D50 (radiotherapy)

D50, the half maximal inhibitory dose, represents the dose of light or ionising radiation that is required for 50% inactivation of a tumor cell population. It can also, in parallel fashion, represent the dose of a drug or toxin necessary to kill 50% of a cellular population.

D50 also is a solution of 50% dextrose in water, also written D50W or for 50% dextrose in normal saline, D50NS.