| An exact approach to direct aperture optimization in IMRT treatment planning. | |
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MedLine Citation:
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PMID: 18065842 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We consider the problem of intensity-modulated radiation therapy (IMRT) treatment planning using direct aperture optimization. While this problem has been relatively well studied in recent years, most approaches employ a heuristic approach to the generation of apertures. In contrast, we use an exact approach that explicitly formulates the fluence map optimization (FMO) problem as a convex optimization problem in terms of all multileaf collimator (MLC) deliverable apertures and their associated intensities. However, the number of deliverable apertures, and therefore the number of decision variables and constraints in the new problem formulation, is typically enormous. To overcome this, we use an iterative approach that employs a subproblem whose optimal solution either provides a suitable aperture to add to a given pool of allowable apertures or concludes that the current solution is optimal. We are able to handle standard consecutiveness, interdigitation and connectedness constraints that may be imposed by the particular MLC system used, as well as jaws-only delivery. Our approach has the additional advantage that it can explicitly account for transmission of dose through the part of an aperture that is blocked by the MLC system, yielding a more precise assessment of the treatment plan than what is possible using a traditional beamlet-based FMO problem. Finally, we develop and test two stopping rules that can be used to identify treatment plans of high clinical quality that are deliverable very efficiently. Tests on clinical head-and-neck cancer cases showed the efficacy of our approach, yielding treatment plans comparable in quality to plans obtained by the traditional method with a reduction of more than 75% in the number of apertures and a reduction of more than 50% in beam-on time, with only a modest increase in computational effort. The results also show that delivery efficiency is very insensitive to the addition of traditional MLC constraints; however, jaws-only treatment requires about a doubling in beam-on time and number of apertures used. Finally, we showed the importance of accounting for transmission effects when assessing or, preferably, optimizing treatment plan quality. |
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Authors:
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Chunhua Men; H Edwin Romeijn; Z Caner Taşkin; James F Dempsey |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S. Date: 2007-12-05 |
Journal Detail:
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Title: Physics in medicine and biology Volume: 52 ISSN: 0031-9155 ISO Abbreviation: Phys Med Biol Publication Date: 2007 Dec |
Date Detail:
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Created Date: 2007-12-10 Completed Date: 2008-04-04 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0401220 Medline TA: Phys Med Biol Country: England |
Other Details:
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Languages: eng Pagination: 7333-52 Citation Subset: IM |
Affiliation:
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Department of Industrial and Systems Engineering, University of Florida, Gainesville, Florida 32611-6595, USA. chhmen@ufl.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Artifacts Clinical Protocols Computer Simulation Dose-Response Relationship, Radiation Head and Neck Neoplasms / ultrasonography Humans Numerical Analysis, Computer-Assisted Phantoms, Imaging Radiotherapy Dosage Radiotherapy Planning, Computer-Assisted / methods* Radiotherapy, Intensity-Modulated / methods* Relative Biological Effectiveness Reproducibility of Results Sensitivity and Specificity |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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