Journal article
Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics
International journal of radiation oncology, biology, physics, Vol.95(1), pp.171-180
05/01/2016
DOI: 10.1016/j.ijrobp.2015.08.030
PMID: 26614424
Abstract
To quantify the dosimetric benefit of using a dynamic collimation system (DCS) for penumbra reduction during the treatment of brain tumors by pencil beam scanning proton therapy (PBS PT).
Collimated and uncollimated brain treatment plans were created for 5 patients previously treated with PBS PT and retrospectively enrolled in an institutional review board-approved study. The in-house treatment planning system, RDX, was used to generate the plans because it is capable of modeling both collimated and uncollimated beamlets. The clinically delivered plans were reproduced with uncollimated plans in terms of target coverage and organ at risk (OAR) sparing to ensure a clinically relevant starting point, and collimated plans were generated to improve the OAR sparing while maintaining target coverage. Physical and biological comparison metrics, such as dose distribution conformity, mean and maximum doses, normal tissue complication probability, and risk of secondary brain cancer, were used to evaluate the plans.
The DCS systematically improved the dose distribution conformity while preserving the target coverage. The average reduction of the mean dose to the 10-mm ring surrounding the target and the healthy brain were 13.7% (95% confidence interval [CI] 11.6%-15.7%; P<.0001) and 25.1% (95% CI 16.8%-33.4%; P<.001), respectively. This yielded an average reduction of 24.8% (95% CI 0.8%-48.8%; P<.05) for the brain necrosis normal tissue complication probability using the Flickinger model, and 25.1% (95% CI 16.8%-33.4%; P<.001) for the risk of secondary brain cancer. A general improvement of the OAR sparing was also observed.
The lateral penumbra reduction afforded by the DCS increases the normal tissue sparing capabilities of PBS PT for brain cancer treatment while preserving target coverage.
Details
- Title: Subtitle
- Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics
- Creators
- Alexandra Moignier - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa. Electronic address: alexandra-moignier@uiowa.eduEdgar Gelover - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IowaDongxu Wang - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IowaBlake Smith - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IowaRyan Flynn - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IowaMaura Kirk - Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PennsylvaniaLiyong Lin - Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PennsylvaniaTimothy Solberg - Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PennsylvaniaAlexander Lin - Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PennsylvaniaDaniel Hyer - Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- International journal of radiation oncology, biology, physics, Vol.95(1), pp.171-180
- DOI
- 10.1016/j.ijrobp.2015.08.030
- PMID
- 26614424
- NLM abbreviation
- Int J Radiat Oncol Biol Phys
- ISSN
- 0360-3016
- eISSN
- 1879-355X
- Publisher
- Elsevier Inc; United States
- Grant note
- P30 CA086862 / NCI NIH HHS
- Language
- English
- Date published
- 05/01/2016
- Academic Unit
- Roy J. Carver Department of Biomedical Engineering; Radiation Oncology
- Record Identifier
- 9984046834302771
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