IMAGE: 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… view more
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
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