Abstract:
The present invention relates to an X-ray parameter measuring arrangement comprising a detector for measuring said parameter configured to be positioned in a position adjacent to an x-ray source arranged to generate a ray formation having a primary ray portion for radiating an object. The position is chosen in such a way that the interference with a reproduced image is reduced or eliminated.

Description:
TECHNICAL FIELD 
     The present invention relates generally to providing dose measurement in an X-ray apparatus, and in particular to an X-ray dose detection arrangement, an X-ray imaging system, and a method for measuring an X-ray dose in an X-ray imaging system. 
     BACKGROUND 
     In X-ray imaging, for example in medical X-ray imaging, it is necessary to control radiation levels. Therefore, the X-ray dose is measured, for example by providing an ionization chamber. The ionization chamber may be provided as an extra-unit between the object, for example a patient, and the detector/x-ray source. However, due to the ionization chamber provided as a separate component, the setup for the X-ray imaging system consumes valuable space. Further, the ionization chamber may be displaced and exposure procedures may be performed without ionization chambers. 
       FIG. 1  is a schematic view of a simplified X-ray source housing  100  according to prior art. The X-ray source housing  100  comprises an X-ray tube  101 , which generates X-rays  102 . The X-rays  102  pass through a collimator  103  and in this case a Dose Area Product (DAP) meter  104 . 
     DAP meters are usually large-area, transmission ionization chambers and associated electronics. In use, the ionization chamber is placed perpendicular to the beam central axis and in a location to completely intercept the entire area of the x-ray beam. The DAP, in combination with information on x-ray field size can be used to determine the average dose produced by the x-ray beam at any distance downstream in the x-ray beam from the location of the ionization chamber. 
     DAP is defined as the integral of dose across the X-ray beam. Therefore DAP includes field non-uniformity effects such as anode-heel-effect, and the use of semi-transparent beam-equalizing shutters (lung shutter). Assuming that the incident beam is totally confined to the patient, the recorded value may essentially provide an upper limit on the X-ray energy absorbed by the patient (i.e. there is no transmission or scatter). DAP&#39;s ability to estimate stochastic risk is degraded because of the lack of dose distribution information within the patient. The best may be to assume an average weighting factor for all the tissues at risk. This may lead to an over or under estimate of risk in certain cases. 
     SUMMARY 
     Thus, there is a need to provide dose measurement in X-ray imaging requiring minimized constructional space and positioning that do not interfere with the reproduced image. The solution of the present invention provides for measuring a number of X-ray parameters, amongst others total dose and ray quality. 
     For these reasons an X-ray parameter measuring arrangement comprising a detector for measuring said parameter configured to be positioned in a position adjacent to an x-ray source arranged to generate a ray formation having a primary ray portion for radiating an object. The position is chosen in such a way that the interference with a reproduced image is reduced or eliminated. In one embodiment, the detector is configured to measure scattered radiation. In another embodiment, the detector is configured to measure a direct radiation. In one embodiment, the detector is arranged on a housing of the x-ray source and configured to detect the scattered rays through an aperture provided in the housing. The detector, according to a second embodiment, is arranged at an opening of a housing of the source from which x-rays emerge, positioned at least partly or entirely in an image field, i.e. the ray formation radiating an object to be examined. The detector may also be arranged inside a housing of the source, in a position of corresponding to a direction from where the rays leave a collimator aperture positioned at least partly or entirely in an image field, i.e. the ray formation radiating an object to be examined. In a fourth, the detector is arranged inside a housing, between the source and a collimator. In a fifth embodiment, the detector is arranged inside or on a surface of a collimator. 
     The X-ray parameter measuring arrangement of the present invention, may be configured to measure one or several radiological parameters including dose of scattered X-rays, total dose, dose rate, Peak Kilovoltage (kVp), half-value layer (HVL), total filtration, exposure time, pulses, pulse rate and dose/pulse. 
     The detector, in one embodiment, comprises a housing enclosing a number of stacked diode layers, each diode layer distanced from each other and provided with a radiation filter between each diode layer and each diode layer connected to a processing unit for generating a signal corresponding to said parameter. The detector may comprise a housing enclosing one or several diodes in one layer. Moreover, the detector in one embodiment comprises a RF communication portion. 
     The invention also relates to an X-ray detector comprising: a number of stacked diode layers, a radiation filter layer between each diode layer; and a processing unit connected each diode layer or a diode in each diode layer. The X-ray detector may further comprise a housing of a radiation blocking material. The processing unit may be realized in Application Specific Integrated Circuit (ASIC). 
     The invention also relates to a computer network for handling radiological information, the network comprising an X-ray examination arrangement, a data collector and a database, wherein the X-ray examination arrangement is provided with an X-ray parameter measuring arrangement comprising a detector for measuring said x-ray parameter, the arrangement is configured to be positioned in a position adjacent to an x-ray source arranged to generate a ray formation having a primary ray portion for radiating an object. 
     The position is chosen in such a way that the interference with a reproduced image is reduced or eliminated. The database may consist of a central application and a locally-installed DICOM or MWL, RDSR, MPPS, DICOMOCR data collector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the attached drawings, wherein elements having the same reference number designation may represent like elements throughout. 
         FIG. 1  illustrates schematically an exemplary X-ray source according to prior art; 
         FIG. 2 a    illustrates schematically an exemplary X-ray source according to present invention; 
         FIG. 2 b    illustrates schematically an exaggerated portion of X-ray source of  FIG. 2   a;    
         FIG. 3  is a cut through an exemplary detector according to one embodiment of the present invention; and 
         FIG. 4  is a schematic communication system for radiography purposes incorporating present invention; 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2 a    is a schematic view of a simplified X-ray source housing  200 . The X-ray source housing  200  comprises an X-ray tube  201 , which generates X-rays  202  with a certain formation (ray image). The X-rays  202  pass through a collimator  203 , which narrows the beam before radiating an object  206  to be examined. 
     According to the invention, at least one x-ray measuring detector  205  is arranged adjacent to the x-ray source housing  200 , between the tube  201  and the object (e.g. patient)  206  to be examined. 
     The source housing comprises a housing  207 . The detector  205  may be mounted adjacent to the tube on the housing, in a first position as illustrated by solid line or in position where the beam exits the housing, as illustrated by dashed line. In this way, when the tube generates a ray formation with a primary ray portion for radiating the object, the detector positioned outside the primary ray portion but inside the ray formation (ray image). 
       FIG. 2 b    illustrates a number of different positions in which the detector(s) (black boxes) may be provided. 
     Detector  2051  is arranged on the housing  207  and is configured to detect the scattered rays  2021 . In this case an aperture is provided in the housing to let through the rays. 
     Detector  2052  is arranged at the opening of the housing  207  from which x-rays emerge. The detector may, at least partly or entirely, be arranged in the image field, i.e. the ray formation that will radiate the object to be examined. However, due to its position on the fringe of the opening, its influence on the reproduced image will be negligible or very little. 
     Detector  2053  is arranged inside the housing  207 , beneath the collimator  203  aperture. Although, in this embodiment, the detector may, at least partly or entirely, be arranged in the image field, i.e. the ray formation that will radiate the object to be examined. However, due to its position on the fringe of the beam formation, its influence on the reproduced image will be negligible or very little. 
     Detector  2054  is arranged inside the housing  207 , between the tube and the collimator  207 . In this case, the primary beam before passing the collimator will be measured and the reproduced image will not be influenced at all. 
     Detector  2055  is arranged inside or on a surface of the collimator  203 . In this case, the primary beam before passing the collimator will be measured and the reproduced image will not be influenced at all. 
     The consequence of positioning of the detector(s)  205  in a space adjacent to the source  201  or in small portion of sight for the primary X-ray beams  202 , is that the detector will not interfere or have very small (negligible) with the rays radiating the object  206  and deteriorate the reproduced image. 
     The X-ray measuring detector  205  (which will be detailed below) comprises a sensor, which is configured to measure radiological parameters, mainly dose of scattered X-rays. The sensor is also capable of measuring other radiological parameters such as dose rate, Peak Kilovoltage (kVp), half-value layer (HVL), total filtration, exposure time, pulses, pulse rate and dose/pulse. 
     The output of the detector may be provided to a computer unit  208  for processing the signals. 
     The detector  205  may be assembled on the source housing separately or built in. 
       FIG. 3  is a cross sectional view of one exemplary detector  305  according to one embodiment of the invention. The detector comprises a sensor part  3051  and electronics  3052  enclosed inside a housing  3053 . 
     The housing  3053 , e.g. made of tin or other suitable x-ray blocking material, has an open end (window)  30531  for allowing through radiation. The open end is however, provided with a light blocking element  30532 . The housing comprises a bottom portion  30533  and a upper portion  30534 . 
     The sensor part  3051  comprises a number of stacked solid state (silicon) diodes  30511  (four rows in this case). Diodes in each row are arranged on a carrier (PCB) (not numbered) connected to a conductor  30512 . 
     A filtering layer  30513 , e.g. made of copper or other suitable material, is arranged between each row comprising diodes and carrier. The rows are distanced using distancing elements  30514  (at each side), e.g. arranged as a frame for each row. The filter layers function as filters between each diode row such that they block radiation from sides but allow radiation falling through the open end  30531  of the housing. 
     The electronic portion comprises  3052  a signal processing unit  30521  (e.g. realized as Application Specific Integrated Circuit (ASIC)). Each row is connected to input of processing unit by means of conductors  30512  as a channel. The output of the signal processing unit may be connected to external processing elements (not shown) through a cable  30522 . Instead or in combination with the cable  30522 , the electronic portion may also be provided with a RF transmitter/receiver  30523  for transmitting processed data to a receiver. The electronics may be provided with power using onboard power source or external power source. 
     The number of diodes in rows and number of layers depends on application are. The detector may comprise only one diode, e.g. for the applications where the sensor is incorporated with the collimator as described above. However, a preferred embodiment comprises at least three or more layers. 
     As mentioned earlier, the sensor comprises stacked diodes, in which each diode layer is radiated by same source radiation. The filter layers between each diode layer changes energy content of the source radiation, i.e. each diode layer is radiated by spectrally different radiation although having a common source radiation. Each diode layer generates a current depending on the radiation intensity and energy. The diode currents are connected to an amplifier (e.g. transimpedance amplifier) with varying amplification and a following amplifier (e.g. voltage amplifier) with varying amplification. The diode specific voltage for each diode layer is then forwarded to an Analogue-to-Digital converter (ADC) for further connection to a processing unit, which processes the signals to compute one or several of dose, kVp, total filter, dose rate, expose time, HVL, etc., for the source radiation. 
       FIG. 4  illustrates a schematic of a network  400 , which may incorporate a detector and measuring teachings of the present invention. The network according to this embodiment comprises an X-ray examination arrangement  401 , such an X-ray machine, CT, radiography machine, etc., provided with at least one detector  405  as described earlier. The examination arrangement  401  and the detector  405  may be connected to RIS/PACS  406  and/or a data collector  407 . The information from data collector  407  may be provided to a database  408  in the computer network. 
     The database may consist of a cloud-based application and a locally-installed DICOM or similar (MWL, RDSR, MPPS, DICOMOCR) data collector. 
     Users such as, operator  4091 , RSO physicist  4092 , radiologist  4093  etc., may access the information form the examination arrangement or detector, for example through a web browser. This enables all individuals in the workflow easy access to the solution without any troublesome software installations. 
     The data collector may be a software solution that may be installed at examination site. The data collector connects the X-ray machines and/or RIS/PACS systems using the DICOM network. 
     The foregoing description of embodiments of the present invention, have been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments of the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments of the present invention. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. 
     It should be noted that the word “comprising” does not exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the invention may be implemented at least in part by means of both hardware and software, and that several “means”, “units” or “devices” may be represented by the same item of hardware. 
     Software and web implementations of various embodiments of the present invention can be accomplished with standard programming techniques with rule-based logic and other logic to accomplish various database searching steps or processes, correlation steps or processes, comparison steps or processes and decision steps or processes. It should be noted that the words “component” and “module,” as used herein and in the following claims, is intended to encompass implementations using one or more lines of software code, and/or hardware implementations, and/or equipment for receiving manual inputs. 
     The various embodiments of the present invention described herein is described in the general context of method steps or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.