Breast securement devices for imaging systems are provided. The securement device can include a breast tray configured to support a patient's breast. In one example, one or more walls extend from the breast tray to receive the patient's breast. In another example, a pair of arms pivotably extend at least partially over the breast tray to receive the patient's breast therebetween. In still another example, a membrane covers the breast tray and the patient's breast and selectively couples to the breast tray via a suction force. In yet another example, a paddle includes a plurality of flexible fingers that contour to the patient's breast, or includes an array of pins that independently slide within of the paddle and contour to the patient's breast, or includes a bladder having non-Newtonian fluid. Additionally or alternatively, a sling may receive the patient's breast and support the breast from below.