medical aerosol deposition in the human lung

8/7/2019 Medical Aerosol Deposition in the Human Lung

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Medical Aerosol Deposition in the Human Lung

Dr. Stefan RiefDr. Stefan RiefDr. Stefan RiefDr. Stefan Rief

Workshop on Microstructure Simulation andWorkshop on Microstructure Simulation andWorkshop on Microstructure Simulation andWorkshop on Microstructure Simulation andVirtual Material DesignVirtual Material DesignVirtual Material DesignVirtual Material Design

Kaiserslautern, January 26Kaiserslautern, January 26Kaiserslautern, January 26Kaiserslautern, January 26thththth

to 27to 27to 27to 27thththth

, 2006, 2006, 2006, 2006


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Kaiserslautern, JanuaryKaiserslautern, JanuaryKaiserslautern, JanuaryKaiserslautern, January 26262626thththth to 27to 27to 27to 27thththth,,,, 2006200620062006

Overview

I. Introduction

II. Model of the Human Lung

III. Simulation of Respiration andHygroscopic Aerosols

IV. Current State and Outlook


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I. Introduction

Simulation of Aerosol Dynamics in the Human Lungoriginates from a joint project of

Medical Background Modeling and Simulation Computer Tomography


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I. Introduction

New Challenges for ITWMs

Filter Simulation Technology Virtual model of a human lung

Simulation of the respiration cycle

Hygroscopic particle growth

Aims of the Project

Prediction of aerosol deposition in the lung

Optimization of particle sizes -> Reduced amountof applied medicine

Knowledge of absorbed dose

CaskCaskCaskCask of aof aof aof a lunglunglunglung


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Overview

I. Motivation





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Model of a human airway tree (Model of a human airway tree (Model of a human airway tree (Model of a human airway tree (KitaokaKitaokaKitaokaKitaoka, 1999):, 1999):, 1999):, 1999):

Outer boundaries of the organ (heart, backbone,

diaphragm, ) are given by a set of algebraic equations

Lung is based on a dichotomous tube model

Branches are characterized by

- di tube diameters

- i branching angles

- r flow dividing ratio


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Model of a human airway tree (Model of a human airway tree (Model of a human airway tree (Model of a human airway tree (KitaokaKitaokaKitaokaKitaoka, 1999):, 1999):, 1999):, 1999):

9 rules determine the branching, e.g.

- conservation of flow rates at branches

- tube length = 3 * tube diameter

- branching is planar

- successive branching planes are perpendicular

- flow-dividing ratio = volume-dividing ratio

- minimum flow rate terminates branching

Morphometric characteristics are in good agreement to literature and lung casks


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~1000 tubes~1000 tubes~1000 tubes~1000 tubes ~7000 tubes~7000 tubes~7000 tubes~7000 tubes


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Overview

I. Motivation





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III. Simulation of Respiration and Hygroscopic Aerosols

Model of the Respiration CycleModel of the Respiration CycleModel of the Respiration CycleModel of the Respiration Cycle instationary, incompressible Navier-Stokes equations

constant pressure at the inlet (trachea)

time-periodic pressure variations at the outlets

no-slip conditions on the tube walls

p=0

p(t) = sin(w*t)


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III. Simulation of Respiration and Hygroscopic Aerosols

Hygroscopic AerosolsHygroscopic AerosolsHygroscopic AerosolsHygroscopic Aerosols

due to large humidity, aerosol particles growsignificantly during the respiration cycle

particle growth obeys a nonlinear ODEparameterized by

- surface tension of water

- saturation rate of air

- temperature

- mobility of water in air

-

diameter has to be updated in each time step

additional collision check due to particlegrowth


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Overview

I. Motivation





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AchievementsAchievementsAchievementsAchievements

Geometric model of a virtual human lung

Growth of hygroscopic aerosols

Respiration cycle

Still To DoStill To DoStill To DoStill To Do

detailed deposition study of aerosol particles ofdifferent size providing

1) suggestion for an optimum aerosol particle size

2) quantitative statement about absorbed dose

ValidationExisting

Data

medical aerosol deposition in the human lung

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