Breast treatments represent 25% of all cases treated with radiation therapy. The close proximity of the target volume to sensitive organs along with significant respiratory-induced movements presents some unique challenges that are difficult to handle using only conventional IGRT methods.
Specifically, the positioning of the arms is known to have an influence on the treatment volume (1).
However, the arms are outside of the field of view and therefore not possible to visualize using the commonly employed IGRT system such as CBCT, orthogonal kV or EPID.
Catalyst™ offers a complete solution for online patient tracking before and during treatment delivery, thus ensuring the best possible treatment outcome without non-prescribed dose.
1 A pilot study of breast cancer patient positioning using optical surface scanning and reprojection. Mattias Jönsson et al. Lund University 2012.
Deep inspiration breath hold
For left breast treatments, deep inspiration breath hold treatment is a proven method for minimizing the dose delivered to the heart muscle while maximizing the dose to the treatment volume. In contrast with most other gating systems, the Catalyst™ system will monitor the respiratory motion without requiring any markers or fiducials to be placed on the patient. General patient motion is also monitored in parallel, thus ensuring maximum patient safety.
Setup and Positioning
During setup, the Catalyst™ system provides true interactive visual guidance by projecting information regarding the required adjustments directly onto the patient’s skin.
This ensures that any significant posture and errors are eliminated early in the process, while these are still easy to correct.
Once initial setup is completed, the Catalyst™ system will continue to monitor the patient’s posture and position during treatment. Large patient movements will immediately trigger an alarm and/or beam hold.
The Catalyst™ system is also continuously calculating the isocentric shift, which enables the detection of slower movements such as the patient relaxing or gradually sliding out of position. These deviations are typically not possible to detect using only the conventional room camera systems.
Respiration gating window setup - Sentinel 4D CT
Sentinel 4D CT helps to set up the gating window of DIBH treatment as well as the free breathing pattern in CT room. This provides maximum flexibility to adapt to different patient capabilities and clinical requirements.
The typical gating window setup with Sentinel 4D CT is 2-3mm* and patient baseline is calculated as an absolute parameter that can be used during the treatment delivery.
* the recommendation of gating window setup by Swedish Gating Workgroup is <4mm.