Initial clinical experience building a dual CT- and MR-guided adaptive radiotherapy program.

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• The institution pioneered clinical MR-guided adaptive radiotherapy (MRgART) in 2014.
• In 2021, a CT-guided adaptive radiotherapy (CTgART) unit was installed, creating a dual-modality ART clinic.
• This review focuses on the factors contributing to the development of a high-volume dual-modality ART program.

Purpose of the Study:

• To review the factors leading to the development of a high-volume dual-modality ART program.
• To analyze the treatment census over the initial one-year period of the dual-modality ART program.
• To compare patient and treatment characteristics between MRgART and CTgART platforms.

Main Methods:

• Analysis of patient and treatment data from MRgART (MRIdian) and CTgART (ETHOS) platforms.
• Inclusion of disease sites, radiation dose and fractionation, and treatment times.
• Review of institutional workflow for adaptive treatment implementation.

Main Results:

• 256 patients treated with adaptive intent from Oct 2021 to Sep 2022 (186 MRgART, 70 CTgART).
• MRgART predominantly treated pancreatic cancer (106/186), while CTgART treated pelvis (23/70) and abdomen (20/70).
• Higher stereotactic body radiotherapy (SBRT) utilization on MRgART (93.0%) vs. CTgART (72.9%); varied treatment times based on site and modality.
• The program facilitated six open clinical trials for MRgART and seven for CTgART.

Conclusions:

• Successful development and implementation of a dual-platform adaptive radiotherapy program.
• Ongoing efforts are crucial for further integration and evidence generation across platforms and disease sites.
• Maximizing access and evidence for dual-modality ART is essential globally.