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Since 2018, physicists at the radiotherapy department at St. Olavs Hospital, Trondheim, have developed Python scripts for automating VMAT treatment planning in RayStation for several tumor localizations [1,2]. VMAT delivers conform radiation doses to tumor volumes while sparing the nearby organs at risk (OARs). Automation reduces the time spent on planning while keeping, or improving, treatment quality.
WBRT is a palliative treatment for patients with multiple brain metastases, mainly aiming to reduce symptoms and extend the patient’s lifespan [3]. Our script automatically produces WBRT plans with a homogeneous and conform dose to the target volume while minimizing the dose to the OARs. The script improves treatment consistency and is now in clinical use.
A major drawback of WBRT is the risk of cognitive decline [4]. Several studies indicate that a reduced hippocampal dose may lower the risk of cognitive decline and thus increase the quality of life of the patients [5]. Nevertheless, WBRT with hippocampal avoidance (HA-WBRT) is not routinely used in Scandinavia and remains debated internationally. A key challenge of HA-WBRT is its resource-intensive planning and delivery process. We developed our WBRT script into a HA-WBRT script using a modified version of Yuen’s field set-up [6]. Compared to WBRT, the automatic HA-WBRT script reduces the dose to the hippocampi by more than 50% at the expence of a slightly less homogenous dose to the target volume. The basics of script-based planning can be used for other tumor locations in order to reduce time and effort spent by the treatment planner and increase overall plan quality and consistency.
[1] M. Funderud et al. ”Script-based automatic radiotherapy planning for cervical cancer”.Acta Oncologica, 62(12), 1798-1807.
[2] J. Frengen et al. ”Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique”. Acta Oncologica, 62(10), 1169–1177.
[3] E. McTyre et al. (2013). ”Whole brain radiotherapy for brain metastasis”. Surgical Neurology International. 4 (Suppl 4): S236 – S244.
[4] K. Johnson (June 2015). ”Whole-Brain Radiotherapy: Risks Worth Benefit?”. Medscape.com.
[5] PD. Brown et al. “Hippocampal Avoidance During Whole-Brain Radiotherapy Plus Memantine for Patients With Brain Metastases: Phase III Trial NRG Oncology CC001”. Journal of Clinical Oncology 2019:38:10:1019-1030.
[6] AHL. Yuen et al. ”Volumetric modulated arc therapy (VMAT) for hippocampal-sparing whole brain radiation therapy: planning comparison with Dual-arc and Split-arc partial-field techniques”. Radiation Oncology 2020:15:42.
