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Percutaneous image-guided interventions, such as radiofrequency ablation (RFA), biopsy, seed implantation, and
several types of drainage, employ needle shaped instruments which have to be inserted into the patient's body.
Precise planning of needle placement is a key to a successful intervention. The planning of the access path has
to be carried out with respect to a variety of criteria for all possible trajectories to the selected target. Since
the planning is performed in 2D slices, it demands considerable experience and constitutes a significant mental
task. To support the process of finding a suitable path for hepatic interventions, we propose a fast automatic
method that computes a list of path proposals for a given target point inside the liver with respect to multiple
criteria that affect safety and practicability. Prerequisites include segmentation masks of the liver, of all relevant
risk structures and, depending on the kind of procedure, of the tumor. The path proposals are computed
based on a weighted combination of cylindrical projections. Each projection represents one path criterion and
is generated using the graphics hardware of the workstation. The list of path proposals is generated in less
than one second. Hence, updates of the proposals upon changes of the target point and other relevant input
parameters can be carried out interactively. The results of a preliminary evaluation indicate that the proposed
paths are comparable to those chosen by experienced radiologists and therefore are suited to support planning
in the clinical environment. Our implementation focuses on RFA and biopsy in the liver but may be adapted to
other types of interventions.
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