Cardiac Radiosurgery

Ventricular tachycardia or VT is a rapid, abnormal heart rhythm that can occur when scar tissue causes an electrical impulse to re-enter and repetitively excite the heart and often terminating with sudden death.  Cardiac Radiosurgery is a promising new modality for the treatment of VT. A challenge to treating VT with cardiac radiosurgery is the complicated motion environment of the heart.  The heart undergoes both respiratory motion and cardiac motion. One focus of our research is to quantify and develop new ways to compensate for this complicated motion environment. The intention of this work it to improve the precision of this treatment allowing minimal radiation to both the surrounding healthy heart and surrounding organs.

Shown above is a cardiac cine MRI image of the heart. The overlaid dots demonstrate the motion tracking we do to quantify the motion of the myocardium.

Above is a demonstration of a technology we have developed called Cardiac Synchronized Volumetric Modulated Arc Therapy (CS VMAT).  With CS VMAT radiation is delivered in very short pulses (roughly 200 msec). The radiation pulses are synchronised with the patient’s heartbeat such that they deliver during the quiescent interval of the cardiac cycle when the heart motion is minimal.

The above picture demonstrates the benefit of CS VMAT. By delivering radiation only during the quiescent intervals we can reduce the our treated volume from red area to that shown is green (shown in the left picture)

Team Members and Collaborators

Team Members:  Steven Thomas, Justin Poon, Tania Karan, Alanah Bergman, Don Ta

Collaborators:  Marc Deyell, Devin Schellenberg, Kirpal Kohli

Related Paper, Presentations and Posters

  • Poon J, Thompson R, Deyell M, Schellenberg D, Kohli K, Clark H, Thomas S, Treatment Window Determination for Cardiac Synchronized VMAT. Proc AAPM 2021
  •  Poon J, Kohli K, Schellenberg D, Deyell M, Thomas S, Effect of dose rate on cardiac synchronized volumetric modulated arc therapy. Proc AAPM 2021
  •  Thomas S, Ta D, Bergman A, Schellenberg D, Deyell M, Poon J, Karan T, Determining respiratory and cardiac motion margins for use in cardiac radiosurgery. Proc COMP 2021
  •  Ta D, Chan A, Thomas S. Development of a Cardiac and Respiratory Phantom (CARP) for use in Radiosurgery Dosimetry. CMBES Proc. [Internet]. 2021May11 [cited 2021Jun.7];44.
  •  Poon J, Kohli K, Deyell MW, Schellenberg D, Reinsberg S, Teke T, Thomas S. Cardiac Synchronized Volumetric Modulated Arc Therapy for Stereotactic Arrhythmia Radioablation–Proof of Principle. Medical Physics. 2020 May 16.
  •  Ta D, Thomas S, Karan T. “Development of a Cardiac Radioablation Phantom Incorporating Cardiac and Respiratory Motion.” Wescan 2020
  •  Justin Poon, Kirpal Kohli, Devin Schellenberg, Marc Deyell, Stefan Reinsberg, Tony Teke, Steven Thomas. Cardiac Synchronized Volumetric Modulated Arc Therapy Young Investigator Symposium Medical Physics. 2019 Nov;46(11).
  •  Karan T, Bergman A, Camborde ML, Poon J, Deyell M, Schellenberg D, Tran E, Ma R, Kohli K, Liu M, Thomas S. Markerless Tracking of Implantable Cardiac Defibrillator Leads for Radiosurgery: A feasibility study: Scientific Session 6: Special Techniques–01. Medical Physics. 2019 Nov;46(11).
  •  Poon J, Kohli K, Deyell M, Schellenberg D, Karan T, Camborde ML, Reinsberg S, Thomas S. Cardiac Lead Detection for Respiratory Motion Tracking: Implications for Cardiac Radiosurgery: Scientific Session 2: Highlights–04. Medical Physics. 2019 Nov;46(11).