Source: www.sciencedaily.com Author: staff, University of Texas at Austin, Texas Advanced Computing Center Comparison between predicted ground-truth clinical target volume (CTV1) (blue) and physician manual contours (red) for four oropharyngeal cancer patients. The primary and nodal gross tumor volume is included (green). From left to right, we illustrate a case from each site and nodal status (base of tongue node-negative, tonsil node-negative, base of tongue node-positive, and tonsil node-positive).Credit: Carlos E. Cardenas, MD Anderson Cancer Center Before performing radiation therapy, radiation oncologists first carefully review medical images of a patient to identify the gross tumor volume -- the observable portion of the disease. They then design patient-specific clinical target volumes that include surrounding tissues, since these regions can hide cancerous cells and provide pathways for metastasis. Known as contouring, this process establishes how much radiation a patient will receive and how it will be delivered. In the case of head and neck cancer, this is a particularly sensitive task due to the presence of vulnerable tissues in the vicinity. Though it may sound straightforward, contouring clinical target volumes is quite subjective. A recent study from Utrecht University found wide variability in how trained physicians contoured the same patient's computed tomography (CT) scan, leading some doctors to suggest high-risk clinical target volumes eight times larger than their colleagues. This inter-physician variability is a problem for patients, who may be over- or under-dosed based on the doctor they work with. It is also a problem for determining best practices, so [...]