  We have previously focused on studying the electron-capture isotopes within
the dynamic spiral-arms model and empirically derived the energy dependence of
the electron attachment rate using the observation of $^{49}$Ti/$^{49}$V and
$^{51}$V/$^{51}$Cr ratios in cosmic rays (Benyamin et al. 2017). We have also
shown how this relation recovers the energy dependence seen in the lab
measurements (Letaw et al. 1985). In this work we use this relation to
construct the $^{44}$Ca/$^{44}$Ti ratio and place a lower limit on the amount
of $^{44}$Ti that is required to be nucleosynthesized at the source. The
results also imply that the acceleration process of the radioisotopes cannot be
much longer than a century time scale (or else the required nucleosynthesized
amount has to be correspondingly larger). We also provide a similar lower limit
on the source $^{60}$Fe by comparing to the recently observed
$^{60}$Fe/$^{56}$Fe (Binns et al. 2016).
