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RayStation was designed from the very beginning with a strong focus on handling the dynamic aspects of radiation therapy. By explicitly representing the time dimension throughout the domain model, RayStation provides the ultimate framework for planning and managing adaptive radiation therapy. RayStation’s adaptive re-planning tools, combined with powerful deformation algorithms, can improve your planning process. These tools allow for more accurate treatment for your patients.

Deformable registration/ rayDeformable

When images of the patient in treatment position, from CT, PET/ CT, cone-beam CT or MR, are acquired during the treatment course, deformable image registration in RayStation allows structures on the planning data set to be propagated to the fraction data set for dose evaluation. It also allows the delivered dose to be deformed back to the planning CT and accumulated for a comparison with the planned dose up to that fraction.

  • Propagation of ROI contours or meshes between images, including 4D-CT;
  • Hybrid intensity and structure based deformation ANACONDA algorithm recommended for adaptive (GPU supported);
  • Biomechanical model based deformation algorithm (MORFEUS based);
  • Tools for analysis and evaluation of deformable registration.

Watch demonstration

Dose tracking/ rayTracker

By dose tracking, we evaluate the dose actually delivered to the patient. This evaluation can teach us important things such as the use of margins. Since we know that the patient geometry will change during the treatment, a generic large margin for the planning target has to be applied to account for that. But possibly this margin is actually too big for the individual patient, causing excess dose to organs-at-risk (OARs).

During the treatment, daily or at least regularily fraction images, e.g., cone beam CTs (CBCTs), are often acquired for patient positioning. In RayStation, it is possible to use these images to recalculate, deform and accumulate doses from different fractions in a common geometry, thereby computing the actual dose delivered to the patient anatomy.

  • Dose calculation based on CBCT;
  • Easy dose accumulation over fractions;
  • Dedicated workspace for evaluating deformable dose accumulation;
  • Fraction schedule shows delivered fractions, acquired images and available doses;
  • Synchronized side-by-side views of planned and delivered dose. 

Adaptive replanning/ rayAdaptive

Based on the information collected through dose tracking, a decision can be made whether or not to modify the treatment plan.

rayAdaptive provides a wide range of adaptive offline or online replanning tools that take into account the accumulated dose and observed deviations of the patient geometry. Plans can then be re-optimized and adjusted to compensate for dose coverage problems or to adapt to adjusted clinical goals.

The replanning options range from simple adaptations such as adjustments of beam weights to complete replanning that involves reoptimization of the intensity modulation.

  • Adaptive re-planning workspace.
  • Fraction schedule showing delivered and re-planned fractions.
  • Toolbar including relevant parts of plan creation, plan optimization and plan approval.
  • Adapted plan creation based on planned fractions.

Clinical case from Provision Center for Proton Therapy

This example demonstrates how important it can be to modify plans based on changes during treatment. A woman presented with a right breast cancer that was very large and invasive. It was expected that the patient would have a fast response so weekly QA CTs were performed during treatment.

Deformable registration was used to determine if the existing plan had adequate coverage. Soon after the treatment commenced, the scans showed significant changes that warranted replanning. The center used the adaptive planning function in RayStation to quickly replan the case and get back to the prescribed dose. The adaptive planning function does not require that the user re-enter the beam parameters or the inverse planning objectives. In total, four adapted plans were implemented over the course of treatment with only a day or so needed each time to complete the planning and quality assurance.

The sum of the doses was easily displayed so that an overall analysis could be made on the efficacy of the delivery. 

Adaptive planning in a case like this is simply unavoidable — in the case of protons that are sensitive to density and anatomical changes in the body, it would be impossible to plan this in an efficient and/or safe manner without advanced technologies such as deformable registration and adaptive therapy.

Figure 1: Original treatment plan
Figure 2: Adapted treatment plan