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Newborns diagnosed with hip dysplasia face severe consequences when treatments fail. The Pavlik harness presents the most common worldwide treatment for correcting this medical hip abnormality in newborns, but becomes increasingly ineffective as subluxation increases. A dynamic finite element analysis on the hip joint would yield results that could provide insight to physicians as to how the Pavlik harness could be optimized to increase its success rate and develop patient-specific treatment plans. The study completes the first step in such an analysis by generating a three-dimensional model of an infant hip joint directly derived from computed tomography imaging in order to accurately represent the anatomical locations of muscle origins and insertions points as well as the unique cartilaginous characteristics of a neonate hip and femur. Such models will further enhance findings on the biomechanics of hip dysplasia that resulted from a preliminary study using computer-aided design to recreate the hip joint. In addition to the models, the orientation of the psoas tendon in a dysplastic hip through full range abduction and flexion was analyzed using a cadaveric dissection. It was determined that the psoas tendon was not an obstruction to reduction when the hip was in flexion so long as the tendon was not adherent to the hip capsule, and therefore can be disregarded in a finite element analysis or dynamic simulation that introduces flexion. The work of this thesis will lay the foundation for complex finite element analyses regarding the biomechanics of hip dysplasia in neonates as well as other hip abnormalities relevant to early child development.

Computed Tomography (CT) is the standard in medical imaging field. In this study, we look at the curvelet transform in an attempt to use it as a basis for representing a function. In doing so, we seek a way to reconstruct a function from the Radon data that may produce clearer results. Using curvelet decomposition, any known function can be represented as a sum of curvelets with corresponding coefficients. It can be shown that these corresponding coefficients can be found using the Radon data, even if the function is unknown. The use of curvelets has the potential to solve partial or truncated Radon data problems. As a result, using a curvelet representation to invert radon data allows the chance of higher quality images to be produced. This paper examines this method of reconstruction for computed tomography (CT). A brief history of CT, an introduction to the theory behind the method, and implementation details will be provided.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24967号 / 医博第5021号 / 新制||医||1069(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 伊達 洋至, 教授 江木 盛時, 教授 川上 浩司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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<p>The typical High Dose Rate (HDR) lung brachytherapy procedure involves inserting treatment catheters into the bronchi next to the tumour location using a bronchoscope. The anterior-posterior and lateral fluoroscopy images are acquired in order to localize the catheters prior to treatment. Although, these images enable accurate reconstruction of the catheter location, they do not allow for the visualization of the tumour or organs-at-risk due to poor soft tissue contrast. Although CT images offer an improved soft tissue contrast, moving the patient with catheters in place prior to each treatment is impractical.</p> <p>An alternative option is to use prior diagnostic or external beam radiation treatment planning CT images. These images cannot be used for treatment planning directly because of the variation in patient positioning between the CT and orthogonal images acquisition. In order to account for positioning differences, a 2D/3D registration algorithm that registers the orthogonal images with a previously acquired CT data was developed. The algorithm utilizes a rigid registration model based on a pixel/voxel intensity matching approach. A similarity measure combining normalized mutual information (NMI), image gradient, and intensity difference was developed. Evaluation of the algorithm was performed using tissue equivalent phantoms, and, in the clinical setting using data from six patients. The mean registration error was 2.1 mm and 3.2 mm for phantoms and patients respectively.</p> <p>External objects such as the treatment table and ECG leads are often in CT images, affecting the above mentioned 2D/3D registration. To address this, an algorithm for automatic removal of external objects from CT images was developed. This was applied to automatic contouring and removal of the fiducial markers in CT images used for external beam radiation therapy treatment planning for breast cancer. The algorithm was further modified to compute the girth of patients as part of a diagnostic radiology clinical trial.</p> / Doctor of Philosophy (PhD)

Biliary diseases are uncommon, potentially fatal causes of acute abdomen in dogs. Little information is present comparing the performance of computed tomography (CT) to ultrasound in identifying canine biliary pathology. Thirty-five client-owned dogs presenting for acute abdomen signs received an abdominal ultrasound and contrast-enhanced abdominal CT. Two authors reviewed the randomized, anonymized CT and ultrasound studies. Twenty-eight dogs had biliary pathology and seven dogs serving as controls had no evidence of biliary disease. The final diagnoses of patients with biliary pathology included cholelithiasis, gallbladder mucoceles, cholangiohepatitis/cholangitis, extrahepatic biliary obstruction, gallbladder wall edema, gallbladder wall mass, and cystic mucosal hyperplasia. Computed tomography was more accurate in identifying cholelithiasis than ultrasound. No statistical difference in the odds to identify other biliary pathology was identified between ultrasound and CT. Findings from this study suggest CT may be used in place of ultrasound in canine patients presenting for acute abdominal signs of biliary origin.

Introduction: We argue, for studies of growth or treatment changes, superimposed CBCT images ought to be employed routinely. The location of 3D landmarks on curved structures, however, has been complex. In this study, a reliable method of CBCT superimposition was developed with the aid of AMIRA XImage® software. The specific focus was to develop a practical method for cranial base superimpositions at sella turcica in serial CBCT images. Subsequently, evaluations of the anterior curvature of hypophyseal fossa during growth were completed to confirm the stability. Comparisons of surface changes in the superimposed images in different regions were also made. Methods: Samples of pre- and post-orthodontic CBCT data were procured from Case Western Reserve University. Cranial base changes in 10 adolescent patients of Class I and II hypodivergent, normodivergent, and hyperdivergent malocclusions, were observed over an average interval of 2 years and 5 months. Cranial base models were superimposed using a rigid registration technique, and 3D models constructed from manual segmentation in the AMIRA software. Surface distance changes of the entire cranial base were compared to that of the anterior portion of sella turcica. Results: Mean surface distance changes for the entire cranial base and anterior sella were 0.73-1.57 ± 0.71-1.30 mm and 0.37-0.63 ± 0.29-0.43 mm, respectively. The area above a threshold of 0.5 mm was 61.02-74.11% (cranial base) and 40.70-50.94% (anterior sella) as well. Paired t-tests were applied to compare differences between the mean distance and area above the threshold for data of cranial base versus anterior sella. Both illustrated p-values less than 0.0001 and were statistically significant. Intra-rater reliability was evaluated by completing segmentation and registration three consecutive times on each CBCT volume. Mean surface differences were within 0.01 mm with the exception of one patient. In addition, all subjects exhibited less than 1.00% deviation except three patients, which deviated by 1.03%, 1.46%, and 1.64%, respectively. Conclusions: A practical method of superimposition of serial CBCT images was developed. Through production of color maps, the surface distance of the anterior portion of sella turcica was shown to change much less than the clivus and remaining cranial base structures in pre- and post-treatment scans of growing children. Lastly, the method of superimposition developed here may assist future studies of skeletal changes with accuracy. / Oral Biology