Field Value of a Grid Lookup Field

Is there any possibilty to use the value of a field (like {My_Field} that is a Grid Lookup field. When I use {My_Field} in PHP programming section, I get the value of the field itself, not the value of the lookup field. But I want the lookup field value in a variable like: {My_Field.value} or something.

Thanks for help and answers.

Since it is a lookup you can always simply do the query for the lookup by hand using {My_Field} just perform an sc_lookup or an sc_select