Development of Magnetic Resonance-Compatible Head Immobilization Device and Initial Experience of Magnetic Resonance-Guided Radiation Therapy for Central Nervous System Tumors

Joongyo Lee; Na Young Shin; Seo Jin Lee; Yoon Jin Cho; In Ho Jung; Ji Won Sung; Sei Joon Kim; Jun Won Kim

doi:10.1016/j.prro.2024.04.012

Development of Magnetic Resonance-Compatible Head Immobilization Device and Initial Experience of Magnetic Resonance-Guided Radiation Therapy for Central Nervous System Tumors

Pract Radiat Oncol. 2024 Apr 30:S1879-8500(24)00093-6. doi: 10.1016/j.prro.2024.04.012. Online ahead of print.

Authors

Joongyo Lee¹, Na Young Shin², Seo Jin Lee³, Yoon Jin Cho⁴, In Ho Jung⁴, Ji Won Sung⁴, Sei Joon Kim⁴, Jun Won Kim⁵

Affiliations

¹ Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea; Department of Radiation Oncology, Gil Medical Center, Gachon University College of Medicine, Incheon, South Korea.
² Department of Radiation Oncology, Ajou University School of Medicine, Suwon, South Korea.
³ Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, South Korea.
⁴ Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea.
⁵ Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea. Electronic address: junwon@yuhs.ac.

PMID: 38697347
DOI: 10.1016/j.prro.2024.04.012

Abstract

Purpose: We aimed to develop and investigate positional reproducibility using a fixation device (Unity Brain tumor Immobilization Device [UBID]) in patients with brain tumor undergoing magnetic resonance (MR)-guided radiation therapy (RT) with a 1.5 Tesla (T) MR-linear accelerator (MR-LINAC) to evaluate its feasibility in clinical practice and report representative cases of patients with central nervous system (CNS) tumor.

Materials and methods: Quantitative analysis was performed by comparing images obtained by placing only the MR phantom on the couch with those obtained by placing UBID next to the MR phantom. Twenty patients who underwent RT for CNS tumors using 1.5T MR-LINAC between June and October 2022 were retrospectively analyzed. Among them, 5 did not use UBID, whereas 15 used UBID. The positional reproducibility of UBID was evaluated using the median interfractional and intrafractional errors in the first 10 fractions.

Results: Each MR quality factor of the MR phantom with UBID satisfied the criteria presented by Elekta. Median values of median shifts in the mediolateral, anteroposterior, and craniocaudal axes for interfractional errors were 2.98, 2.35, and 1.40 mm, respectively. For intrafractional errors, the median values were 0.05, 0.03, and 0.06 mm, respectively. The median values of the median rotations in pitch, roll, and yaw for both interfractional and intrafractional rotations were 0.00°. One patient diagnosed with an optic nerve sheath meningioma received RT with motion monitoring during irradiation. In 2 patients, changes in the tumor cavity and residual lesions were observed in the MRI obtained using 1.5T MR-LINAC on the day of the first treatment and immediately before the 21^st fraction, respectively; therefore, offline/online adaptation was performed.

Conclusions: The reproducible and immobile UBID is clinically feasible in patients with CNS tumors receiving RT with 1.5T MR-LINAC. Based on our initial experience, we developed a workflow for 1.5T MR-LINAC treatment of CNS tumors.