SU‐F‐J‐188: Clinical Implementation of in Room Mobile CT for Image Guided Proton Therapy

Abstract

Purpose: To implement soft‐tissue image‐guided proton therapy using inroom mobile CT. Methods: Anthropomorphic phantom was first used to determine the setup accuracy using in‐ room mobile CT. Laser and bbs were used for the initial setup (marked isocenter). CT data was then acquired with in‐room mobile CT (daily CT). The shift between the marked isocenter and the planned isocenter (final isocenter) was determined from the daily CT using in‐house Computer Assisted Targeting (CAT) software. Orthogonal DRRs of the day was also generated from the daily CT. The phantom was then transferred on the treatment couch top to the treatment machine using a transportation system, and again aligned to the marked isocenter. Couch shifts were made to align the phantom to the final isocenter using the shifts as determined using the CAT software, and verified using orthogonal X‐ray images with the daily DRRs. Results: Phantom data suggests that following the setup procedure as described above, targeting accuracy could be within 1 mm. Patient data are being acquired and analyzed. Conclusion: In‐room mobile CT is capable of providing soft‐tissue image‐guided proton therapy.

Current state and future applications of radiological image guidance for particle therapy

“…Pioneering work on the use of a horizontal CT for in‐room, on‐isocenter imaging of seated patients was performed at National Institute of Radiological Sciences in Japan at the end of the 1990s . Many particle therapy centers have since decided to adopt in‐room sliding CTs for image guidance . The CT scanners on rails are often installed several meters away from the gantry at an angle to reduce interference with the treatment workflow and neutron exposure.…”

“…47,48 Many particle therapy centers have since decided to adopt in-room sliding CTs for image guidance. [49][50][51] The CT scanners on rails are often installed several meters away from the gantry at an angle to reduce interference with the treatment workflow and neutron exposure. The robotic patient positioner (couch) would first move the patient to the predetermined imaging isocenter and the CT scanner subsequently slides to the imaging location.…”

The Mobius AIRO mobile CT for image‐guided proton therapy: Characterization & commissioning

“…Although other facilities have acquired mobile helical CT systems, such as the BodyTom (Neurologica Corporation, Danvers, MA, USA) and the Aquilion LB (Toshiba), our proton therapy facility is the first to acquire the AIRO Mobile CT System for proton treatment localization . We are also the first to use this technology for patient localization in a small‐compact proton facility where space limitations exist.…”

“…Unfortunately, due to the size and geometry of proton therapy units, imaging has largely been limited to orthogonal kV/kV x‐ray systems . Recently, people have reported on the use of in‐room CT scanners for proton beam radiation therapy localization . Some proton vendors are developing technologies for CBCT (Proteus ® ONE, IBA, Belgium, HITACHI, Tokyo, Japan).…”