How to Get Repeater Row index out side Repeater?

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ASP.NET2

<asp:Repeater runat="server" ID="columnRepeater" OnItemDataBound="columnRepeater_ItemDataBound">
<itemtemplate>

<asp:HiddenField runat="server" ID="hfLgrItmLnIdR" />
                                    <asp:ImageButton runat="server" ID="imgbtnPopup" ImageUrl="~/images/add.png" OnClick="imgbtnPopup_Click" />

i Want get Repeater Row index in these imgbtnPopup button click event. Any one can help me..