Total Amount In Collections

Once we change a Patient’s Billing Options to “date turned over to collections”, this patient now appears as the color red in the Active Patients List.
Is there a way to determine the amount of balance that all those patients in red have–in total?

SELECT
   SUM(postedbal - ageunapplied) AS "AmtInCollections"
FROM
   sos.ptpayors a
   JOIN sos.payors b ON a.payornum = b.payornum
WHERE
   b.collectdate IS NOT NULL