title: Evaluation of deep learning techniques on a novel hierarchical surgical tool dataset

authors: Rodrigues, Mark William

subjects: Science & Technology

abstract: A new hierarchically organised dataset for artificial intelligence and machine learning research is presented, focusing on intelligent management of surgical tools. In addition to 360 surgical tool classes, we create a four level hierarchical structure for our dataset defined by 2 specialities, 12 packs and 35 sets. We employ different convolutional neural network training strategies to evaluate image classification and retrieval performance on this dataset, including the utilisation of prior information in the form of a taxonomic hierarchy tree structure. We evaluate the effects of image size and the number of images per class on model predictive performance. Experiments with the mapping of image features and class embeddings in semantic space using measures of semantic similarity between classes show that providing prior information results in a significant improvement in image retrieval performance on our dataset.

text: Evaluation of deep learning techniques on a novel hierarchical surgical tool dataset A new hierarchically organised dataset for artificial intelligence and machine learning research is presented, focusing on intelligent management of surgical tools. In addition to 360 surgical tool classes, we create a four level hierarchical structure for our dataset defined by 2 specialities, 12 packs and 35 sets. We employ different convolutional neural network training strategies to evaluate image classification and retrieval performance on this dataset, including the utilisation of prior information in the form of a taxonomic hierarchy tree structure. We evaluate the effects of image size and the number of images per class on model predictive performance. Experiments with the mapping of image features and class embeddings in semantic space using measures of semantic similarity between classes show that providing prior information results in a significant improvement in image retrieval performance on our dataset.

year: 2022

title: Fast Monte Carlo Simulation of ⁹⁰Y Bremsstrahlung using a Kernel-based Photon Source

authors: Zakariah, Suhaili

subjects: Monte Carlo

abstract: In targeted radionuclide therapy using ⁹⁰Y, bremsstrahlung photons can be used for imaging and subsequently for absorbed dose estimation. Monte Carlo simulation is a reliable method to study bremsstrahlung imaging but it takes a long computation time as not all ⁹⁰Y disintegrations result in emission of a bremsstrahlung photon. Furthermore the electron transport simulation is particularly time consuming. This research proposes that bremsstrahlung photons produced from the decay of a ⁹⁰Y point source are replaced with a kernel-based photon source for faster Monte Carlo simulation.
This study is divided into three main parts. First, a ⁹⁰Y point source in a spherical water phantom is fully simulated using Monte Carlo simulation. The characteristics of the bremsstrahlung photons produced from the ⁹⁰Y decay are investigated. The full Monte Carlo simulation of ⁹⁰Y point source provides the relationships between the emission position, energy and emission angle of the bremsstrahlung photon. These are recorded as probability distribution functions (PDFs).
Then, a kernel-based photon source which comprises of an array of photon-emitting concentric spherical shells is developed. The energy spectrum and angular distributions of the emitted photons are defined for each shell using the PDFs obtained previously from the full ⁹⁰Y Monte Carlo simulation. The kernel-based photon source shows a very close approximation to the distribution of bremsstrahlung photons generated by the full Monte Carlo simulation of ⁹⁰Y point source if the shells are sufficiently closely spaced.
Finally, the accuracy and speed of the kernel-based photon source are evaluated. A simplified gamma camera model, which consists of a collimator and NaI(Tl) detector is simulated to obtain the point spread function (PSF) of the point source ‘image’. The PSF can be represented as a Gaussian function. Estimation of σ of the Gaussian function and thus the full-width half-maximum (FWHM) is used to compare the different kernel-based photon source models to represent a ‘real’ source generated by a full Monte Carlo ⁹⁰Y simulation. The results show that the FWHMs of the photon source with kernels are comparable to full Monte Carlo simulation of ⁹⁰Y point source. The FWHM determined for a photon point source with the spectrum of ⁹⁰Y bremsstrahlung underestimates the full Monte Carlo simulation of the true ⁹⁰Y point source. This demonstrates that it is important to account for the photons being emitted at a distance away from the source and all of the photons cannot be assumed to come from a single point. It is more computationally efficient to use this source model than the kernel-based photon sources as it has the shortest computation time, however it is quite inaccurate. Simplifying the kernel-based source by assuming the photon emission as isotropic reduces the accuracy of the model slightly, though the reduction in simulation time is sufficiently small that the more accurate anisotropic kernel should be preferred.
The kernel-based photon source proposed in this study can be used to accurately represent the bremsstrahlung photons produced from the beta decay of a ⁹⁰Y point source. This approach greatly improves the simulation speed by almost 30 times.

text: Fast Monte Carlo Simulation of ⁹⁰Y Bremsstrahlung using a Kernel-based Photon Source In targeted radionuclide therapy using ⁹⁰Y, bremsstrahlung photons can be used for imaging and subsequently for absorbed dose estimation. Monte Carlo simulation is a reliable method to study bremsstrahlung imaging but it takes a long computation time as not all ⁹⁰Y disintegrations result in emission of a bremsstrahlung photon. Furthermore the electron transport simulation is particularly time consuming. This research proposes that bremsstrahlung photons produced from the decay of a ⁹⁰Y point source are replaced with a kernel-based photon source for faster Monte Carlo simulation.
This study is divided into three main parts. First, a ⁹⁰Y point source in a spherical water phantom is fully simulated using Monte Carlo simulation. The characteristics of the bremsstrahlung photons produced from the ⁹⁰Y decay are investigated. The full Monte Carlo simulation of ⁹⁰Y point source provides the relationships between the emission position, energy and emission angle of the bremsstrahlung photon. These are recorded as probability distribution functions (PDFs).
Then, a kernel-based photon source which comprises of an array of photon-emitting concentric spherical shells is developed. The energy spectrum and angular distributions of the emitted photons are defined for each shell using the PDFs obtained previously from the full ⁹⁰Y Monte Carlo simulation. The kernel-based photon source shows a very close approximation to the distribution of bremsstrahlung photons generated by the full Monte Carlo simulation of ⁹⁰Y point source if the shells are sufficiently closely spaced.
Finally, the accuracy and speed of the kernel-based photon source are evaluated. A simplified gamma camera model, which consists of a collimator and NaI(Tl) detector is simulated to obtain the point spread function (PSF) of the point source ‘image’. The PSF can be represented as a Gaussian function. Estimation of σ of the Gaussian function and thus the full-width half-maximum (FWHM) is used to compare the different kernel-based photon source models to represent a ‘real’ source generated by a full Monte Carlo ⁹⁰Y simulation. The results show that the FWHMs of the photon source with kernels are comparable to full Monte Carlo simulation of ⁹⁰Y point source. The FWHM determined for a photon point source with the spectrum of ⁹⁰Y bremsstrahlung underestimates the full Monte Carlo simulation of the true ⁹⁰Y point source. This demonstrates that it is important to account for the photons being emitted at a distance away from the source and all of the photons cannot be assumed to come from a single point. It is more computationally efficient to use this source model than the kernel-based photon sources as it has the shortest computation time, however it is quite inaccurate. Simplifying the kernel-based source by assuming the photon emission as isotropic reduces the accuracy of the model slightly, though the reduction in simulation time is sufficiently small that the more accurate anisotropic kernel should be preferred.
The kernel-based photon source proposed in this study can be used to accurately represent the bremsstrahlung photons produced from the beta decay of a ⁹⁰Y point source. This approach greatly improves the simulation speed by almost 30 times.

year: 2011

title: Social marketing in Aotearoa New Zealand: Analysing its evolution to  inform, improve, and justify its future

authors: Antric, Tim

subjects: Social marketing

abstract: Plotting the evolution and experience of social marketing in Aotearoa New Zealand, this thesis charts a creative landscape of productive future research directions in the field.
Starting with the question, “What can the social marketing discipline learn from the unique experience of social marketers in Aotearoa New Zealand?”, the research draws from appreciative inquiry interviews with 20 experienced social marketers and reviews of relevant government documents and published commentaries. Analysis of the findings sparked three substantive papers included in this thesis by publication: two of these have already been published, and one is currently being revised for resubmission. Presented in chapters four to six, the three papers analyse the growth and decline of social marketing in Aotearoa New Zealand; the overlapping functions of social marketing and public relations; and the incorporation of indigenous communities’ values into social marketing.
1.	The growth and decline of social marketing
In an original developmental framework for social marketing in Aotearoa New Zealand, the first of the three papers tracks four phases through four different governments as follows: (1) Foundation (1984-1990); (2) Establishment (1990-1999); (3) Growth (1999-2008); and (4) Decline (2008-2017).  The research found that political support is key to enabling ongoing social marketing contributions to social change and argues for the development of an evidence base for effective communication to political decision-makers to attract such support.
2.	Public relations, reputation and social marketing 
In identifying the strong interdisciplinary nature of social marketing in Aotearoa New Zealand, the second paper focuses on the intersections of public relations, marketing, advertising and health promotion. It illustrates how local definitions of, and practices within, social marketing draw from different disciplines. 
Social marketing has also been shaped by the nation’s founding document, Te Tiriti o Waitangi (The Treaty of Waitangi). The Crown’s revised principles of Te Tiriti offer further opportunity to improve social marketing through indigenous autonomy, partnership, active protection, equity and options.
3.	Decolonising social marketing through an indigenous lens
The third paper tackles the question: can social marketing address health inequity between Māori and non-Maori? It deals with this question in the context of the international shift in social marketing away from a focus on individual change to a focus on societal and social change. The paper’s findings support an ongoing critical analysis of social marketing from an indigenous worldview.
Conclusions
Overall, the thesis looks at the impact of political ideologies on the function of social marketing and makes novel suggestions on how social marketing academics and practitioners can attract political support. It calls for increasing interdisciplinarity to engage effectively with contemporary issues and encourages social marketers to search for “soul” in organisations. 
The thesis also identifies indigenous Māori culture as a potential inspiration for social marketers to improve their interactions with indigenous people in Aotearoa New Zealand as well as across the globe. It recommends that future social marketing interventions not only be informed by indigenous worldviews but also be led by indigenous communities involved from the planning stages.

text: Social marketing in Aotearoa New Zealand: Analysing its evolution to  inform, improve, and justify its future Plotting the evolution and experience of social marketing in Aotearoa New Zealand, this thesis charts a creative landscape of productive future research directions in the field.
Starting with the question, “What can the social marketing discipline learn from the unique experience of social marketers in Aotearoa New Zealand?”, the research draws from appreciative inquiry interviews with 20 experienced social marketers and reviews of relevant government documents and published commentaries. Analysis of the findings sparked three substantive papers included in this thesis by publication: two of these have already been published, and one is currently being revised for resubmission. Presented in chapters four to six, the three papers analyse the growth and decline of social marketing in Aotearoa New Zealand; the overlapping functions of social marketing and public relations; and the incorporation of indigenous communities’ values into social marketing.
1.	The growth and decline of social marketing
In an original developmental framework for social marketing in Aotearoa New Zealand, the first of the three papers tracks four phases through four different governments as follows: (1) Foundation (1984-1990); (2) Establishment (1990-1999); (3) Growth (1999-2008); and (4) Decline (2008-2017).  The research found that political support is key to enabling ongoing social marketing contributions to social change and argues for the development of an evidence base for effective communication to political decision-makers to attract such support.
2.	Public relations, reputation and social marketing 
In identifying the strong interdisciplinary nature of social marketing in Aotearoa New Zealand, the second paper focuses on the intersections of public relations, marketing, advertising and health promotion. It illustrates how local definitions of, and practices within, social marketing draw from different disciplines. 
Social marketing has also been shaped by the nation’s founding document, Te Tiriti o Waitangi (The Treaty of Waitangi). The Crown’s revised principles of Te Tiriti offer further opportunity to improve social marketing through indigenous autonomy, partnership, active protection, equity and options.
3.	Decolonising social marketing through an indigenous lens
The third paper tackles the question: can social marketing address health inequity between Māori and non-Maori? It deals with this question in the context of the international shift in social marketing away from a focus on individual change to a focus on societal and social change. The paper’s findings support an ongoing critical analysis of social marketing from an indigenous worldview.
Conclusions
Overall, the thesis looks at the impact of political ideologies on the function of social marketing and makes novel suggestions on how social marketing academics and practitioners can attract political support. It calls for increasing interdisciplinarity to engage effectively with contemporary issues and encourages social marketers to search for “soul” in organisations. 
The thesis also identifies indigenous Māori culture as a potential inspiration for social marketers to improve their interactions with indigenous people in Aotearoa New Zealand as well as across the globe. It recommends that future social marketing interventions not only be informed by indigenous worldviews but also be led by indigenous communities involved from the planning stages.

year: 2021