High resolution imaging of tumor pO2 with Cherenkov-excited luminescence scanned imaging (Conference Presentation)

Cherenkov excitation of molecular probes in tissue can be used for photodynamic effect or diagnostic luminescence imaging. Excitation of dendritic platinum-based metalloporphyrn molecule complexes as an oxygen sensor (PtG4) has been shown to allow oxygen measurement in vivo with spatial resolution defined by the exciting x-ray beam. By sweeping the beamlet shapes and geometries, and detecting the emitted luminscence lifetime, a highly accurate pO2 distribution can be reconstructed of the tissue volume. This has been shown in tumors as well as in normal tissues, and now for implanted microtubes. Additional imaging of luminescent agents based upon Cherenkov or direct radio-excitation could be used for molecular sensing. The combination of depth, concentration, and radiation dose have been analyzed for the tradeoffs in signal to noise, and the signal to background optimization has been completed. The use of this approach can be applied to any clinical radiation therapy linac.