The relative biological potency of a specific type of ionizing radiation is a measure of its effectiveness in producing biological effects. It is quantitatively determined by comparing the number of rads of 250 Kv x-rays required to achieve a particular biological endpoint with the number of rads of the given radiation type needed to produce the same effect, considering factors such as timing, dosage distribution, and other relevant exposure factors. This measure is primarily employed in radiobiological research and radiotherapy. In radiation protection work, a more generalized quality factor (QF) is often used.