The comparison of background subtraction methods for low level radioactivity in biological samples by a liquid scintillation counter

The relationship between background count rate and quenching indicating parameters (QIP) is referred as ''background quenching curve'' in this paper. In the experiment using different quenching level samples containing 3H of 0.83 Bq (50 dpm) or 1.67 Bq (100 dpm), the net count rate was calculated from the measured values by subtracting four different kind backgrounds. The net radioactivity obtained by dividing the net count rate (which is obtained from the background counts and the background quenching curve) by the counting efficiency, was closer to the expected value than those obtained by other three methods. (author)