In a method for correctly geometrically assigning x-ray images of a patient an optically operating recording device is attached to an x-ray device generating the x-ray images. A heater temperature is controlled so that a diameter of a growing crystal becomes approximately equal to an inner diameter of the second crucible, and the crystal is grown by maintaining a surface of the growing crystal in a state covered with the encapsulating material until termination of crystal growth. One or more supports coupled to the lower tray may be repositioned to inhibit rocking of the lower tray.