Anterior mandibular occlusal projection Receptor Placement: Seat the patient tilted back so that the occlusal plane is 45 degrees above horizontal. Place the receptor in the mouth with the long axis perpendicular to the sagittal plane and push it posteriorly until it touches the rami. Center the receptor with the pebbled side (tube side) down, and ask the patient to bite lightly to hold the receptor in position. Projection of Central Ray: Orient the central ray with −10 degrees angulation through the point of the chin toward the middle of the receptor; this gives the ray −55 degrees of angulation to the plane of the receptor. Point of Entry: The point of entry of the central ray is in the midline and through the tip of the chin.