SNM: PET directs radiation treatment planning in head and neck cancers

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Incorporation of biological information using 18F-fluorodeoxyglucose (FDG) and 18F-fluoromisonidazole (FMISO) PET imaging into tumor volume delineation will potentially improve radiation treatment planning and outcomes in head and neck cancers, according to research presented at SNM annual meeting this week in Salt Lake City.

In this study, a patient with an advanced case of head and neck cancer showing hypoxia within the tumor was scanned using PET and two imaging agents, FDG, which measures glucose metabolism, and FMISO, which helps image and quantify hypoxia. FDG flux and FMISO flux images were generated using a two-tissue compartmental model for an advanced head and neck cancer patient and were co-registered to the treatment planning CT using the Philips Healthcare's Pinnacle RTP software. A high-dose intensity modulated radiation therapy (IMRT) plan was designed based on this information, which showed that treatment planning with molecular imaging is possible.

“The research that we are conducting with Philips is extending the use of molecular imaging for radiotherapy planning, moving closer to more personalized treatment of hard-to-treat cancers based on the biology of each individual patient’s tumor,” said lead author Kristi Hendrickson, PhD, a medical physicist at the University of Washington Medical Center in Seattle.

“By modeling the data acquired from PET scans, we can potentially reduce damage to surrounding healthy tissue, as well as provide the ability to do ‘dose painting,’ delivering a highly customized form of radiation therapy for each patient,” she said.

Hendrickson and colleagues demonstrated that the feasibility of using FDG and FMISO PET imaging for delineating gross tumor volume and in directing dose-escalated IMRT to hypoxic sub-volumes of head and neck cancer.

Further studies are needed to compare static imaging and dynamic imaging to influence radiation treatment planning decisions in patients with head and neck cancer, concluded Hendrickson and colleagues.