Betabox: a beta particle imaging system based on a position sensitive avalanche photodiode

Area of Science:

• Nuclear Instrumentation
• Biomedical Imaging
• Radiochemistry

Background:

• Positron Emission Tomography (PET) relies on detecting beta particles emitted from radiotracers.
• Direct imaging of beta particle distribution within microfluidic systems is challenging.
• Existing methods lack the spatial resolution and sensitivity for cellular-level analysis.

Purpose of the Study:

• To develop and characterize a novel beta camera system (Betabox) for quantitative imaging of beta particles.
• To assess the performance of Betabox for imaging Fluorine-18 (18F) in microfluidic devices.
• To evaluate the impact of temperature and microfluidic chip materials on imaging performance.

Main Methods:

• A position sensitive avalanche photodiode (PSAPD) based beta camera (Betabox) was developed.
• Quantitative performance metrics including background rate, efficiency, spatial resolution, and count rate were measured.
• Measurements were conducted at room temperature (21°C) and physiological temperature (37°C).
• The effect of polymer microfluidic chip materials on spatial resolution and sensitivity was investigated.

Main Results:

• Betabox achieved a low background rate (<2 cph mm⁻²) at both 21°C and 37°C.
• The absolute detection efficiency for 18F was 46% ± 1%.
• Spatial resolution ranged from 0.4 mm FWHM at the center to 1 mm at 5 mm from the center.
• Microfluidic chip materials degraded spatial resolution and sensitivity, with ~180 µm degradation per 100 µm of LDPE.

Conclusions:

• Betabox provides quantitative planar imaging of beta particles with high efficiency and spatial resolution.
• The system is suitable for direct coupling to microfluidic chips for biological applications, including cellular uptake studies.
• Performance is maintained at physiological temperatures, and the impact of microfluidic materials is quantifiable.