TITLE

SBRT for cardiac arrhythmia ablation

AUTHOR(S)

A. Lo; B. Loo; Maguire, P.; Soltys, S. G.; L. Wang; P. Zei

PUB. DATE

March 2013

SOURCE

Journal of Radiosurgery & SBRT;2013 Supplement 2.1, Vol. 2, p15

SOURCE TYPE

Academic Journal

DOC. TYPE

Article

ABSTRACT

Purpose: Stereotactic Body Radiation Therapy (SBRT) for cardiac ablation of ventricular tachycardia (VT) represents an alternative to standard catheter-based methods for treating VT. This study reports the steps and considerations for treatment setup, target definition, treatment planning and treatment delivery with CardioPlan 3-D contouring software (CyberHeart) and Cyberknife (Accuray). Methods: A selected patient was observed under fluoroscopy to visualize his existing pacemaker lead. Because of extensive metallic components it was not suitable for Synchrony (Accuray) tracking. A dummy lead with a single metal end was implanted via percutaneous right axillary vein access for tracking purpose. Cardiac motion about 1 cm was observed with breathe hold. FHS 4D-CT, breathe hold CT were performed with patient rolled about 15 degree to the right so the dummy lead could be identified clearly by Synchrony tracking. CT images were loaded into CardioPlan 3-D contouring software. The cardiologist visualized the heart in 3D, segmented to show various volumes and contoured a 3D target that was projected into CT slices. The SS (structure set) was transferred to Multiplan (Accuray). The radiation oncologist refined a composite target incorporating cardiac motion and PET uptake and a PTV (planning target volume) that allows dose to extend to the interior wall and chamber. Adjacent critical organs were also contoured. Special shells were created during planning to create a conformal dose distribution around the PTV while keeping dose to critical organs to minimum. Results: A Synchrony treatment plan with Iris collimator of 25 Gy in 1 fraction to 75% isodose line, 175 non zero beams and 27671 MU was created that covered 97% of PTV, doses to critical organ were all acceptable. Patient setup took half an hour including placing monitors to monitor vital signs, identified the dummy lead and built Synchrony tracking model. Actual radiation delivery with Synchrony took 90 minutes with a 30 minute rest period in between that the patient requested. Total elapsed time was under 3 hours. The cardiologist then removed the dummy lead. Patient was admitted under observation overnight and discharged next day. Conclusions: The first Cyberknife SBRT cardiac ablation of ventricular tachycardia was performed successfully. 25 Gy was high enough based on success with animal testing and low enough to be safe based on other SBRT experience. This procedure combines complex target definition and tracking strategy that represents a new and less invasive option to treat VT. Disclosure: No significant relationships.

ACCESSION #

92611091

 

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