572 research outputs found

    Effects of municipal smoke-free ordinances on secondhand smoke exposure in the Republic of Korea

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    ObjectiveTo reduce premature deaths due to secondhand smoke (SHS) exposure among non-smokers, the Republic of Korea (ROK) adopted changes to the National Health Promotion Act, which allowed local governments to enact municipal ordinances to strengthen their authority to designate smoke-free areas and levy penalty fines. In this study, we examined national trends in SHS exposure after the introduction of these municipal ordinances at the city level in 2010.MethodsWe used interrupted time series analysis to assess whether the trends of SHS exposure in the workplace and at home, and the primary cigarette smoking rate changed following the policy adjustment in the national legislation in ROK. Population-standardized data for selected variables were retrieved from a nationally representative survey dataset and used to study the policy action’s effectiveness.ResultsFollowing the change in the legislation, SHS exposure in the workplace reversed course from an increasing (18% per year) trend prior to the introduction of these smoke-free ordinances to a decreasing (−10% per year) trend after adoption and enforcement of these laws (β2 = 0.18, p-value = 0.07; β3 = −0.10, p-value = 0.02). SHS exposure at home (β2 = 0.10, p-value = 0.09; β3 = −0.03, p-value = 0.14) and the primary cigarette smoking rate (β2 = 0.03, p-value = 0.10; β3 = 0.008, p-value = 0.15) showed no significant changes in the sampled period. Although analyses stratified by sex showed that the allowance of municipal ordinances resulted in reduced SHS exposure in the workplace for both males and females, they did not affect the primary cigarette smoking rate as much, especially among females.ConclusionStrengthening the role of local governments by giving them the authority to enact and enforce penalties on SHS exposure violation helped ROK to reduce SHS exposure in the workplace. However, smoking behaviors and related activities seemed to shift to less restrictive areas such as on the streets and in apartment hallways, negating some of the effects due to these ordinances. Future studies should investigate how smoke-free policies beyond public places can further reduce the SHS exposure in ROK

    Ergonomics in laparoscopic surgery: a work system analysis to reduce work-related musculoskeletal disorders across surgeons in Peruvian hospitals

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    Laparoscopic surgery, also called minimally invasive surgery, is a type of surgery in which the surgeon operates by viewing the surgery on a screen that projects images from a camera inserted into the patient's abdomen. Laparoscopic tools are long (usually up to 35 cm) and require fine motor skills and visual perception for manipulation, restricting the degrees of freedom to move within the patient. This restriction causes surgeons to operate with limited vision and restricted movement and force them to work with assistants who assist in conducting the cameras, acting as "the surgeons' eyes". Because of its minimally invasive nature, laparoscopic surgery is well accepted by patients but is challenging and complex for the surgeon. This is due to the restriction of movement and perception that forces surgeons to adopt awkward postures with high exposition, which increases the likelihood of work-related musculoskeletal disorders (WRMSD). WRMSDs are detrimental to surgeons' health and potentially may impact patient safety. Studies often highlight the problems of surgeons in high-income countries, whose solutions and clinical guides often cannot be applied to countries like Peru, which have severe deficiencies in its healthcare system. For this reason, the thesis proposes a contextualised investigation of the Peruvian surgical work system to investigate the main factors contributing to the development of WRMSD in laparoscopic surgeons, which may affect patient safety. The analysis aimed to propose possible recommendations to support redesigning the laparoscopic surgery work system in Peruvian hospitals. Five studies were developed to achieve the aims based on the Systems Engineering Initiative for patient safety model, an ergonomics model for healthcare systems analysis. The first three studies were developed parallel with a mixed convergent design approach concluding in an integrating study. The last two studies (study four and five) had a quantitative approach. The first study used a qualitative approach by collecting information through interviews with laparoscopic surgeons and observing their work in real surgeries. The second study adopted a quantitative approach through a questionnaire-based survey applied to 140 surgeons in Peru. The third study analysed the extent to which the postures adopted by surgeons in real surgeries increase the risk of WRMSD and their association with factors in the work system using the RULA method. The results of the three studies were integrated into an integrative study, concluding that the raised height of the operating table and other system factors related to tasks, person and technology raises the risk of WRMSD. Based on these results, the fourth study analysed the relationship between surgeons and operating tables to understand how many surgeons could reach suitable working heights. The study concluded that no operating table available in Peruvian hospitals nor in the market would be suitable for 90% of Peruvian surgeons. The tables were too high to accommodate surgeons with optimal working surface height to perform laparoscopic surgery. Then, a fifth study was conducted to determine an acceptable working height based on surgeon preferences and system factors and concluded that surgeons would accept a working height between 49 cm to 70 cm in height, which is lower than current operating tables. The lowest height was reached when surgeons had to operate on obese patients and perform intracorporeal suturing tasks. Finally, the thesis concludes with recommendations for redesigning working heights for 90% of the Peruvian medical population, considering work system elements of the Peruvian context

    Magnetic Resonance Imaging of the fetal cardiovascular system and congenital heart disease

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    An early diagnosis of congenital heart diseases (CHD) has important prognostic impact. Prenatal echocardiography is an indispensable part of prenatal screening in many countries. However, it might provide poor diagnostic quality in some cases. Complementary diagnostic methods for postnatal life are missing prenatally. This work aims to investigate the use of fetal cardiovascular magnetic resonance imaging (MRI) as an adjunct to fetal echocardiography. This manuscript is divided into the anatomical visualization of CHD and the quantification of the impact of fetal motion on cardiovascular flow-measurements. 101 singleton pregnant women carrying fetus with suspected CHD in fetal echocardiography were prospectively recruited for fetal cardiac MRI. In 85 participants 2D and 3D MRI data could be reconstructed successfully and compared to echocardiographic and postnatal data. Furthermore, 10 pregnant women from the first sub study and 10 adult volunteers were recruited. The impact of simulated fetal motion in the adult volunteers was investigated. The artifacts observed during this study were compared to the artefacts in fetal flow-measurements by a three-point scoring system. MRI reconstructions of vascular structures showed a good agreement with 2D-echocardiography, while 3D-MRI reconstructions were superior to 2D-MRI data regarding their quality and diagnostic accuracy. Additional anatomic structures were identified in 10 cases with MRI and could be confirmed postnatally. Flow-measurements corrupted by simulated fetal motion within the middle third of an acquisition showed significant errors in contrast to measurements under motion corruption during the first and last third of the acquisition. The velocity of motion did not have a major impact. A three-point scoring system could readily identify the amount and impact of fetal motion on the later acquisition. 3D fetal cardiac MRI is a reliable imaging method with potential complementary use to fetal echocardiography. Additionally, valid fetal cardiovascular flow-measurements under the face of fetal motion can be reliably identified at the point of their acquisition, already.Die frühe Diagnose angeborener Herzfehler hat eine prognostische Bedeutung. Eine pränatale Echokardiographie ist in vielen Ländern unverzichtbarer Standard pränataler Screening Untersuchungen. Dennoch müssen oft Abstriche bei der Bildqualität gemacht werden. Während postnatal ergänzende Bildgebungstechniken zur Verfügung stehen, fehlen diese Alternativen pränatal. Die vorliegende Arbeit soll die Möglichkeiten der fetalen kardiovaskulären Magnetresonanztomographie (MRT) als ergänzende Diagnostik zur fetalen Echokardiographie untersuchen. Die vorliegende Arbeit ist untergliedert in die anatomische Darstellung angeborener Herzfehler mittels der MRT und die Untersuchung des Einflusses fetaler Bewegung auf kardiovaskuläre Flussmessungen. 101 schwangere Teilnehmerinnen mit Feten mit dem V.a. einen angeborenen Herzfehler in der fetalen Echokardiographie wurden prospektiv für eine fetale Kardio-MRT rekrutiert. 2D und 3D Bilddatenrekonstruktionen von 85 Feten der Teilnehmerinnen konnten mit den echokardiographischen, sowie postnatalen Daten verglichen werden. Weiterhin wurden 10 erwachsene Proband*innen, sowie 10 schwangere Teilnehmerinnen aus der ersten Substudie rekrutiert. Einflüsse simulierter fetaler Bewegung in den erwachsenen Proband*innen wurden untersucht. Beobachtete Artefakte in den gewonnen Flussmessungen wurden mittels eines Bewertungssystems mit denen der fetalen Messungen verglichen. Vaskuläre Strukturen in MRT-Datensätzen zeigten eine gute Übereinstimmung mit Messungen in echokardiographischen 2D-Datensätzen, wobei 3D-MRT Datensätze hinsichtlich Qualität und diagnostischer Genauigkeit den 2D-MRT Daten überlegen waren. In 10 Fällen gelang die Darstellung zusätzlicher anatomischer Gegebenheiten in der MRT, welche postnatal bestätigt werden konnten. Flussmessungen, welche durch simulierte fetale Bewegung im mittleren Drittel einer Aufnahme verzerrt wurden, wiesen signifikante Fehler auf. Dies konnte bei Messungen unter dem Einfluss fetalen Bewegungen im ersten oder letzten Drittel der Aufnahme nicht beobachtet werden. Die Geschwindigkeit der Bewegungen spielte eine untergeordnete Rolle. Das Ausmaß fetaler Bewegung während einer Aufnahme, sowie ihr Einfluss auf die Flussmessungen kann mittels eines Drei-Punkte-Bewertungssystems zuverlässig identifiziert werden. Fetale Kardio-MRT bietet eine zuverlässige Möglichkeit mittels 3D-Darstellung der fetalen Gefäße die pränatale Echokardiographie als bildgebende Methode zu ergänzen. Zudem können valide Flussmessungen trotz Einfluss fetaler Bewegung zuverlässig zum Zeitpunkt der Aufnahme identifiziert werden

    Development and Validation of Mechatronic Systems for Image-Guided Needle Interventions and Point-of-Care Breast Cancer Screening with Ultrasound (2D and 3D) and Positron Emission Mammography

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    The successful intervention of breast cancer relies on effective early detection and definitive diagnosis. While conventional screening mammography has substantially reduced breast cancer-related mortalities, substantial challenges persist in women with dense breasts. Additionally, complex interrelated risk factors and healthcare disparities contribute to breast cancer-related inequities, which restrict accessibility, impose cost constraints, and reduce inclusivity to high-quality healthcare. These limitations predominantly stem from the inadequate sensitivity and clinical utility of currently available approaches in increased-risk populations, including those with dense breasts, underserved and vulnerable populations. This PhD dissertation aims to describe the development and validation of alternative, cost-effective, robust, and high-resolution systems for point-of-care (POC) breast cancer screening and image-guided needle interventions. Specifically, 2D and 3D ultrasound (US) and positron emission mammography (PEM) were employed to improve detection, independent of breast density, in conjunction with mechatronic and automated approaches for accurate image acquisition and precise interventional workflow. First, a mechatronic guidance system for US-guided biopsy under high-resolution PEM localization was developed to improve spatial sampling of early-stage breast cancers. Validation and phantom studies showed accurate needle positioning and 3D spatial sampling under simulated PEM localization. Subsequently, a whole-breast spatially-tracked 3DUS system for point-of-care screening was developed, optimized, and validated within a clinically-relevant workspace and healthy volunteer studies. To improve robust image acquisition and adaptability to diverse patient populations, an alternative, cost-effective, portable, and patient-dedicated 3D automated breast (AB) US system for point-of-care screening was developed. Validation showed accurate geometric reconstruction, feasible clinical workflow, and proof-of-concept utility across healthy volunteers and acquisition conditions. Lastly, an orthogonal acquisition and 3D complementary breast (CB) US generation approach were described and experimentally validated to improve spatial resolution uniformity by recovering poor out-of-plane resolution. These systems developed and described throughout this dissertation show promise as alternative, cost-effective, robust, and high-resolution approaches for improving early detection and definitive diagnosis. Consequently, these contributions may advance breast cancer-related equities and improve outcomes in increased-risk populations and limited-resource settings

    OPTICAL COHERENCE TOMOGRAPHY OPHTHALMIC SURGICAL GUIDANCE

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    Optical coherence tomography (OCT) performs high-resolution cross-sectional and volumetric tissue imaging in situ through the combination of confocal gating, coherence gating, and polarization gating. Because it is noninvasive, OCT has been used in multiple clinical applications such as tissue pathology assessment and interventional procedure guidance. Moreover, OCT can perform functional measurements such as phase-sensitive measurement of blood flow and polarization-sensitive measurement of tissue birefringence. These features made OCT one of the most widely used imaging systems in ophthalmology. In this thesis, we present several novel OCT methods developed for microsurgery guidance and OCT image analysis. The thesis mainly consists of five parts, which are shown as follows. First, we present a BC-mode OCT image visualization method for microsurgery guidance, where multiple sparsely sampled B-scans are combined to generate a single cross-sectional image with an enhanced instrument and tissue layer visibility and reduced shadowing artifacts. The performance of the proposed method is demonstrated by guiding a 30-gauge needle into an ex-vivo human cornea. Second, we present a microscope-integrated OCT guided robotic subretinal injection method. A workflow is designed for accurate and stable robotic needle navigation. The performance of the proposed method is demonstrated on ex-vivo porcine eye subretinal injection. Third, we present optical flow OCT technique that quantifies accurate velocity fields. The accuracy of the proposed method is verified through phantom flow experiments by using a diluted milk powder solution as the scattering medium, in both cases of advective flow and turbulent flow. Fourth, we present a wrapped Gaussian mixture model to stabilize the phase of swept source OCT systems. A closed-form iteration solution is derived using the expectation-maximization algorithm. The performance of the proposed method is demonstrated through ex-vivo, in-vivo, and flow phantom experiments. The results show its robustness in different application scenarios. Fifth, we present a numerical landmark localization algorithm based on a convolutional neural network and a conditional random field. The robustness of the proposed method is demonstrated through ex-vivo porcine intestine landmark localization experiments

    Pathophysiology of Spinal Cord Injury (SCI)

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    Spinal cord injury (SCI) leads to paralysis, sensory, and autonomic nervous system dysfunctions. However, the pathophysiology of SCI is complex, and not limited to the nervous system. Indeed, several other organs and tissue are also affected by the injury, directly or not, acutely or chronically, which induces numerous health complications. Although a lot of research has been performed to repair motor and sensory functions, SCI-induced health issues are less studied, although they represent a major concern among patients. There is a gap of knowledge in pre-clinical models studying these SCI-induced health complications that limits translational applications in humans. This reprint describes several aspects of the pathophysiology of spinal cord injuries. This includes, but is not limited to, the impact of SCI on cardiovascular and respiratory functions, bladder and bowel function, autonomic dysreflexia, liver pathology, metabolic syndrome, bones and muscles loss, and cognitive functions

    Mitigation of motion-induced artifacts in cone beam computed tomography using deep convolutional neural networks

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    Background: Cone beam computed tomography (CBCT) is often employed on radiation therapy treatment devices (linear accelerators) used in image-guided radiation therapy (IGRT). For each treatment session, it is necessary to obtain the image of the day in order to accurately position the patient, and to enable adaptive treatment capabilities including auto-segmentation and dose calculation. Reconstructed CBCT images often suffer from artifacts, in particular those induced by patient motion. Deep-learning based approaches promise ways to mitigate such artifacts. Purpose: We propose a novel deep-learning based approach with the goal to reduce motion induced artifacts in CBCT images and improve image quality. It is based on supervised learning and includes neural network architectures employed as pre- and/or post-processing steps during CBCT reconstruction. Methods: Our approach is based on deep convolutional neural networks which complement the standard CBCT reconstruction, which is performed either with the analytical Feldkamp-Davis-Kress (FDK) method, or with an iterative algebraic reconstruction technique (SART-TV). The neural networks, which are based on refined U-net architectures, are trained end-to-end in a supervised learning setup. Labeled training data are obtained by means of a motion simulation, which uses the two extreme phases of 4D CT scans, their deformation vector fields, as well as time-dependent amplitude signals as input. The trained networks are validated against ground truth using quantitative metrics, as well as by using real patient CBCT scans for a qualitative evaluation by clinical experts. Results: The presented novel approach is able to generalize to unseen data and yields significant reductions in motion induced artifacts as well as improvements in image quality compared with existing state-of-the-art CBCT reconstruction algorithms (up to +6.3 dB and +0.19 improvements in peak signal-to-noise ratio, PSNR, and structural similarity index measure, SSIM, respectively), as evidenced by validation with an unseen test dataset, and confirmed by a clincal evaluation on real patient scans (up to 74% preference for motion artifact reduction over standard reconstruction). Conclusions: For the first time, it is demonstrated, also by means of clinical evaluation, that inserting deep neural networks as pre- and post-processing plugins in the existing 3D CBCT reconstruction and trained end-to-end yield significant improvements in image quality and reduction of motion artifacts
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