Several scintillator materials can be used for RLM. CdWO4 has a moderately high light yield (12,000-15,000 photon/MeV), high effective atomic number (Zeff = 64), high density (7.9 g/cm3), and no significant afterglow. The set-up was mounted on a custom-built wide-field microscope equipped with short focal tube lens (4X/0.2 NA; Nikon, CFI Plan Apochromat λ), 20X/0.75 NA air objective (Nikon, CFI Plan Apochromat λ), and deep-cooled electronmultiplying charge-coupled device (EM-CCD; Hamamatsu Photonics, ImagEM C9100-13).
Brightfield images were acquired with no EM gain. For RLM imaging, images were taken with a 20X objective, an exposure time of 10-300s, an EM gain of 600/1200, and 1×1 pixel binning. We used the brightfield mode to set the microscope into focus. Optimal radioluminescence focus was achieved when the organoids displayed sharp positive contrast in the corresponding brightfield image. For fluorescence microscopy, we used 387 mm/447 mm filter set (Semrock, filter ref: DAPI-1160B-000) for Hoechst imaging (live marker) and 469 nm/525 nm filter set (Thorlabs, filter ref: MDF-GFP1) for 2-NBDG or SYTOX green (dead marker) imaging.
Brightfield images were acquired with no EM gain. For RLM imaging, images were taken with a 20X objective, an exposure time of 10-300s, an EM gain of 600/1200, and 1×1 pixel binning. We used the brightfield mode to set the microscope into focus. Optimal radioluminescence focus was achieved when the organoids displayed sharp positive contrast in the corresponding brightfield image. For fluorescence microscopy, we used 387 mm/447 mm filter set (Semrock, filter ref: DAPI-1160B-000) for Hoechst imaging (live marker) and 469 nm/525 nm filter set (Thorlabs, filter ref: MDF-GFP1) for 2-NBDG or SYTOX green (dead marker) imaging.