R Trevillian*, J Marcel, N Yegya-raman, L Yin, Z Zhang, H Chen, S Feigenberg, J Arkles, B Teo, W Zou, K Cengel, University of Pennsylvania, Philadelphia, PA

• 
  R Trevillian

(Saturday, 3/26/2022) 10:30 AM - 12:30 PM [Central Time (GMT-5)]

Room: Celestin D-E

Purpose: Stereotactic body radiation therapy targeting arrhythmogenic cardiac substrate (cSBRT) is a noninvasive approach which has clinical efficacy in patients with ventricular tachycardia (VT) that is refractory to standard therapies. In our institution, cSBRT is planned on average or regular CT with single fraction 25Gy VMAT technique. As the treatment target typically experiences significant respiratory motion which is further complicated by the cardiac motion, the dosimetric impact to target, organs and cardiac substructures due to motion interplay is of interest to investigate.

Methods: 16 ventricular tachycardia patients that were treated with 10MV FFF VMAT radiotherapy were identified. The delivery log files were obtained and used to derive partial split-arc plans administered to different phases of 4DCT sets according to the log time signature. The total dose was summed from the partial plans that were propagated to the original CT image set using deformable image registration. The dosimetric parameters were evaluated against the original plan to assess the motion effect.

Results: We have successfully developed a workflow that investigates the interplay of the machine delivery parameters with the respiratory and cardiac motion captured from 4DCT. Using data from a previously treated patient, we have validated this approach and found that the PTV D95% shows a 0.86Gy reduction, while the ITV and GTV maintain robust coverage. The dose to cord, esophagus, heart and lung has insignificant change due to motion. The max dose to stomach and great vessels, left atrium and LAD increases from 7.54Gy to 11.83Gy and 0.68 to 1.61Gy, respectively.

Conclusion: With the delivery log file, we were able to obtain the motion interplay effect to the target, organs and cardiac substructures. We are in the process of using the workflow investigating additional patients with VT and plan to demonstrate the results at the meeting.

Keywords

Radiation Therapy, Heart, Dose Volume Histograms

Taxonomy

TH- External Beam- Photons: Motion management - intrafraction

Contact Email