Feasibility of Utilizing Spot-Scanning Proton Arc (SPArc) for Whole Lung Irradiation and Mitigate the Breathing-Induced Interplay Effect
L Zhao, G Liu, A Qin, D Yan, X Li, C Stevens, R Deraniyagala, X Ding*, Department of Radiation Oncology, Beaumont Health System, Royal Oak, MI
Presentations
(Saturday, 3/26/2022) [Central Time (GMT-5)]
Purpose: We performed a dosimetric study using three different treatment modalities: Spot-scanning Proton Arc therapy (SPArc), Intensity Modulated Proton Therapy (IMPT) and volumetric modulated arc therapy(VMAT) for bilateral whole lung irradiation (WLI).
Methods: A 13-year-old teenager with malignant neoplasm of bone and articular cartilage who presented with bilateral whole lung metastasis were retrospectively selected in this study. The clinical VMAT plan used three 360 degree arcs with 6 MV based on the Elekta Versa HD. IMPT plan was generated used two iso and four treatment fields and SPArc plan with single iso and single arc was generated through in-house scripting in RayStation. Prescription is 1500cGy in 10 fractions. Treatment delivery efficiency, dose-volume histograms (DVHs) and integral body dose were compared. The interplay effect was assessed based on the 4D dynamic dose accumulation method.
Results: The mean dose to the heart was 541 cGy (SPArc), compared with 721 cGy (IMPT), and 956 cGy (VMAT), respectively. The integral body dose was 137 Gy·L in VMAT, 146Gy·L in IMPT, and 98 Gy·L in SPArc. The LINAC logfile showed that VMAT took 317 seconds to deliver all three arcs. It costs the IMPT plan approximately 875 seconds. The total SPArc treatment time is 423 seconds based on the DynamicARC® delivery sequence model's simulation which reduced 25% of the total treatment delivery time compared to IMPT. The average D98 of ten starting phases for SPArc interplay effect is 1445 cGy compared to 1354 cGy for IMPT.
Conclusion: SPArc technique showed a significant dosimetric benefit in cardiac and body integral dose sparing compared to VMAT and IMPT. Additionally, SPArc could simplify the clinical workflow with a single iso and improve the treatment delivery efficiency through the arc trajectory compared to the IMPT. Furthermore, SPArc effectively mitigated the interplay effect compared with IMPT.
Funding Support, Disclosures, and Conflict of Interest: The first author is supported in part by Ion Beam Application (IBA, Belgium) research grant and Beaumont Seed Grant Award.
ePosters
Keywords
Taxonomy
TH- External Beam- Particle/high LET therapy: Proton therapy – computational dosimetry-deterministic
Contact Email