Poster - 31: Predicting IQ and hearing loss following radiotherapy in pediatric brain tumors: proton vs photon

Journal Article · Mon Aug 15 04:00:00 EDT 2016 · Medical Physics

DOI:https://doi.org/10.1118/1.4961805· OSTI ID:22689338

Fortin, Dominique; Ng, Angela; Tsang, Derek; Sharpe, Michael; Laperriere, Norm; Hodgson, David ^[1]

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1. Princess Margaret Cancer Centre, University of Toronto (Canada)

Purpose: The increased sparing of normal tissues in intensity modulated proton therapy (IMPT) in pediatric brain tumor treatments should translate into improved neurocognitive outcomes. Models were used to estimate the intelligence quotient (IQ) and the risk of hearing loss 5 years post radiotherapy and to compare outcomes of proton against photon in pediatric brain tumors. Methods: Patients who had received intensity modulated radiotherapy (IMRT) were randomly selected from our retrospective database. The existing planning CT and contours were used to generate IMPT plans. The RBE-corrected dose was calculated for both IMPT and IMRT. For each patient, the IQ was estimated via a Monte Carlo technique, whereas the reported incidence of hearing loss as a function of cochlear dose was used to estimate the probability of occurrence. Results: The integrated brain dose was reduced in all IMPT plans, translating into a gain of 2 IQ points on average for protons for the whole cohort at 5 years post-treatment. In terms of specific diseases, the gains in IQ ranged from 0.8 points for medulloblastoma, to 2.7 points for craniopharyngioma. Hearing loss probability was evaluated on a per-ear-basis and was found to be systematically less for proton versus photon: overall 2.9% versus 7.2%. Conclusions: A method was developed to predict IQ and hearing outcomes in pediatric brain tumor patients on a case-by-case basis. A modest gain was systematically observed for proton in all patients. Given the uncertainties within the model used and our reinterpretation, these gains may be underestimated.

• OSTI ID: 22689338
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 8 Vol. 43; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
AUDITORY ORGANS
BRAIN
MONTE CARLO METHOD
NEOPLASMS
PATIENTS
PEDIATRICS
PHOTONS
PLANNING
PROTON BEAMS
RADIATION DOSES
RADIOTHERAPY