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Expanded Visual Guidance of Breath-Hold for CBCT-Guided Online Adaptive Radiotherapy (ART) in a Closed-Bore Configuration

T Kim, J Shin*, J Kim, E Barberi, L Henke, S Mutic, B Cai, Washington University School of Medicine, St. Louis, MO


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: quality CBCT images with reduced motion artifact are critical for CBCT-guided online ART. Although visual guidance is beneficial for respiratory motion management in imaging and radiotherapy, there are cumbersome issues with conventional approaches in closed bore-type systems such as space limitation, collisions, hygiene, storage and cable-related safety. Here we developed an expanded visual guidance system to aid breath-hold CBCT scans and tested an online ART system coupled with a closed-bore ring gantry LINAC.

Methods: expanded visual guidance system was combined with a pressure sensor-based respiratory motion management system. Two key components were designed and developed: an extended screen and a projector on an adjustable stand. The feasibility of installation, clinical workflow and system performance was tested on the investigators. In addition, CBCT and 2D kV fluoroscopic and planar images of a motion phantom were acquired with the full system installed.

Results: proposed approach removed all issues with conventional visual guidance approaches. In the feasibility study, the investigators confirmed that projection screen size can be increased using the extended screen so a wide and long projection screen can be fully utilized for visual guidance in the closed bore configuration for both upper torso and pelvic treatment sites. Also, projection location can be adjusted by using the adjustable stand which makes this solution applicable for various patient habitus. The imaging tests on the phantom provided end-to-end testing from detecting a motion of the object to providing the visual guidance during imaging.

Conclusion: system can be incorporated with any motion management system and can be a universal solution for closed bore-type systems such as CT and MRI. The feasibility study of breath-hold control on fast CBCT in X-ray-based radiotherapy with 8 abdominal cancer patients is ongoing.


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