Given the comparable tumour-to-background ratio as [18F]FTT in preclinical PET imaging, [18F]rucaparib, as an exact chemical match of rucaparib together with the fluorescence properties of rucaparib (absorption and emission at excitation wavelengths 355 and 405 nm [36]), conveniently would allow direct imaging of the delivery and engagement of rucaparib (or even other PARP inhibitors) in intracellular or in tumour tissue using various imaging techniques (PET, fluorescence microscope and flow cytometry). This evidence concerns the gene PARP1 and neoplasm.