A method for preparing a 3-D dental x-ray image of at least one section of an object configured as a volume (42, V1, V2) using an x-ray machine, comprising the positioning of the object relative to the machine, wherein the volume (42, V1, V2) is created as the 3-D x-ray image from a plurality of x-ray projection images during an at least partial revolution of the system consisting of an x-ray tube (4, 4') and an x-ray image detector (6, 6') around at least a section of the object, characterized in that, - before creating the 3-D x-ray image of the volume (42, V1, V2), at least part of the object is displayed in a graphic representation (40, 71, 72, 73) having at least part of a surface and/or a contour of the object, wherein a visual 3-D image or a three-dimensional contour is calculated from a plurality of visual images, and wherein the relative position of the graphic representation (40, 71, 72, 73, 74) to the current machine and patient position is known, - the volume (42, V1, V2) that is to be imaged and depends on the position of the object relative to the machine, and on the selection of the adjustment and/or control data, is shown at least approximately in the correct position in the three-dimensional contour or the visual 3-D image of the graphic representation (40, 71, 72, 73, 74), - when the position and/or size of the volume (42, V1, V2) to be imaged changes in the graphic representation (40, 71, 72), the adjustment and/or control data for creating the 3-D x-ray image are determined, - the position and/or size of the volume (42, V1, V2) reproduced in the graphic representation (40, 71, 72, 73, 74) is changed before creating the x-ray image, wherein the relative position of the patient to the machine and/or the adjustment and/or control data needed to create the volume (42, V1, V2) is adapted to the changed position and/or size of the volume (42, V1, V2), - the volume (42, V1, V2) depicted on a display is moved on the display by means of an input device, and the position data and/or the size of the displayed volume (42, V1, V2) are transmitted to the x-ray machine, and - the volume (42, V1, V2) that is depicted on a display and can be moved on the display by means of the input device is only moved while retaining at least a partial overlap with the depicted anatomical structure. - before creating the 3-D x-ray image of the volume (42, V1, V2), at least part of the object is displayed in a graphic representation (40, 71, 72, 73) having at least part of a surface and/or a contour of the object, wherein a visual 3-D image or a three-dimensional contour is calculated from a plurality of visual images, and wherein the relative position of the graphic representation (40, 71, 72, 73, 74) to the current machine and patient position is known, - the volume (42, V1, V2) that is to be imaged and depends on the position of the object relative to the machine, and on the selection of the adjustment and/or control data, is shown at least approximately in the correct position in the three-dimensional contour or the visual 3-D image of the graphic representation (40, 71, 72, 73, 74), - when the position and/or size of the volume (42, V1, V2) to be imaged changes in the graphic representation (40, 71, 72), the adjustment and/or control data for creating the 3-D x-ray image are determined, - the position and/or size of the volume (42, V1, V2) reproduced in the graphic representation (40, 71, 72, 73, 74) is changed before creating the x-ray image, wherein the relative position of the patient to the machine and/or the adjustment and/or control data needed to create the volume (42, V1, V2) is adapted to the changed position and/or size of the volume (42, V1, V2), - the volume (42, V1, V2) depicted on a display is moved on the display by means of an input device, and the position data and/or the size of the displayed volume (42, V1, V2) are transmitted to the x-ray machine, and - the volume (42, V1, V2) that is depicted on a display and can be moved on the display by means of the input device is only moved while retaining at least a partial overlap with the depicted anatomical structure.