Improved proton CT imaging using a bismuth germanium oxide scintillator.

Area of Science:

• Medical Physics
• Radiological Imaging
• Particle Therapy

Background:

• Range uncertainty poses a significant challenge in proton therapy treatment planning.
• Proton imaging techniques, including proton radiography and proton computed tomography (pCT), are crucial for verification.
• Existing pCT systems face limitations that necessitate improved detection and processing methods.

Purpose of the Study:

• To develop and evaluate a novel pCT detection system utilizing a bismuth germanium oxide (BGO) scintillator and CCD camera.
• To enhance image processing techniques for more accurate proton range determination.
• To demonstrate the feasibility and performance of the new pCT system for medical applications.

Main Methods:

• A pCT detection system was designed using a thick BGO scintillator and a CCD camera, improving upon previous plastic scintillator systems.
• Scintillation light intensity was integrated along the proton path and acquired as a 2D distribution.
• A light-to-range conversion table was employed to derive proton range and reconstruct pCT images, with improved spatial dependence error analysis.

Main Results:

• The BGO scintillator's shorter proton range reduced errors compared to plastic scintillators.
• Errors in acquired pixel values were less than 0.5 mm, and material image pixel-value errors were within 3.1%.
• A pCT image of a chicken piece was successfully acquired, revealing structures as small as 1 mm, marking a first for biological materials.

Conclusions:

• The developed BGO-based pCT system offers improved accuracy and speed for proton imaging.
• The system demonstrates potential for high-resolution imaging of biological tissues.
• Future work anticipates acquiring 200 MeV pCT images, further advancing proton therapy verification.