3,359 research outputs found
Using Image Translation To Synthesize Amyloid Beta From Structural MRI
Amyloid-beta and brain atrophy are known hallmarks of Alzheimer’s Disease (AD) and can be quantified with positron emission tomography (PET) and structural magnetic resonance imaging (MRI), respectively. PET uses radiotracers that bind to amyloid-beta, whereas MRI can measure brain morphology. PET scans have limitations including cost, invasiveness (involve injections and ionizing radiation exposure), and have limited accessibility, making PET not practical for screening early-onset AD. Conversely, MRI is a cheaper, less-invasive (free from ionizing radiation), and is more widely available, however, it cannot provide the necessary molecular information. There is a known relationship between amyloid-beta and brain atrophy. This thesis aims to synthesize amyloid-beta PET images from structural MRI using image translation, an advanced form of machine learning. The developed models have reported high-similarity metrics between the real and synthetic PET images and high-degree of accuracy in radiotracer quantification. The results are highly impactful as it enables amyloid-beta measurements form every MRI, for free
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Cancer Care in Pandemic Times: Building Inclusive Local Health Security in Africa and India
This is a book about improving cancer care in Africa and India that is a child of its pandemic times. It has been collaboratively researched and written by colleagues in Kenya, Tanzania, India and the UK, working within a cross-country, multidisciplinary research project, Innovation for Cancer Care in Africa (ICCA). Since this was a health-focused research project, ICCA researchers during the pandemic not only continued to work on the cancer research project but were also called upon by their governments to respond to immediate pandemic needs. In combining these two concerns, for improving cancer care and responding to pandemic needs, our original project aims have been challenged, deepened and reworked. ICCA’s initial collaborative research focus included—against the grain of most global health literature—the potential role of enhanced local production of essential healthcare supplies for improving cancer care in African countries. The pandemic experience has strikingly validated these earlier findings on the importance of industrial development for health care. The pandemic crystallised for researchers and policymakers an often overlooked phenomenon: global health security is built on the foundations of strong local health security. We argue in this book that new analytical thinking from social scientists and others is required on how to build local health security. We use the “lens” of original research on cancer care in East Africa and India to build up an understanding of the scope for the development of stronger synergies between local health industries and health care, in order to strengthen local health security and develop tools for policy making. The rethinking and reimagining presented here is required for different African countries, for India and the wider world, and this research on cancer care has taught us that this imperative goes much wider than infectious diseases
Intra-fraction motion of pelvic oligometastases and feasibility of PTV margin reduction using MRI guided adaptive radiotherapy
PurposeThis study assesses the impact of intra-fraction motion and PTV margin size on target coverage for patients undergoing radiation treatment of pelvic oligometastases. Dosimetric sparing of the bowel as a function of the PTV margin is also evaluated.Materials and methodsSeven patients with pelvic oligometastases previously treated on our MR-linac (35 Gy in 5 fractions) were included in this study. Retrospective adaptive plans were created for each fraction on the daily MRI datasets using PTV margins of 5 mm, 3 mm, and 2 mm. Dosimetric constraint violations and GTV coverage were measured as a function of PTV margin size. The impact of intra-fraction motion on GTV coverage was assessed by tracking the GTV position on the cine MR images acquired during treatment delivery and creating an intra-fraction dose distribution for each IMRT beam. The intra-fraction dose was accumulated for each fraction to determine the total dose delivered to the target for each PTV size.ResultsAll OAR constraints were achieved in 85.7%, 94.3%, and 100.0% of fractions when using 5 mm, 3 mm, and 2 mm PTV margins while scaling to 95% PTV coverage. Compared to plans with a 5 mm PTV margin, there was a 27.4 ± 12.3% (4.0 ± 2.2 Gy) and an 18.5 ± 7.3% (2.7 ± 1.4 Gy) reduction in the bowel D0.5cc dose for 2 mm and 3 mm PTV margins, respectively. The target dose (GTV V35 Gy) was on average 100.0 ± 0.1% (99.6 – 100%), 99.6 ± 1.0% (97.2 – 100%), and 99.0 ± 1.4% (95.0 – 100%), among all fractions for the 5 mm, 3 mm, and 2 mm PTV margins on the adaptive plans when accounting for intra-fraction motion, respectively.ConclusionA 2 mm PTV margin achieved a minimum of 95% GTV coverage while reducing the dose to the bowel for all patients
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