Introducing Pareto Front Evaluation As A Concept For Objective Evaluation Of Inverse Planning And Delivery Techniques

Main Category: Radiology / Nuclear Medicine
Also Included In: Cancer / Oncology
Article Date: 22 Sep 2008 - 4:00 PDT

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Pareto optimality is a concept that formalises the trade-off between a given set of mutually contradicting objectives. A solution is Pareto optimal when it is not possible to improve one objective without deteriorating at least one of the other. A set of Pareto optimal solutions constitute the Pareto front.

The Pareto concept applies well to the inverse planning process, which involves inherently contradictory objectives, i.e. high and uniform target dose on one hand, and sparing of surrounding tissue and nearby OARs on the other. Due to the specific characteristics of a TPS or delivery technique the Pareto front for a given case is likely to differ from one TPS or delivery technique to another. The purpose of this study was to design and test a method that may be used as an evaluation tool for TPSs and delivery techniques.

A number of plans with varying target conformity and sparing of OAR were created for different TPSs and delivery techniques. OAR. Case specific Pareto fronts were created based on the aforementioned parameters.

Pareto fronts were successfully sampled for all cases studied. All produced Pareto fronts did indeed follow the definition of the Pareto concept.

The issue of designing a model for unbiased comparison of parameters with such large inherent dis¬crepancies as different TPSs or delivery techniques proved problematic. Different TPSs, for instance, may differ in strictly physical parameters while biological parameters may be comparable.

It is concluded that it is possible to use Pareto front evaluation as a comparative tool for a number of parameters in radiotherapy. Examples of such parameters are optimisation algorithms of TPSs, the variation between accelerators or delivery techniques and the degradation of a plan during the treatment planning process.

Ottosson Rickard et al. Department of Oncology (R), University Hospital Herlev, Herlev, Denmark

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