Rayleigh theory of ultrasound scattering applied to liquid-filled contrast nanoparticles
Flegg, M., Poole, C., Whittaker, A.K., Keen, I., & Langton, C.M. (2010) Rayleigh theory of ultrasound scattering applied to liquid-filled contrast nanoparticles. Physics in Medicine and Biology, 55(11), pp. 3061-3076.
We present a novel modified theory based upon Rayleigh scattering of ultrasound from composite nanoparticles with a liquid core and solid shell. We derive closed form solutions to the scattering cross-section and have applied this model to an ultrasound contrast agent consisting of a liquid-filled core (perfluorooctyl bromide, PFOB) encapsulated by a polymer shell (poly-caprolactone, PCL). Sensitivity analysis was performed to predict the dependence of the scattering cross-section upon material and dimensional parameters. A rapid increase in the scattering cross-section was achieved by increasing the compressibility of the core, validating the incorporation of high compressibility PFOB; the compressibility of the shell had little impact on the overall scattering cross-section although a more compressible shell is desirable. Changes in the density of the shell and the core result in predicted local minima in the scattering cross-section, approximately corresponding to the PFOB-PCL contrast agent considered; hence, incorporation of a lower shell density could potentially significantly improve the scattering cross-section. A 50% reduction in shell thickness relative to external radius increased the predicted scattering cross-section by 50%. Although it has often been considered that the shell has a negative effect on the echogeneity due to its low compressibility, we have shown that it can potentially play an important role in the echogeneity of the contrast agent. The challenge for the future is to identify suitable shell and core materials that meet the predicted characteristics in order to achieve optimal echogenity.
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|Item Type:||Journal Article|
|Keywords:||Medical Imaging, Ultrasound, Nanoparticles, Rayleigh theory|
|Subjects:||Australian and New Zealand Standard Research Classification > PHYSICAL SCIENCES (020000) > OTHER PHYSICAL SCIENCES (029900) > Medical Physics (029903)|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Science and Technology|
Current > Institutes > Institute of Health and Biomedical Innovation
Past > Schools > Physics
|Copyright Owner:||Copyright 2010 Institute of Physics and Engineering in Medicine|
|Deposited On:||12 Nov 2010 08:39|
|Last Modified:||01 Mar 2012 00:19|
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