This thesis includes the development, construction and testing of internal organ
phantoms, with focus on the liver, for biomechanical testing. Phantoms have various
biomedical applications such as surgical simulations, minimally invasive surgery, soft
tissue characterization, diagnostic tools and instrumentation calibration. However, there
is little work present in literature regarding phantoms and the work that is currently
available does not account for the non-linear viscoelastic properties as well as the
Glisson’s capsule. In this work, three different phantoms are presented: a fluid-filled
phantom, a perfused phantom and a hydrogel-based liver phantom. A testing apparatus is
designed, built and used to measure the force-displacement data during the indentation of
the phantom.
The first phantom that is designed and constructed follows the basis of a fluid-filled
vessel. It is composed of a linear low-density polyethylene (LLDPE) bag filled with
different fluids namely: water, a 1:1 water/glycerine mixture and glycerine. The
phantoms are subjected to quasi-static loading as well as relaxation testing. The effect of
density and viscosity, its size, and confined and unconfined boundary conditions are
characterized.
The second phantom is designed to investigate the effects of hepatic macrocirculation on
the biomechanical properties of the liver. The phantom is made of two-part silicone
(Smooth-On, ECOFLEX 00-30), and contains a network of conduits to model the large
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blood vessels in the liver. A perfusion system that captures the general features of the
human hepatic circulation is used to help investigate the effects of the different flow
parameters such as pressure and flow rate on the biomechanical characteristics of the
liver. The perfusion system is designed to reproduce comparable pressures to the human
portal vein and hepatic artery.
The third phantom is made of two parts, a hydrogel inner layer with a LLDPE outer layer.
The idea behind this phantom is to represent the organ as accurately as possible by
accounting for the capsule that surrounds the organ as well as the biphasic (solid and
fluid) nature of the organ. A biphasic poroviscoelastic model is used to model the
hydrogel while the LLDPE uses a non-linear hyperelastic and viscoelastic model.
Modeling is done in ABAQUS to fit the experimental data obtained from quasi-static
indentation and relaxation testing using a parametric study.
In conclusion, phantoms replicating the non-linear viscoelastic properties observed in
organs are presented and characterized.
Main Thesis Contributions
• Development and characterization of a simple fluid-filled phantom to represent
the mechanical properties of the liver
• Development and characterization of hydrogel-based liver phantom with
representation of the biphasic nature of the organ and the Glisson’s capsule.
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• Development and characterization of perfused liver phantom with ability to be recreated
with various vessel configurations.
• Development of testing set-up to characterize various phantoms.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OSUL.10219/2092 |
| Date | 08 October 2013 |
| Creators | Omri, Karim |
| Publisher | Laurentian University of Sudbury |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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