Catheter Ablation -> Ventricular Arrhythmias -> Experimental methods D-PO01 - Featured Poster Session (ID 11) Poster

D-PO01-180 - Quality Of Radiation Coverage In Stereotactic Radioablation Of Scar-related Ventricular Tachycardia (ID 130)

Abstract

Background: Radioablation has been proposed as an alternative treatment strategy for patients with refractory, scar-related VT. In the planning stage, percentage of target coverage (PTC), new conformity index (nCI), and homogeneity index (HI) are analysis tools that helps assess the quality of the radiation coverage.
Objective: To analyze the PTC, nCI, and HI of the treatment plans of 5 patients with scar-related refractory VT, who underwent radioablation as part of our pilot study.
Methods: After creating the dose-volume histograms, the PTC, nCI and HI were calculated using MultiPlan. PTC is the % of the planned target volume (PTV) covered by the chosen prescription dose. In simple terms, the nCI describes the degree to which the irradiated volume conforms to the shape and size of the PTV, whereas HI measures the uniformity of dose within the PTV. For both, the ideal value is 1, and it increases as radiation coverage exceeds the PVT (i.e. covers part of the healthy tissue) and becomes less homogeneous within the PVT.
Results: Results are presented in the Table. For PTC, in all patients less than 100% of the PTV was covered by 25 Gy of radiation; a more significant reduced dose was prescribed in patient 1 and 5 to limit exposure to the stomach and proximal conduction system. As for nCI and HI, they exceeded 1 in all patients, with a mean of 1.5±0.4 and 1.3±0.05, respectively.
Conclusion: Given the asymmetrical nature of the scar, as well as its location surrounded by radiosensitive organs, it is hard to provide uniform, full-dose irradiation with minimal spillage of significant doses to the surrounding healthy tissues.
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