Investigating the generalisation of an atlas-based synthetic-CT algorithm to another centre and MR scanner for prostate MR-only radiotherapy

There is increasing interest in MR-only radiotherapy planning since it provides superb soft-tissue contrast without the registration uncertainties inherent in a CT–MR registration. However, MR images cannot readily provide the electron density information necessary for radiotherapy dose calculation. An algorithm which generates synthetic CTs for dose calculations from MR images of the prostate using an atlas of 3 T MR images has been previously reported by two of the authors. This paper aimed to evaluate this algorithm using MR data acquired at a different field strength and a different centre to the algorithm atlas. Twenty-one prostate patients received planning 1.5 T MR and CT scans with routine immobilisation devices on a flat-top couch set-up using external lasers. The MR receive coils were supported by a coil bridge. Synthetic CTs were generated from the planning MR images with (sCT₁v) and without (sCT) a one voxel body contour expansion included in the algorithm. This was to test whether this expansion was required for 1.5 T images. Both synthetic CTs were rigidly registered to the planning CT (pCT). A 6 MV volumetric modulated arc therapy plan was created on the pCT and recalculated on the sCT and sCT₁v. The synthetic CTs' dose distributions were compared to the dose distribution calculated on the pCT. The percentage dose difference at isocentre without the body contour expansion (sCT–pCT) was ΔDsCT = (0.9 \pm 0.8)% and with sCT₁v–pCT was ΔDsCT₁v = (-0.7 \pm 0.7)% (mean  ±  one standard deviation). The sCT₁v result was within one standard deviation of zero and agreed with the result reported previously using 3 T MR data. The sCT dose difference only agreed within two standard deviations. The mean  ±  one standard deviation gamma pass rate was ΓsCT = 96.1 \pm 2.9% for the sCT and ΓsCT₁v = 98.8 \pm 0.5% for the sCT₁v (with 2% global dose difference and 2mm distance to agreement gamma criteria). The one voxel body contour expansion improves the synthetic CT accuracy for MR images acquired at 1.5 T but requires the MR voxel size to be similar to the atlas MR voxel size. This study suggests that the atlas-based algorithm can be generalised to MR data acquired using a different field strength at a different centre

Comprehensive deep learning-based framework for automatic organs-at-risk segmentation in head-and-neck and pelvis for MR-guided radiation therapy planning

Introduction: The excellent soft-tissue contrast of magnetic resonance imaging (MRI) is appealing for delineation of organs-at-risk (OARs) as it is required for radiation therapy planning (RTP). In the last decade there has been an increasing interest in using deep-learning (DL) techniques to shorten the labor-intensive manual work and increase reproducibility. This paper focuses on the automatic segmentation of 27 head-and-neck and 10 male pelvis OARs with deep-learning methods based on T2-weighted MR images.Method: The proposed method uses 2D U-Nets for localization and 3D U-Net for segmentation of the various structures. The models were trained using public and private datasets and evaluated on private datasets only.Results and discussion: Evaluation with ground-truth contours demonstrated that the proposed method can accurately segment the majority of OARs and indicated similar or superior performance to state-of-the-art models. Furthermore, the auto-contours were visually rated by clinicians using Likert score and on average, 81% of them was found clinically acceptable

Mathematical Modeling Of Viral Zoonoses In Wildlife

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89481/1/j.1939-7445.2011.00104.x.pd

The experience is in the journey: an appreciative case study investigating early career teachers' employment in rural schools

Rural communities play a vital role in the Australian economy; their viability can be determined by the school, located at the centre of most towns. Yet rural communities struggle to attract and retain professionals, including teachers, who are central to their livelihood. This study investigated the positive experiences of five early career teachers’ attracted to teach in one rural school in South Australia. A case-study methodology collected data through surveys, digital representations, narrative inquiries, and semi-structured interviews. Early career teachers reported they faced: economic factors associated with relocation; social challenges in building relationships; having to learn about rural communities; and, dealing with personal preconceptions, expectations and possible anxieties as a result of being moved from one’s comfort zone. However, a key factor that contributed to their sustained employment included their own personal approach or attitude to the change, as this helped them to participate in and be accepted by the rural community. Other contributing factors included: a focus on rurality in initial teacher education; and, personal and professional support that built a sense of belonging to the rural community. The positive experiences of these early career teachers in sustained employment is shared through their views on how to adjust to living and working in a rural area. These perspectives may be applicable to other communities and professional groups considering rural employment: how the change impacts on an individual’s attraction to particular work in rural areas; the extent to which certain professionals are retained in rural towns; and, ultimately the long-term sustainability of rural communities.Sarah Hazel and Faye McCallu

Chapter 6: Reflecting on the potential of EntreCompEdu to stimulate teachers’ entrepreneurial thinking and activity.

EntreCompEdu is a professional development framework for educators, designed as a complement to the European Commission’s Entrepreneurship Competence Framework (EntreComp). The purpose of this chapter is to reflect upon EntreCompEdu’s potential to stimulate teachers’ entrepreneurial thinking and activity. The chapter is structured in three main sections. The first describe the policy context and the gap in teacher education that EntreCompEdu seeks to address. The second offers an overview of the framework’s main components. The third reflects on the pilot phase of implementation, focusing on two case studies to illustrate the factors that influence EntreCompEdu’s impact and future direction. The reflections are those of the lead author of EntreCompEdu, three of those who facilitated the professional development sessions and the project manager. We follow Borton’s ‘(1970) simple ‘What? So What? and Now What?’ model to shape our reflections. Our subjective narratives are based on specific professional experiences as we critically reflect on the framework’s implementation within the context of Covid-19 and other challenges associated with transnational projects. We conclude that EntreCompEdu can stimulate teachers’ entrepreneurial thinking, although its sustainability in school is contingent on a range of individual and organisational factors discussed

Environmental drivers of spatiotemporal foraging intensity in fruit bats and implications for Hendra virus ecology

Abstract In the Australian subtropics, flying-foxes (family Pteropididae) play a fundamental ecological role as forest pollinators. Flying-foxes are also reservoirs of the fatal zoonosis, Hendra virus. Understanding flying fox foraging ecology, particularly in agricultural areas during winter, is critical to determine their role in transmitting Hendra virus to horses and humans. We developed a spatiotemporal model of flying-fox foraging intensity based on foraging patterns of 37 grey-headed flying-foxes (Pteropus poliocephalus) using GPS tracking devices and boosted regression trees. We validated the model with independent population counts and summarized temporal patterns in terms of spatial resource concentration. We found that spatial resource concentration was highest in late-summer and lowest in winter, with lowest values in winter 2011, the same year an unprecedented cluster of spillover events occurred in Queensland and New South Wales. Spatial resource concentration was positively correlated with El Niño Southern Oscillation at 3–8 month time lags. Based on shared foraging traits with the primary reservoir of Hendra virus (Pteropus alecto), we used our results to develop hypotheses on how regional climatic history, eucalypt phenology, and foraging behaviour may contribute to the predominance of winter spillovers, and how these phenomena connote foraging habitat conservation as a public health intervention