Use a variable in element find logic

I need to use the value from a variable to find an element to click.

The variable value is being extracted from a database using C# (data binding won't work because I am already bound to the data, but this value did not exist at the time of binding).

The variable name is varDocID

I am trying to use it to compare to the OnClick event of the image I need to click in a grid with many instances of the same image.

~$(varDocID) does not work as it does not use the value and only tries to comapre to the variable name instead of the variable value.

Please advise.