CT perfusion image processing: analysis of liver tumors

Perfusion CT imaging of the liver has potential to improve evaluation of tumour angiogenesis. Quantitative parameters can be obtained applying mathematical models to Time Attenuation Curve (TAC). However, there are still some difficulties for an accurate quantification of perfusion parameters due, for example, to algorithms employed, to mathematical model, to patient’s weight and cardiac output and to the acquisition system. In this thesis, new parameters and alternative methodologies about liver perfusion CT are presented in order to investigate the cause of variability of this technique. Firstly analysis were made to assess the variability related to the mathematical model used to compute arterial Blood Flow (BFa) values. Results were obtained implementing algorithms based on “ maximum slope method” and “Dual input one compartment model” . Statistical analysis on simulated data demonstrated that the two methods are not interchangeable. Anyway slope method is always applicable in clinical context. Then variability related to TAC processing in the application of slope method is analyzed. Results compared with manual selection allow to identify the best automatic algorithm to compute BFa. The consistency of a Standardized Perfusion Index (SPV) was evaluated and a simplified calibration procedure was proposed. At the end the quantitative value of perfusion map was analyzed. ROI approach and map approach provide related values of BFa and this means that pixel by pixel algorithm give reliable quantitative results. Also in pixel by pixel approach slope method give better results. In conclusion the development of new automatic algorithms for a consistent computation of BFa and the analysis and definition of simplified technique to compute SPV parameter, represent an improvement in the field of liver perfusion CT analysis.

Development of control-oriented models of Dual Clutch Transmission systems

A control-oriented model of a Dual Clutch Transmission was developed for real-time Hardware In the Loop (HIL) applications, to support model-based development of the DCT controller. The model is an innovative attempt to reproduce the fast dynamics of the actuation system while maintaining a step size large enough for real-time applications. The model comprehends a detailed physical description of hydraulic circuit, clutches, synchronizers and gears, and simplified vehicle and internal combustion engine sub-models. As the oil circulating in the system has a large bulk modulus, the pressure dynamics are very fast, possibly causing instability in a real-time simulation; the same challenge involves the servo valves dynamics, due to the very small masses of the moving elements. Therefore, the hydraulic circuit model has been modified and simplified without losing physical validity, in order to adapt it to the real-time simulation requirements. The results of offline simulations have been compared to on-board measurements to verify the validity of the developed model, that was then implemented in a HIL system and connected to the TCU (Transmission Control Unit). Several tests have been performed: electrical failure tests on sensors and actuators, hydraulic and mechanical failure tests on hydraulic valves, clutches and synchronizers, and application tests comprehending all the main features of the control performed by the TCU. Being based on physical laws, in every condition the model simulates a plausible reaction of the system. The first intensive use of the HIL application led to the validation of the new safety strategies implemented inside the TCU software. A test automation procedure has been developed to permit the execution of a pattern of tests without the interaction of the user; fully repeatable tests can be performed for non-regression verification, allowing the testing of new software releases in fully automatic mode.

Fenomeni di transizione degli organismi edilizi, criteri operativi di inserimento ambientale e procedure di intervento

La presente tesi indaga le potenzialità, in termini di criteri operativi di inserimento ambientale e procedure di intervento, che possono derivare dall’analisi dei fenomeni insediativi facendo riferimento ai concetti di ‘transizione’ e ‘resilienza’. L’attuale periodo di crisi sembra scaturire dal disequilibrio di due fattori: le esigenze umane e l’ambiente. La contestualizzazione degli interventi, il graduale adattamento alle risorse ambientali locali e la valorizzazione dei processi “dal basso” sembrano consentire di riappropriarsi sia del valore identitario dei luoghi, dando risposta ai problemi di natura sociale evidenziati, sia della eco-compatibilità delle trasformazioni, del corretto utilizzo delle risorse energetiche e della gestione delle dinamiche economiche, in risposta ai problemi ambientali analizzati. Il prefigurare applicazioni pratiche del modello di trasformazione indagato alla scala edilizia, utilizzando tavole parametriche di analisi del costruito, viste d’insieme planivolumetriche ed elaborazioni di dati e immagini, può consentire la gestione di eventuali fasi di programmazione e di pianificazione da parte delle amministrazioni finalizzate a favorire e non ostacolare i presenti e futuri fenomeni di transizione. Particolarmente significativa appare l’analisi delle diverse tendenze di ricerca progettuale in atto, con riferimento a contributi caratterizzati da un’impostazione fenomenologica e tipo-morfologica, che dimostra l’attualità degli argomenti affrontati. La ricerca di Dottorato si conclude con l’applicazione dei criteri operativi di inserimento ambientale e delle procedure di intervento individuati ad uno specifico caso di studio.

Evaluation of Human Exposure to Magnetic Fields Generated by Electric Power Systems in Complex Configurations

The international growing concern for the human exposure to magnetic fields generated by electric power lines has unavoidably led to imposing legal limits. Respecting these limits, implies being able to calculate easily and accurately the generated magnetic field also in complex configurations. Twisting of phase conductors is such a case. The consolidated exact and approximated theory regarding a single-circuit twisted three-phase power cable line has been reported along with the proposal of an innovative simplified formula obtained by means of an heuristic procedure. This formula, although being dramatically simpler, is proven to be a good approximation of the analytical formula and at the same time much more accurate than the approximated formula found in literature. The double-circuit twisted three-phase power cable line case has been studied following different approaches of increasing complexity and accuracy. In this framework, the effectiveness of the above-mentioned innovative formula is also examined. The experimental verification of the correctness of the twisted double-circuit theoretical analysis has permitted its extension to multiple-circuit twisted three-phase power cable lines. In addition, appropriate 2D and, in particularly, 3D numerical codes for simulating real existing overhead power lines for the calculation of the magnetic field in their vicinity have been created. Finally, an innovative ‘smart’ measurement and evaluation system of the magnetic field is being proposed, described and validated, which deals with the experimentally-based evaluation of the total magnetic field B generated by multiple sources in complex three-dimensional arrangements, carried out on the basis of the measurement of the three Cartesian field components and their correlation with the field currents via multilinear regression techniques. The ultimate goal is verifying that magnetic induction intensity is within the prescribed limits.

Statistical analysis of the error associated with the simplification of the stratigraphy in geotechnical models

The uncertainties in the determination of the stratigraphic profile of natural soils is one of the main problems in geotechnics, in particular for landslide characterization and modeling. The study deals with a new approach in geotechnical modeling which relays on a stochastic generation of different soil layers distributions, following a boolean logic – the method has been thus called BoSG (Boolean Stochastic Generation). In this way, it is possible to randomize the presence of a specific material interdigitated in a uniform matrix. In the building of a geotechnical model it is generally common to discard some stratigraphic data in order to simplify the model itself, assuming that the significance of the results of the modeling procedure would not be affected. With the proposed technique it is possible to quantify the error associated with this simplification. Moreover, it could be used to determine the most significant zones where eventual further investigations and surveys would be more effective to build the geotechnical model of the slope. The commercial software FLAC was used for the 2D and 3D geotechnical model. The distribution of the materials was randomized through a specifically coded MatLab program that automatically generates text files, each of them representing a specific soil configuration. Besides, a routine was designed to automate the computation of FLAC with the different data files in order to maximize the sample number. The methodology is applied with reference to a simplified slope in 2D, a simplified slope in 3D and an actual landslide, namely the Mortisa mudslide (Cortina d’Ampezzo, BL, Italy). However, it could be extended to numerous different cases, especially for hydrogeological analysis and landslide stability assessment, in different geological and geomorphological contexts.

Efficacia e complicanze durante la curva di apprendimento della Thulep: risultati a breve e medio termine delle prime 48 procedure

MATERIALI E METODI: Tra il 2012 e il 2013, abbiamo analizzato in uno studio prospettico i dati di 48 pazienti sottoposti a ThuLEP con approccio autodidatta. I pazienti sono stati rivalutati a 3, 6, 12 e 24 mesi con la valutazione del PSA, il residuo post-minzionale (RPM), l'uroflussometria (Qmax), l'ecografia transrettale e questionari validati (IPSS: international prostate symptom score e QoL: quality of life) RISULTATI: Il volume medio della prostata è di 63 ± 5,3 ml. Il tempo operatorio medio è stato di 127,58 ± 28.50 minuti. Il peso medio del tessuto asportato è stato di 30,40 ± 13,90 gr. A 6 mesi dopo l'intervento l'RPM medio è diminuito da 165,13 ± 80,15 ml a 7,78 ± 29.19 ml, mentre il Qmax medio è aumentato da 5.75 ± 1.67ml / s a 18.1 ± 5.27 ml / s. I valori medi dei IPSS e QoL hanno dimostrato un progressivo miglioramento: da 19.15 (IQR: 2-31) e 4 (IQR: 1-6) nel preoperatorio a 6.04 (IQR: 1-20) e 1.13 (IQR: 1-4), rispettivamente. Durante la curva di apprendimento si è assistito ad un progressivo aumento del peso del tessuto enucleato e ad una progressiva riduzione del tempo di ospedalizzazione e di cateterismo. Tra le principali complicanze ricordiamo un tasso di incontinenza transitoria del 12,5% a 3 mesi e del 2.1% a 12 mesi. CONCLUSIONI: ThuLEP rappresenta una tecnica chirurgica efficace, sicura e riproducibile indipendentemente dalle dimensioni della prostata. I nostri dati suggeriscono che la ThuLEP offre un miglioramento significativo dei parametri funzionali comparabili con le tecniche tradizionali, nonostante una lunga curva di apprendimento.

Nuove procedure sintetiche sostenibili per la preparazione di strutture poliuretaniche

Questo lavoro di tesi si inserisce in un contesto di ricerca molto attuale, il quale, studia nuove procedure sintetiche sostenibili per la preparazione di strutture poliuretaniche. Partendo dall’etilene carbonato e dall’esametilendiammina, due molecole che possono essere ricavate da fonti rinnovabili, sono state ottimizzate la sintesi e la purificazione di un carbammato: bis(2-idrossietil)-esan-1,6-diildicarbammato (BHEDC), senza l’impiego di solventi ed in condizioni blande. Il BHEDC è conosciuto in letteratura, ma è poco studiato e non viene attualmente utilizzato come monomero. In questo lavoro il bis(2-idrossietil)-esan-1,6-diildicarbammato è stato polimerizzato in massa con diverse percentuali di bis(2-idrossietil)-tereftalato (BHET), il quale non è ricavabile da fonti naturali ma è ottenibile dal riciclo chimico del Poli-Etilene Tereftalato (PET). Sono state successivamente analizzate la struttura chimica e le proprietà termiche nonché spettroscopiche dei nuovi composti poliuretanici, così da poterne definire le correlazioni tra la struttura e le prestazioni finali. Infine, è stata messa a punto una procedura di tipo one-pot per la preparazione dei poliuretani sopra citati; questa prevede la sintesi diretta dei polimeri senza la necessità dello stadio di purificazione del bis(2-idrossietil)-esan-1,6-diildicarbammato.

Set up of a procedure for correlation analysis between current discharge and dose delivery in a pulsed power plasma device for medical application

This thesis work aims to find a procedure for isolating specific features of the current signal from a plasma focus for medical applications. The structure of the current signal inside a plasma focus is exclusive of this class of machines and a specific analysis procedure has to be developed. The hope is to find one or more features that shows a correlation with the dose erogated. The study of the correlation between the current discharge signal and the dose delivered by a plasma focus could be of some importance not only for the practical application of dose prediction but also for expanding the knowledge anbout the plasma focus physics. Vatious classes of time-frequency analysis tecniques are implemented in order to solve the problem.

Multimodal Registration Procedure for the Initial Spatial Alignment of a Retinal Video Sequence to a Retinal Composite Image

Accurate placement of lesions is crucial for the effectiveness and safety of a retinal laser photocoagulation treatment. Computer assistance provides the capability for improvements to treatment accuracy and execution time. The idea is to use video frames acquired from a scanning digital ophthalmoscope (SDO) to compensate for retinal motion during laser treatment. This paper presents a method for the multimodal registration of the initial frame from an SDO retinal video sequence to a retinal composite image, which may contain a treatment plan. The retinal registration procedure comprises the following steps: 1) detection of vessel centerline points and identification of the optic disc; 2) prealignment of the video frame and the composite image based on optic disc parameters; and 3) iterative matching of the detected vessel centerline points in expanding matching regions. This registration algorithm was designed for the initialization of a real-time registration procedure that registers the subsequent video frames to the composite image. The algorithm demonstrated its capability to register various pairs of SDO video frames and composite images acquired from patients.

Surgical hip dislocation for osteochondral transplantation as a salvage procedure for a femoral head impaction fracture

Obturator anterior hip dislocation is very rare. Poor results are described in patients with additional large transchondral fractures and treatment of these injuries remains challenging. Appropriate treatment recommendations are missing in the literature. This case report introduces surgical hip dislocation for osteochondral autograft transplantation with graft harvest from the nonweightbearing area of the head-neck junction as a salvage procedure in a large femoral head defect. We report the treatment and outcome of a 48-year-old man who sustained an anterior dislocation of the left hip after a motorcycle accident. After initial closed reduction in the emergency room, imaging analysis revealed a large osteochondral defect of the femoral head within the weightbearing area (10 × 20 mm, depth: 5 mm). The hip was exposed with a surgical hip dislocation using a trochanteric osteotomy. An osteochondral autograft was harvested from a nonweightbearing area of the femoral head and transferred into the defect. The patient was prospectively examined clinically and radiologically. Two years postoperatively, the patient was free of pain and complaints. The function of the injured hip was comparable to that of the contralateral, healthy hip and showed satisfying radiologic results. Surgical hip dislocation with a trochanteric flip osteotomy is a simple, one-step technique that allows full inspection of the hip to treat osteochondral femoral defects by osteochondral transplantation. The presented technique, used as a salvage procedure in a large femoral head defect, yielded good clinical and satisfying radiologic outcomes at the midterm.

Treatment of slipped capital femoral epiphysis with a modified Dunn procedure

Surgical procedures with use of traditional techniques to reposition the proximal femoral epiphysis in the treatment of slipped capital femoral epiphysis are associated with a high rate of femoral head osteonecrosis. Therefore, most surgeons advocate in situ fixation of the slipped epiphysis with acceptance of any persistent deformity in the proximal part of the femur. This residual deformity can lead to secondary osteoarthritis resulting from femoroacetabular cam impingement.

Procedural and mid-term results in patients with aortic stenosis treated with implantation of 2 (in-series) CoreValve prostheses in 1 procedure

This study sought to assess post-procedural and mid-term outcome of patients, in which a second "in-series" CoreValve prosthesis (Medtronic, Minneapolis, Minnesota) was implanted during the same procedure.