Table 3 The percentage uncertainty components for activity per unit mass of \(^{99\text {m}}\)Tc and \(^{177}\)Lu solutions used in the NEMA phantom

Capacitance

0.1

0.1

Ion chamber reproducibility

0.1

0.1

Calibration factor

0.88

0.48

Standard error of the mean

0.0104

0.0209

Voltage change measurement

0.00624

0.00441

Volume correction

0.00061

0.00007

Decay correction to reference time

0.01074

0.00039

Decay correction within measurement (start to middle)

0.00326

0.00013

Decay correction within measurement (end to middle)

0.00326

0.00013

Background

0.01139

0.04539

Weighing (negligible)

1.51 \(\times 10^{-9}\)

3.02 \(\times 10^{-9}\)

Combined uncertainty

0.892

0.503