WPF: Set Printing Orientation to Landscape?

In WPF C#, how can I set printer page settings to landscape. I am trying to print a flowdocument. I have tried different things but nothing seems to be working.

Here is my code.

IDocumentPaginatorSource dps = this.MyFlowDoc;
// pd.PrintTicket.PageOrientation = System.Printing.PageOrientation.Landscape;
// pd.PrintTicket.PageMediaSize = new System.Printing.PageMediaSize(System.Printing.PageMediaSizeName.ISOA4Rotated);
pd.PrintQueue.CurrentJobSettings.CurrentPrintTicket.PageOrientation = System.Printing.PageOrientation.Landscape;
pd.PrintDocument(dps.DocumentPaginator, "MyInvoice");