Gamma-ray sources imaging and test-beam results with MACACO III Compton camera

Area of Science:

• Medical Physics
• Nuclear Instrumentation
• Radiotherapy

Background:

• Hadron therapy offers precise radiation delivery, but requires real-time monitoring to ensure accurate dose deposition.
• Conventional radiotherapy methods lack precise real-time dose verification during treatment.
• Prompt gamma imaging is a promising technique for in-vivo dosimetry in hadron therapy.

Purpose of the Study:

• To develop and test a Compton camera prototype for real-time prompt gamma imaging during hadron therapy.
• To evaluate the system's performance in terms of linearity, energy resolution, and imaging capabilities.
• To assess the potential of the system for detecting target position shifts in proton therapy.

Main Methods:

• A Compton camera prototype utilizing Lanthanum (III) bromide scintillator crystals and silicon photomultipliers was developed.
• Detector characterization and performance evaluation were conducted in laboratory settings and at two proton therapy facilities (PARTREC and CNA).
• Imaging capabilities were assessed using various radioactive sources and a proton beam, analyzing the system's response to target position variations.

Main Results:

• Improved detector linearity and an energy resolution of 5.2% FWHM at 511 keV were achieved.
• The system successfully obtained images at 4.439 MeV from a graphite target irradiated with a proton beam.
• The Compton camera prototype demonstrated the ability to distinguish 1 mm target position shifts at different beam intensities.

Conclusions:

• The developed Compton camera prototype shows significant potential for real-time prompt gamma imaging in hadron therapy.
• The system's capability to detect small target shifts enhances its utility for ensuring accurate radiation delivery.
• Further implementation in proton therapy centers could improve treatment accuracy and patient safety through real-time monitoring.