All-digital PET technology cancels the coincidence identification circuit board, liberates the fixed hardware architecture of PET scanner, and makes the LEGO-like system integration possible. Our team have developed a novel all-digital PET R&D Plug and Imaging (PnI) platform based on these exciting features. Consequently, many application-adaptive PET scanners have sprung up, such as Proton PET, Brain PET, Helmet PET and Bi-dynamic PET.