High-Speed Radiation Therapy Architecture for Clinical Cancer Care

Clinical oncology departments confront significant operational bottlenecks driven by increasing patient numbers, complex target volume geometries, and intra-fraction anatomical motion that can compromise dose conformity. Lengthy radiation delivery sessions not only reduce clinical throughput but also increase the risk of patient movement during treatment, necessitating wide planning target volume margins that expose surrounding healthy tissue to radiation. To address these delivery constraints and anatomical targeting challenges, Siemens Healthineers launched the Accela radiotherapy solution, engineered to deploy NeoArc dynamic modulated arc therapy across routine and advanced stereotactic oncology workflows.

Rotational Kinematics and High-Dose Delivery Mechanisms
The core engineering advancement of the Accela platform centers on the mechanical acceleration of linear accelerator sub-assemblies to compress treatment intervals. Long treatment times in stereotactic body radiation therapy (SBRT) typically expose targets to physiological drift, respiratory shifts, and patient discomfort. Accela addresses these intra-fraction variables by integrating high rotational velocity with elevated photon output rates.

The platform achieves a mechanical gantry rotation speed of 2.5 revolutions per minute, paired with a beam delivery dose rate reaching up to 40 Gray per minute. Photon beam delivery is driven by an 8-megavolt flattening filter-free energy beam line. Operating without a physical flattening beam filter removes photon attenuation, maximizing the forward dose flux while shortening the monitor units required to deposit prescribed therapeutic doses into target tissue.

Single Breath-Hold Protocols and Intra-Fraction Motion Mitigation
By combining high dose output with synchronized continuous gantry rotation, the NeoArc delivery technique completes complex multi-site stereotactic treatments in 60 seconds. This delivery speed enables radiation oncologists to execute stereotactic ablation within a single patient breath-hold. Eliminating multi-phase respiratory gating intervals minimizes the positional variation of mobile thoracic and abdominal tumors, allowing for tighter margin definitions around neoplastic lesions.

Beam conformation during dynamic arc delivery is governed by a re-engineered multi-leaf collimator assembly. Integrated planning software relies on algorithmic optimization and artificial intelligence modules to balance multi-leaf collimator leaf transit, gantry trajectory speeds, and variable dose delivery rates, producing steep dose gradients between clinical targets and adjacent organs at risk.

Image-Guided Verification and Departmental Integration
Accela integrates the large-format HyperSight cone-beam computed tomography panel directly onto the gantry structure. High-resolution volume acquisition provides rapid soft-tissue imaging immediately prior to treatment delivery. This anatomical verification minimizes setup errors, enables adaptive re-planning workflows, and ensures precise target localization without adding substantial pre-beam acquisition delays.

The mechanical and software architecture behind Accela and the NeoArc protocol reflects an eight-year collaborative engineering effort conducted with international cancer research centers. Clinical advisors included teams from Mayo Clinic, Washington University School of Medicine Siteman Cancer Center, University Hospital Zurich, Seidman Cancer Center at University Hospitals Cleveland Medical Center, Maastro Clinic, Mass General Brigham Cancer Center, and Memorial Sloan Kettering Cancer Center.

Additional Context:
This section details technical specifications and competitive benchmarking not included in the original product announcement.

Linear accelerator performance in stereotactic body radiation therapy is historically benchmarked against flattening filter-free photon outputs, gantry rotation rates, and on-board volumetric imaging acquisition speeds. Standard modern C-arm medical linear accelerators, such as the Varian TrueBeam platform, deliver 10-megavolt flattening filter-free beams at up to 2,400 monitor units per minute (approximately 24 Gray per minute) with standard gantry rotation velocities limited to 1.0 revolution per minute (6 degrees per second). By increasing gantry velocity to 2.5 revolutions per minute (15 degrees per second) and dose delivery rates to 40 Gray per minute, Accela provides a substantially higher dose delivery rate and gantry speed profile than traditional commercial platforms.

Comparable dedicated high-speed stereotactic delivery systems include the Elekta Versa HD, which supports high dose rates through its High Dose Rate mode delivering 6-megavolt and 10-megavolt flattening filter-free beams up to 2,200 monitor units per minute, combined with the Agility multi-leaf collimator featuring 160 leaves with leaf speeds up to 6.5 centimeters per second. While conventional volumetric modulated arc therapy architectures require two to three rotational passes over several minutes to deliver stereotactic ablative doses, the integration of 40 Gray per minute outputs with 15-degree-per-second gantry rotation in the Accela system allows continuous volumetric modulation to reach ablative targets within unified 60-second delivery windows.

Edited by Natania Lyngdoh, Induportals editor, with AI assistance.

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