The Spinning Manny Indexed Overlay System for VMAT total body irradiation

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Modern intensity-modulated techniques like Volumetric Modulated Arc Therapy-Total Body Irradiation (VMAT-TBI) offer improved outcomes over conventional TBI.
• Complexity, particularly the need for patient repositioning between head-first-supine (HFS) and feet-first-supine (FFS) orientations, limits VMAT-TBI adoption.

Purpose of the Study:

• To introduce and evaluate the Spinning Manny Indexed Overlay System, a novel rotational platform designed to simplify VMAT-TBI treatments.
• To address the logistical challenges associated with patient rotation during VMAT-TBI.

Main Methods:

• The Spinning Manny platform, a carbon fiber overlay, was assessed for mechanical stability, weight-bearing capacity (up to 159 kg), and isocenter reproducibility (within 1 mm).
• Dosimetric characterization included CT imaging, attenuation measurements (e.g., 4.3% at 6 MV, 30° beam angle), and end-to-end testing with anthropomorphic and solid water phantoms.
• Clinical implementation involved 136 patients, with workflow efficiency and dose delivery accuracy verified through in vivo dosimetry and treatment plan comparisons.

Main Results:

• The system demonstrated excellent mechanical stability and dosimetric integrity, with low beam attenuation.
• End-to-end tests achieved high gamma passing rates (e.g., 96.9% for lung regions).
• Clinical use in 136 patients, including 83% requiring HFS-to-FFS transitions, confirmed efficient workflow integration and accurate in vivo dose delivery (96.1% ± 5.5% of prescription).

Conclusions:

• The Spinning Manny Indexed Overlay System effectively overcomes a major logistical barrier in VMAT-TBI by facilitating accurate and reproducible patient transitions.
• The system's reliability, demonstrated through mechanical and dosimetric evaluations and successful clinical implementation, supports its use in diverse patient populations.
• Sharing this design aims to promote wider access to and adoption of VMAT-TBI globally.