Search for dissertations about: "scatter reduction"
Showing result 1 - 5 of 22 swedish dissertations containing the words scatter reduction.
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1. Characterisation and application of a laser-based hard x-ray source
Abstract : Hard X-rays are generated by focusing 110 fs laser pulses with intensities of about 1017 W·cm-2 onto solid metal targets. Characteristic properties of this X-ray source are the small source size, the short pulse duration and the high peak flux. READ MORE
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2. Calculation of scatter in cone beam CT : Steps towards a virtual tomograph
Abstract : Scattered photons—shortly scatter—are generated by interaction processes when photon beams interact with matter. In diagnostic radiology, they deteriorate image quality since they add an undesirable signal that lowers the contrast in projection radiography and causes cupping and streak artefacts in computed tomography (CT). READ MORE
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3. Energy and intensity modulated radiation therapy with electrons
Abstract : In recent years intensity modulated radiation therapy with photons (xIMRT) has gained attention due to its ability to reduce the dose in the tissues close to the tumour volume. However, this technique also results in a large low dose volume. READ MORE
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4. Evaluation of absorbed dose and image quality in mammography
Abstract : Mammography refers to the X-ray examination of the human breast, and is considered the single most important diagnostic tool in the early detection of breast cancer, which is by far the most common cancer among women. There is good evidence from clinical trials, that mammographic screening can reduce the breast cancer mortality with about 30%. READ MORE
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5. Effective use of X rays in diagnostic radiology : Guidance for the optimisation of image quality and absorbed dose in the patient by use of a Monte Carlo computational model of the imaging chain
Abstract : The primary objective of this thesis is to give guidance for the reduction of absorbed dose in the patient and the improvement of image quality by the optimisation of the various parameters which control the performance of the radiological imaging system. The optimisation means that image quality (contrast in screen-film imaging and signal-to-noise ratio in digital imaging) is kept constant and combinations of operating parameters which yields the lowest mean absorbed dose in the patient is determined. READ MORE