Multi-criteria optimization for planning volumetric-modulated arc therapy for prostate cancer

Abstract

We aimed to compare the volumetric-modulated arc therapy (VMAT) plans with or without multi-criteria optimization (MCO) on commercial treatment-planning systems (Eclipse, Varian Medical System, Palo Alto, CA, USA) for patients with prostate cancer. We selected 25 plans of patients with prostate cancer who were previously treated on the basis of a VMAT plan. All plans were imported into the Eclipse Treatment Planning System version 15.6, and re-calculation and re-optimization were performed. The MCO plan was then generated. The dosimetric quality of the plans was evaluated using dosimetric parameters and dose indices that account for target coverage and sparing of the organs at risk (OARs). We defined the rectum, bladder, and bilateral femoral heads. The VMAT-MCO plan offers an improvement of gross treatment volume coverage with increased minimal dose and reduced maximal dose. In the planning treatment volume, the Dmean and better gradient, homogeneity, and conformity indexes improved despite the increasing hot and cold spots. When implemented through the MCO plan, a steeper fall off the adjacent OARs in the overlap area was achieved to obtain lower dose parameters. MCO generated better sparing of the rectum and bladder through a tradeoff of the increasing dose to the bilateral femoral heads within the tolerable dose constraints. Compared with re-optimization and re-calculation, respectively, significant dose reductions were observed in the bladder (241 cGy and 254 cGy; p<0.001) and rectum (474 cGy and 604 cGy, p<0.001) with the MCO. Planning evaluation and dosimetric measurements showed that the VMAT-MCO plan using visualized navigation can provide sparing of OAR doses without compromising the target coverage in the same OAR dose constraints.

ICON-P – A double-blind evaluation of quality improvements with individualized CONstraints from low-cost knowledge-based radiation therapy planning in prostate cancer

“…Here beam profiles are optimized in an automated stepwise iterative sequence based on both established (hard) constraints and physician-defined optional objectives (soft constraints) ranked a priori to achieve a plan that achieves all the hard constraints and as many of the soft constraints as possible as measured by an optimal Pareto surface [16] . Commercial solutions like the Elekta iCycle, and implementations within Varian Eclipse and Raystation have been reported [17] , [18] , [19] .…”

Comparative Study of Eclipse and RayStation Multi-Criteria Optimization-Based Prostate Radiotherapy Treatment Planning Quality

“…Sometimes, clinicians prefer reducing the dose given to the rectum to mitigate the risk of rectal toxicity at the expense of dose reduction to the PTV within an acceptable range, resulting in a decrease of treatment effectiveness [ 14 , 15 ]. Achieving the right balance between risk mitigation and effective treatment outcomes for each patient requires an iterative process of parameter tuning and multiple re-optimizations, which can be highly time-consuming when performed by a RT treatment planner manually [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

“…To address this time-consuming issue and improve RT plan quality, multi-criteria optimization (MCO) has become available in commercial RT treatment planning systems such as RaySearch Laboratories AB RayStation (Stockholm, Sweden) [ 17 , 18 , 20 , 22 , 23 , 24 , 25 , 26 , 27 ], and Varian Medical Systems, Inc. Eclipse (Palo Alto, CA, USA) over the last decade [ 16 , 17 , 20 , 21 , 24 , 28 ]. This function allows the planner to use an intuitive interface to explore a series of Pareto optimal plans with different dosimetric trade-offs between PTV coverage and OARs sparing through a Pareto surface (also known as Pareto front).…”

“…All Pareto optimal plans on the Pareto surface are automatically computed by the planning system based on objectives set by the planner. A treatment plan is considered Pareto optimal when any improvement in one objective can only be achieved with another scarified [ 16 , 17 , 18 , 19 , 22 ].…”

“…A few studies have specifically evaluated the use of the MCO function of RayStation [ 23 , 25 , 26 ] and Eclipse [ 17 ] treatment planning systems for prostate RT planning. In 2014, Ghandour et al [ 26 ] conducted the first clinical study to evaluate the RayStation MCO function with nine prostate cancer patients and reported that the MCO plan quality was comparable to the traditional approach but with the added benefit of planning time reduction.…”