Multiobjective inverse planning for intensity modulated radiotherapy with constraint-free gradient-based optimization algorithms

Lahanas, M; Schreibmann, E; Baltas, D

dc.contributor.author	Lahanas, M	en
dc.contributor.author	Schreibmann, E	en
dc.contributor.author	Baltas, D	en
dc.date.accessioned	2014-03-01T01:19:18Z
dc.date.available	2014-03-01T01:19:18Z
dc.date.issued	2003	en
dc.identifier.issn	0031-9155	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15411
dc.subject.classification	Engineering, Biomedical	en
dc.subject.classification	Radiology, Nuclear Medicine & Medical Imaging	en
dc.subject.other	Algorithms	en
dc.subject.other	Constraint theory	en
dc.subject.other	Convergence of numerical methods	en
dc.subject.other	Dosimetry	en
dc.subject.other	Inverse problems	en
dc.subject.other	Optimization	en
dc.subject.other	Inverse planning	en
dc.subject.other	Radiotherapy	en
dc.subject.other	algorithm	en
dc.subject.other	article	en
dc.subject.other	brain tumor	en
dc.subject.other	controlled study	en
dc.subject.other	decision making	en
dc.subject.other	dosimetry	en
dc.subject.other	mathematical computing	en
dc.subject.other	modulation	en
dc.subject.other	priority journal	en
dc.subject.other	problem solving	en
dc.subject.other	process optimization	en
dc.subject.other	prostate cancer	en
dc.subject.other	radiation beam	en
dc.subject.other	radiation dose	en
dc.subject.other	radiation energy	en
dc.subject.other	radiotherapy	en
dc.subject.other	simulation	en
dc.subject.other	treatment planning	en
dc.subject.other	velocity	en
dc.subject.other	Algorithms	en
dc.subject.other	Brain Neoplasms	en
dc.subject.other	Humans	en
dc.subject.other	Linear Energy Transfer	en
dc.subject.other	Male	en
dc.subject.other	Neoplasms	en
dc.subject.other	Prostatic Neoplasms	en
dc.subject.other	Quality Control	en
dc.subject.other	Radiation Protection	en
dc.subject.other	Radiometry	en
dc.subject.other	Radiotherapy Dosage	en
dc.subject.other	Radiotherapy Planning, Computer-Assisted	en
dc.subject.other	Radiotherapy, Conformal	en
dc.subject.other	Reproducibility of Results	en
dc.subject.other	Sensitivity and Specificity	en
dc.title	Multiobjective inverse planning for intensity modulated radiotherapy with constraint-free gradient-based optimization algorithms	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0031-9155/48/17/308	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0031-9155/48/17/308	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	We consider the behaviour of the limited memory L-BFGS algorithm as a representative constraint-free gradient-based algorithm which is used for multiobjective (MO) dose optimization for intensity modulated radiotherapy (IMRT). Using a parameter transformation, the positivity constraint problem of negative beam fluences is entirely eliminated: a feature which to date has not been fully understood by all investigators. We analyse the global convergence properties of L-BFGS by searching for the existence and the influence of possible local minima. With a fast simulated annealing (FSA) algorithm we examine whether the L-BFGS solutions are globally Pareto optimal. The three examples used in our analysis are a brain tumour, a prostate tumour and a test case with a C-shaped PTV. In 1% of the optimizations global convergence is violated. A simple mechanism practically eliminates the influence of this failure and the obtained solutions are globally optimal. A single-objective dose optimization requires less than 4 s for 5400 parameters and 40 000 sampling points. The elimination of the problem of negative beam fluences and the high computational speed permit constraint-free gradient-based optimization algorithms to be used for MO dose optimization. In this situation, a representative spectrum of possible solutions is obtained which contains information such as the trade-off between the objectives and range of dose values. Using simple decision making tools the best of all the possible solutions can be chosen. We perform an MO dose optimization for the three examples and compare the spectra of solutions, firstly using recommended critical dose values for the organs at risk and secondly, setting these dose values to zero.	en
heal.publisher	IOP PUBLISHING LTD	en
heal.journalName	Physics in Medicine and Biology	en
dc.identifier.doi	10.1088/0031-9155/48/17/308	en
dc.identifier.isi	ISI:000185573300008	en
dc.identifier.volume	48	en
dc.identifier.issue	17	en
dc.identifier.spage	2843	en
dc.identifier.epage	2871	en