Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
권호 표지
DOI QR코드

DOI QR Code

Simulating the Effect of Junction Setup Error in Dual-Isocentric Volumetric Modulated Arc Therapy for Pelvic Radiotherapy with a Large Target

  • Hojeong Lee (Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital) ;
  • Dong Woon Kim (Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital) ;
  • Ji Hyeon Joo (Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital) ;
  • Yongkan Ki (Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital) ;
  • Wontaek Kim (Department of Radiation Oncology, Pusan National University School of Medicine) ;
  • Dahl Park (Department of Radiation Oncology, Pusan National University Hospital) ;
  • Jiho Nam (Department of Radiation Oncology, Pusan National University Hospital) ;
  • Dong Hyeon Kim (Department of Radiation Oncology, Pusan National University School of Medicine) ;
  • Hosang Jeon (Department of Radiation Oncology and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital)
  • Received : 2024.03.04
  • Accepted : 2024.06.10
  • Published : 2024.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

Purpose: The use of two adjacent radiation beams to treat a lesion that is larger than the maximum field of a machine may lead to higher or lower dose distribution at the junction than expected. Therefore, evaluation of the junction dose is crucial for radiotherapy. Volumetric modulated arc therapy (VMAT) can effectively protect surrounding normal tissues by implementing a complex dose distribution; therefore, two adjacent VMAT fields can effectively treat large lesions. However, VMAT can lead to significant errors in the junction dose between fields if setup errors occur due to its highly complex dose distributions. Methods: In this study, setup errors of ±1, ±3, and ±5 mm were assumed during radiotherapy for treating large lesions in the lower abdomen, and their effects on the treatment dose distribution and target coverage were analyzed using gamma pass rate (GP) and homogeneity index (HI). All studies were performed using a computational simulation method based on our radiation treatment planning software. Results: Consequently, when the setup error was more than ±3 mm, most GP values using a 3%/3-mm criterion decreased by <90%. GP was independent of the direction of the field gap (FG), whereas HI values were relatively more affected by negative values for FG. Conclusions: Therefore, the size and direction of setup errors should be carefully managed when performing dual-isocentric VMATs for large targets.

Keywords

Acknowledgement

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea, funded by the Korean government (2022R1F1A1064176), and a 2023 research grant from Pusan National University Yangsan Hospital.

References

  1. Cao F, Harrop S, Cooper N, Steiner P, Karvat A. The dose junction issue associated with photon beams for large volume radiation therapy and the sensitivity to set-up error. J Med Phys Appl Sci. 2017;2:8.
  2. Zhou Y, Ai Y, Han C, Zheng X, Yi J, Xie C, et al. Impact of setup errors on multi-isocenter volumetric modulated arc therapy for craniospinal irradiation. J Appl Clin Med Phys. 2020;21:115-123.
  3. Prabhu RS, Dhakal R, Piantino M, Bahar N, Meaders KS, Fasola CE, et al. Volumetric modulated arc therapy (VMAT) craniospinal irradiation (CSI) for children and adults: a practical guide for implementation. Pract Radiat Oncol. 2022;12:e101-e109.
  4. Morrison CT, Symons KL, Woodings SJ, House MJ. Verification of junction dose between VMAT arcs of total body irradiation using a Sun Nuclear ArcCHECK phantom. J Appl Clin Med Phys. 2017;18:177-182.
  5. Semenenko VA, Reitz B, Day E, Qi XS, Miften M, Li XA. Evaluation of a commercial biologically based IMRT treatment planning system. Med Phys. 2008;35:5851-5860.
  6. Teoh M, Clark CH, Wood K, Whitaker S, Nisbet A. Volumetric modulated arc therapy: a review of current literature and clinical use in practice. Br J Radiol. 2011;84:967-996.