RESUMO
A low dose technique has been recently proposed for tomographic studies of the lung, which makes use of a gamma camera to detect 90 degrees Compton-scattered photons from external planar gamma source. In this paper, we present a detailed Monte Carlo study of this technique. A 20 x 20 x 20 cm3 water phantom was simulated as a target and a large gamma camera equipped with an imaging collimator as a detector. The multiple scattering contamination of the single scattered signal was studied as a function of the source-detector geometry and of the incident energy in the range 100-500 keV. The multiple to single scatter ratio has an approximate 1/E0.7 dependence and increases almost linearly with the phantom depth and the transversal thickness at 90 degrees . Simulation has been also performed with a 16 x 16 x 10 cm3 sawdust phantom of 0.3 g/cm3 density; the Monte Carlo results agree to within a few percent with experimental data.
Assuntos
Neoplasias Femorais/patologia , Tumores de Células Gigantes/patologia , Neoplasias Primárias Múltiplas/patologia , Osteossarcoma/patologia , Adenocarcinoma/patologia , Idoso , Feminino , Neoplasias Femorais/diagnóstico por imagem , Humanos , Osteossarcoma/diagnóstico por imagem , Radiografia , Fatores de Tempo , Neoplasias Uterinas/patologiaAssuntos
Ameloblastoma , Neoplasias Ósseas , Metástase Neoplásica , Tíbia , Adulto , Humanos , MasculinoAssuntos
Neoplasias Ósseas/patologia , Tumores de Células Gigantes/patologia , Rádio (Anatomia) , Adulto , Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/cirurgia , Tumores de Células Gigantes/diagnóstico por imagem , Tumores de Células Gigantes/cirurgia , Humanos , Masculino , Radiografia , Rádio (Anatomia)/diagnóstico por imagem , Rádio (Anatomia)/patologia , Rádio (Anatomia)/cirurgiaRESUMO
BACKGROUND: Due to pharmacokinetic and pharmacodynamic reasons, the elderly are at particular risk of incurring unwanted side effects of drugs commonly used in anaesthesia. The bispectral index (BIS) is an EEG-derived value that measures the sedative component of the anaesthetic state. The BIS could be useful in guiding titration of anaesthetic drugs in the elderly. METHODS: A review of the published data was performed by the authors in order to assess the suitability of BIS technology application to the geriatric population. RESULTS: Age-related EEG differences exist in the normal population but they do not affect the BIS. The BIS correlates with depth of sedation independently of age. Senile dementia may be associated with significantly lower BIS values. CONCLUSIONS: The BIS is a useful guidance for titration of anaesthetic drugs in the elderly. The presence of senile dementia may be a confounding factor in the interpretation of the BIS values during anaesthesia.
Assuntos
Idoso/fisiologia , Anestesia , Eletroencefalografia/efeitos dos fármacos , Humanos , Monitorização IntraoperatóriaRESUMO
Anewborn with a transient myeloproliferative disorder and a myeloid/natural killer cell leukemia phenotype is described. The blasts expressed CD7, CD33, CD34, CD56, and CD117 but did not react with cytoplasmic myeloperoxidase and were negative for cy CD22, HLA-DR, and CD90 expression. No megakaryoblastic surface markers were identified. The blast population disappeared from the peripheral blood and bone marrow within 2 months, but hepatomegaly and recurrent respiratory insufficiency persisted. The patient died of unilateral pneumonia in the third month of life. Neither extramedullary infiltration nor other hematologic signs of disease progression were found.