Intensity modulated radiation therapy class solutions in Philips Pinnacle treatment planning for central nervous system malignancies: Standardized, efficient, and effective

Background: The use of intensity modulated radiation therapy (IMRT) is becoming more commonplace in the treatment of central nervous system (CNS) malignancies. However, the determination of beam arrangements is still an empirical process, and optimization of any given plan may take hours on the part of the dosimetrist and the physician to achieve optimal conformity and normal tissue doses. Regional CNS class solutions (CS) for IMRT planning with the Philips Pinnacle treatment planning system (version 8.0; ADAC Laboratories, Milpitas, CA) have been in partial implementation at our institution since 2009. The purpose of this present work was to investigate their validity in clinical practice.Materials and Methods: The plans of 55 patients treated for high-grade gliomas since 2009 were analyzed retrospectively. Thirty plans were categorized as having been planned with class solutions and 25 plans with user-defined optimization. Each plan was evaluated based on the following: (1) mean dose to the brain; (2) brain V30; and (3) Radiation Therapy Oncology Group (RTOG) conformity index (CI _RTOG). These data were then compared with 140 historical benchmark plans that were generated using user-defined optimization prior to 2009.Results: The CS plans for gliomas in frontal, parietal-occipital, and temporal regions typically resulted in superior mean brain dose, brain V30, and conformity index when compared with user-defined plans. The CS plans for brainstem gliomas exhibited improved CI _RTOG, but not brain V30 and brain mean dose. In trials of planning efficiency, the CS technique reduced treatment planning time by more than 2 times, independent of prior planning experience.Conclusions: We have developed a CS protocol for IMRT planning of gliomas that has dramatically simplified this complex planning process, allowing dosimetrists of all levels of experience to produce highly conformal plans in a time efficient manner.