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Optimization of Radiochemical Reactions using Droplet Arrays
Published on: February 12, 2021
Optimization of microfluidic PET tracer synthesis with Cerenkov imaging.
Alex A Dooraghi1, Pei Y Keng, Supin Chen
1Crump Institute for Molecular Imaging, University of California, Los Angeles (UCLA), Los Angeles, CA, USA. MVanDam@mednet.ucla.edu.
The Analyst
|August 10, 2013
Summary
Cerenkov imaging on microfluidic chips allows for quantitative radioisotope visualization. This technique optimizes radiolabeled compound synthesis, improving yields by enabling precise control and minimizing radioactive loss.
Area of Science:
- Radiochemistry and Nuclear Medicine
- Microfluidics and Lab-on-a-Chip Technologies
- Medical Imaging and Instrumentation
Background:
- Microfluidic platforms offer advantages for synthesizing radiolabeled compounds.
- On-chip visualization of radioisotopes is crucial for optimizing synthesis and developing new technologies.
- Cerenkov imaging, using CCD cameras, can localize beta particle-emitting isotopes.
Purpose of the Study:
- To investigate the physical characteristics of Cerenkov photon yield during [(18)F]FDG synthesis on an electrowetting on dielectric (EWOD) microfluidic platform.
- To demonstrate how Cerenkov imaging can be used for synthesis optimization.
- To establish the quantitative potential of Cerenkov imaging for radiolabeled compound synthesis.
Main Methods:
- Simulations using Geant4 (Monte Carlo program) to model Cerenkov photon yield from (18)F beta particles interacting with materials used in EWOD chips.
- Controlled experimental measurements varying ratios of [(18)O]H2O, DMSO, and MeCN to validate simulation findings.
- Application of Cerenkov imaging to guide optimization of mixing protocols and identify sources of radioactive loss.
Main Results:
- Simulations indicated that most (18)F beta particle energy for Cerenkov emission is deposited on the EWOD chip's glass plates, suggesting a universal calibration factor for radioactivity quantification.
- Experimental validation confirmed a consistent calibration factor, independent of solvent composition, though potential underestimation due to droplet discoloration was noted.
- Cerenkov imaging identified and helped correct for radioactive vapor loss, leading to an increase in crude radiochemical yield from 50 ± 3% to 72 ± 13%.
Conclusions:
- Cerenkov imaging is a valuable tool for both quantitative and qualitative analysis in microfluidic radiolabeling.
- The findings support the use of a single calibration factor for radioactivity quantification in this system.
- Optimization guided by Cerenkov imaging significantly enhances radiochemical yields in microfluidic synthesis.
