Sampling issues for optimization in radiotherapy

Ferris, Michael C.; Einarsson, Rikhardur; Jiang, Zi‐Tao; Shepard, David

doi:10.1007/s10479-006-0083-y

Cited by 9 publications

(6 citation statements)

References 26 publications

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“…Here the tailEUD is basically a sum of "underdose ramps", similar to those used in one of our previous papers [10], see also [8]. This first order approximation of the tail EUD (equation 2.12) is in fact completely independent of the choice of f. Incidentally, unlike most other underdose measures that have been used as planning objectives, tailEUD has a non-zero slope at D i = D. It remains to be seen, how well the approximations (2.11, 2.12) agree with the exact tail EUD from equation 2.7.…”

Section: Tail Eudmentioning

confidence: 98%

Evaluating Target Cold Spots By the use of Tail EUDs

Bortfeld

Craft

Dempsey

et al. 2008

International Journal of Radiation Oncology*Biology*Physics

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Purpose-To propose a new measure of target underdose that can be used in the evaluation and optimization of radiotherapy dose distributions.Methods and Materials-We compare various formulations of the equivalent uniform dose (EUD) and introduce a modification of existing EUD definitions, which we call tail EUD. Tail EUD is a measure of "cold spots" below the prescription dose in the target dose distribution. It has units of Gy. We investigate the mathematical properties of various target EUD concepts, including tail EUD. We apply the tail EUD measure retrospectively to intensity modulated radiation therapy (IMRT) treatment plans from our plan database. We also use tail EUD as an optimization objective in the optimization of prostate, pancreas, and head&neck plans.Results-Tail EUD has desirable mathematical properties. In particular, it is convex and it leads to convex level sets (i.e., no local minima) if the EUD from which it is derived is concave. The tail EUD value is correlated with the subjective degree of target coverage. Constraining tail EUDs to a certain level in plan optimization leads to comparable target coverage in different plans and treatment sites.Conclusions-The newly introduced concept of tail EUD appears to be useful both for plan evaluation and optimization. In addition, it can potentially be applied in the design of new clinical protocols.

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Section: Tail Eudmentioning

confidence: 98%

Evaluating Target Cold Spots By the use of Tail EUDs

Bortfeld

Craft

Dempsey

et al. 2008

International Journal of Radiation Oncology*Biology*Physics

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“…For more in-depth study of this area, go to http://www.trinity.edu/aholder/HealthApp/oncology/ for a depository of recent papers and a list of interested researchers. [27,28] developed optimization tools for radiation treatment planning in the MATLAB programming environment. Their optimization tools apply in both the intensity modulated radiation therapy environment and/or the three-dimensional conformal radiotherapy environment.…”

Section: Performance Improvementmentioning

confidence: 99%

Operations research

Pierskalla¹

2009

Information Knowledge Systems Management

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Prologue:In Evita, Andrew Lloyd Webber and Tim Rice wrote: Politics, the Art of the Possible. To those of us in the operations research community, we postulate: Operations Research, the Science of Better -(i.e. better processes, better systems and better decisions). Using our own and other scientific, engineering, mathematical, and social sciences methodologies, operations researchers help decision makers make better decisions; decisions leading to improvements: greater quality, lower costs, greater revenues, better access, better scheduling, lower risks, more satisfaction -with the goal of always striving for the best or optimal decisions.1389-1995/09/$17.00  2009 -IOS Press and the authors. All rights reserved 242 W.P. Pierskalla / Operations research sectors, health-care sectors, and virtually every other sector in which strategic or operational decisions must be made to improve planning, performance and outcomes.Most operations research applications involve analyzing complex situations. The approach taken begins by looking at the complex situation from a systems perspective. Inside the system, processes are diagrammed and analyzed and a model is constructed based on the flows of people, products, services, technologies and information. Using this structure, the approach models the objectives desired to be achieved, the fixed and variable constraints on the system, all available options for decisions, evaluation of all possible outcomes, estimation of risks and bringing to bear the latest tools and techniques leading to improved or optimal decisions on system operation and outcomes. In most applications, it is frequently the case that multiple objectives such as to improve quality, lower costs, improve access and improve satisfaction are simultaneously achieved. In some cases, multiple objectives trade-off against one another and the decision maker has to weigh these objectives and choose among them. In this latter situation, operations research also provides decision analytic methodologies for optimally weighing and choosing among competing objectives.Because this book is about "Engineering the Health Care System", this chapter will be devoted to operations research applications in health care delivery with mentions of theory and methodologies as appropriate. We have space to cover only some of the applications from the thousands available but hope to do so with enough breadth of topic and depth of description to give a flavor for the capabilities of operations research in developing better or best solutions for many complex health care issues. If one wishes to have a brief introduction to the theory and methodologies mentioned in this chapter see Gass and Harris [35] and the website Wikipedia, http://en.wikipedia.org/wiki/Main Page.Operations research has been used in the development of theories and methodologies and in applications in many areas of health services delivery. Some of these areas are strategic in decision making and others are operational. Some examples are:1. Health care and health care syst...

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“…Examples of the benefits of this procedure on breast, pancreatic, head, and neck cases, for example, can be found in Ferris et al (2004).…”

Section: Computational Performancementioning

confidence: 99%

An Optimization Framework for Conformal Radiation Treatment Planning

Lim

Ferris

Wright

et al. 2007

INFORMS Journal on Computing

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A n optimization framework for three-dimensional conformal radiation therapy is presented. In conformal therapy, beams of radiation are applied to a patient from different directions, where the aperture through which the beam is delivered from each direction is chosen to match the shape of the tumor, as viewed from that direction. Wedge filters may be used to produce a gradient in beam intensity across the aperture. Given a set of equispaced beam angles, a mixed-integer linear program can be solved to determine the most effective angles to be used in a treatment plan, the weight (exposure time) to be used for each beam, and the type and orientation of wedges to be used. Practical solution techniques for this problem are described; they include strengthening of the formulation and solution of smaller approximate problems obtained by a reduced parametrization of the treatment region. In addition, techniques for controlling the dose-volume histogram implicitly for various parts of the treatment region using hot-and cold-spot control parameters are presented. Computational results are given that show the effectiveness of the proposed approach on practical data sets.

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Sampling issues for optimization in radiotherapy

Cited by 9 publications

References 26 publications

Evaluating Target Cold Spots By the use of Tail EUDs

Evaluating Target Cold Spots By the use of Tail EUDs

Operations research

An Optimization Framework for Conformal Radiation Treatment Planning

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