Sviluppo di un metodo di radioterapia adattativa tramite immagini portali e Cone-Beam CT

Il presente lavoro, svolto presso il servizio di Fisica Sanitaria dell’Azienda Ospedaliera Universitaria di Parma, consiste nello sviluppo di un metodo innovativo di radioterapia adattativa. Il metodo è stato applicato a pazienti affetti da varie patologie, trattati con tecnica VMAT, (Volumetric Modulated Arc Therapy), altamente conformata al target. Il metodo sviluppato si compone di due fasi: nella prima fase vengono effettuate due analisi su immagini portali, di ricostruzione della dose all'isocentro e l'analisi gamma 2D. Se almeno una di queste fallisce, si interviene con la seconda fase, che vede l'acquisizione della CBCT del paziente e la taratura in densità elettronica della stessa. Si calcola dunque il piano su CBCT, previa operazione di contouring da parte del medico e, infine, si esegue l'analisi gamma 3D sulle matrici di dose calcolate sulla CT e sulla CBCT del paziente, quantificando gli indici gamma sulle strutture PTV, CTV e OAR di interesse clinico. In base ai risultati, se necessario, si può intervenire sul piano di trattamento. Le analisi gamma 2D e 3D sono state svolte avvalendosi di un software toolkit chiamato GADD-23 (Gamma Analysis on 2D and 3D Dose Distributions) implementato e sviluppato appositamente in ambiente Matlab per questo lavoro di tesi; in particolare, la realizzazione di GADD-23 è stata resa possibile grazie all'interazione con due software di tipo open-source, Elastix e CERR, specifici per l’elaborazione e la registrazione di immagini mediche. I risultati ottenuti mostrano come il metodo sviluppato sia in grado di mettere in luce cambiamenti anatomici che alcuni pazienti hanno subìto, di tipo sistematico, in cui è possibile prendere in considerazione una ripianificazione del trattamento per correggerli, o di tipo casuale, sui quali può essere utile condurre l'attenzione del medico radioterapista, sebbene non sia necessario un replanning.

Tecniche di elaborazione di immagini tomografiche con raggi X finalizzate alla creazione di modelli virtuali 3D

In questo elaborato sono state messe a confronto differenti procedure per la creazione di file in formato STL a partire da dati tomografici. Questo tipo di formato di dati è attualmente molto richiesto in quanto è adottato dalle stampanti 3D. I tre software presi in analisi, nello specifico, sono: DEVIDE, un programma open source, compatibile sia con Windows che con Linux, sviluppato presso la Delft University of Technology, nei Paesi Bassi; Imagej, un programma informatico di elaborazione digitale delle immagini, accessibile a tutti, basato su Sun-Java e sviluppato dal National Institutes of Health negli Stati Uniti; e infine VGStudioMax, un software sviluppato in Germania dalla VolumeGraphics GmbH. Un confronto diretto di questi software ha portato ad evidenziare i pregi ed i difetti d’ognuno di questi programmi, prendendo come criteri svariati fattori, tra cui la possibilità di scelta di uno o più soglie per i livelli di grigio, la velocità di esecuzione, il fatto che sia open-source o meno, ecc. I risultati ottenuti tramite l’utilizzo di slice filtrate riguardanti una Cera Anatomica e un Feticcio Africano, sono stati molto soddisfacenti, in quanto hanno permesso la realizzazione di modelli virtuali 3D di entrambi i reperti nel formato richiesto.

Energy harvesting from piezoelectric devices embedded in a 3D printed wing

This thesis work has been carried out at Clarkson University in Potsdam NY, USA and involved the design of a low elongation wing, consisting of parts made by polylactide (PLA) using the fused deposition model (FDM) technology of Rapid Prototyping, then assembled together in a thin aluminum spar. The aim of the research is to evaluate the feasibility of collecting electrical energy by converting mechanical energy from the vibration of the wing flutter. With this aim piezoelectric stripes were glued in the inner part of the wing, as well as on the aluminum spar, as monomorphic configuration. During the phases of the project, particular attention was given to the geometry and the materials used, in order to trigger the flutter for low flow velocity. The CAD software SolidWorks® was used for the design of the wing and then the drawings were sent to the Clarkson machine shop in order to to produce the parts required by the wing assembly. FEM simulations were performed, using software MSC NASTRAN/PATRAN®, to evaluate the stiffness of the whole wing as well as the natural vibration modes of the structure. These data, in a first approximation, were used to predict the flutter speed. Finally, experimental tests in the Clarkson wind tunnel facility were carried out in order to validate the results obtained from FEM analysis. The power collected by the piezoelectrics under flutter condition was addressed by tuning the resistors downstream the electronic circuit of the piezoelectrics.

La penna 3D e l'insegnamento della geometria: un'esperienza sul campo

In questa tesi si presenta l’attività didattica "Fascinating World of Geometric Forms", la relativa sperimentazione fatta su un campione di 175 studenti al quarto anno di scuola secondaria di secondo grado e i risultati ottenuti. In questo progetto, grazie alla penna 3D, è stato possibile fare matematica costruttiva in classe. Gli studenti hanno potuto disegnare e costruire nello spazio 3D, senza più essere costretti a disegnare in prospettiva sul foglio. La ricerca principalmente tenta di sviluppare l'intuito geometrico, pertanto è facilmente adattabile a studenti di varie età. Si propongono una serie di attività volte a rispondere alla domanda "Come uscire dal piano?" e, a tal proposito, si suggeriscono vari metodi: aggiungere la profondità agli elementi del piano; comporre sviluppi piani di poliedri; ruotare figure geometriche piane limitate attorno a un asse contenuto nel piano della figura; comporre nello spazio sezioni piane di quadriche. Questo progetto di ricerca, sviluppato sotto la supervisione del professor Alberto Parmeggiani del Dipartimento di Matematica di Bologna e in collaborazione con il professor Gianni Brighetti del Dipartimento di Psicologia di Bologna, si pone come obiettivo quello di avvicinare gli studenti allo studio della geometria dello spazio e, soprattutto, di sviluppare in loro la capacità di creare immagini mentali e concetti figurali.

Radiologia distribuita: Cloud e Post Processing 3D

L’effetto dell’informatica e dell’automazione sulle procedure medico sanitarie si sta manifestando in maniera sempre più ampia, portando notevoli vantaggi per la salute e il benessere di tutti i pazienti e al tempo stesso ponendo sfide sempre più complesse alle istituzioni sanitarie e ai produttori di dispositivi medico-sanitari. Al di là dei meriti del singolo prodotto o tecnologia, esiste un fattore strategico che dovrebbe essere sempre considerato nel momento di progettare un software o un dispositivo da utilizzare in ambito sanitario (da parte dei produttori) o nel momento di pianificare l’acquisto di sistemi medicali o diagnostici complessi (da parte delle istituzioni sanitarie): l’aspetto dell’Integrazione, ovvero la capacità del sistema di inserirsi in maniera semplice, efficace e poco costosa in un Workflow (flusso di lavoro) completamente integrato. Nel primo capitolo di questo elaborato finale è stato fatto un quadro generale sull’organizzazione del flusso di lavoro in radiologia e sono stati trattati i vari standard di comunicazione e scambio dati in ambito clinico, in primis DICOM, HL7 e IHE. L’oggetto del secondo capitolo è l’organizzazione e gli obbiettivi del Dipartimento di Radiologia attuati dal Gruppo Villa Maria (GVM) e il confronto di questi ultimi con il contenuto del documento: ‘Linee guida per l’assicurazione di qualita` in teleradiologia ‘che è stata redatta dal Istituto Superiore di Sanita` destinata ad apportare, non solo ai medici radiologi ed ai TSRM ma anche agli altri professionisti della sanità coinvolti, gli elementi di informazione e di metodo per l’organizzazione della teleradiologia nel rispetto delle esigenze della deontologia medica, della sicurezza del paziente, compreso il consenso, anche per quanto riguarda la radioprotezione, la privacy e la qualità. Nel terzo capitolo sono elencati gli strumenti con cui il Dipartimento di radiologia intende perseguire i suoi obbiettivi. Il quarto capitolo tratta la mia esperienza presso una clinica esterna al GVM, in particolare la clinica Santo Stefano, di Porto Potenza Picena, dove sono stati fatti dei test volti a valutare i tempi di caricamento di esami di TAC e RMN sul cloud di GVM.

Content characterization of 3D Videos

Il principale scopo di questa tesi è focalizzato alla ricerca di una caratterizzazione dei contenuti in video 3D. In una prima analisi, le complessità spaziale e temporale di contenuti 3D sono state studiate seguendo le convenzionali tecniche applicate a video 2D. In particolare, Spatial Information (SI) e Temporal Information (TI) sono i due indicatori utilizzati nella caratterizzazione 3D di contenuti spaziali e temporali. Per presentare una descrizione completa di video 3D, deve essere considerata anche la caratterizzazione in termini di profondità. A questo riguardo, nuovi indicatori di profondità sono stati proposti sulla base di valutazioni statistiche degli istogrammi di mappe di profondità. Il primo depth indicator è basato infatti sullo studio della media e deviazione standard della distribuzione dei dati nella depth map. Un'altra metrica proposta in questo lavoro stima la profondità basandosi sul calcolo dell’entropia della depth map. Infine, il quarto algoritmo implementato applica congiuntamente una tecnica di sogliatura (thresholding technique) e analizza i valori residui dell’istogramma calcolando l’indice di Kurtosis. Gli algoritmi proposti sono stati testati con un confronto tra le metriche proposte in questo lavoro e quelle precedenti, ma anche con risultati di test soggettivi. I risultati sperimentali mostrano l’efficacia delle soluzioni proposte nel valutare la profondità in video 3D. Infine, uno dei nuovi indicatori è stato applicato ad un database di video 3D per completare la caratterizzazione di contenuti 3D.

Tomographic 3D reconstruction through linear inversion for breast microwave imaging

In the present thesis we address the problem of detecting and localizing a small spherical target with characteristic electrical properties inside a volume of cylindrical shape, representing female breast, with MWI. One of the main works of this project is to properly extend the existing linear inversion algorithm from planar slice to volume reconstruction; results obtained, under the same conditions and experimental setup are reported for the two different approaches. Preliminar comparison and performance analysis of the reconstruction algorithms is performed via numerical simulations in a software-created environment: a single dipole antenna is used for illuminating the virtual breast phantom from different positions and, for each position, the corresponding scattered field value is registered. Collected data are then exploited in order to reconstruct the investigation domain, along with the scatterer position, in the form of image called pseudospectrum. During this process the tumor is modeled as a dielectric sphere of small radius and, for electromagnetic scattering purposes, it's treated as a point-like source. To improve the performance of reconstruction technique, we repeat the acquisition for a number of frequencies in a given range: the different pseudospectra, reconstructed from single frequency data, are incoherently combined with MUltiple SIgnal Classification (MUSIC) method which returns an overall enhanced image. We exploit multi-frequency approach to test the performance of 3D linear inversion reconstruction algorithm while varying the source position inside the phantom and the height of antenna plane. Analysis results and reconstructed images are then reported. Finally, we perform 3D reconstruction from experimental data gathered with the acquisition system in the microwave laboratory at DIFA, University of Bologna for a recently developed breast-phantom prototype; obtained pseudospectrum and performance analysis for the real model are reported.

3D bloodstain pattern analysis: ballistic reconstruction of the trajectories of blood drops and determination of the centres of origin of the bloodstains

For crime scene investigation in cases of homicide, the pattern of bloodstains at the incident site is of critical importance. The morphology of the bloodstain pattern serves to determine the approximate blood source locations, the minimum number of blows and the positioning of the victim. In the present work, the benefits of the three-dimensional bloodstain pattern analysis, including the ballistic approximation of the trajectories of the blood drops, will be demonstrated using two illustrative cases. The crime scenes were documented in 3D, using the non-contact methods digital photogrammetry, tachymetry and laser scanning. Accurate, true-to-scale 3D models of the crime scenes, including the bloodstain pattern and the traces, were created. For the determination of the areas of origin of the bloodstain pattern, the trajectories of up to 200 well-defined bloodstains were analysed in CAD and photogrammetry software. The ballistic determination of the trajectories was performed using ballistics software. The advantages of this method are the short preparation time on site, the non-contact measurement of the bloodstains and the high accuracy of the bloodstain analysis. It should be expected that this method delivers accurate results regarding the number and position of the areas of origin of bloodstains, in particular the vertical component is determined more precisely than using conventional methods. In both cases relevant forensic conclusions regarding the course of events were enabled by the ballistic bloodstain pattern analysis.

A picture is worth a thousand words--the utility of 3D visualization illustrated by a case of survived pancreatic transection

It is one of the most important tasks of the forensic pathologist to explain the forensically relevant medical findings to medical non-professionals. However, it is often difficult to comment on the nature and potential consequences of organ injuries in a comprehensive way to individuals with limited knowledge of anatomy and physiology. This rare case of survived pancreatic transaction after kicks to the abdomen illustrates how the application of dedicated software programs for three-dimensional reconstruction can overcome these difficulties, allowing for clear and concise visualization of complex findings.

Getting in touch-3D printing in Forensic Imaging

With the increasing use of medical imaging in forensics, as well as the technological advances in rapid prototyping, we suggest combining these techniques to generate displays of forensic findings. We used computed tomography (CT), CT angiography, magnetic resonance imaging (MRI) and surface scanning with photogrammetry in conjunction with segmentation techniques to generate 3D polygon meshes. Based on these data sets, a 3D printer created colored models of the anatomical structures. Using this technique, we could create models of bone fractures, vessels, cardiac infarctions, ruptured organs as well as bitemark wounds. The final models are anatomically accurate, fully colored representations of bones, vessels and soft tissue, and they demonstrate radiologically visible pathologies. The models are more easily understood by laypersons than volume rendering or 2D reconstructions. Therefore, they are suitable for presentations in courtrooms and for educational purposes.

The examination and identification of bite marks in foods using 3D scanning and 3D comparison methods

Bite mark analysis offers the opportunity to identify the biter based on the individual characteristics of the dentitions. Normally, the main focus is on analysing bite mark injuries on human bodies, but also, bite marks in food may play an important role in the forensic investigation of a crime. This study presents a comparison of simulated bite marks in different kinds of food with the dentitions of the presumed biter. Bite marks were produced by six adults in slices of buttered bread, apples, different kinds of Swiss chocolate and Swiss cheese. The time-lapse influence of the bite mark in food, under room temperature conditions, was also examined. For the documentation of the bite marks and the dentitions of the biters, 3D optical surface scanning technology was used. The comparison was performed using two different software packages: the ATOS modelling and analysing software and the 3D studio max animation software. The ATOS software enables an automatic computation of the deviation between the two meshes. In the present study, the bite marks and the dentitions were compared, as well as the meshes of each bite mark which were recorded in the different stages of time lapse. In the 3D studio max software, the act of biting was animated to compare the dentitions with the bite mark. The examined food recorded the individual characteristics of the dentitions very well. In all cases, the biter could be identified, and the dentitions of the other presumed biters could be excluded. The influence of the time lapse on the food depends on the kind of food and is shown on the diagrams. However, the identification of the biter could still be performed after a period of time, based on the recorded individual characteristics of the dentitions.

3D Computerized Occlusion Rating of Embolized Experimental Aneurysms Using Noninvasive 1.5T MR Imaging

For embolized cerebral aneurysms, the initial occlusion rate is the most powerful parameter to predict aneurysm rerupture and recanalization. However, the occlusion rate is only estimated subjectively in clinical routine. To minimize subjective bias, computer occlusion-rating (COR) was successfully validated for 2D images. To minimize the remaining inaccuracy of 2D-COR, COR was applied to 1.5T 3D MR imaging.

Extended CT scale overcomes restoration caused streak artifacts for dental identification in CT--3D color encoded automatic discrimination of dental restorations

OBJECTIVE: Besides DNA, dental radiographs play a major role in the identification of victims in mass casualties or in corpses with major postmortem alterations. Computed tomography (CT) is increasingly applied in forensic investigations and is used to scan the dentition of deceased persons within minutes. We investigated different restoration materials concerning their radiopacity in CT for dental identification purposes. METHODS: Extracted teeth with different filling materials (composite, amalgam, ceramic, temporary fillings) were CT scanned. Radiopacities of the filling materials were analyzed in extended CT scale images. RESULTS: Radiopacity values ranged from 6000-8500HU (temporary fillings), 4500-17000HU (composite fillings) and >30710HU (Amalgam and Gold). The values were used to define presets for a 3D colored volume rendering software. CONCLUSIONS: The effects of filling material caused streak artifacts could be distinctively reduced for the assessment of the dental status and a postprocessing algorithm was introduced that allows for 3D color encoded visualization and discrimination of different dental restorations based on postmortem CT data.

Use of a 3D perfusion bioreactor with osteoblasts and osteoblast/endothelial cell co-cultures to improve tissue-engineered bone

The delivery of oxygen, nutrients, and the removal of waste are essential for cellular survival. Culture systems for 3D bone tissue engineering have addressed this issue by utilizing perfusion flow bioreactors that stimulate osteogenic activity through the delivery of oxygen and nutrients by low-shear fluid flow. It is also well established that bone responds to mechanical stimulation, but may desensitize under continuous loading. While perfusion flow and mechanical stimulation are used to increase cellular survival in vitro, 3D tissue-engineered constructs face additional limitations upon in vivo implantation. As it requires significant amounts of time for vascular infiltration by the host, implants are subject to an increased risk of necrosis. One solution is to introduce tissue-engineered bone that has been pre-vascularized through the co-culture of osteoblasts and endothelial cells on 3D constructs. It is unclear from previous studies: 1) how 3D bone tissue constructs will respond to partitioned mechanical stimulation, 2) how gene expression compares in 2D and in 3D, 3) how co-cultures will affect osteoblast activity, and 4) how perfusion flow will affect co-cultures of osteoblasts and endothelial cells. We have used an integrated approach to address these questions by utilizing mechanical stimulation, perfusion flow, and a co-culture technique to increase the success of 3D bone tissue engineering. We measured gene expression of several osteogenic and angiogenic genes in both 2D and 3D (static culture and mechanical stimulation), as well as in 3D cultures subjected to perfusion flow, mechanical stimulation and partitioned mechanical stimulation. Finally, we co-cultured osteoblasts and endothelial cells on 3D scaffolds and subjected them to long-term incubation in either static culture or under perfusion flow to determine changes in gene expression as well as histological measures of osteogenic and angiogenic activity. We discovered that 2D and 3D osteoblast cultures react differently to shear stress, and that partitioning mechanical stimulation does not affect gene expression in our model. Furthermore, our results suggest that perfusion flow may rescue 3D tissue-engineered constructs from hypoxic-like conditions by reducing hypoxia-specific gene expression and increasing histological indices of both osteogenic and angiogenic activity. Future research to elucidate the mechanisms behind these results may contribute to a more mature bone-like structure that integrates more quickly into host tissue, increasing the potential of bone tissue engineering.

3D ultrasound in fetal spina bifida

3D ultrasound can be used to study the fetal spine, but skeletal mode can be inconclusive for the diagnosis of fetal spina bifida. We illustrate a diagnostic approach using 2D and 3D ultrasound and indicate possible pitfalls.