How can I find all radio buttons within the same logical “group” using jQuery?

Question

I'm writing some code that highlights all <input type=radio /> within a "radio group" when any one of them is changed.
In the event handler for the radio "change" event, I use the following code to find all other similar radios:

radioHandler: function (event) {
    var element = $(this);
    var name = element.attr("name");
    // Find all radios in the same group:
    element.closest("form")
        .find("input[type=radio][name='" + name + "']")
        .each(function(){
            ... etc ...
        });
},

This works perfectly if the radios are indeed contained within a form.
However, I also want it to work if there are radios outside the form too.

For example, assuming all radios use the same name, the following represents 3 different radio groups (and all browsers behave this way):

       o Radio A | o Radio B | o Radio C          (Group - no form)
<form> o Radio D | o Radio E | o Radio F </form>  (Group - form 1)
<form> o Radio G | o Radio H | o Radio I </form>  (Group - form 2)

If I have an element, what's the best way to find ONLY the radios that are part of its "group"?

Also, for bonus points ... what if the element isn't part of the current document -- ie, it is contained within another "detached" context? The current solution works fine (because element.closest(...) uses the element's context).