapêutica
18.
Biophys Chem ; 42(1): 101-9, 1992 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1581510

RESUMO

The binding of 4',6-diamidino-2-phenylindole (DAPI) to bovine serum albumin (BSA) has been investigated between pH 6 and 8, in 0.05 M phosphate buffer at 20 degrees C, by fluorescence titrations and the results analyzed according to a procedure previously reported (R. Favilla and A. Mazzini, Biochim. Biophys. Acta 788 (1984) 48). The dye binds to the protein with a blue shift of about 4 nm in its fluorescence emission maximum, but with an enhancement factor of 10 of its fluorescence quantum yield. The dissociation constant decreases from 100 microM to 54 microM as the pH is increased from 6 to 8, with a constant number of nearly three equivalent binding sites. The complete displacement of DAPI bound to BSA by Ca2+ suggests a possible specificity of this substantially electrostatic interaction. The fluorescence decay of DAPI bound to the protein shows a double exponential kinetics, with a tau 1 = 0.97 ns and tau 2 = 2.78 ns. These results, compared with those obtained for DAPI alone, tau 1 = 0.16 ns and tau 2 = 2.8 ns, are rationalized in terms of two different rotamers of DAPI. Both rotamers are able to bind to the protein, but only one of them undergoes an intramolecular proton transfer, from the 6-amidinium group to the indole aromatic ring, in the excited singlet state of DAPI alone. When DAPI interacts with BSA this transfer does not occur and consequently a large increase of fluorescence is observed.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Corantes Fluorescentes/metabolismo , Indóis/metabolismo , Soroalbumina Bovina/metabolismo , Animais , Sítios de Ligação , Cálcio/metabolismo , Bovinos , Polarização de Fluorescência , Corantes Fluorescentes/química , Indóis/química , Matemática , Soroalbumina Bovina/química , Espectrometria de Fluorescência
20.
Radiol Med ; 82(1-2): 48-51, 1991.
Artigo em Italiano | MEDLINE | ID: mdl-1654579

RESUMO

Prognosis of patients affected with hepatocellular carcinoma (HCC) has been improved by the modern imaging techniques allowing an early diagnosis and by the value of the therapeutic protocols employed. Staging has also become more and more important. Bone metastases from HCC are reportedly rare. The authors observed a 5.5% incidence in 90 cases of hepatocarcinoma. The metastases were demonstrated by radiography, CT, and nuclear scintigraphy, in patients with skeletal pain. The plain film appearance of skeletal metastases from HCC was osteolytic in all cases; no surrounding sclerosis was seen. CT scans demonstrated the destructive nature of these lesions, which were associated with bulky soft-tissue masses. Metastases exhibited increased radiotracer (99mTc-MDP) uptake at bone scintigraphy. The authors believe that bone scintigraphy should be included in the staging protocols of the HCCs which need a potentially curative therapy.


Assuntos
Neoplasias Ósseas/secundário , Carcinoma Hepatocelular/secundário , Neoplasias Hepáticas/patologia , Idoso , Neoplasias Ósseas/diagnóstico por imagem , Carcinoma Hepatocelular/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia
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