A feasibility study of 18F-fluorodeoxyglucose positron emission tomography targeting and simultaneous integrated boost for intensity-modulated radiosurgery and radiotherapy.
OBJECTIVE
The authors hypothesized that the efficacy of intensity-modulated radiation therapy (IMRT) can be enhanced by selectively increasing the radiation dose to the biologically active positron emission tomography (PET)-documented positive tumor subregions while simultaneously maintaining the overall clinically established target dose.


METHODS
The authors undertook a feasibility study to evaluate IMRT PET/computerized tomography (CT) protocol for boost treatment in selected cancer patients. Prior to treatment, FDG-PET and CT scans were acquired using an integrated PET/CT scanner, ensuring accurate correlation between image sets. After acquisition, tumor volume and objects-at-risk (OARs) were outlined on the CT scans; any PET-positive tumor subregions were similarly outlined. Daily dosages of 1.8 to 2 Gy were prescribed to tumor volume and the margin whereas additional dosages of 10 to 20% were delivered to PET-positive subregions. Dosage-volume histogram-derived constraints were used in inverse planning to specify the desired dose to one or more PET-positive tumor subregions, CT-delineated tumor volume, and OARs. The IMRT treatment was delivered using a micromultileaf collimator. Simultaneous integrated boost radiation was successfully delivered using IMRT with PET/CT planning. Excellent dose conformality was achieved in the tumor volume and the dose to PET-positive tumor subregions was increased while minimizing the dose to OARs.


CONCLUSIONS
When coupled with IMRT, PET/CT scanning allows dose escalation to biologically active subregions within the tumor volume. Further study is needed to determine if dose escalation to FDG-PET-active sites correlates with improved treatment outcome. Finally, in extracranial sites, PET scanning should only be performed with a dedicated PET/CT device because present image fusion technologies are inadequate for accurately registering deformable objects.
Solberg
Timothy D
TD
Department of Radiation Oncology, David Geffen School of Medicine, University of California, 90095-6951, USA. solberg@radonc.ucla.edu
Agazaryan
Nzhde
N
Goss
Bryan W
BW
Dahlbom
Magnus
M
Lee
Steve P
SP
D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000628:therapy*; D006801:Humans; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18