1.  Field of the Invention
The present invention relates to an imaging system displaying imaging information that has been acquired by means of a medical diagnostic imaging device. 
2.  Description of the Prior Art
Imaging systems of the above general type serve in medical technology for displaying diagnostic imaging information obtained using different modalities ( medical diagnostic imaging devices) such as radiological CT devices, conventional radiology devices, MR devices, etc.  Usually, the image information is transferred onto a transparent film, particularly an X-ray film, and is diagnosed at film viewing devices which are known per se, these being constructed in the fashion of light boxes.  Images such as these represent a xe2x80x9cfrozen statexe2x80x9d; that is, the characteristics of an image, such as contrast and the like, can no longer be influenced. 
Adjustment of such characteristics is only possible when the observer does not view the image information at a film viewing device, but rather at a graphic workstation, such as are sold by Siemens AG under the names xe2x80x9cMagicViewxe2x80x9d and xe2x80x9cProminence,xe2x80x9d since extensive possibilities for image processing are available with such units.  Viewing of diagnostic image information at the monitors of such workstations, however, usually is outside of the typical work habits of the diagnosing physicians, who are used to making their diagnoses at a film viewing device and are not accustomed to working with computer and mouse. 
Displaying of image information on a projection surface by means of a video projector, instead of by means of a transparent film and a film viewing device or by means of a monitor, is known. 
Operating devices on the basis of input interfaces known as virtual touchscreens (SIVIT-Siemens Virtual Touchscreen) is also known.  Here, a video projector projects operating elements onto a projection surface.  Movement of a finger on the projection surface, which is illuminated with an infrared lamp, is picked up by an infrared-sensitive video camera, and is interpreted like movement with a mouse; the lingering of the finger at a specific position being recognized as the equivalent of a mouse click.  A further simplification of the operating procedures is possible by means of an additional evaluation of the gestures of the operator.  Such virtual touchscreens are described in German PS 196 12 949 and German OS 197 08 240. 
It is an object of the present invention to provide an imaging system of the general type described initially, wherein even an operator who is unaccustomed to working with a graphic workstation can influence the reproduction of the image information. 
The above object is achieved in accordance with the principles of the present invention in an imaging system for displaying image information acquired using a medical diagnostic imaging device, the system having at least one projection surface and a projection device which reproduces the image information on the projection surface, and an optical detector which detects gestures of an operator or which detects the position of a pointing element held by an operator, and a control unit which evaluates output data from the optical detector to generate control signals based on the output data for controlling the reproduction of the image information by the projection device. 
In the imaging system of the invention, because the image information is not displayed on a monitor, but rather on a projection surface, the operator is given a perspective that corresponds to that when working with a film viewing device.  As a result of the evaluation of the gestures of the operating person, he or she is able to influence the reproduction of the image information without having to work at a computer or a graphic workstation or having to be familiar with such workstations. 
Accordingly, a virtual touchscreen is employed, having operating elements which are activated by a hand, preferably a finger, of an operator, with the aid of a pointer or of a light pointer as a pointing element, for example. 
According to a preferred embodiment of the invention, the control unit contains an image processing stage, and the control unit evaluates the output data of the detector for controlling the image processing stage.  With a suitable design of the image processing stage, it is then possible to control by gesture all the image processing steps which are otherwise common with mouse control, such as windowing, dimensioning of objects, 3D functions, etc. 
In another version of the invention, the control unit contains circuitry for mixing different image information, making it possible to operate complex functions such as image fusion, that is, the mixing of image information originating in different modalities.  For example, it is possible in image fusion to a virtual endoscopy display, such as can be calculated on the basis of three-dimensional image data acquired by means of a radiological CT device, with the image information acquired in a real endoscopic examination of the corresponding body region. 
Furthermore, the control device can have the capability of retrieving different image information, so that it is possible to display and process random images that are stored in the imaging system or archived externally.  The control unit can contain speech recognition circuitry for detecting the speech of an operator, and the control unit can evaluate the output data of the recognition circuitry speech either for controlling the imaging system or for creating and storing alphanumeric comments, which are allocated to the displayed image information.  It is also possible to execute other operating actions using voice control, or to dictate a diagnosis of the image information directly, as is taught in xe2x80x9cDiktieren auf das Papierxe2x80x9d (Elektronik 16/1997, p. 47). 
In order to guarantee the necessary security, or to prevent misuse, the means for detecting speech recognition circuit can contain voice recognition capability, so that commands or dictation are only recognized if they are spoken by an authorized person.