Implementation of the Calypso system: a commissioning experience.

Area of Science:

• Medical Physics
• Radiation Oncology
• Image-Guided Therapy

Background:

• The Calypso system is a tool for real-time tracking during radiation therapy.
• Its integration into clinical workflows requires evaluation of its impact on imaging and treatment delivery.

Purpose of the Study:

• To assess the clinical implementation of the Calypso system.
• To investigate its effects on kilovoltage cone beam computed tomography (kV-CBCT) image quality.
• To evaluate dosimetric impact on Volumetric Modulated Arc Therapy (VMAT) prostate treatments.

Main Methods:

• kV-CBCT image quality was assessed using CATPHAN 504 phantom with and without the Calypso electromagnetic array.
• Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were analyzed.
• Dosimetric influence was evaluated by measuring couch attenuation and its effect on VMAT prostate treatment plans for X6 and X6 flattening filter free (FFF) beams.

Main Results:

• A significant increase in noise and decrease in SNR were observed with the array.
• A minor decrease in CNR (2.5%) was noted, with no change in absolute contrast.
• Maximum couch attenuation reached 13.19% (X6 FFF), while mean array attenuation was 1.67%.
• VMAT plan mean dose reduction was minimal (0.61% for X6, 0.31% for X6 FFF).

Conclusions:

• The Calypso system demonstrates no significant detrimental effect on kV-CBCT image quality.
• The system does not significantly alter the dose distribution for VMAT prostate treatments.
• Clinical implementation of the Calypso system is feasible without compromising image quality or treatment accuracy.