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1.
Res Vet Sci ; 157: 1-5, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36827790

RESUMO

The aim of this study was to serially evaluate serum cardiac troponin I (cTnI) concentrations in dogs with parvoviral enteritis (CPVE), and investigate the association with outcome and serum pancreas-specific lipase (Spec cPL) concentrations. Dogs with CPVE that were hospitalised for at least 5 days were included. cTnI and Spec cPL concentrations were measured on days 1, 3 and 5 of hospitalisation. Twenty-nine dogs (20 survivors, 9 non-survivors) were included. Spec cPL was indicative of pancreatitis (>400 µg/L) on at least one day in 10/29 (34.5%) dogs. Serum median (range) cTnI concentration was higher (P = 0.021) in non-survivors on day 5 [0.032 (0.001-0.395) ng/mL] compared to day 1 [0.012 (0.003-0.196) ng/mL]. Non-survivors had higher (P = 0.014) cTnI concentrations on day 5 [0.032 (0.001-0.395) ng/mL] compared to survivors [0.001 (0.001-0.042) ng/mL], but not at admission or on day 3 (P > 0.05). Serum cTnI concentrations were not significantly different (P = 0.465) between the three Spec cPL groups [group 1 (Spec cPL ≤ 200 µg/L): 0.007 (0.001-0.527) ng/mL; group 2 (Spec cPL: 201-399 µg/L): 0.0045 (0.001-0.196) ng/mL; group 3 (Spec cPL ≥ 400 µg/L): 0.011 (0.001-0.278) ng/mL]. cTnI and Spec cPL concentrations were not significantly correlated (rho = -0.043, P = 0.703). Serial measurement of cTnI had prognostic value in the examined cohort. However, cTnI was not correlated with spec cPL.


Assuntos
Doenças do Cão , Enterite , Infecções por Parvoviridae , Parvovirus Canino , Parvovirus , Cães , Animais , Troponina I , Lipase , Pâncreas , Infecções por Parvoviridae/veterinária , Enterite/veterinária
2.
Vet J ; 274: 105715, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34252549

RESUMO

The aim of this study was to serially evaluate the serum concentrations of total thyroxine (tT4), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) in dogs with canine parvoviral enteritis (CPVE) during a 5-day hospitalisation period and assess the association of these hormone concentrations with the outcome and the development of systemic inflammatory response syndrome (SIRS). Dogs with confirmed CPVE that were hospitalised for at least 5 days were included. The thyroid hormones concentrations were measured on days 1, 3 and 5 of hospitalisation. Twenty-eight dogs were included. All (28/28, 100%), 19/28 (69.7%) and 23/28 (82.1%) dogs had a low serum tT4, fT4 and TSH concentration, respectively, on at least 1 day during the hospitalisation period. Overall, 11/28 (39.3%) dogs were diagnosed with SIRS on at least 1 day. In survivors, serum tT4 concentration was significantly higher on day 5 (median, range: 11.8 nmol/L, <6.4-32.2 nmol/L) compared to those on days 1 (<6.4 nmol/L, <6.4-20.1 nmol/L; P = 0.010) or 3 (7.6 nmol/L, <6.4-25.2 nmol/L; P = 0.019). Survivors had a significantly higher tT4 concentration (median, range: 11.8 nmol/L, <6.4-32.2 nmol/L) on day 5 compared to non-survivors (<6.4 nmol/L, <6.4-7.2 nmol/L; P = 0.002). Regardless of the day of hospitalisation, dogs with SIRS had significantly lower tT4 (<6.4 nmol/L, <6.4-16.3 nmol/L) compared to dogs without SIRS (8.6 nmol/L, <6.4-32.2 nmol/L; P = 0.006). A significant difference was also found in fT4 between dogs with SIRS (<3.9 pmol/L, <3.9-16.2 pmol/L) and dogs without SIRS (15.1 pmol/L, <3.9-59.2; pmol/L; P < 0.001). Non-thyroidal illness syndrome was frequently observed in dogs with CPVE, and a negative association between tT4 and fT4 concentrations and SIRS was noted. Serial measurements of tT4 concentrations appeared to have prognostic value.


Assuntos
Doenças do Cão/diagnóstico , Síndromes do Eutireóideo Doente/veterinária , Infecções por Parvoviridae/veterinária , Síndrome de Resposta Inflamatória Sistêmica/veterinária , Hormônios Tireóideos/sangue , Animais , Doenças do Cão/sangue , Doenças do Cão/virologia , Cães , Enterite/veterinária , Síndromes do Eutireóideo Doente/sangue , Feminino , Masculino , Parvovirus Canino/isolamento & purificação , Síndrome de Resposta Inflamatória Sistêmica/sangue , Resultado do Tratamento
3.
Saudi J Biol Sci ; 28(1): 35-39, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33424280

RESUMO

Medical exposure of the general population due to radiological investigations is the foremost source of all artificial ionising radiation. Here, we focus on a particular diagnostic radiological procedure, as only limited data are published with regard to radiation measurements during urethrograpic imaging. Specifically, this work seeks to estimate patient and occupational effective doses during urethrographic procedures at three radiology hospitals. Both staff and patient X-ray exposure levels were calculated in terms of entrance surface air kerma (ESAK), obtained by means of lithium fluoride thermoluminescent dosimeters (TLD-100(LiF:Mg:Cu.P)) for 243 urethrographic examinations. Patient radiation effective doses per procedure were estimated using conversion factors obtained from the use of Public Health England computer software. In units of mGy, the median and range of ESAK per examination were found to be 10.8 (3.6-26.2), 7.0 (0.2-32.3), and 24.3 (9.0-32.0) in Hospitals A, B, and C, respectively. The overall mean and range of staff doses (in µGy) were found to be 310 (4.0-1750) per procedure. With the exception of hospital C, the present evaluations of radiation dose have been found to be similar to those of previously published research. The wide range of patient and staff doses illustrate the need for radiation dose optimisation.

4.
Phys Med ; 60: 188-198, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30910431

RESUMO

AIMS AND OBJECTIVES: To investigate the value of advanced multiparametric MR imaging biomarker analysis based on radiomic features and machine learning classification, in the non-invasive evaluation of tumor heterogeneity towards the differentiation of Low Grade vs. High Grade Gliomas. METHODS AND MATERIALS: Forty histologically confirmed glioma patients (20 LGG and 20 HGG) who underwent a standard 3T-MRI tumor protocol with conventional (T1 pre/post-contrast, T2-FSE, T2-FLAIR) and advanced techniques (Diffusion Tensor and Perfusion Imaging, 1H-MR Spectroscopy), were included. A semi-automated segmentation technique, based on T1W-C and DTI, was used for tumor core delineation in all available parametric maps. 3D Texture analysis considered 12 Histogram, 11 Co-Occurrence Matrix (GLCM) and 5 Run Length Matrix (GLRLM) features, derived from p, q, MD, FA, T1W-C, T2W-FSE, T2W-FLAIR and raw DSCE data. Along with 1H-MRS metabolic ratios and mean rCBV values, a total of 581 attributes for each subject were obtained. A Support Vector Machine - Recursive Feature Elimination (SVM-RFE) algorithm and SVM classifier were utilized for feature selection and classification, respectively. RESULTS: Three different SVM classifiers were evaluated with consecutively SVM-RFE feature subsets. Linear SMO classifier demonstrated the highest performance for determining the optimal feature subset. Finally, 21 SVM-RFE top-ranked features were adopted, for training and testing the SMO classifier with leave-one-out cross-validation, achieving 95.5% Accuracy, 95% Sensitivity, 96% Specificity and 95.5% Area Under ROC Curve. CONCLUSION: Results demonstrate that quantitative analysis of phenotypic characteristics, based on advanced multiparametric MR neuroimaging data and texture features, utilizing state-of-the-art radiomic analysis methods, can significantly contribute to the pre-treatment glioma grade differentiation.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Glioma/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Biomarcadores Tumorais , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Neoplasias Encefálicas/patologia , Glioma/patologia , Humanos , Imageamento Tridimensional/métodos , Gradação de Tumores/métodos , Sensibilidade e Especificidade , Máquina de Vetores de Suporte
5.
Radiat Prot Dosimetry ; 182(4): 472-479, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29961846

RESUMO

Mapping of the photoneutron spectrum and flux performed at several positions over the treatment table of a 15 MV medical linac. Neutron activation technique has been applied to obtain the neutron spectra in the mixed γ -n field. Thick foils have been used due to the low neutron flux and the measurements were unfolded using the MINUIT minimizer. GEANT4 code simulations have been performed to reproduce the photoneutrons' spectrum and estimate the flux along the treatment table. The mixed radiation field around medical linear accelerator was evaluated and the variation of the ambient dose equivalent over the treatment table was estimated. Photoneutrons' ambient dose equivalent inside the irradiation field estimated as 0.56 ± 0.05 while the peripheral as 0.42 ± 0.04 mSv Gy-1. The effective dose inside the irradiation field is ranged between 0.004 and 0.049 while the peripheral up to 0.035 mSv Gy-1.


Assuntos
Exposição Ocupacional/análise , Aceleradores de Partículas , Doses de Radiação , Radiometria/métodos , Carga Corporal (Radioterapia) , Desenho de Equipamento , Análise de Falha de Equipamento , Grécia , Humanos , Nêutrons , Fótons , Proteção Radiológica/métodos
6.
Appl Radiat Isot ; 138: 40-44, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28757351

RESUMO

The objectives of this study are to assess pediatric radiation exposure in certain barium studies and to quantify the organ and effective doses and radiation risk resultant from patients' irradiation. A total of 69 pediatric barium studies for upper and lower gastrointestinal tract. Patients' radiation dose was quantified in terms of Entrance surface air kerma (ESAKs) using exposure parameters and DosCal software. Organ and effective doses (E) were extrapolated using national Radiological Protection Board software (NRPB-R279). The mean ± (SD) and the range of patient doses per procedure were 3.7 ± 0.4 (1.0-13.0)mGy, 7.4 ± 1.7(5.5-8.0)mGy and 1.4 ± 0.9 (0.5-3.6)mGy for barium meal, swallow and enema, respectively. The mean effective doses were 0.3 ± 0.03 (0.08-1.1)mSv, 0.2 ± 1.6 (0.44-0.7)mSv and 0.3 ± 0.9 (0.1-0.8)mSv at the same order. The radiation dose were higher compared to previous studies. Therefore, pediatrics are exposed to avoidable radiation exposure. Certain optimization measures are recommended along with establishing national diagnostic reference level (DRL) to reduce the radiation risk.


Assuntos
Bário , Meios de Contraste , Trato Gastrointestinal/diagnóstico por imagem , Trato Gastrointestinal/efeitos da radiação , Sulfato de Bário , Criança , Pré-Escolar , Diatrizoato de Meglumina , Feminino , Gastroenteropatias/diagnóstico por imagem , Humanos , Lactente , Masculino , Doses de Radiação , Proteção Radiológica , Radiometria/métodos , Radiometria/estatística & dados numéricos , Fatores de Risco
7.
Mediators Inflamm ; 2017: 9621724, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28260841

RESUMO

Cell migration is an instrumental process involved in organ development, tissue homeostasis, and various physiological processes and also in numerous pathologies. Both basic cell migration and migration towards chemotactic stimulus consist of changes in cell polarity and cytoskeletal rearrangement, cell detachment from, invasion through, and reattachment to their neighboring cells, and numerous interactions with the extracellular matrix. The different steps of immune cell, tissue cell, or cancer cell migration are tightly coordinated in time and place by growth factors, cytokines/chemokines, adhesion molecules, and receptors for these ligands. This review describes how a disintegrin and metalloproteinases interfere with several steps of cell migration, either by proteolytic cleavage of such molecules or by functions independent of proteolytic activity.


Assuntos
Movimento Celular , Desintegrinas/metabolismo , Metaloproteases/metabolismo , Animais , Catálise , Adesão Celular , Quimiocinas/metabolismo , Quimiotaxia , Citoesqueleto/metabolismo , Homeostase , Humanos , Inflamação/metabolismo , Leucócitos/metabolismo , Ligantes , Invasividade Neoplásica , Neoplasias/patologia , Neovascularização Fisiológica , Cicatrização
9.
Appl Radiat Isot ; 117: 36-41, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27094250

RESUMO

The objectives of this study were to measure the entrance surface air kerma (ESAK) and the effective doses in pediatric patients undergoing micturating cystourethrography (MCU) procedures. The ESAK was determined using calibrated thermoluminescent dosimeters (TLD- GR 200 A) in 167 pediatric patients. The patient population was categorized into three groups according to age (0-5 years (group 1), 6-10 years (group 2) and 11-15 years (group 3)). The mean ESAK±SD and range (mGy) resulting from a MCU procedure was estimated to be 2.2±0.5 (0.8-9.2), 2.48±0.6 (0.9-8.1) and 3.90±0.6 (1.1-10.3) for group 1, 2 and 3, respectively. The mean effective dose was between 0.03 and 0.4 mSv per procedure for the pediatric population. Pediatric patients were exposed to avoidable radiation doses because no gonad shields were used.


Assuntos
Cistografia/estatística & dados numéricos , Exposição à Radiação/análise , Exposição à Radiação/estatística & dados numéricos , Monitoramento de Radiação/estatística & dados numéricos , Contagem Corporal Total/estatística & dados numéricos , Adolescente , Distribuição por Idade , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Sudão/epidemiologia , Micção
10.
Radiat Prot Dosimetry ; 165(1-4): 397-401, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25899610

RESUMO

Patients are exposed to significant radiation doses during diagnostic and interventional urologic procedures. This study aimed to measure patient entrance surface air kerma (ESAK) and to estimate the effective dose during intravenous urography (IVU), extracorporeal shock-wave lithotripsy (ESWL), and ascending urethogram (ASU) procedures. ESAK was measured in patients using calibrated thermo luminance dosimeters, GR200A). Effective doses (E) were calculated using the National Radiological Protection Board (NRPB) software. A total of 179 procedures were investigated. 27.9 % of the patients underwent IVU procedures, 27.9 % underwent ESWL procedures and 44.2 % underwent ASU procedures. The mean ESAK was 2.1, 4.18 and 4.9 mGy for IVU, ESWL, and ASU procedures, respectively. Differences in patient ESAK for the same procedure were observed. The mean ESAK values were comparable with those in previous studies.


Assuntos
Fluoroscopia/métodos , Litotripsia/métodos , Doses de Radiação , Radiometria/métodos , Uretra/diagnóstico por imagem , Urografia/métodos , Adolescente , Adulto , Idoso , Ar , Algoritmos , Calibragem , Fluoroscopia/efeitos adversos , Humanos , Litotripsia/efeitos adversos , Pessoa de Meia-Idade , Proteção Radiológica/métodos , Reprodutibilidade dos Testes , Software , Urografia/efeitos adversos , Raios X , Adulto Jovem
11.
Phys Med ; 31(7): 757-62, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25843889

RESUMO

PURPOSE: European legislation concerning the protection of workers from exposure to Electromagnetic Fields (EMF) was recently (26.6.2013) completed by Directive 2013/35/ΕU. This Directive is a specific one of the framework Directive 89/391/EEC and part of the overall legislation for Occupational Health and Safety (OHS). Magnetic Resonance Imaging (MRI) systems have played a key role, both in the postponement of the former 2004/40 EMF Directive and in the formation of the latest limits adopted by the new Directive. On the other hand, MRI systems are associated with the exposure of personnel to EMF of various frequencies and modulations, arousing peculiar safety issues. Therefore, we will try to acquire the highly important knowledge of the exact occupational exposure levels, in all working scenarios and practices. METHODS: Different MRI systems (1.5 and 3 T) have been chosen for a variety of measurements in order to assess occupational exposure compared to the limits (ALs) of the Directive and to the main OHS principles. Gradient function of MRI systems results in low frequency exposure, while high frequency exposure comes from the application of the RF excitation frequency. RESULTS: In most of the cases the RMS and peak value measurements do not exceed the corresponding ALs, apart from a few specific hot spots, manageable through OHS principles. DISCUSSION: Complete occupational exposure results can form the basis for dealing with multiple exposures present in MRI systems. Peculiar RF harmonic components, of no safety concern, were detected. Their origin is under examination.


Assuntos
Campos Eletromagnéticos/efeitos adversos , Imageamento por Ressonância Magnética/efeitos adversos , Exposição Ocupacional/análise , Ondas de Rádio/efeitos adversos
12.
Heredity (Edinb) ; 114(1): 38-47, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25052417

RESUMO

Although ex situ conservation is indispensable for thousands of species, captive breeding is associated with negative genetic changes: loss of genetic variance and genetic adaptation to captivity that is deleterious in the wild. We used quantitative genetic individual-based simulations to model the effect of genetic management on the evolution of a quantitative trait and the associated fitness of wild-born individuals that are brought to captivity. We also examined the feasibility of the breeding strategies under a scenario of a large number of loci subject to deleterious mutations. We compared two breeding strategies: repeated half-sib mating and a method of minimizing mean coancestry (referred to as gc/mc). Our major finding was that half-sib mating is more effective in reducing genetic adaptation to captivity than the gc/mc method. Moreover, half-sib mating retains larger allelic and adaptive genetic variance. Relative to initial standing variation, the additive variance of the quantitative trait increased under half-sib mating during the sojourn in captivity. Although fragmentation into smaller populations improves the efficiency of the gc/mc method, half-sib mating still performs better in the scenarios tested. Half-sib mating shows two caveats that could mitigate its beneficial effects: low heterozygosity and high risk of extinction when populations are of low fecundity and size and one of the following conditions are met: (i) the strength of selection in captivity is comparable with that in the wild, (ii) deleterious mutations are numerous and only slightly deleterious. Experimental validation of half-sib mating is therefore needed for the advancement of captive breeding programs.


Assuntos
Adaptação Biológica/genética , Aptidão Genética , Variação Genética , Endogamia , Modelos Genéticos , Animais , Simulação por Computador , Conservação dos Recursos Naturais/métodos , Espécies em Perigo de Extinção , Feminino , Fertilidade , Genética Populacional , Masculino , Locos de Características Quantitativas , Seleção Genética
13.
Phys Med ; 30(1): 47-56, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23517668

RESUMO

The aim of this study is twofold: (a) determination of the spectral differences for flattening-filter-free (FFF) versus standard (STD) linac under various clinical conditions, (b) based on an extensive list of clinically important beam configurations, identification of clinical scenarios that lead to higher macroscopic dose perturbations due to the presence of high-Z material. The focus is on dose enhancement due to contrast agents including high-Z elements such as gold or gadolinium. EGSnrc was used to simulate clinical beams under various irradiation conditions: open/IMRT/spit-IMRT fields, in/out-off-field areas, different depths and field sizes. Spectra were calculated and analyzed for about 80 beams and for a total of 480 regions. Quantitative differential effects in beam quality were characterized using energy-dependent and cumulative dose perturbation metrics. Analysis of the spectral database showed that even though the general trends for both linacs (FFF/STD) were the same, there were crucial differences. In general, the relative changes between different conditions were smaller for FFF spectra. This was because of the higher component of low-energy photons of the FFF linac, which already lead to higher dose enhancement than for the STD linac (photon energies were more "uniformly" distributed for FFF spectra and henceforth their perturbation resulted in lesser relative changes). For out-of-field FFF spectra and split-IMRT fields the strongest enhancement were observed (∼25 and ∼5 respectively). Different spectral scenarios lead to different dose enhancements, however, they scale with the higher effective-Z of the materials and were directly related to the lower range of the spectra (<200 keV).


Assuntos
Aceleradores de Partículas , Doses de Radiação , Método de Monte Carlo , Fótons/uso terapêutico , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada
14.
ScientificWorldJournal ; 2012: 546171, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22919334

RESUMO

PURPOSE: To evaluate the diagnostic value of 3T (1)H-MRS in grading cerebral gliomas using short and long echo times. METHODS: 1H-MRS was performed on 71 patients with untreated cerebral gliomas. Metabolite ratios of NAA/Cr, Cho/Cr, Cho/NAA, and mI/Cr were calculated for short and long TE and compared between low and high grade gliomas. Lipids were qualitatively evaluated. ROC analysis was performed to obtain the cut-off values for the metabolic ratios presenting statistical difference between the two glioma grades. RESULTS: Intratumoral Cho/Cr at both TEs and long TE Cho/NAA were significantly different between low and high grade gliomas. Peritumoral NAA/Cr of both TEs, as well as long TE Cho/Cr and Cho/NAA ratios, significantly differentiated the two tumor grades. Diagnostic sensitivity of peritumoral short TE NAA/Cr proved to be superior over the other metabolic ratios, whereas intratumoral short TE Cho/Cr reached the highest levels of specificity and accuracy. Overall, short TE 1H-MRS reached higher total sensitivity in predicting glioma grade, over long TE. CONCLUSION: An advantage was found in using short TE over long TE 1H-MRS in the discrimination of low versus high grade gliomas. Moreover, the results suggested that the peritumoral area of gliomas may be more valuable in predicting glioma grade than using only the intratumoral area.


Assuntos
Neoplasias Encefálicas/patologia , Glioma/patologia , Adolescente , Adulto , Idoso , Neoplasias Encefálicas/diagnóstico , Glioma/diagnóstico , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Gradação de Tumores , Sensibilidade e Especificidade , Adulto Jovem
15.
ScientificWorldJournal ; 2012: 754380, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22645448

RESUMO

PURPOSE: To determine whether in vivo proton magnetic resonance spectroscopy at 3T can provide accurate breast lesion characterization, and to determine the effect of gadolinium on the resonance of tCho. METHODS: Twenty-four positive-mammogram patients were examined on a 3T MR scanner. 1H-MRS was performed before and after gadolinium administration. tCho peak was qualitatively evaluated before and after contrast injection. RESULTS: Fourteen out of 27 lesions proved to be malignant after histopathological diagnosis. Using 1H-MRS, before contrast injection, 6/14 confirmed malignancies and 11/13 benign lesions were correctly classified; while, after contrast injection, 11/14 confirmed malignancies and 12/13 benign processes were correctly classified. Post gadolinium 1H-MRS proved useful in picking up tCho signal, improving the overall accuracy, sensitivity, and specificity by 35%, 83%, and 9%, respectively. CONCLUSION: 1H-MRS overall accuracy, sensitivity, and specificity in detecting breast lesion's malignancy were increased after gadolinium administration. It is prudent to perform 1H-MRS before contrast injection in large breast lesions to avoid choline underestimation. In cases of small or non-mass lesions, it is recommended to perform 1H-MRS after contrast injection for better voxel prescription to enable a reliable preoperative diagnosis.


Assuntos
Neoplasias da Mama/diagnóstico , Mama/patologia , Gadolínio/farmacologia , Espectroscopia de Ressonância Magnética/métodos , Mamografia/métodos , Adulto , Idoso , Neoplasias da Mama/patologia , Colina/metabolismo , Meios de Contraste/farmacologia , Detecção Precoce de Câncer/métodos , Feminino , Humanos , Cinética , Imageamento por Ressonância Magnética/métodos , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Radiat Prot Dosimetry ; 147(1-2): 118-21, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21733856

RESUMO

Barium studies investigations (barium swallow, barium meal and barium enema) are the basic routine radiological examination, where barium sulphate suspension is introduced to enhance image contrast of gastrointestinal tracts. The aim of this study was to quantify the patients' radiation doses during barium studies and to estimate the organ equivalent dose and effective dose with those procedures. A total of 33 investigations of barium studies were measured by using thermoluminescence dosemeters. The result showed that the patient entrance surface doses were 12.6 ± 10, 44.5 ± 49 and 35.7 ± 50 mGy for barium swallow, barium meal, follow through and enema, respectively. Effective doses were 0.2, 0.35 and 1.4 mSv per procedure for barium swallow, meal and enema respectively. Radiation doses were comparable with the previous studies. A written protocol for each procedure will reduce the inter-operator variations and will help to reduce unnecessary exposure.


Assuntos
Sulfato de Bário , Trato Gastrointestinal/diagnóstico por imagem , Doses de Radiação , Intensificação de Imagem Radiográfica , Radiometria/métodos , Adolescente , Adulto , Simulação por Computador , Meios de Contraste , Enema , Fluoroscopia , Humanos , Pessoa de Meia-Idade , Método de Monte Carlo , Adulto Jovem
17.
Med Phys ; 38(5): 2342-52, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21776768

RESUMO

PURPOSE: This study investigates the benefits of a modified flattening filter free (FFF) linac over the standard (STD) linac equipped with the flattening filter. Energy and angular spread of the electron beam of the FFF linac were modified. Modification of FFF beam parameters is explored to maximize the monitor unit efficiency and to minimize the head scatter in IMRT delivery for large target volumes or targets lying away from the central axis. METHODS: The EGSnrc code is used to model FFF and STD linacs and study basic beam properties for both linac types in various beam configurations. Increasing energy of FFF linac results in similar beam attenuation properties and maximized dose rate compared to STD linac. Matching beam attenuation properties allows a more direct exploration of beam flatness of FFF linac in regard to IMRT delivery, especially away from the central axis where the effective dose rate is considerably smaller than the one at the central axis. Flatness of open beam dose profile of FFF linac is improved by increasing the angular spread of the electron beam. The resulting dose rate within the treatment field and outside of the field (peripheral dose) are characterized and compared to the unmodified FFF and STD linacs, RESULTS: In order to match beam penetration properties, the energy of FFF is adjusted from 6.5 to 8.0 MeV for small to medium field sizes and from 6.5 to 8.5 MeV for larger ones. Dose rate of FFF vs STD linac increased by a factor of 1.9 (6.5 MeV) and 3.4-4.1 (8.0-8.5 MeV). Adjusting the mean angular spread of the electron beam from 0 degrees to 5 degrees-10 degrees resulted in complete flattening of photon beam for field sizes between 10 x 10 cm2 and 15 x 15 cm2 and partial flattening for field sizes from 15 x 15 cm2 to 30 x 30 cm2. Values of angular spread > or =14 degrees are not recommended as they exceed the opening of the primary collimator, affecting the area at the edges of the field. FFF fields of sizes smaller than 6 x 6 cm2 are already flat and beam flattening is not necessary. Overall, the angular spread of 5 degrees-10 degrees is sufficient and can satisfactorily flatten open beam dose profiles even for larger field sizes. Increasing the electron beam angular spread amounts to a slight decrease of dose rate of FFF linac. However, for angular spread, 5 degrees-10 degrees dose rate factor of FFF vs STD is still about 1.6-2.6, depending on the field size (and the adjusted energy). Similarly, in case of peripheral dose, a moderate increase in dose can be observed for angular spread of 5 degrees-10 degrees and for field sizes 10 x 10 cm2 to 30 x 30 cm2. Lastly, beam flatness of not modified FFF linac can be conveniently described by an analytical function representing a ratio of STD vs FFF doses: 1 + b|r|(n). CONCLUSIONS: A modified FFF beamline with increased energy and electron beam angular spread results in satisfactory flattened beam and high dose rate within the field. Peripheral dose remaining at similar (or smaller) level than that of STD linac for the same delivered dose within the treatment field.


Assuntos
Filtração/instrumentação , Aceleradores de Partículas/instrumentação , Radioterapia Conformacional/instrumentação , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento
18.
Radiat Prot Dosimetry ; 147(1-2): 171-5, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21743069

RESUMO

Pneumonia is an important cause of hospital admission among children in the developed world and it is estimated to be responsible for 3-18 % of all paediatric admissions. Chest X ray is an important examination for pneumonia diagnosis and for evaluation of complications. This study aims to determine the entrance surface dose (ESD), organ, effective doses and propose a local diagnostic reference level. The study was carried out at the university hospital of Larissa, Greece. Patients were divided into three groups: organ and effective doses were estimated using National Radiological Protection Board software. The ESD was determined by thermoluminescent dosemeters for 132 children and 76 comforters. The average ESD value was 55 ± 8 µGy. The effective dose for patients was 11.2 ± 5 µSv. The mean radiation dose for comforter is 22 ± 3 µGy. The radiation dose to the patients is well within dose constraint, in the light of the current practice.


Assuntos
Pediatria , Pneumonia/diagnóstico , Doses de Radiação , Monitoramento de Radiação/normas , Proteção Radiológica/normas , Radiografia Torácica , Dosimetria Termoluminescente , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido
19.
Radiat Prot Dosimetry ; 147(1-2): 122-5, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21743077

RESUMO

Enteroclysis is a minimally invasive radiographic examination of the small intestine. During the procedure, considerable radiation dose is delivered to the patients. This study intends to: (a) evaluate the radiation dose to the patient using thermoluminescent dosemeters (TLDs, according to the protocol used at Radiology Department, University Hospital of Larissa, Greece; (b) estimate the thyroid surface dose (TSD) and doses to some radiosensitive organs located in the irradiation field. A total of 46 patients was examined. Patients were divided into two groups according to the digital X-ray machine used. The mean entrance surface dose (ESD) was 601.2 ± 96.2 mGy and the mean fluoroscopy time was 8.5 ± 3 min, while the mean TSD was 0.34 ± 0.6 mGy. The ESD for group A was lower by 20 % than group B due to fluoroscopic mode used. The dose values were higher than those in the literature. A local diagnostic reference level was introduced for further patient dose optimisation.


Assuntos
Fluoroscopia , Intestino Delgado/diagnóstico por imagem , Doses de Radiação , Dosimetria Termoluminescente , Adulto , Grécia , Humanos , Estudos Prospectivos
20.
IEEE Trans Inf Technol Biomed ; 15(4): 647-54, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21427025

RESUMO

Although magnetic resonance spectroscopy (MRS) methods of 1.5Tesla (T) and 3T have been widely applied during the last decade for noninvasive diagnostic purposes, only a few studies have been reported on the value of the information extracted in brain cancer discrimination. The purpose of this study is threefold. First, to show that the diagnostic value of the information extracted from two different MRS scanners of 1.5T and 3T is significantly influenced in terms of brain gliomas discrimination. Second, to statistically evaluate the discriminative potential of publicly known metabolic ratio markers, obtained from these two types of scanners in classifying low-, intermediate-, and high-grade gliomas. Finally, to examine the diagnostic value of new metabolic ratios in the discrimination of complex glioma cases where the diagnosis is both challenging and critical. Our analysis has shown that although the information extracted from 3T MRS scanner is expected to provide better brain gliomas discrimination; some factors like the features selected, the pulse-sequence parameters, and the spectroscopic data acquisition methods can influence the discrimination efficiency. Finally, it is shown that apart from the bibliographical known, new metabolic ratio features such as N-acetyl aspartate/ S, Choline/ S, Creatine/ S , and myo-Inositol/ S play significant role in gliomas grade discrimination.


Assuntos
Neoplasias Encefálicas/classificação , Glioma/classificação , Espectroscopia de Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/métodos , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/patologia , Glioma/diagnóstico , Glioma/patologia , Humanos , Reprodutibilidade dos Testes
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