Dosimetric comparison between dynamic wave arc and co-planar volumetric modulated radiotherapy for locally advanced pancreatic cancer

Document Type : Original Paper

Authors

1 Department of Clinical Oncology, Sohag University Hospital, Sohag University, Sohag, Egypt

2 Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

3 Department of Radiation Oncology and Image-applied Therapy, Graduate School fo Kyoto, Kyoto University

4 Division of Medical Physics, Department of Information Technology and Medical Engineering, Human Health Sciences, Graduate School of Medicine, Kyoto University

5 Department of Clinical Oncology, Sohag University Hospital, Sohag University, Sohag, Egypt.

6 Department of Radiation Oncology and Image-Applied Therapy Kyoto University Graduate School of Medicine、Kyoto, Japan.

Abstract

Introduction: Dose reduction to the duodenum is important to decrease gastrointestinal toxicities in patients with locally advanced pancreatic cancer (LAPC) treated with definitive chemoradiotherapy. We aimed to compare dynamic wave arc (DWA), a volumetric-modulated beam delivery technique with simultaneous gantry/ring rotations passing the waved trajectories, with coplanar VMAT (co-VMAT) with respect to dose distributions in LAPC cases.
Materials and Methods: DWA and co-VMAT plans were created for 13 patients with LAPC. The prescribed dose was 45.6 or 48 Gy in 15 fractions. The dose volume indices (DVIs) for target volumes and organs at risk were compared between the corresponding plans. Gamma passing rate, monitor unit (MU), and beam-on time were also compared.
Results: DWA significantly reduced the duodenal V39Gy, V42Gy, and V45Gy by 1.1, 0.8, and 0.2 cm3, and increased the liver mean dose and D2cm3 of the spinal cord planning volume by 1.0 and 1.5 Gy, respectively. Meanwhile, there was no significant difference in the target volumes except for D2% of PTV (111.5% in DWA vs. 110.5% in co-VMAT). Further, the gamma passing rate was similar in both plans. MU and beam-on time increased in DWA by 31 MUs and 15 seconds, respectively.
Conclusion: DWA generated significantly lower duodenal doses in LAPC cases, albeit with slight increasing liver and spinal cord doses and increasing MU and the beam delivery time. Further evaluation is needed to know how the dose differences would affect the clinical outcomes in chemoradiotherapy for LAPC.

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Articles in Press, Accepted Manuscript
Available Online from 27 April 2021
  • Receive Date: 16 February 2021
  • Revise Date: 19 April 2021
  • Accept Date: 27 April 2021