Dust mass-loss rate from a massive star given a set of parameters? I've been looking for examples at how mass-loss rates are determined.

I'm studying a circumstellar dust shell ejected from a Wolf-Rayet star. I have some parameters like, expansion velocity of the shell (60km/s), the dust mass of the shell (0.1 M_sun), the radii of the shell (R_in=10000 AU and R_out=60000) and its age (T=26000 yrs).

I was wondering if there's a formula relating those parameters and if they are sufficient to determine the dust mass-loss rate or its dependent on other factors.

Could anyone help?
Roughly: the mass loss rate for a spherically symmetric wind is given by
$$\dot{M} = 4\pi r^2 \rho v_w,$$
where $\rho$ is the density in the wind, $r$ is the radius at which that density is measured and $v_w$ is the wind velocity.

Here you have $v_w$ and have the mass of material within two concentric radii - so you can work out the average density at some average radius in the shell.

The age of the shell is not relevant to the mass-loss rate, but assuming the wind parameters are unchanged over that time, they do tell you ho much mass has been lost in total $\simeq \dot{M} \tau$.