Conclusion
The LRM is a high-resolution, large-field-of-view, and cost-effective approach to image radiotracer uptake with single-cell resolution in vitro.
Methods
We have developed a new imaging modality, the lensless radiomicroscope (LRM), for in vitro, cellular-resolution imaging of β- and α-emitting radionuclides. The palm-sized instrument is constructed from off-the-shelf parts for a total cost of less than $100, about 500 times less than the radioluminescence microscope, its closest equivalent. The instrument images radiopharmaceuticals by direct detection of ionizing charged particles via a consumer-grade complementary metal-oxide semiconductor detector.
Results
The LRM can simultaneously image more than 5,000 cells within its 1 cm2 field of view, a 100-times increase over state-of-the-art technology. It has spatial resolution of 5 μm for brightfield imaging and 30 μm for 18F positron imaging. We used the LRM to quantify 18F-FDG uptake in MDA-MB-231 breast cancer cells 72 h after radiation treatment. Cells receiving 3 Gy were 3 times larger (mean = 3,116 μm2) than their untreated counterparts (mean = 940 μm2) but had 2 times less 18F-FDG per area (mean = 217 Bq/mm2), a finding in agreement with the clinical use of this tracer to monitor response. Additionally, the LRM was used to dynamically image the uptake of 18F-FDG by live cancer cells, and thus measure their avidity for glucose.