title: Implementation of an analytical model for leakage neutron equivalent dose in a proton radiotherapy planning system.
abstract: Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects.
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. jeley@som.umaryland.edu.|Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030, USA. jeley@som.umaryland.edu.
authors.forename: John
authors.initials: J
authors.lastname: Eley
authors.affiliation: Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803, USA. newhauser@lsu.edu.|Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809, USA. newhauser@lsu.edu.
authors.forename: Wayne
authors.initials: W
authors.lastname: Newhauser
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. khomann@houstonmethodist.org.|Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030, USA. khomann@houstonmethodist.org.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Homann
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. rhowell@mdanderson.org.|Graduate School of Biomedical Sciences, The University of Texas, 6767 Bertner Ave., Houston, TX 77030, USA. rhowell@mdanderson.org.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Howell
authors.affiliation: Department of Physics and Astronomy, Louisiana State University and Agricultural and Mechanical College, 202 Nicholson Hall, Tower Drive, Baton Rouge, LA 70803, USA. cschn19@tigers.lsu.edu.|Mary Bird Perkins Cancer Center, 4950 Essen Lane, Baton Rouge, LA 70809, USA. cschn19@tigers.lsu.edu.
authors.forename: Christopher
authors.initials: C
authors.lastname: Schneider
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291, Germany. m.durante@gsi.de.
authors.forename: Marco
authors.initials: M
authors.lastname: Durante
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291, Germany. christoph.bert@uk-erlangen.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bert