text: The method was first described by Williams et al. in the clinical context. The method was used by numerous other studies. This is perhaps the simplest of all the mathematical methods for the calculation of K but the one most sensitive to noise present in the data. A tissue TAC is modelled as a convolution of measured arterial input function with IRF, the estimates for IRF are obtained iteratively to minimise the differences between the left- and right-hand side of the following Equation:
  where,  is a convolution operator, C(t) is the bone tissue activity concentration of tracer (in units: MBq/ml) over a period of time t, C(t) is the plasma concentration of tracer (in units: MBq/ml) over a period of time t, and IRF(t) is the impulse response of the system (i.e., a tissue in this case). The K is obtained from the IRF in a similar fashion to that obtained for the spectral analysis, as shown in the figure.