NKI – Accurate Dose Delivery for Radiation Therapy: Adapting Treatment to Daily Anatomy #SWI2015
For radiation oncology, we treat patients with head and neck tumours over the course of 6-7 weeks. This treatment is usually based on one CT scan prior to treatment. We use that as an input for dose calculations in the patient based on a collapsed cone superposition algorithm. To optimise the dose distribution we use an inverse optimization algorithm, all in commercial software. Typically, the computation and optimization times require about 1-2 hours for this patient group. This is translated into settings of the linear accelerator that is used to deliver the dose to the patient.
From experience, we know that the daily posture of the patients is not the same as it was during the CT scan. We already have tools to compute the deformation vector field to map one posture to the other. Our request is to devise clever ways to translate this deformation to adjusted settings of the linear accelerator, such that the intended dose is delivered despite the different patient anatomy. The deformations may include tumor shrinkage or swelling of healthy tissue.