RESUMO
This paper presents the application of a computational methodology for optimizing the conversion of medical tomographic images in voxel anthropomorphic models for simulation of radiation transport using the MCNP code. A computational system was developed for digital image processing that compresses the information from the DICOM medical image before it is converted to the Scan2MCNP software input file for optimization of the image data. In order to validate the computational methodology, a radiosurgery treatment simulation was performed using the Alderson Rando phantom and the acquisition of DICOM images was performed. The simulation results were compared with data obtained with the BrainLab planning system. The comparison showed good agreement for three orthogonal treatment beams of (60)Co gamma radiation. The percentage differences were 3.07%, 0.77% and 6.15% for axial, coronal and sagital projections, respectively.
Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/radioterapia , Método de Monte Carlo , Imagens de Fantasmas , Intensificação de Imagem Radiográfica/instrumentação , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Radioterapia Assistida por Computador/métodos , Humanos , Imageamento Tridimensional/instrumentação , Imageamento Tridimensional/métodos , Planejamento da Radioterapia Assistida por Computador/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodosRESUMO
WHAT IS KNOWN AND OBJECTIVE: Some antimicrobial agents are active in vitro against Leptospiras. The use of penicillins at the late stage of leptospirosis is still controversial. We aimed to evaluate the use of penicillin in patients with leptospirosis-associated acute kidney injury (AKI). METHODS: A retrospective study was conducted of patients with leptospirosis admitted to two hospitals in Fortaleza city, Brazil, between 1985 and 2008. AKI was defined according to the RIFLE and AKIN classifications. Patients were divided in two groups according to whether they were treated with a penicillin or not. RESULTS: Two hundred and eighty-seven patients were included, with an average age of 36·8±15·6 years and mostly male (80·8%). One hundred and twelve patients (39%) received a penicillin. Patients treated with a penicillin were younger (32±14 years vs. 39±16 years, P=0·0002) and had a shorter hospital stay (8·4±5·0 vs. 11±7·7 days, P<0·0001). There was no difference in the onset of symptoms before hospital admission between the two groups (6·5±3·0 vs. 7·7±4·7, P=0·33). Systolic blood pressure was lower in the penicillin group (111±21 vs. 119±22 mmHg, P=0·04). AKI, need of dialysis and renal recovery at the time of hospital discharge were more frequent in patients who did not use a penicillin (P<0·05). Mortality was similar in both groups (11·6% vs. 13·7%, P=0·60). CONCLUSION: Treatment of leptospirosis with antibiotics, including the penicillin, remains controversial. The main benefit of using penicillin in the present study was a reduction in the length of hospital stay and fewer complications, such as AKI, but its use was not associated with a decrease in mortality. On balance of risks and benefits, we recommend the use of penicillin in late-stage leptospirosis.
Assuntos
Injúria Renal Aguda/tratamento farmacológico , Leptospirose/tratamento farmacológico , Penicilinas/uso terapêutico , Injúria Renal Aguda/microbiologia , Injúria Renal Aguda/mortalidade , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Brasil , Criança , Feminino , Humanos , Tempo de Internação , Leptospirose/complicações , Leptospirose/mortalidade , Masculino , Pessoa de Meia-Idade , Penicilinas/administração & dosagem , Estudos Retrospectivos , Fatores de Tempo , Adulto JovemRESUMO
The purpose of this study is to investigate the influence of lung heterogeneity inside a soft tissue phantom on percentage depth dose (PDD). PDD curves were obtained experimentally using LiF:Mg,Ti (TLD-100) thermoluminescent detectors and applying Eclipse treatment planning system algorithms Batho, modified Batho (M-Batho or BMod), equivalent TAR (E-TAR or EQTAR), and anisotropic analytical algorithm (AAA) for a 15 MV photon beam and field sizes of 1 x 1, 2 x 2, 5 x 5, and 10 x 10 cm 2 . Monte Carlo simulations were performed using the DOSRZnrc user code of EGSnrc. The experimental results agree with Monte Carlo simulations for all irradiation field sizes. Comparisons with Monte Carlo calculations show that the AAA algorithm provides the best simulations of PDD curves for all field sizes investigated. However, even this algorithm cannot accurately predict PDD values in the lung for field sizes of 1 x 1 and 2 x 2 cm 2 . An overdosage in the lung of about 40% and 20% is calculated by the AAA algorithm close to the interface soft tissue/lung for 1 x 1 and 2 x 2 cm 2 field sizes, respectively. It was demonstrated that differences of 100% between Monte Carlo results and the algorithms Batho, modified Batho, and equivalent TAR responses may exist inside the lung region for the 1 x 1 cm 2 field.