Τμήμα Ιατρικής (ΜΔΕ)

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Open Access
3-d cone beam αναπαράσταση με χρήση παράλληλης επεξεργασίας σε περιβάλλον MATLAB
(2009-02-09T08:06:04Z) Μπασαγιάννης, Γεώργιος; Παλληκαράκης, Νικόλαος; Κωστόπουλος, Γεώργιος; Παλληκαράκης, Νικόλαος; Μπεζεριάνος, Αναστάσιος
Τμήμα Ιατρικής (ΜΔΕ)
3d αναπαράσταση με παράλληλη επεξεργασία μέσω Matlab
Open Access
3D joint kinematics quantification with 3D fluoroscopy : Implementation of algorithm proposed by Mahfouz MR
(2014-05-27) Πετρόπουλος, Γεώργιος; Παλληκαράκης, Νικόλαος; Παλληκαράκης, Νικόλαος; Stagni, Rita; Τσαγγάρης, Σωκράτης; Bliznakova, Kristina; Petropoulos, Georgios
Τμήμα Ιατρικής (ΜΔΕ)
Dynamic assessment of three-dimensional (3D) joint kinematics is essential for understanding normal joint function as well as the effects of injury or disease. The knowledge of one or two series of bi-dimensional fluoroscopic projections of the joint in motion (mono-planar or bi-planar fluoroscopy), and the 3D model of the joint segments, were claimed to be sufficient to reconstruct the absolute and relative 6 Degrees Of Freedom (DOFs) pose of bones or prostheses in the 3D space. The software MultiTrack was developed at the Health Sciences and Technologies - Interdepartmental Center for Industrial Research (HST - ICIR) for the joint kinematics estimation with 3D Video Fluoroscopy (3DF) [1] using C++ language with ITK [2] segmentation & registration toolkit and VTK [3] visualization toolkit. An optimization procedure finds the 6 degrees of freedom pose that optimizes a metric quantifying the matching of the 3D model and its relevant projections. The metric, currently implemented in the software, is based on the contour segmentation of the object to be tracked and on the use of 3D adaptive distance maps (ADM) [4,5]. However, the contour extraction is a time consuming procedure for the user. Different methods were proposed in the literature to reduce the user interaction, each with its proper pros and cons. In the current thesis a few of the for-mentioned methods are discussed in order to evaluate each of them in terms of accuracy, speed and user dependency. At the final step the algorithm proposed by Mafhouz et al. [6], initially proposed for prostheses, is implemented inside the MultiTrack framework. To be properly characterized, the above method is tested on in vivo datasets and under various sources of error.
Open Access
3D segmentation of great vessels using active contours and morphological image processing techniques
(2010-05-25T06:15:31Z) Montejo Garcia, Cristina; Santos, Andres; Nikolaos, Pallikarakis
Τμήμα Ιατρικής (ΜΔΕ)
The scope of this project is to present a semi-automated vessels segmentation algorithm, to describe its usage and results. This will be achieved combining several segmentation algorithms to get proper vessel segmentation and visualization. Consequently, automatic segmentation can significantly reduce the scan-to-diagnosis time, thus helping the clinicians to reach the fundamental goal of efficient patient management. In order to complete our project, we can identify different phases: - Correct reading of CT and MR images and extraction of data needed for the post-processing. - Processing of these images using the most appropriate segmentation techniques to get the desired contour. - Visualization of the contour.
Open Access
3D simultaneous algebraic reconstruction technique for cone-beam projections
(2010-06-15T13:48:14Z) Chlewicki, Wojciech; Παλληκαράκης, Νικόλαος; Παλληκαράκης, Νικόλαος
Τμήμα Ιατρικής (ΜΔΕ)
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Open Access
A radiomics extraction parameterization analysis for machine learning based regression models
(2023-02-24) Λαμπρινάκος, Ιωάννης; Lamprinakos, Ioannis
Τμήμα Ιατρικής (ΜΔΕ)
Neuroendocrine Tumors (NETs) are inhomogeneous neoplasms, the most common origin sites of which being the gastrointestinal and pulmonary system. Many treatment methods have been developed to treat this type of cancer, as well as combinations of these are applied. One of these methods is Peptide Receptor Radionuclide Therapy (PRRT) that uses radiation, which is delivered continuously at a decreasing rate to cause retention and/or tumor cell death. Lutathera®, or 177Lu-DOTA-TATE as scientifically named, is a radiolabeled somatostatin analog that is both FDA and EMA approved for PRRT. Radiomics, a non-invasive and quantitative mining medical imaging information tool, are used to extract information from medical images and contribute to diagnosis as well as cancer prognosis, by improving diagnostic accuracy, assisting differential diagnosis between benign and malignant lesions, as well as classifying the risk of disease progression. These quantitative characteristics, which are known as Radiomic Features, can be thus extracted and used for theragnostic reasons. This thesis aims to investigate the ability of the radiomic features that were extracted from images of 68Ga-DOTA-TOC and 177Lu-DOTA-TATE from 21 patients with NETs who underwent therapy with 177Lu-DOTA-TATE to predict the post-therapeutic doses. Four different experiments were conducted and every time parameter values such as Voxel Size and Bin Width changed. Then, in every experiment, image filters named “Wavelets” were once extracted and once omitted. Therefore, 3412 features were extracted from each ROI, including wavelets and 436 features were extracted, excluding wavelets. Moreover, features were selected by following a strict pipeline including Mutual Information regression, efficiency with Pearson and Spearman correlations and, lastly, Backward Elimination Sequential Feature Selection (SFS) and Recursive Feature Elimination (RFE) were used as wrapper methods. Then, a predictive machine learning regression model that included 9 algorithms, both linear and nonlinear, was developed. The performance of this model was judged by taking into account two different metrics, Mean Absolute Error (MAE) and R2. The analysis of our results revealed that when the parameter values (Bin Width, Voxel Size) decreased, more accurate results were acquired. Also, we observed that linear based algorithms seemed to be more efficient than nonlinear ones, with Ridge algorithm being the most prevailing in every experiment for both metrics, and Linear Regression algorithm being the second most prevailing. We also concluded that wavelets-based features were of great importance in our study, since when they were included in our model, better results were yielded.
Open Access
Acoustical behavior of single ultrasound contrast agent microbubbles
(2010-04-19T09:19:54Z) Δερμιτζάκης, Αριστείδης; Παλληκαράκης, Νικόλαος; Παλληκαράκης, Νικόλαος; Τσαγκάρης, Σωκράτης; Κουτσούνης, Δημήτριος
Τμήμα Ιατρικής (ΜΔΕ)
Ultrasound contrast agents (UCA) is a relatively new tool, used in medical ultrasound imaging to enhance the diagnostic abilities of ultrasound and potentially offer a therapeutic value in medical ultrasounds. UCAs are bi or single-layered bubbles, that contain a highly backscattering gas. By injecting them into the blood flow, we locally increase the echogenicity and therefor enhance the contrast of the blood-tissue interface. This way we can provide a improved image of the structure of the organs, we can more accurately diagnose abnormal of defected areas on them, and if the containing gas is replaced with an appropriate drug, focus drug delivery can be achieved, providing potential healing of the disease. ! Up to now, most of the studies done in order to investigate the microbubbles - ultrasound interaction are mostly population studies, which due to their roughly approach cannot clearly diagnose and explain the complex nonlinear and dynamic properties of UCAs and their response to ultrasound field. Because of that, our knowledge on the UCAsʼ, is yet limited although the potential improvements at imaging and therapeutic technics that would be gained from a thorough understanding of this interactions can be very big. ! In this thesis, a study of single microbubbles is presented, using a system developed by the group of Ultrasound imaging in Edinburgh University. The system uses a specially modified commercial ultrasound machine, phased array probes and a specially designed single microbubbles measuring system. The system has the ability to feed, insonify and capture the backscattered echo from a single microbubble, with the use of fully calibrated and characterized ultrasound - probe system. The aim of the project is to contribute in the understanding of the behavior of the UCAs when insonified with an ultrasound wave, and the underlying physical mechanism behind that. The response of two different commercially available UCAs under insonification by ultrasound waves of varying acoustical pressure is presented. The UCAs used are Definity and biSphere. In total echoes from 842 biSphere and 1994 Definity microbubbles have ben captured and the data have been analyzed with in house made matlab codes. Also the response of the bubbles when insonified by consequent pulses of different repetition frequency has been investigated. For this reason, echoes from other 1221 Definity and 459 biSphere microbubbles have been captured and analyzed. The fully understanding of the agent - ultrasound interaction mechanisms can be the basis for creating improved signal processing tools for ultrasound imaging contrast enhancement that would improve imaging abilities of the modality, and potentially use of UCAs as a therapeutic mean.
Open Access
Age-differences in working-memory as a function of habituation: An EEG study of "proactive interference" resolution in working-memory performance during a visual recognition task
(2014-05-16) Correia, João Miguel Mendonça; Παλληκαράκης, Νικόλαος; Nilsson, Lars-Goran; Person, Jonas; Κωστόπουλος, Γεώργιος; Γκατζούνης, Γεώργιος
Τμήμα Ιατρικής (ΜΔΕ)
As life expectancy increases in modern societies, a greater importance has recently started to be given to cognitive aging. Alzheimer's disease (AD) affects the memory capability of individuals at advanced ages, independently of their general physical health. However, AD is suggested to have an undetectable development many years prior the first clear behavioral symptoms. This silent presence of AD may allow scientists to detect its initial stages, at which a combination of prevention treatments, such as medication and cognitive training, can be more effective. This study extends a line of research that aims to identify possible 'silent' biomarkers of AD using working memory performance and electrophysiological recordings (EEG) in healthy adults. Working memory (aka., short-term memory) is a memory sub-type used in everyday life that allows us to execute tasks in short periods of time. Given the significant parallels of working memory with other forms of long-term memory and its clear facility to be employed in experimental settings of short duration, working memory is a suitable candidate to identify early biomarkers of memory deficits ingeneral. In this study we assessed the cognitive performance and the electrophysiological response - via EEG signals - in a visual working memory recognition task that included the interference of past memories over the present ones. This 'proactive interference' effect is evaluated has a possible biomarker candidate for AD. Our findings reveal that subjects take longer reaction times in the recognition of visual items in the proactive interference condition in comparison to no interference. Additionally, we report an early (170-180 ms) and a later (430-450 ms) EEG components (ERP) that underlies the neural processing responsible for the resolution of this working memory interference. These two time intervals are interpreted as revealing the resolution of proactive interference at two difference stages of visual information processing ('letters'): the phonological (sub-lexical) and semantic (lexical) levels respectively.
Open Access
Alloplastic or homograft implantation for nasal reconstruction
Δρόσου, Αλίκη-Κωνσταντίνα; Drosou, Aliki-Konstantina
Τμήμα Ιατρικής (ΜΔΕ)
Reconstructive and aesthetic rhinoplasty commonly requires utilizing implants to recreate nasal contour or strengthen the support for the nasal frame and soft tissues. Implants are divided into three main categories: autografts, homografts and alloplasts. Each aforementioned group is characterized by notable benefits and deficits. An ideal implantable material must possess biocompatibility, strength and elasticity. The material should be unable of inducing inflammatory reactions, be carcinogenic, delicate in mechanical strain, inflexible, and non-sterile. Several surgeons would argue that autografts should be the dominant choice for nasal reconstruction and regeneration. Autogenous tissue has long been advocated as the mainstay for nasal implants and is most commonly employed for structural and augmentation grafting in the nasal tip, as well as for dorsal malformations. However, the finite availability and non-predictable absorption of both autologous and homologous implants have made newer alloplastic implants imported to crucial considerations for dorsal augmentation. Conservative surgeons believe in making natural-appearing, well-supported, well-balanced noses. Conclusively, often the need to add something to create projection, balance, or support is desired.
Open Access
An automated graphical probabilistic framework for the detection of lung tumors in thoracic CT scan images
Δαμόπουλος, Δημήτριος; Νικήτα, Κωνσταντίνα; Νικήτα, Κωνσταντίνα; Σταφυλοπάτης, Ανδρέας; Κουτσούρης, Δημήτριος; Damopoulos, Dimitrios
Τμήμα Ιατρικής (ΜΔΕ)
The subject of this thesis is the development of a automated graphical probabilistic framework to segment lung tumors from thoracic CT scan images. The feature space that we use to represent the images consists mostly of the responses of the initial images to convolution kernels of a Gabor lter bank. We are then constructing an AdaBoost strong classi er over a collection of simple decision trees. The output of our strong classi er is used to construct the unary potentials of a Markov Random Field (MRF) model, that improves our results by enforcing structure.
Open Access
Analysis and interpretation of next generation sequencing data from the nitrogen fixing bacterium Klebsiella oxytoca under different environmental conditions
(2023-06-26) Γκουβέλης, Μιχαλάκης; Gkouvelis, Michalakis
Τμήμα Ιατρικής (ΜΔΕ)
Nitrogen fixation is employed by diazotrophic bacteria to alleviate the lack of fixed nitrogen compounds in their environment. Excess fixed nitrogen is released in their surroundings, in a form that can be used by plants. This makes free living diazotrophic bacteria potential candidates for biosynthetic strains that would provide nitrogen to crops instead of chemical fertilizers, which cause significant environmental pollution. For this to happen, the metabolic regulation that allows the bacteria to invest high amounts of energy, translational machinery, and space in the proteome for the nitrogenase, which is used for nitrogen fixation, must be fully understood. Klebsiella oxytoca is a model organism for the study of nitrogen fixation, and its nitrogen fixation mechanism has been successfully used by non-diazotrophic biosynthetic strains for the conduction of nitrogen fixation. In this project we used next generation sequencing data by K. oxytoca wild-type and gene knockout samples that were grown in low and high nitrogen conditions, to examine how its genes and pathways are regulated during nitrogen stress. The data consisted of transcriptomic reads and the analysis performed included quality control, preprocessing, alignment, creation of count tables, differential gene expression, and enrichment pathway analysis. The findings of this study show a significant upregulation of nitrogen fixation and nitrogen metabolism related genes during diazotrophic conditions, and at the same time downregulation of carbon metabolism energy consumption related genes. To a lesser extent, there was a down regulation of genes related to translation and growth of the cell. These phenomena were also evident in the enrichment of pathways, where activation of nitrogen compensation processes, and deactivation of energy consumption and growth processes were observed in diazotrophic conditions. In the gene knockout samples that were not able to fix atmospheric nitrogen and were grown in a low nitrogen environment, an increase in stress related process was observed. From these findings we conclude that during nitrogen stress the cells activate their nitrogen fixation machinery, and to accommodate it they decrease their translation and energy consumption, so the nitrogenase will have plenty of energy and space to act as long as it is needed. When there is no nitrogen fixation, and the nitrogen stress accumulates over time, the cells activate stress related processes that help them adapt in extreme conditions as a last line of defense.
Open Access
Analysis of otoacoustic emission signals using wavelet transform
(2010-06-16T07:54:21Z) Δημητρέλος, Γιώργος; Μπεζεριάνος, Αναστάσιος; Μπεζεριάνος, Αναστάσιος; Παλληκαράκης, Νικόλαος; Μαραγκός, Πέτρος; Dimitrelos, George
Τμήμα Ιατρικής (ΜΔΕ)
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Open Access
Angiogenesis measurements in mammography using time-resolved dual energy analysis
(2012-01-09) Μπίλλας, Ηλίας; Παναγιωτάκης, Γιώργος; Speller, Robert; Παναγιωτάκης, Γιώργος; Κανδαράκης, Ιωάννης; Κωσταρίδου, Ελένη; Billas, Ilias
Τμήμα Ιατρικής (ΜΔΕ)
The aim of this project is the application of Dual Energy technique in breast phantoms using Complimentary-Metal-Oxide-Semiconductor (CMOS)Active-Pixel-Sensor (APS). This includes both, lab experimentation on developed breast phantoms, as well as simulations validating the results. Initially, phantoms were carefully prepared simulating the properties of real breast tissue and were imaged using X-ray unit. The next step in this project involved image processing and data representation. Using the dual energy technique, different concentrations of contrast agent (Iodine) were measured to relate clinical to medium kinetic measurements. With respect to this projects‟ clinical application, the implementation of this technique can be used to evaluate the iodine projected thickness (mg/cm2) using Contrast Enhanced Digital Mammography (CEDM) based on Dual Energy technique for the breast cancer detection.
Open Access
Application of breast compression algorithm for mammography
(2010-06-07T05:45:52Z) Καζακλή, Σοφία; Παλληκαράκης, Νικόλαος; Κουτσούρης, Δημήτριος; Τσαγγάρης, Σωκράτης; Παλληκαράκης, Νικόλαος; Kazakli, Sofia
Τμήμα Ιατρικής (ΜΔΕ)
Mammography is currently the gold standard technique for early detection of breast cancer before it becomes clinically palpable. Breast compression is essential part of mammography which provides better contrast and smaller radiation dose. It optimizes the image quality and the visualization of small lesions by reducing the breast thickness. The overall goal of this thesis is to simulate the complete mammographic imaging chain, starting from the creation of breast phantoms, compression, and mammogram simulation. A specific aim is to carry out a study that compares the quality of breast lesions on simulated mammographic images obtained from both uncompressed and compressed breast models. For the creation of the breast models, we use a software breast phantom which incorporates a 3D voxel array with geometric primitives, a ductal network, and a model for lesions. Further on, a Simulation Algorithm for Soft Tissue Compression (SASTC) is used for the compression of the breast phantoms. For this purpose, the algorithm was implemented into C++ language and incorporated into the available Breast Simulator software. The SASTC algorithm is based on the spring-mass model according to which the volume of the breast phantom is divided into a number of elements, each one consisting of 27 nodes and the nodes are connected with springs. The compression algorithm allows stretching and compression of the volume object. Due to these deformations the voxels of the breast’s volume are distorted. Several algorithms are developed to correct for these distortions. These algorithms are based on interpolation techniques and on the Jordan Curve Theorem. We designed 11 models of small breast phantoms that included microcalcifications of different sizes. These breast phantoms as well as the compressed model of each phantom are subjected to mammography simulation to create mammograms. The x-ray image acquisition model, used for the acquirement of the mammographic images, is based on a combination of ray tracing techniques and the x-ray attenuation law. A comparison between the acquired mammograms of both uncompressed and compressed breast phantom was performed. A preliminary visual evaluation demonstrates that the clarity of the structures in the breast model is improved in the images of the compressed breast. Quantitative evaluation involving contrast calculations supports the former results.
Open Access
Application of deep learning methods for the optimization of organs at risk (OARs) delineation in breast cancer radiotherapy treatment planning
Μακρή-Λεβίδου, Ελένη; Makri-Levidou, Eleni
Τμήμα Ιατρικής (ΜΔΕ)
During breast radiotherapy treatment planning, contouring the healthy organs surrounding breast has a significant role. Unfortunately, this process, of contouring the organs at risks (OARs), can be time consuming and in many cases difficult to shape them correctly. So, this thesis is inspired to solve this problem using a CNN to eliminate contouring time.
Open Access
Assessment of colorectal cancer screening methods
(2022-06-16) Παναγάκη, Αντωνία; Panagaki, Antonia
Τμήμα Ιατρικής (ΜΔΕ)
Background: In the light of the 21st century, colorectal cancer (CRC) remains one of the most challenging diseases, as it is the third most commonly occurring cancer that affects humanity. The available screening modalities for CRC fall into two broad categories 1) the in-vitro screening tests that can primarily detect CRC, and 2) the imaging methods that identify precancerous adenomatous polyps and CRC. Tests that primarily detect cancer are: i. Guaiac-based fecal occult blood test (gFOBT) ii. Fecal immunochemical test (FIT) iii. Fecal DNA tests Tests that detect both adenomatous polyps and cancer include: i. Flexible sigmoidoscopy ii. Colonoscopy iii. Double-contrast barium enema iv. Capsule Endoscopy v. Computed tomography colonography The main purpose of this master thesis is to analyze the in-vitro screening methods of the CRC, in a form of a systematic review. Methods: PubMed was screened for relevant studies (meta-analysis, systematic reviews, randomized control trials) over the last five years, in English language, for humans reporting on the characteristics of gFOBT, FIT, and fecal DNA tests used in screening CRC in the asymptomatic population. Results: Out of 132 studies initially identified twenty-three (23) were finally included. The sensitivity and the specificity of each method were pooled, also the advantages and the disadvantage, and comparison between the in-vitro modalities of CRC screening is attempted. Discussion: Among the laboratory methods of CRC screening, FIT is the one that demonstrates better accuracy. Since the cut-off level of Hb/g stool of FIT affects the sensitivity and the specificity of the method, it may be assumed that the optimal threshold is 20 Hb/g in stool. It is considered the most efficient laboratory modality in annual or biannual screening. The gFOBT is as well an available option that is validated in the current guidelines for CRC screening. The newer fecal DNA test presents promising accuracy but needs further research and development to improve its performance and be incorporated into the guidelines.
Open Access
Assessment of errors and quantification of the required planning target volume margins for image guided radiation therapy : a study of three major Greek hospitals
Κοζομπόλης, Αναστάσιος; Θεοδώρου, Κυριακή; Κάππας, Κωνσταντίνος; Τσούγκος, Ιωάννης; Kozompolis, Anastasios
Τμήμα Ιατρικής (ΜΔΕ)
The treatment process of external beam radiation therapy of tumors inevitably introduces geometrical uncertainties. These errors might be introduced during the preparation phase of the treatment (systematic errors), or during the execution of the treatment (random errors). Investigating the errors and assessing their magnitude is a prerequisite for the quantification of the required margin by which the Clinical Target Volume (CTV) must be expanded in order for the Planning Target Volume (PTV) to be acquired. In this thesis, the required PTV margins were calculated for the radiotherapy departments of three major Greek hospitals: the University Hospital of Patras, the University Hospital of Larissa and the Theageneio Anticancer Hospital of Thessaloniki. Specifically, the protocols followed by each department were studied and reviewed, the sources of all geometrical uncertainties throughout the course of radiotherapy were investigated, the errors were calculated, the required PTV margins were quantified per anatomical site for each hospital and a comparison of the results between the departments was made. In total, data from 278 patients and 2094 CBCT scans were recorded, studied and reviewed. Four different methods of statistical processing of the data were suggested for the computation of the setup error, with two of them being introduced by this thesis as the most representative for departments that follow a hybrid correction strategy protocol. Moreover, a simple and practical method for the assessment of organ motion was introduced and suggested, using the vendor image registration software available in our departments. Also, the delineation error of several anatomical sites was found, on the basis of a delineation experiment conducted in the departments of Patras and Larissa with the participation of the physicians. Finally, a comparison of the results between the three departments allowed for the extraction of useful conclusions regarding the operation of each department, as well as for the formulation of suggestions regarding protocol optimization in order to succeed the limitation of errors and the reduction of the required PTV margins.
Open Access
Auto shielding calculation in diagnostic X-ray rooms
(2023-06) Σαββάκης, Σταύρος; Savvakis, Stavros
Τμήμα Ιατρικής (ΜΔΕ)
Every room with radiation needs to be shielded to limit radiation exposure to employees and members of the public to an acceptable level. Medical physicists and specialists in radiation shielding must calculate the necessary thickness of materials in every barrier in rooms with radiation. The task of the software is to calculate the shielding of X-Ray rooms. The software can calculate the thickness of every barrier in the room with the material chosen by the user to shield a specific barrier. To achieve this, the user must collect all the necessary data, the least distance of every barrier, occupancy factor, workload, use factor etc. The design of radiation shielding for diagnostic installation can be approached in several different ways. There are two common approaches to calculate the thickness of the shielding material: NCRP report 147 and British Institute of Radiology (BIR) report – Radiation Shielding for diagnostic X rays. For this thesis used NCRP report. Most of the definitions of the thesis and all DATA come from NCRP report 147. At the end of the thesis, most of the examples of NCRP 147 have been used to test the results of the program.
Open Access
Aνάπτυξη συστήματος μελέτης μηχανικών ιδιοτήτων μαλακών βιολογικών υλικών κυλινδρικού σχήματος
(2007-10-22T08:23:33Z) Μαρμαράς, Αναστάσιος; Σοκόλης, Δημήτριος; Τσαγγάρης, Σωκράτης; Τσαγγάρης, Σωκράτης; Προβατίδης, Χριστόφορος; Μαθιουλάκης, Δημήτριος; Marmaras, Anastasios
Τμήμα Ιατρικής (ΜΔΕ)
Αναπτύχθηκε διάταξη μέτρησης μηχανικών ιδιοτήτων μαλακών ιστών κυλινδρικού σχήματος. Η διάταξη αποτελείται από: 1. Υδατόλουτρο μέσα στο οποίο ανάρτάται ο μαλακός ιστός. 2. Συσκευή μεταβολής της πίεσης στο εσωτερικό του αυλού του ιστού. 3. Αισθητήρες πίεσης στον αυλό, μηχανικής τάσης στα άκρα και μέτρησης διαμέτρου του ιστού. 4. Πρόγραμμα ελέγχου της διάταξης και διεξαγωγής πειραμάτων σε περιβάλλον LabView. 5. Συλλογή προγραμμάτων επεξεργασίας των μετρήσεων στο περιβάλλον Origin.
Open Access
Aυτοματοποιημένος υπολιγισμός θωρακίσεων ακτινοδιαγνωστικών θαλάμων
Λίβα, Στυλιανή; Liva, Styliani
Τμήμα Ιατρικής (ΜΔΕ)
Κύριος στόχος της παρούσας Διπλωματικής Εργασίας αποτελεί η μελέτη του προβλήματος που αφορά την ακτινοπροστασία ακτινοδιαγνωστικών εγκαταστάσεων, καθώς και τον υπολογισμό της απαιτούμενης θωράκισης, σύμφωνα με τους Κανονισμούς Ακτινοπροστασίας. Η χρησιμότητα κάθε είδους θωράκισης έναντι των ιοντίζουσων ακτινοβολιών είναι η ελάττωση της δόσης της ακτινοβολίας, μέσα στα επιτρεπτά όρια, στην οποία εκτίθενται το επαγγελματικό προσωπικό, οι ασθενείς αλλά και οι απλοί επισκέπτες που βρίσκονται στους εν λόγω χώρους ακτινοβόλησης ή των γειτονικών χώρων. Στο γενικό μέρος πραγματοποιείται μια ανασκόπηση σχετικά με την ανακάλυψη και τις ιδιότητες των ιοντίζουσων ακτινοβολιών, τις βλάβες που μπορεί να προκληθούν από την ιοντίζουσα ακτινοβολία τόσο στα κύτταρα ενός οργανισμού όσο και την επίδραση στη γενική υγεία. Επιπλέον, αναφέρονται οι οδηγίες σχετικά με τις απαιτήσεις ακτινοπροστασίας από Διεθνείς Οργανισμούς, αλλά και από την Ελληνική Επιτροπή Ατομικής Ενέργειας. Στην συνέχεια, γίνεται αναφορά στον βασικό στόχο της θωράκισης ακτινοπροστασίας και στην γενική τεχνογνωσία που σχετίζεται με την αποτελεσματική θωράκισης ενός ακτινοδιαγνωστικού χώρου με αναφορά σε ενδεικτικά παραδείγματα ακτινοπροστασίας. Στην συνέχεια της μελέτης αυτής γίνεται αναφορά σε έννοιες όπως πρωτογενής ακτινοβολία, σκεδαζόμενη ή διαρρέουσα ακτινοβολίας, πρωτογενής/δευτερογενής θωράκιση, συντελεστής επιβάρυνσης (Workload), συντελεστής χρήσης (Use factor), συντελεστής κατάληψης (Occupancy factor), σχετική απόδοση ακτίνων Χ (Κ0), η τιμή air Kerma, καθώς και σε παραλλαγές των εξισώσεων που χρησιμοποιούνται σε τέτοιου είδους υπολογισμούς ακτινοπροστασίας. Επίσης, αναλύονται παλαιότεροι ή σύγχρονοι μέθοδοι, όπου υπολογίζουν το πάχος θωράκισης ή άλλες μετρήσεις που απαιτούνται για έναν ακτινοδιαγνωστικό θάλαμο, έτσι ώστε να μην γίνεται υπέρβαση των Περιοριστικών Επιπέδων Δόσεων (Π.Ε.Δ.) που ορίζονται από τους κανονισμούς ακτινοπροστασίας. Ακόμη πραγματοποιήθηκε σύγκριση μεταξύ των παλαιότερων μοντέλων κανονισμού ακτινοπροστασίας NCRP 116 (National Council on Radiation Protection & Measurements ),NCRP 49 και NCRP 147 το οποίο είναι και το πιο σύγχρονο και ρεαλιστικό μοντέλο. Επίσης γίνεται και μια σύγκριση του NCRP με τις οδηγίες που προτείνει ο κανονισμός BIR-IPEM (British Institute of Radiology and Institute of Physics in Engineering in Medicine). Στο τέλος της εργασίας παρουσιάζεται ένα πρόγραμμα στο οποίο μπορούν να υπολογίζονται σύμφωνα με την μέθοδο NCRP 147 οι απαιτούμενες θωρακίσεις στους θαλάμους όπου πραγματοποιούνται ακτινοδιαγνωστικές εξετάσεις. Η ύπαρξη αυτού του προγράμματος έχει ως σκοπό την πραγματοποίηση θωρακίσεων σε ακτινοδιαγνωστικούς θαλάμους γλιτώνοντας χρόνο από τους υπολογισμούς των τύπων που πρέπει να χρησιμοποιηθούν αλλά και πιθανά λάθη που μπορεί να γίνουν στους υπολογισμούς όταν αυτοί πραγματοποιούνται να το ανθρώπινο χέρι.
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Bacteriological study and drug susceptibility in chronic rhinosinusitis (CRS)
(2020-10-21) Γεωργίου, Γεώργιος; Georgiou, Georgios
Τμήμα Ιατρικής (ΜΔΕ)
Chronic sinusitis is a heterogeneous group of inflammatory disorders of the nose and the paranasal sinuses, with different variations( CRSwNP or CRSsNP) and different underlying pathophysiology. This diversity in the pathophysiology of Chronic Rhinosinusitis led to the finding that it consists of biological subtypes or endotypes, defined by distinct pathophysiological mechanisms that could be identified with corresponding biomarkers. 0,5% of upper respiratory tract infections are complicated by acute rhinosinusitis. In Europe, the frequency of CRS is 10.9%. In the last decade, an increase in its frequency by 18% has been observed. It is the third most common diagnosis for the administration of antibiotics. Regarding the causative factors of CRS, many microbes are included. Anaerobes play a leading role (Bacteroides, Anaerobic gram-positive cocci, Fusobacterium species), which cause more than 50% of infections. Less common strains are Staphylococcus aureus, Haemophilus influenza, Pseudomonas aeruginosa, Escherichia coli, Betahemolytic Streptococcus, και Neisseria spp. Fungi play a leading role in immunosuppressed patients ( Aspergillus sp., Fusarium sp. ) and anaerobes. 50% of infections are polymicrobial infections. In patients with Cystic Fibrosis, the most common microbes are Pseudomonas aeruginosa and Staphylococcus aureus.