Search for dissertations about: "tomography"

Showing result 16 - 20 of 1142 swedish dissertations containing the word tomography.

2. 16. Inverse Problems in Tomography and Fast Methods for Singular Convolutions

   Author : Fredrik Andersson; Matematik LTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik; Unequally spaced FFT; Integral transforms; Singular integrals; Lippmann?Schwinger equation; Helmholtz equation; Inverse problems; Fast Gauss transform; Fast summation; Convolution; Radon transform; Tomography;

   Abstract : There are two, partially interlaced, themes treated in this thesis; inverse problems of tomographic type and fast and accurate methods for the application of convolution operators. Regarding the first theme, the inverse problem of Doppler tomography is considered and the Doppler moment transform is introduced for that purpose. READ MORE

4. 17. Metal artifacts in computed tomography : impact of reduction methods on image quality and radiotherapy treatment planning

   Author : Karin Andersson; Per Thunberg; Eva Norrman; Jan Persliden; Anders Tingberg; Örebro universitet; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; computed tomography; metal artifacts; image quality; visual grading analysis; radiotherapy; proton therapy; hip prosthesis; dental implants;

   Abstract : Degradation of image quality by metal artifacts is a common problem in computed tomography (CT) imaging, which can limit the diagnostic value of a CT examination and also introduce inaccuracies in radiotherapy (RT) treatment planning. In recent years, commercial metal artifact reduction (MAR) methods have been launched by several CT vendors. READ MORE

5. 18. Are gadolinium contrast media really less nephrotoxic than iodine agents in radiographic examinations? A comparison in relation to their ability to attenuate x-rays in a pig model

   Author : Barbara Elmståhl; Malmö Diagnostisk radiologi; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Angiography; Computed tomography; toxicity; Contrast media; Glomerular filtration; Gadolinium; Iodine; Kidney failure; Nephrotoxicity.; Medicin människa och djur ; radiology; Clinical physics; Medicine human and vertebrates ; tomography; medical instrumentation; Diagnostik; Diagnostics; medicinsk instrumentering; tomografi; radiologi; Klinisk fysiologi;

   Abstract : Purpose: To confront the statement that gadolinium contrast media (Gd-CM) are less nephrotoxic than iodine contrast media (I-CM) when used in x-ray angiographic and computed tomographic (CT) examinations. Methods: I) For CT measurements (mean density in Hounsfield numbers) 20-mL syringes filled with I- and Gd-CM at 0.01, 0.02, 0. READ MORE

6. 19. Low-dose computed tomography of the abdomen and lumbar spine

   Author : Muhammed Alshamari; Håkan Geijer; Seppo Koskinen; Örebro universitet; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Tomography; X-Ray Computed; Radiography; Radiation Dosage; Abdomen; Spine; Lumbosacral Region; Regression Analysis; Kirurgi; Surgery;

   Abstract : Radiography is a common radiologic investigation despite abundant evidence of its limited diagnostic value. On the other hand, computed tomography (CT) has a high diagnostic value and is widely considered to be among the most important advances in medicine. READ MORE

7. 20. Advances in time–domain induced polarisation tomography : Data acquisition, processing and modelling

   Author : Per-Ivar Olsson; Teknisk geologi; []
   Keywords : Tomography; Signal–to–noise ratio; Waveform; Duty–Cycle; induced polarisation; Electrical properties;

   Abstract : What would you find below your feet – how do you find out? Perhaps you could look at a geological map, drill, or dig? That could work, but sometimes the maps are not detailed enough, and digging everywhere to find out is impractical. Imagine if you could develop a method that allows you to see straight through the ground, as x–rays through the body! To some extent, such methods already exist; you can for example send electric current into the ground that tells you what lies beneath when it returns. READ MORE