title: Multisession Radiosurgery for Hearing Preservation.
abstract: Clinically relevant dose-tolerance limits with reliable estimates of risk in 1-5 fractions for cochlea are still unknown. Timmerman׳s limits from the October 2008 issue of Seminars in Radiation Oncology have served as the basis for clinical practice, augmented by updated constraints in TG-101 and QUANTEC, but the corresponding estimates of risk have not yet been well-reported. A total of 37 acoustic neuroma CyberKnife cases from Medstar Georgetown University Hospital treated in 3 or 5 fractions were combined with single-fraction Gamma Knife data from the 69 cases in Timmer 2009 to form an aggregate dataset of 106 cochlea cases treated in 1-5 fractions. Probit dose-response modeling was performed in the DVH Evaluator software to estimate normal tissue complication probability. QUANTEC recommends keeping single-fraction maximum dose to the cochlea less than 14Gy to maintain less than 25% risk of serviceable hearing loss, and our 17.9% risk estimate for 14Gy in 1 fraction is within their predicted range. In 5 fractions, our estimate of the Timmerman 27.5Gy maximum cochlea dose limit was 17.4%. For cases in which lower risk is required, the Timmerman 12Gy in 1 fraction and the TG-101 limit of 25Gy in 5 fractions had an estimated risk level of 11.8% and 13.8%, respectively. High-risk and low-risk dose tolerance with risk estimates in 1-5 fractions are all presented.
authors.affiliation: Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, DC. Electronic address: axr11@gunet.georgetown.edu.
authors.forename: Abdul
authors.initials: A
authors.lastname: Rashid
authors.affiliation: Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Sana D
authors.initials: SD
authors.lastname: Karam
authors.affiliation: Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Beenish
authors.initials: B
authors.lastname: Rashid
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Dalong
authors.initials: D
authors.lastname: Pang
authors.affiliation: Department of Neurosurgery, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Walter
authors.initials: W
authors.lastname: Jean
authors.affiliation: Bott Cancer Center, Holy Redeemer Hospital, Meadowbrook, PA.
authors.forename: Jimm
authors.initials: J
authors.lastname: Grimm
authors.affiliation: Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, DC.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Collins
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003051:Cochlea / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D005260:Female; D034381:Hearing Loss / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000532:radiotherapy*; D011829:Radiation Dosage; D011836:Radiation Tolerance; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult