ABSTRACT
Flow in a porous medium can be driven by the deformations of the boundaries of the porous domain. Such boundary deformations locally change the volume fraction accessible by the fluid, creating non-uniform porosity and permeability throughout the medium. In this work, we construct a deformation-driven porous medium transport model with spatially and temporally varying porosity and permeability that are dependent on the boundary deformations imposed on the medium. We use this model to study the transport of interstitial fluid along the basement membranes in the arterial walls of the brain. The basement membrane is modeled as a deforming annular porous channel with the compressible pore space filled with an incompressible, Newtonian fluid. The role of a forward propagating peristaltic heart pulse wave and a reverse smooth muscle contraction wave on the flow within the basement membranes is investigated. Our results identify combinations of wave amplitudes that can induce either forward or reverse transport along these transport pathways in the brain. The magnitude and direction of fluid transport predicted by our model can help in understanding the clearance of fluids and solutes along the Intramural Periarterial Drainage route and the pathology of cerebral amyloid angiopathy.
Subject(s)
Brain , Extracellular Fluid , Extracellular Fluid/metabolism , Extracellular Fluid/physiology , Porosity , Humans , Brain/metabolism , Brain/blood supply , Brain/physiology , Basement Membrane/metabolism , Basement Membrane/physiology , Mathematical Concepts , Biological Transport/physiology , Models, Biological , Computer Simulation , Models, Neurological , Animals , PermeabilityABSTRACT
INTRODUCTION: The Philippines is a lower-middle-income island country with over 153 000 new cancer diagnosis each year. Despite many patients needing radiotherapy as part of disease management, there remains limitations to access. Currently, the Philippines has 50 linear accelerator facilities serving a population of 110 million. However, given the recommendation of 1 linear accelerator for every 250 thousand people, it is evident that the demand for accessible radiotherapy resources is significantly underserved in the country. This paper outlines the collaboration between GenesisCare Solutions (GCS) and Fairview Cancer Center (FCC) to address efficiency and access within the radiotherapy department at FCC. METHODS: Through international collaboration between GCS and FCC, areas for improvement were identified and categorized into four domains: Dosimetry quality, Patient workflow, Data & Reporting, and Information Technology (IT) Infrastructure. Action plans were developed then implemented. A baseline measurement was obtained for each domain, and post-implementation evaluation undertaken at 3 months, 6 months, and 12 months. Data captured within the electronic medical record system was extrapolated, and average treatment times were established for pre- and post-engagement. A paired, 2-tailed t-test was used for statistical analysis of outcome parameters using IBM SPSS version 23 for all statistics. RESULTS: Twelve months post-initial engagement, all four domains saw positive outcomes. Improved plan quality linked to Intensity Modulated Radiotherapy (IMRT) utilization rates saw an increase from 20% to 54%. A significant reduction in patient average wait times was also observed, from 27 to 17 min (p ≤ 0.001). Prior to engagement, tracking patient demographics and diagnosis was not prioritized, post engagement an average of 92% diagnosis entry compliance was achieved. CONCLUSION: Through the collaboration of GCS and FCC, objectives in all action plan domains were achieved, highlighting the benefits of collaboration between low-middle-income and high-income institutions.