Plan complexity metrics for head and neck VMAT competition plans

Hiroyuki Okamoto; Akihisa Wakita; Kensuke Tani; Satoshi Kito; Masahiko Kurooka; Takumi Kodama; Naoki Tohyama; Yukio Fujita; Satoshi Nakamura; Kotaro Iijima; Takahito Chiba; Hiroki Nakayama; Miyuki Murata; Tomonori Goka; Hiroshi Igaki

doi:10.1016/j.meddos.2024.01.007

Plan complexity metrics for head and neck VMAT competition plans

Med Dosim. 2024 Feb 16:S0958-3947(24)00009-8. doi: 10.1016/j.meddos.2024.01.007. Online ahead of print.

Authors

Affiliations

¹ Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku Tokyo, 104-0045, Japan. Electronic address: hiokamot@ncc.go.jp.
² Division of Medical Physics, EuroMediTech Co., LTD., 2-20-4 higashigotanda, shinagawa-ku Tokyo, 141-0022, Japan.
³ Department of Radiology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku Tokyo,113-8677, Japan.
⁴ Department of Radiation Therapy, Tokyo Medical University Hospital, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
⁵ Department of Radiation Oncology, Saitama Cancer Center, 780 Ooazakomuro, Inamachi, Kitaadachi-gun Saitama 362-0806, Japan.
⁶ Division of Medical Physics, Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, 1-17 Toyosuna, Mihama-ku Chiba, Chiba, 261-0024, Japan.
⁷ Department of Radiation Sciences, Komazawa University, 1-23-1, komazawa, setagaya-ku Tokyo, 154-8525, Japan.
⁸ Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku Tokyo, 104-0045, Japan.
⁹ Department of Radiological Technology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku Tokyo, 104-0045, Japan.
¹⁰ Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku Tokyo, 104-0045, Japan.

PMID: 38368182
DOI: 10.1016/j.meddos.2024.01.007

Abstract

Previous plan competitions have largely focused on dose metric assessments. However, whether the submitted plans were realistic and reasonable from a quality assurance (QA) perspective remains unclear. This study aimed to investigate the relationship between aperture-based plan complexity metrics (PCM) in volumetric modulated arc therapy (VMAT) competition plans and clinical treatment plans verified through patient-specific QA (PSQA). In addition, the association of PCMs with plan quality was examined. A head and neck (HN) plan competition was held for Japanese institutions from June 2019 to July 2019, in which 210 competition plans were submitted. Dose distribution quality was quantified based on dose-volume histogram (DVH) metrics by calculating the dose distribution plan score (DDPS). Differences in PCMs between the two VMAT treatment plan groups (HN plan competitions held in Japan and clinically accepted HN VMAT plans through PSQA) were investigated. The mean (± standard deviation) DDPS for the 98 HN competition plans was 158.5 ± 20.6 (maximum DDPS: 200). DDPS showed a weak correlation with PCMs with a maximum r of 0.45 for monitor unit (MU); its correlation with some PCMs was "very weak." Significant differences were found in some PCMs between plans with the highest 20% DDPSs and the remaining plans. The clinical VMAT and competition plans revealed similar distributions for some PCMs. Deviations in PCMs for the two groups were comparable, indicating considerable variability among planners regarding planning skills. The plan complexity for HN VMAT competition plans increased for high-quality plans, as shown by the dose distribution. Direct comparison of PCMs between competition plans and clinically accepted plans showed that the submitted HN VMAT competition plans were realistic and reasonable from the QA perspective. This evaluation may provide a set of criteria for evaluating plan quality in plan competitions.

Keywords: Plan competition; Plan complexity; Plan quality; Pretreatment QA; VMAT.