Reducing Pulmonary Toxicity Using Functional Avoidance Spot-Scanning Proton Arc (SPARC) With 4DCT-Based Lung Ventilation Imaging

Document Type

Conference Proceeding

Publication Date

6-2024

Publication Title

International Journal of Particle Therapy

Abstract

Background and aims: Lung functional imaging has been developed using 4DCT data and imaging processing techiniques to calculated 4DCT-baed lung ventilation. Functional avoidance radiation therapy has emerged as a promising technique using functional imaging to reduce pulmonary toxicity by designing radiation plans that reduce doses to functional regions of the lung. Recently, a novel Spot-Scanning Proton Arc (SPArc) has been proposed to further improve dosimetric results. In this study, we aim to investigate the potential dosimetric gains of SPArc for functional avoidance radiation therapy with 4DCT-based lung ventilation imaging. Methods: 10 patients from a prospective functional avoidance clinical trial treated with volumetric modulated arc therapy (VMAT) were included in this study. SPArc and robustness optimized twofields IMPT plans were generated via RayStation. Functional lung were derived from the 4DCT-based ventilation imaging, which was used as an optimization structure in clinical VMAT as well as IMPT and SPArc planning. The dosimetric outcomes, specifically the dose to the functional lung, were compared among IMPT, SPArc, and VMAT. Normal Tissue Complication Probability (NTCP) was applied to estimate the probability of pulmonary toxicity using dose to functional lung (V5Gy, V10Gy, V20Gy, V30Gy, and mean dose). Results: Both SPArc and IMPT plans achieved similar target volume coverage and without significant dose increase to organ-atrisk structures. Functional lung f5Gy, f10Gy, f20Gy, f30Gy and mean dose were reduced by an average of 38.8%, 16.9%, 4.5%, 2.6% and 5.1Gy, respectively, using IMPT compared to VMAT functional plans. Functional lung f5Gy, f10Gy, f20Gy, f30Gy and mean dose were reduced by an average of 48.0%, 27.5%, 14.0%, 9.1% and 8.8Gy, respectively, using SPArc compared to VMAT functional plans. Using f20Gy as the dose metric for NTCP model, on average, IMPT can reduce the probability of grade 2+ pneumonitis by 6.6% (range: 0.7% to 21.9%) and SPArc can reduce 17.1% (range: 3.2% to 41.4%) with functional plans compared to clinical functional VMAT plans. Conclusions: Our study demonstrated the potential of SPArc to further spare dose to the functional lung while maintaining satisfying target coverage. NTCP results also show the risk of pulmonary complication can be further reduced with functional avoidance SPArc.

Volume

12

Issue

Suppl

First Page

37

Comments

62nd Annual Conference of the Particle Therapy Cooperative Group (PTCOG), June 10-15, 2024, Singapore

DOI

10.1016/j.ijpt.2024.100191

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