Evaluation of the absorbed dose in X-ray microtomography Stijn Bonte

102 Pages·2014·5.48 MB·English

Evaluation of the absorbed dose in X-ray microtomography
Stijn Bonte
Supervisors: Prof. dr. Luc Van Hoorebeke, Prof. dr. ir. Klaus Bacher
Counsellor: Am´elie De Muynck
Master’s dissertation submitted in order to obtain the academic degree of
Master of Science in Engineering Physics
WE05
Chairman: Prof. dr. Dirk Ryckbosch
GE05
Chairman: Prof. dr. Hubert Thierens
Faculty of Engineering and Architecture
Academic year 2013-2014

Evaluation of the absorbed dose in X-ray microtomography
Stijn Bonte
Supervisors: Prof. dr. Luc Van Hoorebeke, Prof. dr. ir. Klaus Bacher
Counsellor: Am´elie De Muynck
Master’s dissertation submitted in order to obtain the academic degree of
Master of Science in Engineering Physics
WE05
Chairman: Prof. dr. Dirk Ryckbosch
GE05
Chairman: Prof. dr. Hubert Thierens
Faculty of Engineering and Architecture
Academic year 2013-2014

Preface
Choosing a topic for my master’s dissertation was not a tough challenge for me. My pref-
erence was for a subject with a good balance between practical and theoretical work. My
expectations were completely met, because it was a year full of simulations, experiments,
unexpected results and searches for explanations. I’m therefore very glad to have had
the opportunity to work on this subject and deepen my insight in the physical nature of
radiation exposure. This was only possible thanks to a lot of people.
First I want to thank my promotor prof. dr. Luc Van Hoorebeke. He could always make
time to discuss my problems and results and was therefore a great help in achieving this
work.
Next I want to thank my second promotor, prof. dr. ir. Klaus Bacher. He allowed to
use his equipment for the experimental determination of the absorbed dose. Due to his
extensive experience with radiation dosimetry, he was able to answer many questions.
OfcourseIwanttothankmycounsellorAm´elieDeMuynckforaccompanyingmethrough
the entire process of research and writing of this thesis.
Special thanks also goes to Thomas De Schryver, member of the UGCT. He developed the
analytical derivation of the dose buildup for monochromatic photon beams of low energy,
which can be found in appendix B.
I also want to thank Manuel Dierick and the other members of the UGCT for their advice
and the interesting conversations we had the last year.
Lastly I want to thank my parents for giving me the opportunity to conduct my studies,
for their support and their advice. I also want to thank Val´erie for always being there for
me.
Stijn Bonte
June 2014
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Overview
Title Evaluation of the absorbed dose in X-ray microtomography
Author Stijn Bonte
Supervisors Prof. dr. Luc Van Hoorebeke
Prof. dr. ir. Klaus Bacher
Counsellor Am´elie De Muynck
Master’sdissertationsubmittedinordertoobtaintheacademicdegreeofMasterofScience
in Engineering Physics
Ghent University
Faculty of Sciences: Department of Physics and Astronomy (WE05)
Chairman: Prof. dr. Dirk Ryckbosch
Faculty of Medicine: Department of Basic Medical Sciences (GE05)
Chairman: Prof. dr. Hubert Thierens
Faculty of Engineering and Architecture
Academic year 2013-2014
Summary: In medical applications of computed tomography, the absorbed dose is thor-
oughly studied. However for X-ray microtomography with submillimeter resolution, this
is not the case. In this master’s thesis, the absorbed dose in microtomography is evalu-
ated, both with experimental methods, using a Farmer type ionisation chamber, as with
Monte Carlo simulations. The influence of several parameters, such as tube high voltage,
target current, distance, surrounding material and beam filtering, is tested. A compari-
son between both methods shows that the results agree to a sufficient extent for the CT
applications at UGCT.
Keywords: Radiation dosimetry, Microtomography, Monte Carlo simulations
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