Medical Physics Seminar – Monday, April 11, 2011
Development of PET imaging-based prescriptions for dose painting in radiotherapy
Stephen Bowen (student of Dr. Robert Jeraj and Soren Bentzen)
Research Assistant, Department of Medical Physics, UW-School of Medicine & Public Health, Madison, WI USA
Prescribed doses in radiation therapy are conventionally uniform across tumor volumes to reflect a fixed local disease control rate of the patient population mean. However, inter-patient and intra-tumor variation in response to uniform doses can result in diminished tumor control for certain patients. Quantitative PET imaging of tumor glucose metabolism, cell proliferation, and hypoxia has been suggested as a technique to individualize prescriptions in a manner that may significantly improve clinical outcome. The concept of prescribing non-uniform dose distributions based on molecular imaging, termed dose painting or theragnostic radiation therapy, hinges on the establishment of a dose-response relationship at the image voxel scale that optimizes a particular clinical endpoint.
This presentation will discuss two methods of defining dose painting prescriptions based on PET imaging: (1) model-derived prescriptions in head-and-neck cancer patients, and (2) empirically-derived prescriptions in veterinary sinonasal cancer patients. The clinical implementation of these dose painting prescriptions will be addressed, with particular emphasis on treatment planning workflows. Lastly, guidelines for the design of prospective dose painting clinical trials will be proposed.