Quantitative assessment of the efficacy of two different treatment plan optimization algorithms in treating tumors in locations of high heterogeneity
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The purpose of this study is to evaluate the differences in treatment optimization algorithms in two leading treatment planning systems, Pinnacle v9.8 (Philips Healthcare, Amsterdam, Netherlands) and Raystation 8A (Raysearch Americas Inc., Garden City, USA). The aim is to compare and contrast between planning systems in terms of sparing of vital organs (SVO) using several gradient and conformity indices, as well as vital organ dose limits.
The study includes patients (N = 18) presenting with lung (10), liver (4), and head and neck (4) tumors and treated with intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) planned using the same objectives and weights, number of iterations, beam angles, and planning target volume (PTV) coverage. Both plans were analyzed for Radiation Therapy Oncology Group (RTOG) conformity index, Paddick conformity index, gradient index (GI), dose gradient index, and sparing of vital organs. This study utilized both segmented and dynamic approaches to multileaf collimation (SMLC and DMLC, respectively) in the Raystation planning system in lung IMRT plans, as some plans could not be optimized in Raystation with SMLC (7).
It was determined that in lung plans, Pinnacle demonstrated better sparing of the right lung and the spinal cord, but Raystation more effectively spared the heart and esophagus. In liver plans, Raystation demonstrated a superior GI, indicating faster dose falloff; this correlated with lower volumes of the liver receiving 24 Gy. In head and neck (H&N) plans, Pinnacle demonstrated superior sparing of the parotid but inferior GI, indicating more rapid dose falloff in Raystation beyond the PTV.
The analysis for the lung, liver, and H&N cases indicated that both planning systems are equivocal for the majority of parameters measured, with a few differentiating trends. In H&N plans, Pinnacle showed improved parotid sparing but inferior performance in calculated GI values. Liver plans showed superiority of Raystation in GI computations, but the most notable differences were in the lung plans where Pinnacle spared the spinal cord significantly more in contrast to Raystation’s performance but also delivered significantly more dose to the esophagus.
KeywordsTreatment planning system TPS Dosimetry Conformity
Paddick conformity index
RTOG conformity index
central nervous system
clinical target volume
dose gradient index
dynamic multileaf collimator
gross tumor volume
intensity modulated radiation therapy
organ at risk
prescription isodose volume
volume of the 50% prescription isodose
planning target volume
effective radius of the 50% prescription isodose
effective radius of the prescription isodose
region of interest
Radiation Therapy Oncology Group
segmented multileaf collimator
sparing of vital organs
treatment planning system
target volume, defined as the PTV for this study
volume of prescription isodose located within the target volume
volume of organ at risk
Compliance with ethical standards
No funding was received for this study.
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
Statement of informed consent was not applicable since the manuscript does not contain any patient data.
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