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Using a realistic, 3-shell head model including the scalp (S), skull (S) and brain (B) with conductivity ratios of 1:1/80:1, respectively, the electrical activity in the human brain recorded by conventional electroencephalography was approximated by 1 or 2 equivalent current dipoles. The dipole locations and vector moments were estimated by minimizing the(More)
The continuous technical development of cranial CT and the accumulation of clinical experience with this method, have resulted in the use of an increasing number of scan protocols for different clinical situations. An investigation was undertaken to find out how this change has influenced the dose delivered to the patient. The eye lens dose was measured at(More)
In four of six patients with methanol intoxication, computed tomography (CT) showed necrotic changes in the area of the putamina. Hemorrhages were also seen in some cases. There was a clear relationship between the severity of the clinical symptoms and the CT findings, indicating the potential of CT for prognosis and possible therapy guidance.
A phantom consisting of a human skull fixed in a cylinder containing water was used to study the occurrence of artifacts and their influence on image quality in CT of the posterior fossa. Only minor differences in interpetrous bone artifact and in deviation in CT numbers in other parts of the posterior fossa were found between eight tested scanner models.(More)
When irradiating targets in the brain, an accurately localised dose is often needed. One crucial moment to achieve this is the positioning of the patient. We have developed a positioning method where the patient is immobilised with a bite block and a head mould, and where the position of the target is determined by X-ray imaging of fiducial markers that are(More)
Five pregnant Rhesus monkeys were catheterized in the hepatic and femoral veins. They were simultaneously given 168 or 176 micrograms of 3H-metoprolol intravenously, and 9 mg of metoprolol per kg body weight orally. The same procedure was repeated a few months after delivery. Analyses of the unlabelled drug in blood were made by gas-chromatography and of(More)
A phantom was constructed with the intention of simulating the clinical situation at examination of the spine. Artifacts from bony vertebral structures were analyzed and the uniformity in a body-shaped object was studied. Tests were carried out on eight CT scanners. A considerable variation in uniformity was found between the tested scanner models. The CT(More)
The spatial dose distribution in a cylindrical polystyrene phantom with a diameter of 200 mm was measured for seven computed tomography (CT) scanners. The measurements were performed in the head mode and mainly for narrow slices in the range 1.5 to 4 mm. Both radial and axial dose profiles were measured and the dose distribution for multiple-scan procedures(More)