Advanced Applications of 3D Dosimetry and 3D Printing in Radiation Therapy

As complex radiotherapy techniques become more readily-practiced, comprehensive 3D dosimetry is a growing necessity for advanced quality assurance. However, clinical implementation has been impeded by a wide variety of factors, including the expense of dedicated optical dosimeter readout tools, high operational costs, and the overall difficulty of use. To address these issues, a novel dry-tank optical CT scanner was designed for PRESAGE 3D dosimeter readout, relying on 3D printed components and omitting costly parts from preceding optical scanners. This work details the design, prototyping, and basic commissioning of the Duke Integrated-lens Optical Scanner (DIOS).

The convex scanning geometry was designed in ScanSim, an in-house Monte Carlo optical ray-tracing simulation. ScanSim parameters were used to build a 3D rendering of a convex ‘solid tank’ for optical-CT, which is capable of collimating a point light source into telecentric geometry without significant quantities of refractive-index matched fluid. The model was 3D printed, processed, and converted into a negative mold via rubber casting to produce a transparent polyurethane scanning tank. The DIOS was assembled with the solid tank, a 3W red LED light source, a computer-controlled rotation stage, and a 12-bit CCD camera. Initial optical phantom studies show negligible spatial inaccuracies in 2D projection images and 3D tomographic reconstructions. A PRESAGE 3D dose measurement for a 4-field box treatment plan from Eclipse shows 95% of voxels passing gamma analysis at 3%/3mm criteria. Gamma analysis between tomographic images of the same dosimeter in the DIOS and DLOS systems show 93.1% agreement at 5%/1mm criteria. From this initial study, the DIOS has demonstrated promise as an economically-viable optical-CT scanner. However, further improvements will be necessary to fully develop this system into an accurate and reliable tool for advanced QA.

Pre-clinical animal studies are used as a conventional means of translational research, as a midpoint between in-vitro cell studies and clinical implementation. However, modern small animal radiotherapy platforms are primitive in comparison with conventional linear accelerators. This work also investigates a series of 3D printed tools to expand the treatment capabilities of the X-RAD 225Cx orthovoltage irradiator, and applies them to a feasibility study of hippocampal avoidance in rodent whole-brain radiotherapy.

As an alternative material to lead, a novel 3D-printable tungsten-composite ABS plastic, GMASS, was tested to create precisely-shaped blocks. Film studies show virtually all primary radiation at 225 kVp can be attenuated by GMASS blocks of 0.5cm thickness. A state-of-the-art software, BlockGen, was used to create custom hippocampus-shaped blocks from medical image data, for any possible axial treatment field arrangement. A custom 3D printed bite block was developed to immobilize and position a supine rat for optimal hippocampal conformity. An immobilized rat CT with digitally-inserted blocks was imported into the SmART-Plan Monte-Carlo simulation software to determine the optimal beam arrangement. Protocols with 4 and 7 equally-spaced fields were considered as viable treatment options, featuring improved hippocampal conformity and whole-brain coverage when compared to prior lateral-opposed protocols. Custom rodent-morphic PRESAGE dosimeters were developed to accurately reflect these treatment scenarios, and a 3D dosimetry study was performed to confirm the SmART-Plan simulations. Measured doses indicate significant hippocampal sparing and moderate whole-brain coverage.

Examination of body image among Canadian adolescents: Relations with physical activity and screen time

Background: Adolescence is a period of life associated with self-perceptions of negative body image. Physical activity levels are low and screen time levels are also high during this stage. These perceptions and behaviours are associated with poor health outcomes, making research on their determinants important. With adolescent populations, certain groups may be at higher risk of body dissatisfaction than others, and body dissatisfaction may influence individual physical activity and screen time levels. Objectives: The objectives of this thesis were to: 1) describe body image among young Canadians, examining possible health inequalities 2) estimate the strength and significance of associations between body satisfaction, physical activity and screen time, and 3) examine the potential etiological role of biological sex. Methods: Objective 1: The 2013/2014 Health Behaviour in School-aged Children study was employed. Sex-stratified Rao-Scott chi-square analyses were conducted to examine associations between socio-demographic factors and body satisfaction. Objective 2: The 2005/2006 and 2013/2014 cross-sectional and 2006 longitudinal HBSC data sets were used. Sex-stratified modified Poisson regressions were conducted and risk estimates and associated confidence intervals obtained. Results: Objective 1: Among males, being older, of East and Southeast Asian ethnicity, and reporting low SES all were associated with body dissatisfaction. Among females, being older, of Arab and West Asian or African ethnicity, being born in Canada, and reporting low SES were all associated with being body dissatisfied. Objective 2: Cross-sectionally, males who reported ‘too fat’ body dissatisfaction were more likely to be physically inactive. Adolescents of both sexes who reported ‘too fat’ body dissatisfaction were more likely to engage in high levels of screen time. Data from the longitudinal component supported the idea that male ‘too fat’ body dissatisfaction temporally leads to physical inactivity, but showed an inverse relationship between body dissatisfaction and screen time. Conclusions: Objective 1: Future prevention efforts in Canada should target subgroups to effectively help those at greatest risk of body dissatisfaction, and ameliorate potential inequalities at the population level. Objective 2: The presence of these relationships may inform future interventions as part of a multi-factorial etiology, in order to increase physical activity and decrease screen time among youth.

Kinome-wide CRISPR-Cas9 screen to identify kinases involved in Taxol resistance in breast cancer

Breast cancer is the most frequently diagnosed cancer in women, accounting for over 25% of cancer diagnoses and 13% of cancer-related deaths in Canadian women. There are many types of therapies for treatment or management of breast cancer, with chemotherapy being one of the most widely used. Taxol (paclitaxel) is one of the most extensively used chemotherapeutic agents for treating cancers of the breast and numerous other sites. Taxol stabilizes microtubules during mitosis, causing the cell cycle to arrest until eventually the cell undergoes apoptosis. Although Taxol has had significant benefits in many patients, response rates range from only 25-69%, and over half of Taxol-treated patients eventually acquire resistance to the drug. Drug resistance remains one of the greatest barriers to effective cancer treatment, yet little has been discerned regarding resistance to Taxol, despite its widespread clinical use. Kinases are known to be heavily involved in cancer development and progression, and several kinases have been linked to resistance of Taxol and other chemotherapeutic agents. However, a systematic screen for kinases regulating Taxol resistance is lacking. Thus, in this study, a set of kinome-wide screens was conducted to interrogate the involvement of kinases in the Taxol response. Positive-selection and negative-selection CRISPR-Cas9 screens were conducted, whereby a pooled library of 5070 sgRNAs targeted 507 kinase-encoding genes in MCF-7 breast cancer cells that were Taxol-sensitive (WT) or Taxol-resistant (TxR) which were then treated with Taxol. Next generation sequencing (NGS) was performed on cells that survived Taxol treatment, allowing identification and quantitation of sgRNAs. STK38, Blk, FASTK and Nek3 stand out as potentially critical kinases for Taxol-induced apoptosis to occur. Furthermore, kinases CDKL1 and FRK may have a role in Taxol resistance. Further validation of these candidate kinases will provide novel pre-clinical data about potential predictive biomarkers or therapeutic targets for breast cancer patients in the future.

Commentary on Henrician Proclamation 1538:A Proclamation Prohibiting Unlicensed Printing of Scripture (1538)

Royal Proclamation prohibiting the printing and publishing of ecclesiastical and other books without prior licence, as well as the importation, sale and publication of English language texts printed on the continent. This Proclamation established the precedent for the pre-publication licensing of literary works in England.
The commentary describes the background to the Proclamation, in particular the significance of the English Reformation, and Henry VIII's increasing interest in regulating and censuring the press. The commentary suggests that while this early instance of press intervention influenced governmental attitudes to censorship throughout the next 150 years, one of the crucial differences between this and later models of ideological control was that the 1538 Proclamation sought to censure print materials in a manner that was decoupled from the economic ownership and exploitation of such works.

Commentary on early Tudor printing privileges 1553: Totell's Printing Patent (1553)

One of the earliest examples of work printed by Richard Pynson, the King's Printer between 1508 and 1530, to make reference to the fact that the work in question was printed under the protection of the King. The royal printing privilege provided one of two different models for preventing the unauthorised reproduction of works after publication which prefigured the introduction of statutory copyright in the early eighteenth century.
The commentary describes the early attitudes of the monarchy towards the regulation of the printing trade within England, and the exercise of the royal prerogative in granting printing privileges not just to the royal printer, but to other favoured subjects both in relation to individual works as well as to entire classes of work (with the latter more often referred to as printing patents).

Commentary on early Tudor printing privileges 1559: Day's privilege for The Cosmographical Glass

An early example of a printing privilege granted to protect the printing of an individual work, in this case William Conningham's The Cosmographical Glass. The commentary describes the early attitudes of the monarchy towards the regulation of the printing trade within England, and the exercise of the royal prerogative in granting printing privileges not just to the royal printer, but to other favoured subjects both in relation to individual works as well as to entire classes of work (with the latter more often referred to as printing patents).

Dynamically mechanical and nano-impact (fatigue) analysis of touch screen thin films deposited on polyethylene terephthalate substrate

Nano-scale touch screen thin film have not been thoroughly investigated in terms of dynamic impact analysis under various strain rates. This research is focused on two different thin films, Zinc Oxide (ZnO) film and Indium Tin Oxide (ITO) film, deposited on Polyethylene Terephthalate (PET) substrate for the standard touch screen panels. Dynamic Mechanical Analysis (DMA) was performed on the ZnO film coated PET substrates. Nano-impact (fatigue) testing was performed on ITO film coated PET substrates. Other analysis includes hardness and the elastic modulus measurements, atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR) and the Scanning Electron Microscopy (SEM) of the film surface.
Ten delta of DMA is described as the ratio of loss modulus (viscous properties) and storage modulus (elastic properties) of the material and its peak against time identifies the glass transition temperature (Tg). Thus, in essence the Tg recognizes changes from glassy to rubber state of the material and for our sample ZnO film, Tg was found as 388.3 K. The DMA results also showed that the Ten delta curve for Tg increases monotonically in the viscoelastic state (before Tg) and decreases sharply in the rubber state (after Tg) until recrystallization of ZnO takes place. This led to an interpretation that enhanced ductility can be achieved by negating the strength of the material.
For the nano-impact testing using the ITO coated PET, the damage started with the crack initiation and propagation. The interpretation of the nano-impact results depended on the characteristics of the loading history. Under the nano-impact loading, the surface structure of ITO film suffered from several forms of failure damages that range from deformation to catastrophic failures. It is concluded that in such type of application, the films should have low residual stress to prevent deformation, good adhesive strength, durable and good resistance to wear.

Occupied childhoods: discourses and politics of childhood and their place in Palestinian and Pan-­Arab screen content for children

This thesis explores changing discourses of childhood and the ways in which power relations intersect with socio-cultural norms to shape screen-based media for Palestinian children. Situated within the interdisciplinary study of childhood, the research is an institutional and textual analysis that includes discursive and micro-level analysis of the socio-political circumstances within which children consume media in present-day Palestine. The thesis takes a social constructionist view, arguing that ‘childhood’ is not a fixed universal concept and that discourses of childhood are produced at specific historical moments as an effect of power. The study has a three-part research agenda. The first section uses secondary literature to explore theories and philosophies relating to definitions of childhood in Arab societies. The second employs participant observation and semi-structured interviews to understand the history and politics of children’s media in the West Bank. The final part of the research activity focuses on the impact that definitions of childhood and the politics of children’s media have on broadcasting outcomes through an analysis of (a) discourses on children’s media that circulate in Palestinian society, and (b) local and pan-Arab cultural texts consumed by Palestinian children. The analysis demonstrates that complex ideological and political factors are at play, which has led to the marginalisation, politicisation and internationalisation of local production for children. Due to the lack of alternatives, local producers often rely on international funding, and are hence forced to negotiate competing definitions of childhood, which while fitting with an international agenda of normalising the Israeli occupation, conflict culturally and politically with local conceptions of childhood and hopes for the Palestinian nation. While the Palestinian community appreciates the positive potential of local production, discourses and strategies around children’s media show that Palestinian children are constructed as vulnerable, incomplete and in constant need of guidance. Pan-Arab content presents a slightly less didactic approach and in certain cases presents childhood as a dynamic space of empowerment. However, by constructing children as ‘consumercitizens’, it alienates Arab (and Palestinian) children from disadvantaged backgrounds,as the preferred audience is middle-class children living in oil-rich countries of the Gulf.

Expanding the Design Space: Forging the Transition from 3D Printing to Additive Manufacturing

Thesis (Master's)--University of Washington, 2016-08

The Undersea World of the Sound Department: the Construction of Sonic Conventions in Sub-aqua Screen Environments

The availability of new underwater cameras and sub-aqua diving gear in the immediate post-war era opened up exciting possibilities for both narrative and documentary filmmakers. While the visual elements of this new world could now be more easily captured on film, the sound elements of the sub-aqua environment remained more elusive. What did, or should, this undersea world sound like? This article examines the use of sound in the sub-aqua scenes of both fictional and documentary films in the 1950s and asks questions about the methods used in the sonification of these worlds. Comparing the operation of underwater sound and human hearing with the production and post-production strategies used by filmmakers, I seek to identify the emergence of a sound convention and its implications for issues of cinematic realism. Central to this convention is the manipulation of sonic frequencies. The sound strategies adopted also raise questions about the malleability of viewer perspective and sound-image relationship in terms of a realist mode of address. Linked to this is the use of sound to enhance audience experience on an affective level. As well as underpinning cinematic realism, these new sound environments offered fresh experiences to audiences seeking new reasons to visit the cinema in an era of widening forms of entertainment.

Prototipagem ágil centrada no utilizador : aplicações de second screen

Com o desenvolvimento das tecnologias da Comunicação, o ser humano tem alterado os seus hábitos de consumo televisivo. Neste contexto, destaca-se o uso de aplicações mobile designadas como Second Screen, as quais, entre outras possibilidades, permitem interagir com conteúdos adicionais aos que se encontram a ser transmitidos na televisão. Sendo este fenómeno relativamente recente, pretende-se compreender qual a abordagem a adotar no desenvolvimento de uma prototipagem ágil de aplicações Second Screen centradas no utilizador. De modo a compreender o respetivo processo, iniciou-se o estudo com um enquadramento teórico, que possibilitou a familiarização com as aplicações Second Screen e ferramentas de prototipagem ágil já existentes. Após o enquadramento teórico, procedeu-se à criação de dois mockups de aplicações Second Screen, que foram testados em Focus Groups. A partir dos dados obtidos, desenvolveram-se dois protótipos ágeis, os quais foram submetidos a uma última fase de testes (Experimentação por observação, Entrevista e Questionário de avaliação, respetivamente). Os participantes deste estudo foram os mesmos para ambas as fases de testes, constituindo um grupo de consumidores, um grupo de designers e um grupo de especialistas na área de prototipagem. Os resultados obtidos, a partir dos protótipos concebidos, comprovam a validade do processo realizado neste estudo, podendo este ser usado para desenvolver protótipos de aplicações mobile e Second Screen.

Norm Friesen: The Place of the Classroom and the Space of the Screen, Relational Pedagogy and Internet Technology. New York, Bern etc.: Lang 2011 [Rezension]

Rezension von: Norm Friesen: The Place of the Classroom and the Space of the Screen, Relational Pedagogy and Internet Technology, New York, Bern etc.: Lang 2011 (183 S.; ISBN 978-1-4331-0959-1)

A computational fluid dynamics study of the stencil printing process

Abstract not available