Ultrasound is a popular, cost-effective and
non-invasive medical imaging modality. If an
ultrasound probe is equipped with a 3D position
sensor, the acquired images can be obtained in their
spatial context, a technique commonly denoted 3D
Combining ultrasound and a pre-operative Computed
Tomography (CT) scan of the same patient can be
beneficial for a number of clinical applications. The
core of this thesis is the development of novel
methods for fully automatic alignment (i.e.
registration) of 3D freehand ultrasound and CT data,
based on the image content and the physical
properties of both modalities.
Furthermore, we introduce new techniques for 3D
freehand ultrasound calibration and reconstruction,
as well as visualization of fused CT and ultrasound data.
Two clinical applications are investigated in detail.
We use a designated version of an automatic
registration algorithm to integrate diagnostic
ultrasound into radiation treatment planning for head
and neck cancer.
Different methods are applied, in the context of
treating liver and kidney metastases, for fusing CT
with both diagnostic and interventional ultrasound of
the abdomen. While diagnostic fusion helps doctors to
assess indeterminate lesions in those organs,
interventional fusion using our techniques allows for
advanced image-guided navigation, in particular, for
needle biopsies and radio-frequency ablations.