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Evaluation of a commercial biologically based IMRT treatment planning system
Author(s) -
Semenenko Vladimir A.,
Reitz Bodo,
Day Ellen,
Qi X. Sharon,
Miften Moyed,
Li X. Allen
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3013556
Subject(s) - multileaf collimator , radiation treatment planning , dosimetry , nuclear medicine , radiation therapy , relative biological effectiveness , medicine , computer science , medical physics , radiology , radiation , physics , quantum mechanics
A new inverse treatment planning system (TPS) for external beam radiation therapy with high energy photons is commercially available that utilizes both dose‐volume‐based cost functions and a selection of cost functions which are based on biological models. The purpose of this work is to evaluate quality of intensity‐modulated radiation therapy (IMRT) plans resulting from the use of biological cost functions in comparison to plans designed using a traditional TPS employing dose‐volume‐based optimization. Treatment planning was performed independently at two institutions. For six cancer patients, including head and neck (one case from each institution), prostate, brain, liver, and rectal cases, segmental multileaf collimator IMRT plans were designed using biological cost functions and compared with clinically used dose‐based plans for the same patients. Dose‐volume histograms and dosimetric indices, such as minimum, maximum, and mean dose, were extracted and compared between the two types of treatment plans. Comparisons of the generalized equivalent uniform dose (EUD), a previously proposed plan quality index ( f EUD ) , target conformity and heterogeneity indices, and the number of segments and monitor units were also performed. The most prominent feature of the biologically based plans was better sparing of organs at risk (OARs). When all plans from both institutions were combined, the biologically based plans resulted in smaller EUD values for 26 out of 33 OARs by an average of 5.6 Gy (range 0.24 to 15 Gy ). Owing to more efficient beam segmentation and leaf sequencing tools implemented in the biologically based TPS compared to the dose‐based TPS, an estimated treatment delivery time was shorter in most (five out of six) cases with some plans showing up to 50% reduction. The biologically based plans were generally characterized by a smaller conformity index, but greater heterogeneity index compared to the dose‐based plans. Overall, compared to plans based on dose‐volume optimization, plans with equivalent target coverage obtained using the biologically based TPS demonstrate improved dose distributions for the majority of normal structures.