In liquid scintillation counting, a small aliquot, filter or swab is added to scintillation fluid and the plate or vial is placed in a scintillation counter to measure the radioactive emissions.  Manufacturers have incorporated solid scintillants into multi-well plates to eliminate the need for scintillation fluid and make this into a high-throughput technique.
A gamma counter is similar in format to scintillation counting but it detects gamma emissions directly and does not require a scintillant.
A Geiger counter is a quick and rough approximation of activity. Lower energy emitters such as tritium can not be detected.