Adaptive Radiation Therapy Planning Using Fluorodeoxyglucose PET -- Locally Advanced Cervical Cancer

Purpose: To review the benefits and detriments of using PET scan in the adaptive treatment planning for cervical cancer radiation therapy and evaluate coverage of PET avid tumor for patients recently treated at Rush Copley Medical Center.;Methods: A thorough literature review was completed for the use of PET scan in adaptive radiation planning. Then, 5 patient plans were reviewed using pre-treatment PET scan. Dose distributions were analyzed. Dose volume histograms and specific parameters were calculated for each patient plan. Plans were reviewed to see if adequate dose coverage was achieved to target the PET volume.;Results: The literature review shows that while PET scan can be used for adaptive radiation therapy, there is still much unknown regarding its potential use. There is a correlation between PET scan response and overall outcome for patients with locally advanced cervical cancer. The chart review shows significant under-dosing of PET avid areas with current treatment techniques, even after subtracting normal tissue contours. Each patient had D90 of < 87Gy and D100 of < 67 Gy. New plans can be created to adequately target the staging PET scan volume but not without sacrificing normal tissue.;Conclusions: PET response has been shown to correlate with positive outcomes for local control for patients with locally advanced cervical cancer. Current treatment plans do not adequately cover staging PET avid target volumes. Treatment plans targeting staging PET avid target volumes results in excess dose to normal structures. Adaptive radiation therapy applied to PET scanning just prior to brachytherapy insertions may provide an attractive method to improve dose to PET avid regions and possibly improve outcomes while limiting toxicity. Using pretreatment PET scan does not provide sufficient accuracy for brachytherapy planning.