JP2008541963A - X-ray apparatus for displaying an image of an object to be examined and use of the X-ray apparatus - Google Patents

Abstract

  An X-ray apparatus that forms an image of a test object containing at least one X-ray contrast chemical element with an X-ray beam transmitted through the test object and an X-ray beam emitted from the test object A. At least one x-ray beam source delivering a substantially multicolor x-ray beam; b. A first detector for detecting a first intensity value of an X-ray beam transmitted through the test object, or a first detection unit; c. A second detector for detecting a second intensity value of the X-ray beam emitted from the test object, or a second detection unit; d. At least one correlation unit for correlating the first intensity value of the transmitted X-ray beam and the second intensity value of the emitted X-ray beam for each pixel; e. An X-ray apparatus having at least one output unit for displaying a test object from a pixel signal obtained by correlation between the first intensity value and the second intensity value, and a method for using the X-ray apparatus are described. Has been. The transmission image and the radiation image are preferably recorded simultaneously. This method can also be combined with another radiographic image, for example from a positron emission tomograph (PET), single photon emission computed tomograph (SPECT).

Description

  The present invention relates to an X-ray apparatus for displaying an image of a test object containing at least one X-ray contrast chemical component by means of an X-ray beam, a method of using the X-ray apparatus, and a test object such as a mammal, in particular The present invention relates to a human X-ray imaging contrast method.

  Medical diagnosis with X-ray beams is a highly developed field for disease diagnosis, such as early detection, X-ray imaging, tumors, vascular disease, and identifying the nature and location of human pathological changes. . This technology is very capable and has a high potential for use.

  An X-ray tube for forming an X-ray beam has, for example, a W-, Mo- or Rh-rotary anode and Al-, Cu-, Ti-, Mo- and Rf-filters. With appropriate filtering, a part of the brake beam is extracted and filtered, and in the most advantageous case the characteristic beam is emitted from the x-ray tube.

  A conventional X-ray film, a memory sheet, or a digital flatbed detector is used as the detector. In computer tomographs, one or more detector rows are used. A plurality of detectors can be connected in parallel. A semiconductor detector is used to directly convert the X-ray beam into an electrical signal. This semiconductor detector consists of cadmium-telluride (CT), cadmium-zinc-telluride (CZT), amorphous selenium, amorphous silicon, or crystalline silicon (MJ Yaffe, JA Rowlands, "X -Ray Detectors for Digital Radiography ", Med. Biol., 42 (1) (1997) 1-39).

  An example for the construction of this type of detector is described in US 5,434,417 A. In order to increase the energy sensitivity of the detector, the detector is formed from a plurality of layers. X-ray beams with different energies penetrate the detector at different depths and form electrical signals by photoelectric action in each layer. This electrical signal can be distinguished according to the energy of the layer and the X-ray photons and can be read directly as a current pulse.

  Computer tomographs (CT) have long been used in clinical practice as a routine method. A tomographic image of the body can be obtained by CT, and this tomographic image achieves a better spatial resolution than conventional projection X-ray images. The density resolution of CT is much higher than that of conventional X-ray technology, but contrast agents are required to reliably identify a number of pathological changes. This contrast agent improves the quality of the morphological information. Here, the contrast agent shows on the one hand the functional course (excretion, blood flow, permeability) in the body, and on the other hand the form is emphasized by contrast shadows (differences in contrast agent concentration for different tissues) .

  In many cases, conventional X-ray techniques cannot be used. This is because the contrast of the test tissue was not sufficient. To this end, X-ray contrast agents have been developed that form high X-ray image densities in the accumulated tissue. Typically iodine, bromine, elements of atomic numbers 34, 42, 44 to 52, 54 to 60, 62 to 79, 82 and 83, and chelates of elements of atomic numbers 56 to 60, 62 to 79, 82 and 83 Are proposed as contrast elements. Examples of iodine compounds are meglumine-Na- or lysine-diatrizoate, iotaramate, ioxitalamate, iopromide, iohexol, iomeprol, iopamidol, ioversol, iopental, iotrolane, iodexanol and iodosilane (INN) (EP0885616A1).

  In some cases, sufficient tissue contrast may not be achieved despite the application of an X-ray contrast agent. Digital subtraction angiography (DSA) has been introduced to achieve further contrast enhancement. Here, radiographs before and after contrast agent administration are subtracted (logarithmically). A subtraction method applied in mammography is disclosed in EP 0 856 616 A1: for projection mammography, first a pre-contrast mammography is recorded, followed by a rapid i. v. And post-contrast mammography is recorded approximately 30 seconds to 1 minute after injection. The data obtained from the two images are correlated with each other and preferably subtracted from each other.

  New developments in the CT field relate to the excitation side, for example the use of synchrotron beams in CT (FA Dilmanian, “Computed Tomography with Monochromatic X-Rays”, Am. J. Physiol. Imaging. 314 (1992) 175-193). A good X-ray image is obtained, for example, by “K-edge subtraction CT” (FA Dilmanian, supra, page 179). Here, a large increase in the absorption coefficient in the binding energy of atomic K electrons is used. Iodine has a K edge with an energy of 33.17 keV. Unfortunately, this method only works with synchrotron beams that can be used, for example, in the large memory ring of DESY. This is because only this beam has advantageous monochromaticity and intensity for this method. Conventional X-ray tubes do not send a monochromatic beam, but send a continuous spectrum. Therefore, the conventional X-ray tube is not suitable for this kind of difference measurement.

  An alternative means is described in DE 101 187 792 A1: Here a method is proposed in which an X-ray beam source with two X-ray anodes of different materials is used to record projection mammography. To record a mammography, the patient is first administered an X-ray contrast agent. The first projection image is then recorded using one of the two x-ray anodes, followed by the second projection image using the other x-ray anode. A correlation image is created by superimposing each individual pixel of the first image with a corresponding individual pixel of the second image. The characteristic beams of the two X-ray anodes are matched to the absorption spectrum of the X-ray contrast agent. The radiant energy of the first X-ray anode is slightly less than the absorbed energy of the contrast-forming element of the X-ray contrast agent, and the radiant energy of the second X-ray anode is slightly larger than the absorbed energy of the contrast-forming element. The disadvantage of this method is that a conventional X-ray tube with only one X-ray anode must be replaced with a bi-anode tube.

In addition to transmission x-rays, radiation x-rays are also described:
For example, WO 2004/041060 A2 describes a device for non-invasive in vivo detection of chemical elements in the human prostate.
The apparatus comprises a sonde, an irradiation system capable of exciting chemical elements for beam radiation, a beam detector within the sonde, and a signal recording processing and display device. The beam detector can image the emitted beam, and the signal recording and display device reproduces the amount of chemical elements at different locations in the prostate corresponding to the detected beam imaging. can do. The detected beam is substantially a fluorescent beam. In the case of examination of the prostate, advantageously the distribution of zinc in the tissue is detected.

Furthermore, DE 3608965 A1 describes a method of detecting various chemical element components in the layer of the region to be examined by means of a gamma beam or an X-ray beam. Here, the Compton scattered beam and the Rayleigh scattered beam are detected separately. The course of the differential scattering coefficient detected from the measured values is affected by the components of various chemical elements contained in each pixel. Therefore, the component of this chemical element can be detected from this process. For this purpose, the region to be examined is irradiated with the primary beam from a number of directions, and beams generated at different angles from this region to be detected are detected at different positions outside the region to be examined by the detector arrangement.
Then, a differential scattering coefficient is detected for each pixel of the layer with respect to various pulse transmission rates from the obtained measurement values.

  In addition, Quanwen Yu et al. , "Preliminary Exploration of Fluorescent X-Ray Computed Tomography to Detect Dual Agents for Biological Study" in: J. Synchrotron Rad. (2001), 8 1030-1034, proposes the use of X-ray fluorescence for the detection of very low concentrations of non-radioactive substances in biomedical research. By this method, the fluorescence Ka line can be used to obtain an image capable of simultaneously detecting multiple agents in a single examination, for example, quantitatively detecting the blood flow in the brain and the concentration of brain cells. be able to. In the previous study, images produced by this method were compared with images obtained by X-ray transmission tomography.

  The X-ray fluorescence method or the X-ray scattering method described in the above publication has a drawback that the details of the test object cannot be displayed due to the difficulty in imaging. Since only the display with a coarse resolution can be performed, it is not possible to display fine details on the image.

  The problem underlying the present invention is therefore to provide an apparatus and a method which can avoid the above-mentioned drawbacks and which can be recorded with various X-ray contrast chemical elements. Furthermore, it is possible to record an X-ray image more easily and comfortably, and to prevent an increase in cost. This technology can be used in a wide range of fields. A relatively small obstacle in the object to be examined can be visualized with as little dose as possible with high position resolution. Avoid motion artifacts.

  The subject is an X-ray device according to claim 1 for displaying an image of an object to be examined containing at least one X-ray contrast chemical element by means of an X-beam, the use of claim 11 of this X-ray device, and The image forming X-ray contrast method according to claim 25 solves the problem. Advantageous embodiments of the invention are described in the dependent claims.

  In the following description of the invention and in the claims, the concepts “radiation” and “radiate” are, on the one hand, X-ray fluorescence, ie the substance irradiated by an electromagnetic beam is excited to emit a beam, On the other hand, it should be understood that it is advantageously Rayleigh scattering. In the latter case, the beam is re-emitted even if there is no pulse transmission from the irradiated material, and at this time, the excited electrons are not generated in the capsule electrons of the atoms of this material, as in the case of fluorescence.

In order to form an image by the X-ray apparatus, an X-ray beam transmitted through the object to be examined and radiated thereby is used. For this purpose, the X-ray apparatus according to the invention has the following configuration:
a. At least one x-ray beam source for delivering a substantially multicolor x-ray beam;
b. A first detector for detecting a first intensity value of an X-ray beam transmitted through a test object, or a detection unit comprising a plurality of detectors connected and / or arranged in parallel;
c. A second detector for detecting a second intensity value of the X-ray beam emitted from the object to be examined, or a second detection unit;
d. At least one correlation unit for correlating the first intensity value of the transmitted X-ray beam and the second intensity value of the emitted X-ray beam for each pixel;
e. At least one output unit for displaying a test object from a pixel signal obtained by correlation between the first intensity value and the second intensity value;

  The transmitted X-ray beam and the emitted X-ray beam can be detected simultaneously or sequentially.

  This X-ray device is advantageously used to image an object to be examined containing at least one X-ray contrast chemical element with an X-ray beam. The X-ray contrast chemical element is advantageously introduced into the test object by means of an X-ray contrast agent. For this purpose, it is administered to a test subject, for example a human or an animal.

  Of course, low-order contrast chemical elements present in the test object have only a small yield in X-ray fluorescence. Therefore, it seems that it is not effective to form an image using this element. Furthermore, in this case, the energy of the X-ray fluorescence photon is small and the reach distance in the body tissue is also small. In particular, there is a fluorescent line that can be recorded from a bright line 28.6 and an element of iodine of 32.3 keV (Z = 53) by a detector that leaves the object to a sufficient extent and is arranged outside the object. can get. When the order of the chemical element is low, the second detector is arranged as close as possible to the region to be examined (ROI: region of interest).

This X-ray apparatus is used to implement the X-ray contrast method of the present invention. This method has the following method steps:
a. Advantageously administering at least one radiographic chemical element;
b. Irradiating a test object with a substantially multicolored X-ray beam;
c. Detecting a first intensity value of the X-ray beam transmitted through the test object;
d. Detecting a second intensity value of the X-ray beam emitted from the test object;
e. Correlating the first intensity value of the transmitted X-ray beam for each pixel with the second intensity value of the emitted X-ray beam;
f. The test object is displayed from the pixel signal obtained by the correlation between the first intensity value and the second intensity value.

Unlike known methods, which are performed and detected only by X-ray transmission tomography (TXCT) or only by X-ray fluorescence, here transmission and radiation are measured simultaneously or sequentially, both techniques according to the invention Combined with each other.
Here, the obtained images are superimposed by an appropriate correlation method. In this way, the respective advantages of both technologies are utilized.

  X-ray transmission tomographs offer the advantage of high achievable temporal and positional resolution. Thus, basically, very small obstacles or other details within the subject body can be elucidated. However, the contrast obtained is often not sufficient to visualize this detail. This is especially true for examination of disorders in soft tissue. Furthermore, examination of a predetermined body region by the TXCT method is also disturbed by skeletal tissue.

  On the other hand, X-ray fluorescence tomographs offer the advantage of providing a very contrast-rich display. This is because when only a given chemical element is properly excited, it emits an electromagnetic beam and this element in the region of interest (ROI) is suitable as a very sensitive measurement sonde. However, the FXCT method has a drawback that the spatial resolution is low, so that a small obstacle cannot be displayed.

  Only by correlating the intensity value of the transmitted X-ray beam with the intensity value of the radiated X-ray beam for each pixel and displaying the object to be inspected from the pixel signal obtained by this correlation, the area to be inspected (ROI) is sufficient The image can be displayed in detail with a good contrast. Certainly, the resolution of the contrast formed image portion is low. However, by correlating each value with each other, this drawback is fully eliminated. This is because the required detailed information can be obtained from the intensity value of the beam measured by TXCT.

  The invention can be used inter alia for human testing. The present invention forms a radiograph to display cavities, blood vessels and blood flow. For example, it can be used for esophageal-stomach-intestinal-pathway display, bronchiography, gallbladder imaging, angiography and arteriography, cerebral angiography, blood flow measurement, mammography, and lymphangiography. The main application techniques of the present invention are computer tomographs (MS-CT, μCT) and their fusion models (PET-CT (Positron Emission Tomograph), SPECT (Single Photon Emission Computer Tomograph), Sonograph, and other optical images. Forming method). In principle, the invention can also be used in the area of non-biological material inspection, for example material inspection.

  In order to perform the inspection, the transmitted beam is recorded by the first detector. The first detector is disposed in the beam path of the X-ray tube that is attenuated by the test object. The radiation beam is measured by a second detector. This second detector is arranged outside the beam path and preferably has an angle of about 90 ° to the beam path. However, the second detector can basically be arranged at any other angular position with respect to the X-ray beam. For example, the detector may be arranged at an angle of 45 ° or 135 ° with respect to the beam emitted from the X-ray beam source so that the detector does not detect the beam passing through the object to be examined. If the X-ray tube is at the 12 o'clock position, a series of detectors are mounted at the 6 o'clock position opposite a normal computer tomograph. Advantageously, the second detector can be arranged at the 3 o'clock position and / or at the 9 o'clock position. With this second detector, both X-ray fluorescence and X-ray scattering (Riley scattering, Copton scattering) can be recorded.

  For selective image detection by a second detector utilizing a radiation x-ray beam, the radiation x-ray beam can be resolved and measured with respect to its energy. When a predetermined radioactive chemical element is present in the test object, the X-ray beam emitted from this contrast chemical element and recorded by the second detector is converted into another radiated X-ray beam, such as a scattered beam (Copton scattering). , Riley scattering) and fluorescent beams emanating from other chemical elements are advantageous. As a result, a predetermined target region (ROI) can be selectively visualized by administering a contrast chemical element to a predetermined organ of a human body, and thus the visualized tissue is particularly large relative to surrounding tissues. Contrast can be added. The structure caused by the skeletal structure also retracts backward with respect to the display of the tissue in this type of image display, so that the skeleton does not substantially interfere with the image display.

  An energy dispersive detector is preferably used to detect and characterize the radiation beam. However, a simple detector can be used for this purpose, and the characterization of the radiation can be ensured by an X-ray optical module (filter combination, monochromator).

  Furthermore, this principle can be similarly applied to the measurement of the intensity value of the transmitted X-ray beam by the first detector. Also in this case, selective display of the region to which the contrast chemical element is administered in the test object (ROI) is achieved.

  Therefore, for example, human soft tissue can be displayed with sufficient contrast according to the present invention. By matching the energy or energy interval of the transmitted and emitted X-ray beams recorded by the detector to the type of contrast chemical element, an effective contrast increase over conventional methods can be achieved. it can.

  To form an X-ray beam, a normal commercially available X-ray tube with a continuous spectrum can be used. This X-ray tube has, for example, a Mo anode, a W anode, or a Rh anode. Depending on the type of contrast chemical element contained in the test object, a voltage that radiates a continuous beam in an area of, for example, 100 keV or higher is applied.

  Basically, the X-ray beam source can be driven without filtering of the radiation beam, and the object to be examined is irradiated with a polychromatic beam in the entire spectral region. However, in order to reduce the beam load on the object to be examined, an X-ray beam that is not energetically necessary or unfavorable for detection can be extracted from the spectrum of the polychromatic X-ray beam source and filtered. For this purpose, an Al filter or a Cu filter that extracts and filters energy in the region of 20 keV (soft beam) is used. Thus, a continuous spectrum should be understood as X-ray emission in the range ≧ 0 keV, preferably ≧ 15 keV, particularly preferably ≧ 17 keV, particularly preferably ≧ 20 keV, for example 100 keV ≧ region X-ray emission. There is no emphasis or exclusion of spectral regions within this limit relative to others. The upper limit of the emission spectrum is determined by the voltage applied to the X-ray anode. The low energy region of the beam is advantageously extracted and filtered to remove a dose related beam for the human body.

Usually, the test object is inspected with a polychromatic X-ray beam and a suitable detector. Optionally, an energy dispersive detector can be used to detect the energy of the irradiated photons.
There are basically two configurations for energy dispersive detectors and detection units:
a. An energy dispersive detector in the form of a Cd (Zn) Te-detector as described at the beginning of the specification. With such a series of detectors, the X-ray spectrum of the emitted X-ray beam can be measured for each pixel.
b. A simple X-ray detector is used. A sorter is disposed in front of the detector. In the simplest case, this sorter consists of a suitable combination filter. However, for energy selection, for example, a monochromator tuned to the X-ray fluorescence of the administered contrast agent can be used.
c. However, it is technically possible to adapt the detector to the contrast agent. Thus, Gd (Zn) Te detectors or Dy (Zn) Te detectors can be used.

  In many cases, the detector is positioned such that minimal Compton scattering is measured.

  In order to detect the intensity value and energy value of the X-ray beam emitted from the test object, the detected photons are divided into at least two different energy regions. These energy regions include, for example, Kα radiation lines and Kβ radiation lines. Compton correction can optionally be performed to increase element specificity. However, as shown in the examples below, this is not always necessary.

  If the inherent X-ray contrast is neglected, an X-ray contrast agent can be administered to a test subject, eg, a human, to perform the method of the present invention. X-ray contrast agents can be administered, for example, enterally or parenterally, i. v. I. m. Or it can be administered by subcutaneous injection or infusion. Subsequently, an X-ray record is created. A contrast agent having a high attenuation coefficient in the selected spectral region itself is suitable. Contrast agents having a K-edge of the absorption spectrum in the spectral region where the absorbing element is selected are likewise suitable. This type of X-ray imaging agent is an imaging chemical element having an atomic number of 35 or 35, here a bromine containing contrast agent, an imaging chemical element having an atomic number of 47 or more, here an iodine containing contrast agent, an atomic number 57 or Further contrast chemical elements, here lanthanide-containing contrast agents, especially gadolinium-containing contrast agents, or atomic number 83 contrast chemical elements, here bismuth-containing contrast agents. Therefore, an X-ray contrast agent containing a contrast chemical element having an atomic number of 35 (bromine) to 83 (bismuth) is suitable. In particular, a contrast agent having a contrast chemical element having an atomic number of 53 (iodine) to 83 (bismuth) is suitable. Similarly, X-ray contrast agents having an imaging chemical element of contrasting chemical element (lanthanide) -83 (bismuth) with atomic number 57 or 57 or more are suitable, particularly preferably atomic number 57-70 (lanthanide: La, Ce, Contrast agents having contrast chemical elements of Pr, Nd, Pm, Sm, EU, Gd, Tb, Dy, Ho, Er, Tm, Yb) are suitable.

  Suitable iodine-containing X-ray contrast agents include aromatic triiodo-containing compounds such as amidotrizoic acid, iohexol, iopamidol, iopanoic acid, iopazic acid, iopromide, ioproic acid, iopidone, iotalamic acid, iopental, ioversol, ioxagrate, Iotrolane, iodixanol, iotroxic acid, oxaglic acid and ioquitaramic acid and ionic dimenol (INN). Trade names for iodine-containing X-ray contrast agents are Urografin (TM) (Schering), Gastrografin (TM) (Schering), Biscopin (TM) (Schering), Ultravist (TM) (Schering) and Isovist (TM). ) (Schering).

  Similarly, metal compounds are also suitable as X-ray contrast agents.

  X-ray contrast agents can be administered enterally or parenterally. Advantageously, for parenteral administration, intravenous (iv) application is selected. An advantageous dose is a dose of 0.75 g / kg body weight in the case of iodine-containing non-ionic contrast agents. This corresponds to approximately 6 mmol / kg body weight. This dose is more advantageously 1.5 g / kg body weight (corresponding to about 12 mmol / kg body weight) and exceptionally 2 gl (corresponding to about 16 mmol / kg) or 5 g / kg body weight (about 39 mmol / kg body weight). Equivalent to). In the case of lanthanide compounds, an advantageous dosage is 0.1 mmol / kg body weight. More advantageously, dosages up to 0.3 mmol / kg body weight or 1 mmol / kg body weight are also suitable.

  Gadolinium radiation lines are 43.0 and 48.7 keV. That is, far above the iodine emission lines of 28.6 and 32.3 keV. The metal composition can contain, for example, all other lanthanides, such as lanthanum, dysprosium or ytterbium, instead of gadolinium atoms.

  Digital detectors have already been provided by various manufacturers for several years (for example, The BBI Newsletter, February 34, 1999, by HG Chotas, JT Dobbins, CE Ravin, "Principles of Digital Radiation with Large-Area, Electronically Readable Detectors: A Review of the Basics" Radiol., 210 (1999) 595-599). This digital detector is often made of amorphous silicon or other semiconductor material. The following detectors are suitable for the X-ray apparatus of the present invention. That is, a phosphor plate (for example, Fuji Chemical Industries, Konica), amorphous silicon (for example, GE Medical, Philips Medical, Siemens Medical), selenium (for example, Philips Medical, Toshiga Sulfurium, Toshiga Sulfurium) A detector comprising a salt (eg by Kodak), cadmium telluride (CT) or cadmium-zinc-telluride (CZT) semiconductor, yttrium oxyorthosilicate, lutetium oxyorthosilicate, sodium iodide or bismuth germanate . Particularly good results are achieved with so-called C (Z) T detectors, ie detectors composed of cadmium- (zinc) -telluride (C (Z) T) semiconductors.

  The structure of an energy dispersive detector made of a semiconductor is described in detail in US Pat. No. 5,434,417A. In this case, segmented semiconductor stripes are provided, and these semiconductor stripes are irradiated with an X-ray beam from the end face side. The beam penetrates the semiconductor material until it interacts with the semiconductor material. The penetration depth depends on the energy of the X-ray photons. If the energy of the X-ray photons is relatively large, the beam will penetrate relatively deeply until it interacts with the detector material and forms a current pulse due to the photoelectric effect, rather than when the energy is relatively small. This current pulse can be derived by electrical contacts attached from individual segments of the detector. The current pulse is processed by a preamplifier.

  On the other hand, the detector can be configured as a flatbed detector. In this embodiment, all pixels are detected simultaneously and supplied to the correlation unit for evaluation. This detector is in this case a flat structure of the individual detectors, preferably a matrix with such sensors in rows and columns.

  It is also possible to provide a detector unit used to detect the emitted X-ray beam and optionally record a radiation image. For this purpose, the detector unit is constituted by an X-ray optical module for energy selection.

  Instead of a flatbed detector, a line detector or a matrix of detectors suitable for recording individual pixels can also be used. In the case of the latter detector, the X-ray beam is combined with a flat-bed detector by a number of such light guides which are simultaneously guided from the object to be examined via the X-ray light guide.

  Further, the detector can be configured to record individual pixels and can be run to record all pixels. In this embodiment, the detector detects only the intensity depending on the energy at the individual pixels during the measurement. The intensity of the individual pixels is then detected, for example line by line, and supplied to the correlation unit for further processing.

  In addition, the detector can have an array of detector sensors each configured to record one pixel and can be run to record all pixels. An array of detector sensors, according to the present invention, is a line of detector sensors or a matrix of detector sensors. In this embodiment, the detector detects individual pixel intensity values line by line, or possibly block by block. In order to record all intensity values, the detector is preferably run perpendicular to the main axis of the array during the measurement. The intensity value detected during the measurement is supplied to the correlation unit.

  In order to display an image of the distribution of contrast chemical elements in the test object, the beam intensities emitted from the respective spatial elements are detected with the same weight. For this purpose, it is also advantageous to irradiate each spatial element from the X-ray beam source with the same beam intensity. In practice, however, this assumption has only been approximate. This is because, on the one hand, the irradiated X-ray beam is attenuated by different degrees of absorption depending on the distance that this beam travels in the test object, and on the other hand, the spatial elements in the test object. This is because the beam radiated from is attenuated by intrinsic absorption according to different distances traveling to the detector in the test object.

  This problem occurs with all emission spectroscopic methods. In order to solve this problem, the second intensity value is first corrected in consideration of the absorption of the irradiated X-ray beam and / or the intrinsic absorption of the X-ray beam emitted in the object to be examined. And the second intensity value are correlated with each other for each pixel only after this correction. This type of correction can be performed by numerical methods. This correction takes into account the geometry of the object to be examined and at least an approximate, position-dependent X-ray density. In order to detect the position dependent X-ray density, an image formed from the first intensity value can be used. In order to detect position-dependent absorption and intrinsic absorption, the first approximation can be based on the position-dependent X-ray density obtained from this measurement. This is because the absorption coefficient of the irradiated X-ray beam is similar to the absorption coefficient of the emitted beam.

  Due to the intrinsic absorption of the emitted beam, the position and angle of the second detector are measured relative to the region of interest (ROI), eg, moved on a circular segment trajectory, and the observation angle and position Can compensate for structural inhomogeneities in test objects having different absorptions. In this case, the image display is obtained by averaging after correcting the intrinsic absorption.

  The signal originating from the preamplifier is then fed to at least one correlation unit. By this correlation unit, the intensity of the X-ray beam transmitted through the pixel of the test object is correlated with the image of the X-ray beam (X-ray scattering and X-ray fluorescence) emitted from the same pixel. The correlation unit can be a correspondingly programmed data processing device.

  In order to correlate the photon intensity values of the two methods (transmission image and radiation image), the two intensity values are correlated with each other for each pixel. They are preferably subtracted or sequentially divided from each other. For this purpose, a comparator or a dividing element can be used to form a correlation for each pixel. Of course, other mathematical operations can be performed to correlate the intensity values of the transmitted and emitted X-ray beams of one pixel.

  In order to process the intensity values of the measured pixels, the following devices are preferably provided, which can be realized in a data processing device.

  d1. First storage unit. With this first storage unit, the first intensity value of the transmitted X-ray beam can be stored for each pixel.

  d2. Second storage unit. With this second storage unit, the second intensity value of the emitted X-ray beam can be stored for each pixel (for example by elements I, Gd, Yb).

  d3. Calculation unit. This calculation unit appropriately correlates the two generated image data sets and forms or calculates an image data set from the information of the transmission data set and the X-ray emission, preferably X-ray fluorescence data.

  This makes it possible to correlate the intensity values of all pixels in transmission and radiation. Here, the radiation image is matched to the contrast agent used using characteristic radiation lines. If a mixture of X-ray contrast agents (eg Ultravist ™ or Gadovist ™), or substances containing iodine and lanthanides (eg Gd or Dy) are used, the characteristic radiation lines will each be Can be used for. The measured data set is subsequently correlated with each other for each pixel and used for image display. Alternatively, the intensity values are correlated with each other for each pixel, and the obtained data is subsequently used for image display. Data obtained for this purpose is transferred to the output unit for each pixel. This output unit includes, for example, a monitor (CRT display or LCD display) or a plotter.

The following drawings and examples are used to describe the present invention in detail. In order to provide a direct impression of the operation of the present invention, correcting the measured X-ray spectrum according to the absorption and intrinsic absorption of the excitation beam is ignored in all cases.
FIG. 1 is a photograph of a test structure on a computer tomograph.
FIG. 2 is a schematic diagram of a structure for forming an image or a subject structure.
FIG. 3 is a schematic diagram of a structure under test for generating a first phantom measurement.
FIG. 4 is a diagram showing a radiation spectrum when the phantom of FIG. 3 is filled with water (FIG. 4a), Ultravist (TM) (FIG. 4b), and Gadovist (TM) (FIG. 4c).
FIG. 5 is a diagram showing a radiation spectrum when the phantom of FIG. 3 is filled with water (FIG. 5a), Ultravist (TM) (FIG. 5b), and Gadovist (TM) (FIG. 5c), each having a thickness of 5 cm. The PMMA disk is arranged between the detector and the phantom.
Figure 6 is a diagram showing the dependence of the intensity of the radiation to the position / shift of the phantom in FIG. 3, K _alpha line and K _beta lines is selected as the energy band (iodine: Figure 6a, gadolinium: Figure 6b, a mixture of iodine and gadolinium: FIG. 6c).
FIG. 7 is a diagram showing a CT tomographic image (transmission image) of a phantom filled with Gd, iodine / Gd mixture, iodine, air, and water.

  FIG. 1 is a photograph of a test component that is a rubber ball 1 in a computer tomograph, and this computer tomograph is fixed to a gantry 2. The rubber ball is placed in the center of the computer tomograph. In various experiments, rubber balls were filled with air, water, and various contrast agent solutions. The rubber ball is placed between the CT tube (above the rubber ball but not shown) and the line detector (below the table visible under the rubber ball but not shown).

  A measurement camera 3 for detecting X-ray fluorescence is arranged at an angle of 90 ° with respect to the connecting line between the CT tube, rubber ball and detector. With this test structure, a tissue, a tumor, or the like filled with a contrast medium is simulated as a test object, and is examined by a computer tomograph. For this purpose, the object was scanned layer by layer and the spectrum was measured.

  Details of the test structure used in this experiment are shown in FIG. The schematic shown there shows a ball 1 which is arranged as a phantom at the isocenter of the gantry 4. The CT tube 5 is disposed at the 12 o'clock position and is fixed thereto. The measurement chamber 3 comprises a detector 6 and a lead tube 7 and is at an angle of 90 ° with respect to the X-ray cone beam. The X-ray cone beam emanates from the CT tube and is directed to the phantom (ball) (see z direction, arrow).

  A CZT detector 6 (Amptek Inc., USA) is used to detect the X-ray beam. This CZT detector has a cadmium-zinc-telluride-crystal with a size of 3 mm × 3 mm × 2 mm and a pinhole of 100/400 μm. The data recorded by the fluorescence detector is supplied from the detector to the multi-channel analyzer 9 via the amplifier 8 and subsequently supplied to the Excel (TM) (Microsoft) graphic table. The data is stored in the PC 10. The signal strength SI = SI (E) is therefore used in digital form as a function of energy E.

  FIG. 3 shows a schematic of the test structure for generating the first phantom measurement. A part of the measurement chamber 3 for fluorescence measurement is shown on the left side of the figure, and the ball 1 is shown in the center of the figure. In FIG. 3, individual sections extending vertically are formed by X-ray beams irradiated from above. Fluorescence reaches the measurement chamber from these cross sections. Dashed lines indicate the respective positions of the CT tube above the image section. The horizontal scale represents the fan beam shift and thus indicates the respective responding cross-section (excited layer) of the ball.

  The “zero measurement” was performed at +45 mm, ie outside the excitation beam.

  After each recording of the spectrum, the entire measurement structure is run 10 mm further in the gantry direction (z direction) and a new spectrum is recorded. Accordingly, different spectra for each layer are obtained depending on the respective position of the ball in the beam or corresponding to the ball geometry.

  Therefore, with this measurement structure, X-ray fluorescence can be measured depending on the topology of the phantom. The layer closest to the detector at z = −60 mm and the layer furthest away from the detector at z = 0 mm were transmitted through (so z = −60 mm has the lowest intrinsic absorption of radiation, and z = 0 mm has the maximum Since the geometric shape is spherical, the absorption effect of transmitted radiation is also significant when the contrast agent concentration is relatively high).

Example 1
In the first measurement, a ball filled with water was measured with a beam of 80 kV, 50 mA for 80 s for each position of the ball according to FIG. 3 (parameter: detector: XR-100.CZT (pin Hole 0.1 mm), ball-detector spacing: 10.0 cm, ball-CT tube spacing 32.0 cm).

  In FIG. 4a, the scattering spectrum of water in the phantom is shown for different positions.

  In the second measurement, a ball filled with a 50 mmol / l iodine solution (Ultravist (TM)) in water was measured for 80 s at each position under conditions of 80 kV and 50 mA (parameter: detector: XR). -100. CZT (pinhole 0.1 mm)).

  The emission spectra obtained at different positions are shown in FIG. 4b. The iodine Kα and Kβ lines (28.6 and 32.3 keV) are markedly distinguished. From the figure, the dependence of the measured X-ray fluorescence intensity on the phantom geometry is significant. The larger the layer through which the phantom beam is transmitted, the greater the measured intensity.

  In the third measurement, a ball filled with a 50 mmol / l gadolinium solution (Ultravist (TM)) in water was measured at 80 kV and 50 mA for 80 s at each position (parameter: detector: XR -100. CZT (pinhole 0.1 mm)).

  The emission spectra obtained at different positions are shown in FIG. 4c. Gadolinium Kα and Kβ lines (43.0 and 48.7 keV) are markedly distinguished. It can be seen that the intensity of the measured radiation beam depends on the geometry of the ball in the beam field, especially in the K-line region.

Example 2
In each measurement of this experiment, each 5 cm thick PMMA disk was placed as a filter between the detector and the phantom to simulate the intrinsic absorption of the X-ray fluorescence beam by the surrounding tissue.

  In FIG. 5a, the scattering spectrum of water in the phantom is shown for different positions.

  In the second measurement, a ball filled with a 50 mmol / l iodine solution (Ultravist (TM)) in water was measured for 80 s at each position under conditions of 80 kV and 50 mA (parameter: detector: XR). -100. CZT (pinhole 0.1 mm)).

  The emission spectra obtained at different positions are shown in FIG. 5b. The intensity of the fluorescent beam is attenuated by the PMMA disk. It has been verified that the strength decreases as the thickness of the disk increases. However, the K-line can be measured even when the ball layer is maximum (center).

  In the third measurement, a ball filled with a 50 mmol / l gadolinium solution (Ultravist (TM)) in water was measured at 80 kV and 50 mA for 80 s at each position (parameter: detector: XR -100. CZT (pinhole 0.1 mm)).

  The emission spectra obtained at different positions are shown in FIG. 5c. Again, the fluorescent beam is attenuated by the inserted PMMA disk. Since the Gadolinium Kα and Kβ lines are between 43.0 keV and 48.7 keV, when a 5 cm thick PMMA disk is present, it was possible to measure a much stronger fluorescent beam than in the case of the previous iodine emission. Therefore, even in this case, the K line could be measured even when the ball layer was the maximum (center).

Example 3
In another experiment, fluorescence intensity values were detected and recorded depending on the position of the ball relative to the x-ray beam.

  In the first measurement, balls filled with a 50 mmol / l iodine solution (Ultravist (TM)) in water were measured at 80 kV and 50 mA for 80 s at each position.

  In FIG. 6a, depending on the position / shift of the fluorescence beam, energy bands corresponding to the Kα line at 28.6 keV with iodine and the Kβ line at 32,3 keV with iodine are selected. Are plotted. The profile of the radiation intensity caused by the shape of the ball can be seen from this drawing.

  In the second measurement, a ball filled with a 50 mmol / l gadolinium solution (Gadovist (TM)) in water was measured for 80 s at each position under the conditions of 80 kV and 50 mA.

  In FIG. 6b, depending on the position / shift of the fluorescence beam, energy bands corresponding to the Kα line at 43.0 keV with gadolinium and the Kβ line at 48.7 keV with gadolinium are selected. Are plotted. The profile of the radiation intensity caused by the shape of the ball can likewise be seen from this drawing.

  In the third measurement, a ball filled with a solution of 25 mmol / l iodine (Ultravist (TM)) and a solution of 25 mmol / l Gadolinium (Gadovist (TM)) in water was placed at 80 kV for 80 s at each position. , And measured at 50 mA.

  In FIG. 6c, depending on the position / shift of the phantom, the intensity of the fluorescent beam is 28.6 keV for Kα line with iodine, Kβ line with 32,3 keV for iodine, and 43.0 keV for gadolinium. The energy band corresponding to the Kα line and the Kβ line of 48.7 keV with gadolinium has been selected and plotted. As can be seen from FIG. 6c, the ball profile is depicted only to an unsatisfactory extent when the signal strength is plotted directly as a function of position. This is due to absorption on the excitation side and intrinsic absorption on the radiation side, and causes an error in the image. If the contrast agent concentration is low and the correction of the absorption of the primary beam and the intrinsic absorption of X-ray fluorescence is insufficient, the ball is displayed in a one-dimensional image.

Example 4
FIG. 7 shows CT tomographic images recorded for the previous example of X-ray fluorescence. From upper left to lower right, gadolinium, a mixture of gadolinium and iodine, iodine, pure water, and air filled balls are shown. The ball filled with air clearly has the lowest X-ray attenuation, followed by the ball filled with water. When using a ball with a contrast element of 50 mmol / l, X-ray attenuation is more pronounced than with water, and quantitative evaluation is possible by detection of Hounsfield units (HU). However, only by adding an X-ray fluorescence image can the intrinsic filling of the ball be described.

FIG. 1 is a photograph of a test structure on a computer tomograph. FIG. 2 is a schematic diagram of a structure for forming an image or a subject structure. FIG. 3 is a schematic diagram of a structure under test for generating a first phantom measurement. FIG. 4 is a diagram showing a radiation spectrum when the phantom of FIG. 3 is filled with water (FIG. 4a), Ultravist (TM) (FIG. 4b), and Gadovist (TM) (FIG. 4c). FIG. 5 is a diagram showing a radiation spectrum when the phantom of FIG. 3 is filled with water (FIG. 5a), Ultravist (TM) (FIG. 5b), and Gadovist (TM) (FIG. 5c), each having a thickness of 5 cm. The PMMA disk is arranged between the detector and the phantom. Figure 6 is a diagram showing the dependence of the intensity of the radiation to the position / shift of the phantom in FIG. 3, K _alpha line and K _beta lines is selected as the energy band (iodine: Figure 6a, gadolinium: Figure 6b, a mixture of iodine and gadolinium: FIG. 6c). FIG. 7 is a diagram showing a CT tomographic image (transmission image) of a phantom filled with Gd, iodine / Gd mixture, iodine, air, and water.

Claims (37)

An X-ray apparatus that forms an image of a test object containing at least one X-ray contrast chemical element with an X-ray beam transmitted through the test object and an X-ray beam emitted from the test object There,
a. At least one x-ray beam source for delivering a substantially multicolor x-ray beam;
b. A first detector for detecting a first intensity value of an X-ray beam transmitted through the test object, or a first detection unit;
c. A second detector for detecting a second intensity value of the X-ray beam emitted from the test object, or a second detection unit;
d. At least one correlation unit that correlates, for each pixel, a first intensity value of the transmitted X-ray beam and a second intensity value of the emitted X-ray beam;
e. At least one output unit for displaying a test object from a pixel signal obtained by the correlation between the first intensity value and the second intensity value;
An X-ray apparatus having The X-ray apparatus according to claim 1,
The correlation unit comprises the following devices:
d1. A first storage unit for storing a first intensity value of the transmitted X-ray beam for each pixel;
d2. A second storage unit for storing a second intensity value of the emitted X-ray beam for each pixel;
d3. A calculation unit for correlating the first intensity value of the transmitted X-ray beam and the second intensity value of the emitted X-ray beam for each pixel;
An X-ray apparatus characterized by that. The X-ray apparatus according to claim 1 or 2,
The X-ray apparatus according to claim 1, wherein the second intensity value is detected by being decomposed depending on the energy of the emitted X-ray beam. The X-ray apparatus according to any one of claims 1 to 3,
The second detector or the second detection unit discriminates an X-ray beam emitted from a contrast chemical element contained in a test object based on their energy from another emitted X-ray beam. An X-ray apparatus characterized by that. The X-ray apparatus according to any one of claims 1 to 4,
The first intensity value and the second intensity value are determined in advance by taking into account the absorption of the X-ray beam irradiated on the test object and / or the intrinsic absorption of the X-ray beam emitted from the test object. An X-ray apparatus characterized in that each pixel is correlated with each other after correction. The X-ray apparatus according to any one of claims 1 to 5,
The X-ray apparatus according to claim 1, wherein the first detector and / or the second detector is a flatbed detector. The X-ray apparatus according to any one of claims 1 to 5,
The X-ray apparatus according to claim 1, wherein the first detector and / or the second detector are configured to record individual pixels and travel to record all pixels. The X-ray apparatus according to any one of claims 1 to 5,
An X-ray apparatus comprising a detection unit configured to be energy selective by an X-ray optical module for detecting the emitted X-ray beam. The X-ray apparatus according to any one of claims 1 to 5,
The first detector and / or the second detector each have an array of detector sensors configured to record one pixel and run to record all pixels; A featured X-ray apparatus.   10. An X-ray apparatus according to any one of claims 1 to 9, wherein another radiation imaging method, for example a positron emission tomograph (PET), a single photon emission computer tomograph (SPECT) and a sonograph, and an optical image An X-ray device that performs radiological diagnosis in combination with a forming method.   The use of the X-ray apparatus according to any one of claims 1 to 10, wherein an X-ray transmitting through the test object contains at least one X-ray contrast chemical element. A method of use for imaging with a beam and an x-ray beam emitted from the object to be examined. Use of the X-ray device according to claim 11,
Perform the following method steps:
a. Irradiating the test object with a substantially multicolored X-ray beam;
b. Detecting a first intensity value of an X-ray beam transmitted through the test object;
c. Detecting a second intensity value of the X-ray beam emitted from the test object;
d. Correlating the first intensity value of the transmitted X-ray beam with the second intensity value of the emitted X-ray beam for each pixel;
e. Displaying the test object from a pixel signal obtained by correlation between the first intensity value and the second intensity value:
The use of the X-ray apparatus characterized by the above-mentioned. Use of the X-ray device according to claim 11 or 12,
Usage, wherein the second intensity value is resolved and detected depending on the energy of the emitted X-ray beam. Use of the X-ray device according to any one of claims 11 to 13,
X-ray beam radiated | emitted from the contrast chemical element contained in the said test object is discriminated based on those energy from another radiation | emission X-ray beam. Use of the X-ray device according to any one of claims 11 to 14,
The first intensity value and the second intensity value take into account the absorption of the X-ray beam irradiated on the test object and / or the intrinsic absorption of the X-ray beam emitted from the test object. Usage, characterized in that after a prior correction, each pixel is correlated with each other. Use of the X-ray device according to any one of claims 11 to 15,
Use, characterized in that a first detector and a second detector or a first detection unit or a second detection unit are provided. Use of the X-ray device according to claim 16,
Usage, wherein the first detector and / or the second detector is a flatbed detector. Use of the X-ray device according to claim 16,
Usage, wherein the first detector and / or the second detector are configured to record individual pixels and run to record all pixels. Use of the X-ray device according to claim 16,
The first detector and / or the second detector each have an array of detector sensors configured to record one pixel and run to record all pixels; Characteristic usage. Use of the X-ray device according to claim 16,
Use, characterized in that a detection unit configured to be energy selective by an X-ray optical module is provided for detecting the emitted X-ray beam. Use of the X-ray device according to any one of claims 11 to 20,
The use wherein the contrast chemical element is selected from the group comprising bromine, iodine, lanthanide, and bismuth. Use of the X-ray device according to any one of claims 11 to 21,
The method according to claim 1, wherein the contrast chemical element is administered enterally or outside the intestinal tract.   23. Use of the X-ray apparatus according to any one of claims 11 to 22, wherein the test region of the test object containing at least one X-ray contrast chemical element is displayed as an image unique to the element. Usage used to display quantity.   24. Use of the X-ray device according to any one of claims 11 to 23, wherein another radiation imaging method, for example positron emission tomography (PET), single photon emission computer tomography (SPECT) and sonograph, and Use of an X-ray device used for radiological diagnosis in combination with an optical imaging method. A method for forming an X-ray contrast image of an object to be inspected by an X-ray beam transmitted through the object to be inspected and an X-ray beam emitted from the object to be inspected, comprising the following method steps: :
a. Irradiating the test object with a substantially multicolored X-ray beam;
b. Detecting a first intensity value of an X-ray beam transmitted through the test object;
c. Detecting a second intensity value of the X-ray beam emitted from the test object;
d. Correlating the first intensity value of the transmitted X-ray beam with the second intensity value of the emitted X-ray beam for each pixel;
e. Displaying the test object from a pixel signal obtained by correlation between the first intensity value and the second intensity value:
An X-ray contrast image forming method. The X-ray contrast image forming method according to claim 25,
An X-ray contrast imaging method, characterized in that at least one X-ray contrast chemical element is administered to the subject before performing the method steps a) to e). The X-ray contrast image forming method according to claim 25 or 26,
The method of forming an X-ray contrast image, wherein the second intensity value is decomposed and detected depending on the energy of the emitted X-ray beam. The X-ray contrast imaging method according to any one of claims 25 to 26,
An X-ray contrast imaging method, wherein an X-ray beam emitted from a contrast chemical element contained in the test object is discriminated based on their energy from another emitted X-ray beam. The X-ray contrast imaging method according to any one of claims 25 to 28,
The first intensity value and the second intensity value take into account the absorption of the X-ray beam irradiated on the test object and / or the intrinsic absorption of the X-ray beam emitted from the test object. An X-ray contrast image forming method, characterized in that the pixels are correlated with each other after the preceding correction. The X-ray contrast imaging method according to any one of claims 25 to 29,
An X-ray contrast imaging method, comprising: a first detector and a second detector, or a first detection unit or a second detection unit. The X-ray contrast image forming method according to claim 30,
The X-ray contrast imaging method, wherein the first detector and / or the second detector is a flatbed detector. The X-ray contrast image forming method according to claim 30,
X-ray contrast imaging, wherein the first detector and / or the second detector are configured to record individual pixels and travel to record all pixels Method. The X-ray contrast image forming method according to claim 30,
The first detector and / or the second detector each have an array of detector sensors configured to record one pixel and run to record all pixels; A characteristic X-ray contrast image forming method. The X-ray contrast image forming method according to claim 30,
A method for forming an X-ray contrast image, wherein a detection unit configured to be energy selective by an X-ray optical module is provided for detecting an emitted X-ray beam. The X-ray contrast imaging method according to any one of claims 25 to 34,
The method for forming an X-ray contrast image, wherein the contrast chemical element is selected from the group including bromine, iodine, lanthanide, and bismuth. The X-ray contrast image forming method according to any one of claims 25 to 35,
A method for forming an X-ray contrast image, wherein the contrast chemical element is administered enterally or outside the intestine.   37. An x-ray contrast imaging method according to any one of claims 25 to 36, wherein another radiographic imaging method, for example a positron emission tomograph (PET), a single photon emission computer tomograph (SPECT) and a sonograph, and An X-ray contrast imaging method for performing radiological diagnosis in combination with an optical imaging method.

Images