Calculate the number of female patients who accepted "HPV quadrivalent" immunization.
female refers to gender = 'F'; "HPV quadrivalent" immunization refers to immunizations where DESCRIPTION = 'HPV quadrivalent';
SELECT COUNT(DISTINCT T1.patient) FROM patients AS T1 INNER JOIN immunizations AS T2 ON T1.patient = T2.PATIENT WHERE T2.DESCRIPTION = 'HPV  quadrivalent' AND T1.gender = 'F'