Evaluation of vibration assessment of sternotomy
Paldanius, Antti (2018)
Paldanius, Antti
2018
Sähkötekniikka
Tieto- ja sähkötekniikan tiedekunta - Faculty of Computing and Electrical Engineering
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2018-10-03
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201810032375
https://urn.fi/URN:NBN:fi:tty-201810032375
Tiivistelmä
Median sternotomy is a common way to gain access to the heart during heart surgery. Early detection of sternal instability could prevent serious, potentially fatal, complica-tions of sternotomy. Tays Heart Hospital has been developing a vibration measurement device for detection of sternal instability in cooperation with Tampere University of Technology. The device has been tested on sternotomy patients and cadavers but in both cases there are many variables such as geometry and material properties of the tissues of the individual test subject.
In this thesis cadaver measurements, phantoms and finite element method were used determine how material properties and the nature of the defect in the measured geome-try affected the frequency response to the vibration sweep produced by the device. Phantoms were built from roughly tissue equivalent materials of known material proper-ties and with simple geometry. Measurement results with the vibration measurement device were obtained from one cadaver and four phantoms.
Finite element models of the phantoms, cadaver thorax and simplified thorax geometries were created and simulated in ANSYS using Harmonic Response analysis. Unfortunate-ly, the model created from the computed tomography data of the cadaver didn’t work due to problems with geometry quality and meshing but results from the two other types of models were obtained. These results were then compared to measured data.
The measurement results from the phantoms indicate that the vibration measurement device requires some design changes to improve its accuracy and repeatability of the measurements. The finite element method simulation results indicate that depending on geometry and material properties the differences between a healthy sternum and a ster-num with small defects may be hard to detect with vibration measurement but once the defect grows the frequency response changes significantly.
In this thesis cadaver measurements, phantoms and finite element method were used determine how material properties and the nature of the defect in the measured geome-try affected the frequency response to the vibration sweep produced by the device. Phantoms were built from roughly tissue equivalent materials of known material proper-ties and with simple geometry. Measurement results with the vibration measurement device were obtained from one cadaver and four phantoms.
Finite element models of the phantoms, cadaver thorax and simplified thorax geometries were created and simulated in ANSYS using Harmonic Response analysis. Unfortunate-ly, the model created from the computed tomography data of the cadaver didn’t work due to problems with geometry quality and meshing but results from the two other types of models were obtained. These results were then compared to measured data.
The measurement results from the phantoms indicate that the vibration measurement device requires some design changes to improve its accuracy and repeatability of the measurements. The finite element method simulation results indicate that depending on geometry and material properties the differences between a healthy sternum and a ster-num with small defects may be hard to detect with vibration measurement but once the defect grows the frequency response changes significantly.