Camera selection for real-time in vivo radiation treatment verification systems using Cherenkov imaging

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Imaging Science

Background:

• Clinical Cherenkov imaging offers novel visual information for radiotherapy.
• Real-time monitoring of surface beam profiles requires advanced camera systems.
• Current systems face challenges with ambient lighting and frame rates.

Purpose of the Study:

• To determine achievable camera performance and hardware needs for clinical Cherenkov imaging.
• To enable real-time, in vivo monitoring of patient surface beam profiles.
• To provide visual information, documentation, and potential treatment verification.

Main Methods:

• Investigated Complementary Metal-Oxide-Semiconductor (CMOS), Charge-Coupled Device (CCD), Intensified Charge-Coupled Device (ICCD), and Electron Multiplying-Intensified Charge Coupled Device (EM-ICCD) cameras.
• Synchronized image intensifiers with Linac pulses for imaging under clinical room lighting.
• Evaluated Cherenkov detection adequacy and maximum frame rates using a solid water phantom and a 6 MV photon beam.

Main Results:

• Intensifier-coupled cameras (ICCD, EM-ICCD) were necessary for Cherenkov imaging in ambient light; standalone CMOS and CCD cameras were insufficient.
• The EM-ICCD achieved 30 fps at 512x512 resolution from a single Linac pulse, while an ICCD was limited to 4.7 fps at 1024x1024.
• An improved intensifier with 30% quantum efficiency in red wavelengths demonstrated potential for 8.6 fps at 1024x1024 resolution at a lower cost than EM-ICCD.

Conclusions:

• An ICCD with an intensifier optimized for red wavelengths shows the most promise for clinical Cherenkov imaging.
• This system can provide real-time display (≥8.6 fps) of radiation dose on the skin at 1024x1024 resolution.
• It offers a viable solution for visual information, documentation, and treatment verification in radiotherapy.