Acridines are organic compounds and nitrogen heterocycles having the formula C13H9N. Acridine is a substituted derivative of the parent ring. It is a planar molecule structurally related to anthracene in which one carbon in the central CH group is replaced by nitrogen. Acridine and its derivatives can be used to make dyes and also used in the pharmaceutical industry. Acridine is a DNA intercalator that easily binds to DNA. Due to its DNA-intercalating properties, acridine or its suitable derivatives are expected to preferentially accumulate in tumors, which are always associated with enhanced DNA replication. Therefore, radiolabeled acridines may have prospect in tumor imaging.