The Clinical Target Volume (CTV) project

The Clinical Target Volume project has as its objective to create a mathematical model of how tumors spread to regional lymph nodes and other locations from the primary tumor. It is a collaborative project of Radiation Oncologists, Otolaryngologists, and Computer Scientists. The basis for the model is that local and regional tumor dissemination is generally believed to take place through the lymphatic system, starting with the lymphatic vessels that drain the anatomic site of the the primary tumor. The University of Washington Foundational Model of Anatomy (FMA) contains a computationally accessible representation of the lymphatic system and its components. This representation can be used to generate the topology of the tumor spread model. The model itself is a Markov chain. We now also have a secondary goal, of generalizing the method for creating such models from other ontological knowledge representations, besides the FMA. Initial work on this idea examined the use of a rule-based representation to predict involved lymph nodes. This was then revised to represent lymphatic vessels as a connected set of Markov chains, one for each lymphatic vessel in a path. We are now working on a more unified Markov chain representation with fewer free parameters.

Publications related to the CTV model project

Once the probability of tumor presence in various lymph nodes is computed, and a threshold is chosen, there is still the problem of drawing the actual contours of a target for radiotherapy planning, which will include the involved nodes but as little else as possible. This problem can be addressed using an atlas of images in which the various lymph node groups are drawn, together with image registration techniques to map the standard atlas to the particular anatomy of an individual patient. This part of the project is not currently active.

Publications related to the contour generation project