Real-time digital x-ray imaging apparatus

Abstract

An x-ray diagnostic apparatus and methods performs Real-Time Digital Radiography with particular application in dental x-ray imaging modalities, such as Orthopantomography, Scannography, Linear Tomography and Cephalography, by using a versatile and modular electronic unit, featuring ultra fast computation capability to serve diversified image sensor typology and scanning modality. In Digital Orthopantomography and Scannography, a plurality of tomographic images at different depths of the jaw can be generated, based on the pre-selection made by the user interface. The image processing unit utilizes for the tomo-synthesis of the diagnostic image an accurate and economic digital simulator of the radiographic film speed, including a digital frequency synthesizer fed with film cassette speed digital input and high resolution clock signal, ensuring accurate and reproducible phase continuity of the output frequency signal. It also introduces an automatic adaptation of the frame acquisition rate in frame transfer mode, based on the actual speed of the cassette unit. By this method the dynamic of the exposure signal is reduced, and a better optimization of the signal response of the x-ray detector is achieved.

1 . A dental x-ray diagnostic apparatus for performing real-time digital radiography of a patient skull, comprising an x-ray source rigidly connected to an x-ray imager providing x-ray generation; said x-ray imager being electrically coupled to an image processing unit and allowing execution of orbital movements of said x-ray source and said x-ray imager around the patient skull, allowing projections as required for Orthopantomography, Scannography and Tomography. 
   
   
       2 . An apparatus as in  claim 1 , further comprising an alignment mechanism to allow alignment of said x-ray source with a second x-ray imager for performing Oephalography. 
   
   
       3 . An apparatus as in  claim 1 , wherein said x-ray imager is relocatable thereby allowing relocation of said x-ray imager in the position for Oephalography. 
   
   
       4 . An image processing unit for performing x-ray imager control and image processing functions in a dental x-ray apparatus, comprising a control logic functional unit containing programmable logic to generate a phase sequence or addressing function for said x-ray imager and control signals to control the enable and data exchange between a FIFO Registry, a Full Adder and an Image Memory through a data bus. 
   
   
       5 . A unit as in  claim 4 , further comprising a functional converter for performing analogue to digital conversion of a video out signal generated by an x-ray imager, synchronized with a pixel rate by said control logic. 
   
   
       6 . A unit as in  claim 5 , wherein digital pixel data output is readable through a parallel data bus. 
   
   
       7 . A unit as in  claim 6 , wherein said parallel data bus is a data channel through which pixel data is exchanged between said converter, said FIFO registry, said Full Adder and said Image Memory. 
   
   
       8 . A unit as in  claim 7 , wherein said FIFO Registry comprises a temporary storage device, wherein pixel data are stored, processed and shifted before transfer to said image memory. 
   
   
       9 . A unit as in  claim 8 , wherein said Full Adder performs an add operation on FIFO data. 
   
   
       10 . A unit as in  claim 9 , further comprising a Cassette Speed Simulator (CSS). 
   
   
       11 . A unit as in  claim 10 , wherein said CSS provides the synthesis of a frequency signal simulating the speed of the film cassette. 
   
   
       12 . A unit as in  claim 11 , wherein digital data is referred to the cassette speed for a given projection, thereby representing the actual speed over a time interval. 
   
   
       13 . A unit as in  claim 12 , wherein said CSS operates on the base of a system clock frequency and in response to input velocity data, synthesizes the output frequency simulating the cassette drive speed, ensuring phase continuity operation by Direct Digital Synthesis (DDS) with phase accumulation. 
   
   
       14 . A unit as in  claim 13 , further comprising a sensor integration control (SIC) for receiving as an input the cassette speed, and providing as an output the corresponding varying duration of the integration time on said sensor. 
   
   
       15 . A unit as in  claim 14 , wherein said output is used by said control logic to control a frame acquisition rate. 
   
   
       16 . A unit as in  claim 15 , wherein said imager is an x-ray image sensor providing conversion of x-rays to light or providing conversion of x-rays to an electric charge. 
   
   
       17 . A unit as in  claim 16 , wherein said x-ray imager has a COD read out section controlled by phase control signals generated by said control logic. 
   
   
       18 . A unit as in  claim 17 , wherein said imager is operated in a full frame mode. 
   
   
       19 . A unit as in  claim 17 , wherein said COD device is controlled by phase control signals generated by said control logic. 
   
   
       20 . A unit as in  claim 19 , wherein said imager is operated in a frame transfer mode. 
   
   
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