Justin Poon1, Kirpal Kohli2, Marc W Deyell3, Devin Schellenberg4, Stefan Reinsberg1, Tony Teke5, Steven Thomas6. 1. Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada. 2. Department of Medical Physics, BC Cancer -Surrey, Surrey, BC, V3V 1Z2, Canada. 3. Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, BC, V6E 1M7, Canada. 4. Department of Radiation Oncology, BC Cancer -Surrey, Surrey, British Columbia, V3V 1Z2, Canada. 5. Department of Medical Physics, BC Cancer -Kelowna, Kelowna, BC, V1Y 5L3, Canada. 6. Department of Medical Physics, BC Cancer -Vancouver, Vancouver, BC, V5Z 4E6, Canada.
Abstract
PURPOSE: Ventricular tachycardia (VT) is a rapid, abnormal heart rhythm that can lead to sudden cardiac death. Current treatment options include antiarrhythmic drug therapy and catheter ablation, both of which have only modest efficacy and have potential complications. Cardiac radiosurgery has the potential to be a noninvasive and efficient treatment option for VT. Cardiac motion, however, must be accounted for to ensure accurate dose delivery to the target region. Cardiac synchronized volumetric modulated arc therapy (CSVMAT) aims to minimize the dose delivered to normal tissues by synchronizing beam delivery with a cardiac signal, irradiating only during the quiescent intervals of the cardiac cycle (when heart motion is minimal) and adjusting the beam delivery speed in response to heart rate changes. METHODS: A CSVMAT plan was adapted from a conventional VMAT plan and delivered on a Varian TrueBeam linear accelerator. The original VMAT plan was divided into three interleaved CSVMAT phases, each consisting of alternating beam-on and beam-off segments synchronized to a sample heart rate. Trajectory log files were collected for the original VMAT and CSVMAT deliveries and the dose distributions were measured with Gafchromic EBT-XD film. RESULTS: Analysis of the trajectory log files showed successful synchronization with the sample cardiac signal. Film analysis comparing the original VMAT and CSVMAT dose distributions returned a gamma passing rate of 99.14% (2%/2 mm tolerance). CONCLUSIONS: The film results indicated excellent agreement between the dose distributions of the original and cardiac synchronized beam deliveries. This study demonstrates a proof of principle cardiac synchronization strategy for precise radiation treatment plan delivery and adjustment to a variable heart rate. The cardiac synchronized technique may be advantageous in radioablation for VT.
PURPOSE:Ventricular tachycardia (VT) is a rapid, abnormal heart rhythm that can lead to sudden cardiac death. Current treatment options include antiarrhythmic drug therapy and catheter ablation, both of which have only modest efficacy and have potential complications. Cardiac radiosurgery has the potential to be a noninvasive and efficient treatment option for VT. Cardiac motion, however, must be accounted for to ensure accurate dose delivery to the target region. Cardiac synchronized volumetric modulated arc therapy (CSVMAT) aims to minimize the dose delivered to normal tissues by synchronizing beam delivery with a cardiac signal, irradiating only during the quiescent intervals of the cardiac cycle (when heart motion is minimal) and adjusting the beam delivery speed in response to heart rate changes. METHODS: A CSVMAT plan was adapted from a conventional VMAT plan and delivered on a Varian TrueBeam linear accelerator. The original VMAT plan was divided into three interleaved CSVMAT phases, each consisting of alternating beam-on and beam-off segments synchronized to a sample heart rate. Trajectory log files were collected for the original VMAT and CSVMAT deliveries and the dose distributions were measured with Gafchromic EBT-XD film. RESULTS: Analysis of the trajectory log files showed successful synchronization with the sample cardiac signal. Film analysis comparing the original VMAT and CSVMAT dose distributions returned a gamma passing rate of 99.14% (2%/2 mm tolerance). CONCLUSIONS: The film results indicated excellent agreement between the dose distributions of the original and cardiac synchronized beam deliveries. This study demonstrates a proof of principle cardiac synchronization strategy for precise radiation treatment plan delivery and adjustment to a variable heart rate. The cardiac synchronized technique may be advantageous in radioablation for VT.
Authors: Rosalind Perrin; Patrick Maguire; Adriano Garonna; Georg Weidlich; Shelley Bulling; Marie Fargier-Voiron; Cedric De Marco; Eleonora Rossi; Mario Ciocca; Viviana Vitolo; Alfredo Mirandola Journal: Front Cardiovasc Med Date: 2022-05-04