Original article Comparison of VMAT and IMRT strategies for cervical cancer patients using automated planning Abdul Wahab M. Sharfo ⇑ , Peter W.J. Voet, Sebastiaan Breedveld, Jan Willem M. Mens, Mischa S. Hoogeman, Ben J.M. Heijmen Department of Radiation Oncology, Erasmus MC-Cancer Institute, Rotterdam, The Netherlands article info Article history: Received 5 September 2014 Received in revised form 4 February 2015 Accepted 9 February 2015 Available online xxxx Keywords: VMAT IMRT Locally advanced cervical cancer Automated knowledge-based planning abstract Background and purpose: In a published study on cervical cancer, 5-beam IMRT was inferior to single arc VMAT. Here we compare 9, 12, and 20 beam IMRT with single and dual arc VMAT. Material and methods: For each of 10 patients, automated plan generation with the in-house Erasmus- iCycle optimizer was used to assist an expert planner in generating the five plans with the clinical TPS. Results: For each patient, all plans were clinically acceptable with a high and similar PTV coverage. OAR sparing increased when going from 9 to 12 to 20 IMRT beams, and from single to dual arc VMAT. For all patients, 12 and 20 beam IMRT were superior to single and dual arc VMAT, with substantial variations in gain among the study patients. As expected, delivery of VMAT plans was significantly faster than delivery of IMRT plans. Conclusions: Often reported increased plan quality for VMAT compared to IMRT has not been observed for cervical cancer. Twenty and 12 beam IMRT plans had a higher quality than single and dual arc VMAT. For individual patients, the optimal delivery technique depends on a complex trade-off between plan quality and treatment time that may change with introduction of faster delivery systems. Ó 2015 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology xxx (2015) xxx–xxx Introduction Volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy with static gantry angles (IMRT) have been compared for various tumour sites, both regarding plan qual- ity and treatment time [1]. In most studies, VMAT was a new tech- nology and plans were compared to previously delivered clinical IMRT plans. Systematic comparisons with variations in the number of IMRT beams and VMAT arcs are scarce [2–4]. Several studies on advanced cervical cancer have demonstrated reduced OAR doses with IMRT compared to 3D conformal radiotherapy [5–9]. To the best of our knowledge, only Cozzi et al. [10] have compared VMAT and IMRT for cervical cancer patients. Recently, we have developed Erasmus-iCycle, an optimizer for automated, multi-criterial beam profile optimization and beam angle selection for coplanar and non-coplanar IMRT [11–17]. In Erasmus-iCycle, the common manual, trial-and-error tweaking of plan parameters by dosimetrists is replaced by a fully automated procedure, based on lexicographic optimization. The automation allows objective comparison of treatment strategies, e.g. with vari- able numbers of IMRT beams, or considering non-coplanar vs. coplanar IMRT [14–16]. Currently, Erasmus-iCycle optimizes beam fluences. For generation of clinical plans, Erasmus-iCycle plans are reconstructed and segmented in the clinical treatment planning system (TPS). In a recent prospective study, we have demonstrated superior plan quality of Erasmus-iCycle plans that were ‘manually’ reconstructed in the clinical TPS (semi-automatic plan generation), compared to the clinical routine of trial-and-error treatment plan- ning. In 97% of cases, the treating physician selected the semi-au- tomatically generated plan for treatment, rather than the IMRT plan generated manually by a dosimetrist without prior knowledge of the Erasmus-iCycle result [17]. Apart from the improved plan quality, the semi-automated procedure also reduced the planning hands-on time by 50% compared to manual planning. Cozzi et al. [10] have retrospectively compared single arc VMAT plans with previously delivered 5-field equi-angular IMRT plans for treatment of cervical cancer patients. In this study, we have sys- tematically compared single and dual arc VMAT plans with IMRT plans with 9, 12 and 20 beams. All these plans were generated semi-automatically (above). Apart from the mutual comparisons, the semi-automatic plans were also compared to clinically delivered 9-beam IMRT plans. http://dx.doi.org/10.1016/j.radonc.2015.02.006 0167-8140/Ó 2015 Elsevier Ireland Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: a.sharfo@erasmusmc.nl (A.W.M. Sharfo). Radiotherapy and Oncology xxx (2015) xxx–xxx Contents lists available at ScienceDirect Radiotherapy and Oncology journal homepage: www.thegreenjournal.com Please cite this article in press as: Sharfo AWM et al. Comparison of VMAT and IMRT strategies for cervical cancer patients using automated planning. Radiother Oncol (2015), http://dx.doi.org/10.1016/j.radonc.2015.02.006