javascript:

                                         function GetRadWindow() {
                                             var oWindow = null;
                                             if (window.radWindow) oWindow = window.radWindow;
                                             else if (window.frameElement.radWindow) oWindow = window.frameElement.radWindow;
                                             return oWindow;
                                         }
                                         function Close(argument) {
                                             GetRadWindow().close(argument);
                                         }

codice code behind:

    Private Sub update_image(ByVal idutente As Int32, ByVal image As String)
        Try
            Dim conString = ConfigurationManager.ConnectionStrings("TrycontactString")
            Dim strConnString As String = conString.ConnectionString
            Using db As New SqlConnection(strConnString)
                db.Open()
                Using sqlcmd As New SqlCommand("Sp_update_imageprofile", db)
                    sqlcmd.CommandType = CommandType.StoredProcedure
                    sqlcmd.Parameters.AddWithValue("@id", SqlDbType.Int).Value = idutente
                    sqlcmd.Parameters.AddWithValue("@imageprofile", SqlDbType.VarChar).Value = image
                    sqlcmd.ExecuteNonQuery()
                    Dim _img As String = Replace(image, "~", "")
                    ViewState("VarImage") = _img
                    ScriptManager.RegisterStartupScript(Page, Me.GetType, "openconferma", "openconferma();", True)
                End Using
            End Using
        Catch ex As SqlException
            Exit Sub
        Catch ex As Exception
            Exit Sub
        End Try
    End Sub

    Protected Sub ImageButton2_Click(sender As Object, e As System.Web.UI.ImageClickEventArgs) Handles ImageButton2.Click
        ScriptManager.RegisterStartupScript(Page, Me.Page.GetType(), "closeWindow", "Close('" & ViewState("VarImage") & "');", True)
    End Sub