title: Effects of energy threshold and dead time on Compton camera performance

authors: Uche, Chibueze Zimuzo

subjects: Compton camera

abstract: We study the effects of energy threshold and dead time on the sensitivity and image resolution of the Compton camera. The simulation model includes the decay times, detection time jitters, energy threshold and detector dead time as well as basic detector parameters such as Doppler broadening, energy resolution and finite detector resolution. The GEANT4 toolkit was used to model the camera geometry and performance for two common nuclear medicine energies that correspond to 99mTc (140.5 keV) and ¹⁸F (511 keV) radiotracers. Results without the energy threshold and time effects show good agreement with previous studies. For 140.5 keV, the inclusion of energy threshold improved image resolution from 10.7 to 9.5 mm with a source-to-detector distance of 5 cm, while the inclusion of time effects made no further difference on resolution. The energy threshold reduced the sensitivity by 48%, and subsequent inclusion of time effects further reduced the sensitivity by 17%. At 511 keV, the application of energy threshold reduced the sensitivity by 6%, while the time effects dominated count rate losses with further reduction of 13%. However, the inclusion of the two effects had negligible impact on the resolution.

text: Effects of energy threshold and dead time on Compton camera performance We study the effects of energy threshold and dead time on the sensitivity and image resolution of the Compton camera. The simulation model includes the decay times, detection time jitters, energy threshold and detector dead time as well as basic detector parameters such as Doppler broadening, energy resolution and finite detector resolution. The GEANT4 toolkit was used to model the camera geometry and performance for two common nuclear medicine energies that correspond to 99mTc (140.5 keV) and ¹⁸F (511 keV) radiotracers. Results without the energy threshold and time effects show good agreement with previous studies. For 140.5 keV, the inclusion of energy threshold improved image resolution from 10.7 to 9.5 mm with a source-to-detector distance of 5 cm, while the inclusion of time effects made no further difference on resolution. The energy threshold reduced the sensitivity by 48%, and subsequent inclusion of time effects further reduced the sensitivity by 17%. At 511 keV, the application of energy threshold reduced the sensitivity by 6%, while the time effects dominated count rate losses with further reduction of 13%. However, the inclusion of the two effects had negligible impact on the resolution.

year: 2011

title: Statistical representations of the housing problem in briefings to incoming ministers, 2008–2020: The politics of housing numbers

authors: Barrett, Patrick

abstract: An interpretive policy studies perspective on what is understood to be the ‘facts’ about the housing problem in New Zealand has potential to uncover the way statistical representations of problems are embedded in larger normative narratives, and the consequential implications for housing policy and governance. This paper analyses such representations as they are evident in policy briefings to incoming Ministers of Housing between 2008 and 2020 by Housing New Zealand (HNZ) and its successor Kāinga Ora, and the way these reflect and reinforce a neoliberal political rationality and an agenda to residualise and marketise state housing support. The briefings represent authoritative accounts by a key bureaucratic advisory agency of the significant issues and priorities in the housing portfolio. The period prior to 2017 saw the emergence of new articulations of housing problems relating to affordability, declining rates of home ownership, an increasing rental population, and increasing homelessness. In the briefings to ministers, these problems were routinely framed as issues of supply and demand and market adjustment, and this has continued following the change of government in 2017. The focus of the paper is on identifying statistical representations within the discursive context that give weight to particular policy choices.

text: Statistical representations of the housing problem in briefings to incoming ministers, 2008–2020: The politics of housing numbers An interpretive policy studies perspective on what is understood to be the ‘facts’ about the housing problem in New Zealand has potential to uncover the way statistical representations of problems are embedded in larger normative narratives, and the consequential implications for housing policy and governance. This paper analyses such representations as they are evident in policy briefings to incoming Ministers of Housing between 2008 and 2020 by Housing New Zealand (HNZ) and its successor Kāinga Ora, and the way these reflect and reinforce a neoliberal political rationality and an agenda to residualise and marketise state housing support. The briefings represent authoritative accounts by a key bureaucratic advisory agency of the significant issues and priorities in the housing portfolio. The period prior to 2017 saw the emergence of new articulations of housing problems relating to affordability, declining rates of home ownership, an increasing rental population, and increasing homelessness. In the briefings to ministers, these problems were routinely framed as issues of supply and demand and market adjustment, and this has continued following the change of government in 2017. The focus of the paper is on identifying statistical representations within the discursive context that give weight to particular policy choices.

year: 2021

title: Decolonisation as a social change framework and its impact on the development of Indigenous-based curricula for Helping Professionals in mainstream Tertiary Education Organisations

authors: Moeke-Pickering, Taima Materangatira

subjects: Indigenous Education

abstract: This research examined the social and political approaches that Indigenous peoples undertook to situate Indigenous-based education programmes in mainstream post-secondary/tertiary education organisations. Indigenous-based helping programmes assist to progress Indigenous aspirations for self-determination and are sites that center Indigenous worldviews. A decolonisation analysis framework that is embedded in the curriculum deepens students’ understanding about the impacts of imperialism, colonisation and post colonial issues. This thesis involved researching two Indigenous-based programmes that are based within mainstream tertiary institutes. The first is the Te Whiuwhiu o te Hau Maori Counselling degree programme which is based at the Waikato Institute of Technology (WINTEC) in Hamilton, Aotearoa, New Zealand. The other is the Native Human Services Social Work degree programme which is based at Laurentian University in Sudbury, Ontario, Canada. I start this thesis with “opening the circle” and situating the context for my research. Next is the literature review chapter. This chapter provides a review of decolonisation-colonisation, decolonisation frameworks within Indigenous education, self-determination and Indigenous peoples, and Maori and Native self-determination strategies relevant to health and education. I used a case study method combined with an Indigenous methodology to guide the research. This involved gathering key pieces of information as well as interviewing participants (graduates, tutors/faculty/developers) from each programme. In chapter four is the Te Whiuwhiu o te Hau case study and in chapter five is found the Native Human Services case study. Each case study covers pre-colonial and colonisation contexts and examines assimilative legislation on Indigenous education and health. The backgrounds of social work and counselling, Native social work and Maori counselling are also presented. In the case studies is the background and rationale for the development of each programme, as well as pertinent information on the course content. Chapter six presents on the findings and conclusion and chapter seven “closes the circle”. The main findings highlighted that Indigenous curricula and pedagogies embrace Indigenous theories and discourse relevant to the helping practice fields. Secondly, each programme fosters students to make positive changes for themselves, for their communities, and for their professions. Another finding is that faculty/tutors promote an inclusive Indigenous pedagogy in the classroom that incorporates cultural ceremonies, encourage personal introspection, builds cultural and professional skills, and teaches critical education. Both programmes reflected a pedagogy that taught students to counter negative narratives while instilling a critical analysis of decolonisation and colonisation. I propose that a decolonisation analysis is both a reflective and healing tool, in that students are provided with the hard evidence about their histories and what happened to their communities. I contend that Indigenous-based programmes contribute to the continuity of Indigenous culture and wellbeing of their communities and, that they play a vital role in advancing Indigenous education priorities.

text: Decolonisation as a social change framework and its impact on the development of Indigenous-based curricula for Helping Professionals in mainstream Tertiary Education Organisations This research examined the social and political approaches that Indigenous peoples undertook to situate Indigenous-based education programmes in mainstream post-secondary/tertiary education organisations. Indigenous-based helping programmes assist to progress Indigenous aspirations for self-determination and are sites that center Indigenous worldviews. A decolonisation analysis framework that is embedded in the curriculum deepens students’ understanding about the impacts of imperialism, colonisation and post colonial issues. This thesis involved researching two Indigenous-based programmes that are based within mainstream tertiary institutes. The first is the Te Whiuwhiu o te Hau Maori Counselling degree programme which is based at the Waikato Institute of Technology (WINTEC) in Hamilton, Aotearoa, New Zealand. The other is the Native Human Services Social Work degree programme which is based at Laurentian University in Sudbury, Ontario, Canada. I start this thesis with “opening the circle” and situating the context for my research. Next is the literature review chapter. This chapter provides a review of decolonisation-colonisation, decolonisation frameworks within Indigenous education, self-determination and Indigenous peoples, and Maori and Native self-determination strategies relevant to health and education. I used a case study method combined with an Indigenous methodology to guide the research. This involved gathering key pieces of information as well as interviewing participants (graduates, tutors/faculty/developers) from each programme. In chapter four is the Te Whiuwhiu o te Hau case study and in chapter five is found the Native Human Services case study. Each case study covers pre-colonial and colonisation contexts and examines assimilative legislation on Indigenous education and health. The backgrounds of social work and counselling, Native social work and Maori counselling are also presented. In the case studies is the background and rationale for the development of each programme, as well as pertinent information on the course content. Chapter six presents on the findings and conclusion and chapter seven “closes the circle”. The main findings highlighted that Indigenous curricula and pedagogies embrace Indigenous theories and discourse relevant to the helping practice fields. Secondly, each programme fosters students to make positive changes for themselves, for their communities, and for their professions. Another finding is that faculty/tutors promote an inclusive Indigenous pedagogy in the classroom that incorporates cultural ceremonies, encourage personal introspection, builds cultural and professional skills, and teaches critical education. Both programmes reflected a pedagogy that taught students to counter negative narratives while instilling a critical analysis of decolonisation and colonisation. I propose that a decolonisation analysis is both a reflective and healing tool, in that students are provided with the hard evidence about their histories and what happened to their communities. I contend that Indigenous-based programmes contribute to the continuity of Indigenous culture and wellbeing of their communities and, that they play a vital role in advancing Indigenous education priorities.

year: 2010