Commissioning and acceptance guide for the GammaPod

Area of Science:

• Medical Physics
• Radiation Oncology
• Medical Imaging

Background:

• Stereotactic radiation therapy for breast cancer requires precise targeting and dose delivery.
• The GammaPod device utilizes a prone positioning system with continuous couch translation and dynamic beam delivery.
• Immobilization is achieved using negative pressure and stereotactic fiducials for accuracy.

Purpose of the Study:

• To report the commissioning process and clinical readiness of the GammaPod system.
• To validate the mechanical, dosimetric, radiation safety, and interlock subsystems.
• To establish reliable methods for quality assurance of this novel radiotherapy device.

Main Methods:

• Commissioning involved detailed testing of mechanical (couch motion, sag), dosimetric (dose calibration, profiles), radiation safety (leakage, surveys), and safety interlock subsystems.
• Absolute dose rate was determined using the TG-21 dosimetry protocol.
• Plan verification included comparing treatment planning system data with measurements for beam characteristics.

Main Results:

• All tested subsystems, including mechanical accuracy and dosimetric parameters, met established criteria.
• The difference in full-width-at-half-maximum for the 25 mm collimator was within acceptable limits (0.2 mm).
• Radiation shielding and safety interlocks performed correctly, adhering to regulatory standards.

Conclusions:

• The commissioning process successfully validated the GammaPod system for clinical implementation.
• The developed methods ensure the reliable and safe delivery of stereotactic radiation therapy for breast cancer.
• GammaPod is ready for clinical use in various breast radiotherapy techniques, including boost, partial-breast irradiation, and stereotactic radiosurgery.