Exploring the visualisation of the cervicothoracic junction in lateral spine radiography using high dynamic range techniques

The C7/T1 junction is an important landmark for spinal injuries. It is traditionally difficult to visualise in a lateral X-ray image due to the rapid change in the bodys anatomy at the level of the junction, where the shoulders cause a large increase in attenuation. To explore methods of enhancing the appearance of this important area, lateral radiographs of a shoulder girdle phantom were subjected to high dynamic range (HDR) processing and tone mapping. A shoulder girdle phantom was constructed using Perspex, shoulder girdle and vertebral bones and water to reproduce the attenuation caused by soft tissue. The design allowed for the removal of the shoulder girdle in order for the cervical vertebrae to be imaged separately. HDR was explored for single and dual-energy X-ray images of the phantom. In the case of single-image HDR, the HDR image of the phantom without water was constructed by combining images created with varying contrast windows throughout the contrast range of an X-ray image. It was found that an overlap of larger contrast windows with a lower number of images performed better than smaller contrast windows and more images when creating an HDR to be tone mapped. Poor results on the phantom without water precluded further testing of single-image HDR on images of the phantom with water, which would have higher attenuation. Dual energy HDR image construction explored images of the phantom both with and without water. A set of images acquired at lower attenuation (phantom without water) was used to evaluate the performance of the various tone mapping algorithms. The tone mapping was then performed on the phantom images containing water. These results showed how each tone mapping algorithm differs and the effects of global vs. local processing. The results revealed that the built-in MatLab algorithm, based on an improved Ward histogram adjustment approach, produces the most desirable result. None of the HDR tone mapped images produced were diagnostically useful. Signal to noise ratio (SNR) analysis was performed on the cervical region of the HDR tone mapped image. It used the scan of the phantom without the shoulder girdle obstruction (imaged under the same conditions) as a reference image. The SNR results quantitatively show that the selection of exposure values affects the visualisation of the tone mapped image. The highest SNR was produced for the 100 - 120 kV dual energy X-ray image pair. The study was limited by the range of HDR image construction techniques employed and the tone mapping algorithms explored. Future studies could explore other HDR image construction techniques and the combination of global and local tone mapping algorithms. Furthermore, the phantom can be replaced by a cadaver for algorithm testing under more realistic conditions

A Pseudo-logarithmic Image Processing Framework for Edge Detection

Abstract. The paper presents a new [pseudo-] Logarithmic Model for Image Processing (LIP), which allows the computation of gray-level ad-dition, substraction and multiplication with scalars within a fixed gray-level range [0;D] without the use of clipping. The implementation of Laplacian edge detection techniques under the proposed model yields superior performance in biomedical applications as compared with the classical operations (performed either as real axis operations, either as classical LIP models).

Logarithmic Image Processing for Color Images

43 pagesInternational audienceThe present paper is an extension to color images of the LIP (Logarithmic Image Processing) framework, initially dedicated to gray level image

Métricas de Registro de Imágenes y Predicción de Dolor de Rodilla por Osteoartritis Crónica: Datos de la Osteoarthritis Initiative

Osteoarthritis (OA) is the most common type of arthritis, is a growing disease in the industrialized world. OA is an incapacitate disease that affects more than 1 in 10 adults over 60 years old. X-ray medical imaging is a primary diagnose technique used on staging OA that the expert reads and quantify the stage of the disease. Some Computer-Aided Diagnosis (CADx) efforts to automate the OA detection have been made to aid the radiologist in the detection and control, nevertheless, the pain inherits to the disease progression is left behind. In this research, it’s proposed a CADx system that quantify the bilateral similarity of the patient’s knees to correlate the degree of asymmetry with the pain development. Firstly, the knee images were aligned using a B-spline image registration algorithm, then, a set of similarity measures were quantified, lastly, using this measures it’s proposed a multivariate model to predict the pain development up to 48 months. The methodology was validated on a cohort of 131 patients from the Osteoarthritis Initiative (OAI) database. Results suggest that mutual information can be associated with K&L OAI scores, and Multivariate models predicted knee chronic pain with: AUC 0.756, 0.704, 0.713 at baseline, one year, and two years’ follow-up.Osteoarthritis (OA) is the most common type of arthritis, is a growing disease in the industrialized world. OA is an incapacitate disease that affects more than 1 in 10 adults over 60 years old. X-ray medical imaging is a primary diagnose technique used on staging OA that the expert reads and quantify the stage of the disease. Some Computer-Aided Diagnosis (CADx) efforts to automate the OA detection have been made to aid the radiologist in the detection and control, nevertheless, the pain inherits to the disease progression is left behind. In this research, it’s proposed a CADx system that quantify the bilateral similarity of the patient’s knees to correlate the degree of asymmetry with the pain development. Firstly, the knee images were aligned using a B-spline image registration algorithm, then, a set of similarity measures were quantified, lastly, using this measures it’s proposed a multivariate model to predict the pain development up to 48 months. The methodology was validated on a cohort of 131 patients from the Osteoarthritis Initiative (OAI) database. Results suggest that mutual information can be associated with K&L OAI scores, and Multivariate models predicted knee chronic pain with: AUC 0.756, 0.704, 0.713 at baseline, one year, and two years’ follow-up

NASA/ASEE Summer Faculty Fellowship Program, 1990, Volume 1

The 1990 Johnson Space Center (JSC) NASA/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program was conducted by the University of Houston-University Park and JSC. A compilation of the final reports on the research projects are presented. The topics covered include: the Space Station; the Space Shuttle; exobiology; cell biology; culture techniques; control systems design; laser induced fluorescence; spacecraft reliability analysis; reduced gravity; biotechnology; microgravity applications; regenerative life support systems; imaging techniques; cardiovascular system; physiological effects; extravehicular mobility units; mathematical models; bioreactors; computerized simulation; microgravity simulation; and dynamic structural analysis

Applications of advanced and dual energy computed tomography in proton therapy

This thesis focuses on advanced reconstruction methods and Dual Energy (DE) Computed Tomography (CT) applications for proton therapy, aiming at improving patient positioning and investigating approaches to deal with metal artifacts. To tackle the first goal, an algorithm for post-processing input DE images has been developed. The outputs are tumor- and bone-canceled images, which help in recognising structures in patient body. We proved that positioning error is substantially reduced using contrast enhanced images, thus suggesting the potential of such application. If positioning plays a key role in the delivery, even more important is the quality of planning CT. For that, modern CT scanners offer possibility to tackle challenging cases, like treatment of tumors close to metal implants. Possible approaches for dealing with artifacts introduced by such rods have been investigated experimentally at Paul Scherrer Institut (Switzerland), simulating several treatment plans on an anthropomorphic phantom. In particular, we examined the cases in which none, manual or Iterative Metal Artifact Reduction (iMAR) algorithm were used to correct the artifacts, using both Filtered Back Projection and Sinogram Affirmed Iterative Reconstruction as image reconstruction techniques. Moreover, direct stopping power calculation from DE images with iMAR has also been considered as alternative approach. Delivered dose measured with Gafchromic EBT3 films was compared with the one calculated in Treatment Planning System. Residual positioning errors, daily machine dependent uncertainties and film quenching have been taken into account in the analyses. Although plans with multiple fields seemed more robust than single field, results showed in general better agreement between prescribed and delivered dose when using iMAR, especially if combined with DE approach. Thus, we proved the potential of these advanced algorithms in improving dosimetry for plans in presence of metal implants

Aerospace medicine and biology. A continuing bibliography with indexes, supplement 224

This bibliography lists 127 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1981

Наноструктурне и микроархитектонске карактеристике врата бутне кости: утицај на повећану коштану фрагилност са старењем код жена

Background: Hip fractures are among the most important health problems in elderly population worldwide, particularly in elderly women. However, despite extensive research on age-related bone fragility, the factors leading to decreased bone strength in advanced age are not yet clear enough. Indeed, in clinical settings bone mineral density (BMD) assessed by dual energy X-ray absorptiometry has been used as an indicator of hip fracture risk. However, as it has been already pointed out that age-related decrease in BMD fails to fully explain the high increase in hip fracture risk with aging, other bone features also account for age-related deterioration in bone strength. Since bone is a hierarchically organized structure, it can be hypothesized that its strength depends on various features from nano-scale to macro-scale. Although numerous studies addressed macro- and microstructural basis of bone fragility, so far the direct data at microarchitectural level have been scarce. Moreover, nanostructure of the bone mineralized matrix has received insufficient attention with regard to effects of aging and its relation to bone fragility. Hypotheses: Our hypotheses were that region-dependant worsening of bone microarchitecture in elderly women leads to increased femoral neck fragility, and that - besides the microarchitectural deterioration - the age-related nanostructural changes at the bone matrix level contribute to increased bone fragility in elderly women. Material and methods: To test these hypotheses, we analyzed bone specimens from the femoral neck region obtained at autopsy in young and elderly women without hip fracture as well as in a group of postmenopausal women who sustained a hip fracture. Following sectioning process, micro-computed tomography was performed to assess bone microarchitectural properties. Bone nanostructure was analyzed via Topography and Phase modes of Atomic Force Microscopy (AFM), while chemical evaluation of bone material composition encompassed energy dispersive X-ray spectroscopy, quantitative backscatter electron imaging, inductively coupled plasma optical emission spectroscopy and direct current argon arc plasma optical emission spectrometry...Увод: Преломи кука су један од најзначајнијих здравствених проблема код старих особа широм света, а посебно код старијих жена. Међутим, упркос многобројним истраживањима узрока фрагилности скелета код старијих особа, још увек се врло мало зна о чиниоцима који доводе до смањене чврстоће кости у старости. Минерална густина кости (bone mineral density, BMD) утврђена применом дензитометријске методе (dual energy X-ray absorptiometry, DXA) је дуго сматрана главним показатељем коштане чврстоће и до данас коришћена у клиничкој процени коштане фрагилности и ризика за прелом кука. Међутим, будући да је више аутора указало на податак да старосни пад BMD не може потпуно објаснити значајни пораст ризика oд преломa кука код старијих особа, неопходно је испитати и допринос других коштаних карактеристика смањењу коштане чврстоће са старењем. Како је кост хијерархијски организована структура, може се претпоставити да њена чврстоћа зависи од различитих елемената коштане грађе од нанометарске до макро-скале. Премда су се многобројне студије усредсредиле на испитивање макроструктурне и микроструктурне основе коштане фрагилности, још увек недостају директни подаци о микроархитектури костију код особа са преломом кука. Поред тога, старосним променама наноструктурних параметара самог материјала од кога је кост изграђена није посвећена одговарајућа пажња, као ни њиховом значају за коштану фрагилност. Хипотеза: Нашe хипотезе су биле да регион-зависно погоршање коштане микроархитектуре код старијих жена повећава њихов ризик за прелом кука, као и да се, осим микроструктурних промена, са старењем јављају и наноструктурне промене на нивоу коштаног матрикса које такође доприносе повећаној коштаној фрагилности код старијих жена..