KR20080020616A - X-ray arrangement for the image representation of an examination object and use of the x-ray arrangement - Google Patents

Abstract

For the high-contrast representation of small lesions or other target areas in tissue in the human body containing at least one contrasting chemical element, an X-ray arrangement is described, comprising at least one X-ray radiation source which emits essentially polychromatic X-ray radiation, a first detector or a plurality of first detectors, which can be used to determine values of a first intensity of X-ray radiation transmitted through the examination object, a second detector or a plurality of second detectors, which can be used to determine values of a second intensity of X-ray radiation emitted by the examination object, at least one correlation unit, which can be used to correlate the first intensity values of the transmitted X-ray radiation with the second intensity values of the emitted X-ray radiation pixel by pixel, and at least one output unit for the representation of the examination object from pixel signals obtainable by correlation of the first intensity values with the second intensity values. The transmission and emission images are preferably recorded simultaneously. The method can also be combined with other radiological images, e.g. positron emission tomography (PET) or single photon emission computer tomography (SPECT). ® KIPO & WIPO 2008

Description

X-ray ARRANGEMENT FOR THE IMAGE REPRESENTATION OF AN EXAMINATION OBJECT AND USE OF THE X-RAY ARRANGEMENT}

The invention relates to the use of X-ray devices, X-ray devices for the graphical display of a subject under test containing one or more radiopaque chemical elements by X-ray radiation, as well as to the subject under test, for example a mammal, in particular An image forming x-ray contrast method for humans.

Medical diagnosis using X-ray radiation is a technically very advanced field for the diagnosis of diseases, for example early detection of tumors, vascular diseases and other pathological lesions of the human body, radiation identification, features and location. This technique is very effective and shows high availability.

To generate X-ray radiation, for example, an X-ray tube with a W-, Mo- or Rh- rotating anode and Al-, Cu-, Ti-, Mo- and Rh filters can be used. In a suitable filtration state, a portion of the bramsstrahlung, if desired, is filtered so that essentially the characterized radiation emerges from the X-ray tube.

As the detector, a conventional X-ray film, a digital plate or a digital flat-bed detector is used. In a computed tomography apparatus, a detector line or several detector lines are used. In addition, several detectors may be connected in parallel. For the direct conversion of X-ray radiation into an electrical signal, a semiconductor detector consisting of cadmium telluride (CT), cadmium-zinc-telluride (CZT), amorphous salts or amorphous or crystalline silicon is used [M. second. M.J.Yaffe and J. a. "X-Ray Detectors for Digital Radiography" by J. A. Rowlands, 1997, Medical Biology, 42 (1), 1-39.

Design examples of such detectors are pointed out in US Pat. No. 5,434,417. In addition, in order to enable the energy sensing of the detector, the latter is formed of several layers. X-ray radiation with different energies is pulled through different depths in this detector and produces an electrical signal in each layer by the optoelectronic effect, which is read along with the layer, as a current pulse, depending on the energy of the X-ray photons. Can be recognized immediately.

Computed tomography equipment (CT) has already been used for a long time as a routine procedure in normal clinical practice. Using CT, cross-sectional images through the body are obtained, which achieves better spatial resolution than in conventional injection radiographs. In addition, although the density resolution of CT is clearly higher than the density resolution of conventional X-ray techniques, contrast media is still required for reliable detection of many pathological changes. The latter improves the quality of morphological information. In this case, on the one hand, functional processes are visualized in the body via contrast medium (excretion, perfusion, permeation), on the other hand, the morphology is the facility of contrast (other contrast medium in various tissues). Concentration).

In many cases, conventional X-ray techniques cannot be used because the contrast of the tissue to be examined is not sufficient. For this purpose, X-ray contrast media have been developed to produce high radiation densities in the tissue in which they accumulate. Typically, iodine, bromine, and elements of atomic numbers 34, 42, 44-52, 54-60, 62-79, 82, and 83 chelate chelates of elements having atomic numbers 56-60, 62-79, 82, and 83 As well as opaque elements. Iodine compounds such as meglumine-sodium- or lysine-diatrizoate, iotalamey, oxythalamate, iopromide, iohexol, iomeprol, iopamidol, ioversol, iobi Tridol, iopentol, iotrollan, iodisanol and dioxane (INN) can be used (EP 0 885 616 A1).

In some cases, despite the administration of X-ray contrast media, proper tissue contrast cannot be achieved. In order to achieve an additional increase in contrast, digital subtraction angiography (DSA) is introduced, in which before and after contrast images (logarithmic) are subtracted from each other. Subtraction methods for use in breast roentgen mammography are disclosed in EP 0 885 616 A1. For injection mammograms, the first contrast mammogram is first recorded, then the patient is infused at a rapid rate with a conventionally used urographic x-ray contrast medium, and then the contrast mammogram is terminated. It is proposed to record about 30 seconds to 1 minute later. The data obtained from the two images are then related to each other and preferably subtracted from each other.

New developments in the field of CT relate to the use of synchrotron radiation in the excitation side, eg CT [F. a. Cancer by 1992 by F. A. Dilmanian. second. Physiological Image Formation ("Computed Tomography with Monochromatic X-Rays") of Am. J. Physiol. Imaging, 314, 175-193. K-Edge Subtraction CT "(op. Cit. By FA Dilmanian, p. 179), whereby the atomic K An effective increase in the absorption coefficient in the binding energy of the electrons is used Elemental iodine has a K-edge at an energy of 33.17 KeV Unfortunately, only this radiation has the desired density and monochromasia for the process Because of this, this process works only by synchrotron radiation, which can be used with large storage rings, for example DESY, while conventional X-ray tubes do not generate any monochromatic radiation but produce rather continuous spectra. So simply not suited for the differences in these measurements.

Alternative possibilities are described in DE 101 18 792 A1. Here, a method is proposed in which an X-ray radiation source with two X-ray anodes made of different materials is used to record the projection weargram. To record the mammogram, the X-ray contrast medium is first administered to the patient. Thereafter, the first projection image is recorded using the first X-ray anode of the two X-ray anodes, and then the second projection image is recorded using the second X-ray anode. By superimposing each individual pixel from the first image onto each individual corresponding pixel from the second image, a correlation image is generated. The characteristic radiation of the two X-ray anodes corresponds to the absorption spectrum of the X-ray contrast medium. The emission energy of the first X-ray anode lies slightly below the absorption energy of the opaque element in the X-ray contrast medium, and the emission energy of the second X-ray anode lies slightly above the absorption energy of the opaque element. The disadvantage of this method is that conventional X-ray tubes must be replaced with only one X-ray anode from a bi-anode tube.

Also for transmission radiography, emission radiography is also described.

Thus, WO 2004/041060 A2 discloses a device having a probe for non-invasive in-vivo determination of a chemical element in the human prostate, a radiation system that excites a chemical element to cause the emission of radiation, emitted radiation. A radiation detector in a probe capable of imaging a signal, a signal recording, processing and display system capable of reproducing an amount of chemical element in the prostate at various spots corresponding to an image of radiation emitted is described. The radiation emitted consists essentially of fluorescence radiation. In the case of a study of the prostate, the distribution of Zn in the tissue is preferably determined.

In addition, DE 36 08 965 A1 describes various chemical elements in the first layer of the inspection area by gamma or X-ray radiation. In this case, Compton scattering radiation and Rayleigh scattering radiation are detected separately. The course of the different scattering coefficients determined from the measured values is influenced by the proportion of the various chemical elements contained in the individual pixels. Thus, the ratio of these chemical elements can be determined from them. To this end, in a myriad of directions, the main beam is drawn through the inspection area, and the radiation exiting the inspection area under various angles is detected by the detector device at various positions outside the inspection area, and then for various pulse transmissions. Different scattering coefficients are determined from the measured values for each pixel of the layer obtained in this case.

In addition, "Preliminary Experiment of Fluorescent X-Ray Computed Tomography to detect Dual Agents for Biological Study" by "Quanwen, Yu", et al. Synchrotron Rad. (2001), 8, 1030-1034, proposes the use of X-ray fluorescence methods to detect very low concentrations of non-radioactive substrates in biomedical research. These methods yield images in which multiple agents can be detected using fluorescence-K _α lines, for example, in a single study to quantitatively detect brain blood flow and brain cell density. In this study, the images generated by these methods are compared with the images obtained by X-ray transmission tomography.

However, the X-ray fluorescence or X-ray scattered light method described in the above publications has disadvantages, and the visualization of small details of the object being inspected is not easily possible due to the difficulty in image formation. Rather, only high resolution visualization is obtained, so that smaller details are very difficult to visualize.

The problem of the present invention is therefore to avoid the drawbacks mentioned above and to find an apparatus and method, in particular in which the image can be produced by different radiopaque chemical elements. In addition, X-ray images can be recorded in a simple and easy way without incurring high costs. This technology is available on a broad base. In addition, less damage to the object under examination can be visualized to have high resolution at the minimum possible radiation dose. Artifacts of movement can be avoided.

This problem involves the use of an X-ray apparatus according to claim 1 to form an image of a test subject comprising at least one radiation opaque chemical element, the use of such an X-ray apparatus according to claim 11, and It can be solved by the image forming X-ray contrast method according to claim 25. Preferred embodiments of the invention are described in the subclaims.

When terms such as "diffuse" and "emission" are used in the description of the invention and in the claims that follow, they on the one hand include X-ray fluorescence, ie radiation of radiation after excitation of the material irradiated by electromagnetic radiation. And, on the other hand, preferably Rayleigh radiation. In the latter case, the radiation is emitted again without pulse transmission from the irradiating material, whereby no excitation to the excited state of the orbital electrons in the atom of this material as in the case of fluorescence by irradiation.

By the X-ray apparatus, X-ray radiation that penetrates and radiates from the object through the graphic display passing through the object under examination is used. Therefore, the X-ray apparatus in the present invention has the following features.

a. At least one X-ray radiation source that emits substantially polychromatic X-ray radiation,

b. A first detector or first detector unit (unit of several detectors connected in parallel and / or arranged) in which the first intensity values of the X-ray radiation transmitted through the object under examination can be determined,

c. A second detector or second detector unit in which second intensity values of X-ray radiation emitted from the subject under examination can be determined,

d. At least one correlation unit, wherein the first intensity values of the transmitted X-ray radiation can be correlated with the second radiation values of the transmitted X-ray radiation in a pixel for pixel,

e. At least one output unit visualizing the object under inspection from pixel signals that can be obtained by a correlation of the first intensity values and the second intensity values.

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

This X-ray apparatus may advantageously be used for the graphical display of the subject under examination, which preferably contains at least one X-ray opaque chemical element by X-ray radiation. Preferably, the X-ray opaque chemical element is injected into the subject under test by X-ray contrast medium and administered to, for example, the subject under test, for example a human or animal.

Opaque chemical elements with low atomic numbers naturally occurring in the object under examination have only a small yield of X-ray fluorescence so that image formation by the use of these elements does not appear viable. In addition, the energy of X-ray fluorescent photons is low in this case so that the range of its action in body tissues is also low. In particular, starting with elemental iodine (Z = 53) with emission lines of 28.6 and 32.3 keV, it is possible to leave the object under inspection to a sufficient extent, so that it can be recorded by a detector arranged outside of the object. In the case of lower atomic number chemical elements, the device of the second detector may be chosen such that the second detector is arranged as close as possible to the region (ROI: governing zone) to be tested.

An X-ray apparatus is used to perform the X-ray contrast method according to the present invention. The method has the following method steps.

a. Preferably dosing at least one chemical element,

b. Irradiation of substantially polychromatic X-ray radiation to the subject under test,

c. Determination of first intensity values of X-ray radiation transmitted through the subject under examination,

d. Determination of second intensity values of X-ray radiation emitted by the subject under examination,

e. The correlation of pixel to pixel of the first intensity values of transmitted X-ray radiation and the second intensity values of emitted X-ray radiation,

f. Visualization of the object under examination from the pixel signals obtained by the correlation of the first intensity values and the second intensity values.

In comparison with known methods in which X-ray transmission tomography (TXCT) is performed or only X-ray luminescence (FXCT) is detected, transmission and radiation are measured here or continuously at the same time and these two techniques are mutually compatible according to the invention. Combined, in this case the images obtained respectively are superimposed by an appropriate correlation method. In this method, the respective advantages of both techniques are used.

So-called X-ray transmission tomography basically offers the advantages of having high and obtainable temporal and spatial resolution so that even the smallest damage or other matters in the human body under test can also be solved. However, the often obtained contrast is also not enough to make these details visible. This is particularly true for testing of damage in soft tissues. In addition, testing of any body region by the TXCT method is also limited by the skeleton.

In contrast, X-ray luminescence tomography is particularly useful because only certain chemical elements emit electromagnetic radiation by proper excitation of these elements so that these elements found in the test area (ROI) are suitable as specific probes that are very sensitive. It offers the advantage of high contrast visualization. However, the FXCT method has the disadvantage of having low spatial resolution so that smaller damage is no longer visible.

High contrast of the area under inspection (ROI) by only the pixel-to-pixel correlation of the intensity values of transmitted X-ray radiation and the intensity values of emitted X-ray radiation and the visualization of the object from the pixel signals obtained during inspection by this correlation. And a detailed image can be calculated. Opaque images have a so-called low resolution. However, since the necessary detail information originates in the intensity values of the radiation measured by TXCT, by the correlation of each value with each other, this defect is healed to a large extent.

The invention can be used in particular to examine humans. The present invention provides for bronchography, cholegraphy and angiography and cardiovascular angiography, for cerebrovascular angiography, and for perfusion measurements, for mammography and for lymphography, mass, tubes ( vessel, suitable for generating radiographs to visualize perfusion, such as to visualize esophageal-gastrointestinal passages. The focus in applied engineering of the present invention is on computed tomography (MS-CT; μCT) and their fusion modality [PET-CT (positron emission tomography), SPECT (single-photon-emitting-computer X-ray). Tomography), sonicography and other methods of optical image formation. In principle, the invention can also be used to study non-living materials, for example in the field of material testing.

To perform the inspection, the transmitted radiation is recorded by a first detector found in the beam path of the X-ray tube that is attenuated by the subject under inspection. The emitted radiation is measured by a second detector arranged outside of this beam path, preferably at an angle of about 90 degrees to the beam path. In addition, this second detector is not detected by the beam being pulled through the object under inspection, but at any other angular position for the X-ray beam, for example 45 degrees or 135 degrees for the beam starting from the X-ray radiation source, In principle, they can be arranged. If the X-ray tube is found at the 12 o'clock position, a typical computed tomography camera has a series of detectors at opposite 6 o'clock positions. The second detector may preferably be arranged at the 3 o'clock position and / or the 9 o'clock position. By this second detector, both X-ray fluorescence and X-ray scatter (leisure scatter, compton scatter) can be recorded.

In order to selectively detect the image with the second detector using the emitted X-ray radiation, the emitted X-ray radiation energy may be measured in disassembled form. If there is a preset emitting chemical element in the object under inspection, the fluorescent radiation and scattered radiation (Compton radiation, generated from another emitted chemical element, for example from another emitted X-ray radiation, recorded by the second detector) Particularly advantageous for screening X-ray radiation, resulting from such opaque elements from Rayleigh radiation). Thus, it is possible to make any region (ROI) highly selective, such as by accumulating the concentration of opaque chemical elements in any organ of the human body, in order to produce a particularly high contrast tissue which makes it visible compared to the surrounding tissue. Do. In addition, the configuration in the graphic display generated from the skeleton is less prominent in this case than the visualization of the tissue, so that the skeleton makes the graphic display substantially non-perturbing.

In order to detect and characterize the emission radiation, an energy dispersion detector is preferably used. However, it is also possible to use a simpler detector for this purpose and to ensure the characterization of the emission by the X-ray optical module (filter combination, monochromator).

Moreover, this principle can be applied in the same way to the measurement of the intensity value of the X-ray radiation transmitted to the first detector. Also in this case, selective visualization of the area within the object under examination in which the opaque chemical element is concentrated is achieved.

Thus, for example, human soft tissue can also be visualized at the high contrast of the present invention. By integrating the energy or energy interval of transmitted and emitted X-ray radiation recorded by a detector with a type of opaque chemical element, an efficient increase in contrast can be achieved compared to conventional methods.

In order to generate X-ray radiation, standard commercially available X-ray tubes with continuous spectra can be used, for example, as tubes with Mo, W or Rh anodes. Depending on the type of opaque chemical element contained in the object under test, a voltage is applied which allows the emission of continuous radiation, for example in the range up to 100 KeV.

In principle, the X-ray radiation source can be operated without filtering the emitted radiation so that the multicolor radiation occurs in the full spectral range in the subject under examination. However, in order to reduce the radiation exposure of the subject under examination, it is also possible to filter such X-ray radiation from the spectrum of the multicolored X-ray radiation source for which energy is not necessary or advantageous for detection. For this purpose, for example, an Al or Cu filter is used which filters energy (soft emission) in the range of 20 KeV or less. Thus, X-ray emission in the range of at least 0 keV, preferably at least 15 KeV, particularly preferably at least 17 KeV, more particularly preferably at least 20 KeV and for example up to 100 KeV is limited to the continuous spectrum, whereby others In comparison, the spectral ranges within these limits are not emphasized or excluded. The upper limit of the emission spectrum is determined by the voltage applied to the X-ray anode. Low energy range radiation is well filtered to eliminate dose-relevant radiation to the human body.

Typically, the subject under examination is examined by multicolor X-ray radiation using an appropriate detector. Optionally, an energy dispersion detector can also be used to determine the energy of the incident photons.

Energy dissipation detectors and detector units are generally of two designs. In other words,

a. An energy dissipation detector according to the Cd (Zn) Te detector format as described at the beginning of the description of the invention. With this series of detectors, the X-ray spectrum of the emitted X-ray radiation can be measured as pixel to pixel.

b. Simple X-ray detectors are used. The simplest case discrimination device which constitutes a suitable filter combination is arranged in front of the detector. However, for energy selection, a monochromator may also be used that is adapted to, for example, the X-ray fluorescence of the administered contrast medium.

c. However, it is certainly technically possible to adapt the detector directly to the contrast medium. Thus, a Gd (Zn) Te detector or a Dy (Zn) Te detector can be used.

In all cases, the detector is positioned so that the lowest possible Compton scatter is measured.

In order to determine the energy as well as the value of the intensity of the X-ray radiation emitted by the subject under examination, the detected photons are divided into at least two different energy ranges including, for example, K _α and K _B emission lines. In order to increase component specificity, compton correction may optionally be performed. However, as shown in the examples further described below, such correction is not necessary.

If the original X-ray contrast is ignored, the X-ray contrast medium can be administered to the subject under test, such as a human, for carrying out the method according to the invention. X-ray contrast media can be administered, for example, orally or parenterally, specifically by intravenous injection, intramuscular injection, or subcutaneous injection or infusion. After that, an X-ray image is created. Such contrast media exhibiting high attenuation coefficients in the selected spectral region are inherently suitable. Contrast media may also be particularly suitable in which the absorption component has a K-edge of the absorption spectrum in the selected spectral region. Such X-ray contrast medium comprises an opaque chemical element, in the case of having an opaque chemical element of element number 35 or higher, the contrast medium comprises bromine, and in the case of having an opaque chemical element of element number 47 or higher, the contrast medium comprises iodine In the case of having an opaque chemical element having an element number of 57 or more, the contrast medium contains a lanthanide element, specifically, gadolinium. In the case of having an opaque chemical element of an element number 83, the contrast medium includes bismuth. Thus, an X-ray contrast medium containing opaque chemical elements of elements 35 (bromine) to 83 (bismuth) may be suitable. Particularly suitable is a contrast medium having an opaque chemical element of elements number 53 (iodine) to 83 (bismuth). In addition, an X-ray contrast medium having an opaque chemical element of element numbers 57 (lanthanide element) to 83 (bismuth) may also be suitable, and element numbers 57 to 70 (lanthanide elements: La, Ce, Pr, Nd, Pm, Particular preference is given to X-ray contrast media having opaque chemical elements of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb).

For example, suitable iodine-containing X-ray contrast media include, for example, amidotrizoate, iohexol, iopamidol, iopanoic acid, iodidic acid, iopromide, ioponic acid, iopton, iotamic acid, iopentol, Compounds including triiodine aromatic compounds such as ioversol, dioxaglat, iotrolan, iodixanol, iotoroxane, iosaglinic acid and iositamic acid, and iosmenol (INN). Under the trade name of X-ray contrast medium containing iodine passage graphene [Urografin ^® (Schering)], Gasthof log Lapin [Gastrografin ^® (Schering)], Billy skopin [Biliscopin ^® (Schering)], Ultra Beast [Ultravist ^® ( Schering) and Isovist ^® (Schering).

For example, Gd-DTPA [(Magnevist ^® (Schering)], Gd-DOTA (Gadoterate, Dotarem), Gd-HP-DO 3A [Gadoteridol, Prohance ^® (Bracco)], Gd-EOB-DTPA (Gadoxetat, Primavist) Metal complexes such as Gd-BOPTA (Gadobenat, MultiHance), Gd-DTPA-BMA [Gadodiamide, Omnsiscan ^® (Amersham Health)], Dy-DTPA-BMA, Gd-DTPA-polylysine and Gd-DTPA-cascade polymers. It may be suitable as an X-ray contrast medium, where DTPA = diethylenetriaminepentaacetic acid, DOTA = 1,4,7,10-tetraazacyclododecene, HP-D03A = 10- (hydroxypropyl) -1 , 4,7,10-tetraazacyclododeken-1,4,7-triacetic acid), EOB-DTPA = 3,6,9-triaza-3,6,9-tris (carboxymethyl-4- (4-ethoxybenzyl) undecanadicarboxylic acid, BOPTA = (4-carboxy-5,8,11-tris (carboxymethyl) -1-phenyl-2-oxa-5,8,11-triazatridekene- 13-oak, benic acid), DTPA-BMA = diethylenetriaminepentaacetate-bis (methylamide), DPTA-polylysine = Ethylene triazol laminate pentaacetate-polylysine, and cascade polymers DPTA-.

X-ray contrast media can be administered orally and parenterally. In the case of parenteral administration, intravenous administration is preferably selected. Preferred dosages are one dose up to 0.75 g of body weight I / kg for iodine containing nonionic contrast media. This corresponds to about 6 mmol of body weight I / kg. It may also be desirable for the single dose to be increased to 1.5 g of body weight I / kg (corresponding to about 12 mmol of body weight I / kg), in exceptional cases 2 g of body weight I / kg (about 16 I). Corresponding to) or 5 g (corresponding to about 39 mmol of body weight I / kg). For lanthanide element complexes, the preferred single dose is about 0.1 mmol / kg of body weight. A single dose of up to 0.3 mmol / kg of body weight or up to 1 mmol / kg of body weight may be appropriate and is also preferred.

The emission line of gadolinium is approximately 43.0 to 48.7 KeV higher than the emission line of iodine which is approximately 28.6 to 32.3 KeV. The metal complex may contain other lanthanide elements such as, for example, lanthanum, dysprosium, ytterbium, instead of gadolinium atoms.

Digital detectors have previously been provided by a number of manufacturers [see, for example, HBI, published in the February 1999 issue of BBI Monthly, page 34, and Radiol 1999, 210, pages 595-599. Chotas, J.T. J.T. Dobbins, C. E. "Principles of Digital Radiography with Large-Area, Electronically Readable Detectors: A Review of the Basics" by CE Ravin. These digital detectors are made of amorphous silicon or other semiconductor material, in the X-ray apparatus according to the invention a detector with a phosphorus plate (for example commercially available from Fuji Chemical Industries and Konica), for example , Detectors with amorphous silicon, commercially available from GE Medical, Philips Medical, Siemens Medical, detectors with salt (for example, available from Philips Medical, Toshiba), gadolinium (for example, available from Kodak) Detector with gadolinium hyposulfite, cadmium telluride (CT) or cadmium zinc tellurium It is suitable for detectors with id semiconductors (CZT), detectors with ytterbium oxyorthosilicates, detectors with lutetium oxyorthosilicates, and detectors with sodium iodide or bismuth germanate. A (Z) T detector, ie a detector consisting of cadmium zinc telluride semiconductor.

Energy dispersion detectors formed from semiconductors are described in detail in US Pat. No. 5,434,417. In the case of this dispersion detector, a segmented semiconductor strip is provided which is irradiated from the front by X-ray radiation. The radiation passes through the semiconductor material until the radiation interacts with the semiconductor material. The passing distance depends on the energy of the X-ray photons. The larger the energy of the X-ray photons, the deeper the radiation passes than in the case of the low energy of the X-ray photons, which persist until the radiation interacts with the detector material to generate a current impulse by the photoelectric effect. The current impulse can be emitted to each segment of the detector by means of applied electrical contact. Current impulses are handled by an input amplifer.

On the other hand, the detector may be designed in the form of a flat bed detector. In this embodiment, the detection of all pixels is done simultaneously and passed to the correlation unit for evaluation. In this case, the detector consists of a large area arrangement of each detector sensor, preferably of a matrix having rows and columns of such sensors.

In addition, a detector unit used to determine the emitted X-ray radiation and selectively record the emitted image, and for this purpose, a detector unit designed to have an X-ray optical module for energy selection may be provided.

Instead of a flat-bed detector, a matrix or line detector of several detectors suitable for picking up each pixel may be used. In the case of more recent detectors, the X-ray radiation from the object under inspection is sent simultaneously via an x-ray fiber optic light guide. Many such optical fiber light guides are coupled to a surface detector.

In addition, the detector can be designed to pick up each pixel and can be moved to pick up all pixels. In this embodiment, the detector can only detect the energy dependent intensity at each pixel during the measurement. The intensity of each pixel is, for example, continuously detected along the line and passed to the correlation unit for further processing.

The detector may also have an array of detector sensors designed to pick up pixels in each case, and may be moved to pick up all pixels. According to the invention, a line of detector sensors or other devices, for example a matrix device of detector sensors, is defined as an array of detector sensors. In this embodiment, the detector detects the intensity value of each pixel by line or optionally block. In order to pick up all intensity values, the detector is preferably moved perpendicular to the major axis of the array during the measurement. The intensity values determined during the measurement are passed to the correlation unit.

For example, in a graphical display that distributes opaque chemical elements to an object during inspection, it is advantageous in each case to detect the radiation intensity with the same weight emitted by each spatial component. It is also advantageous for this purpose to equip each spatial component with the same radiation intensity from the X-ray radiation source in each case. Indeed, these statements are approximately accurate because, on the one hand, the emitted X-ray radiation is attenuated by absorption for different ranges, and on the other hand, depending on how much the object is spaced from the radiation upon inspection, and on the other hand, This is because the radiation emitted by the spatial component of the object at the time of inspection is attenuated by self-absorption for different ranges depending on how far apart they are and the detector placed on the object at the time of inspection.

This problem occurs with all emission spectroscopy. To solve the problem, the second intensity value, which takes into account the absorption of the radiated X-ray radiation of the object under examination and / or the self-absorption of the emitted X-ray radiation, is first corrected, and the first and second intensity values are such. Only after modification are they correlated pixel-by-pixel. Such correction can be performed by numerical processing by at least an approximate position in accordance with the shape of the object under examination and the X-ray opacity under consideration. To determine the position according to the X-ray opacity, an image generated from the first intensity value can be used. Since the absorption coefficient for the radiation treated X-ray radiation is similar to the absorption coefficient of the emitted radiation, in order to determine the position according to absorption and self absorption, the position according to the X-ray opacity obtained from these measurements is the baseline of the first approximation. Can be used as

Because of the self-absorption of the emitted radiation, during the measurement for the inspection area (ROI), for example, a circular segment passage, for example, can be used to offset the structural heterogeneity of the object under inspection that acts differently depending on the viewing angle and viewing point. It may be more desirable to move the position of the detector and each position. In this case, the graphic display is obtained after the correction of the self absorption is averaged.

Then, a signal originating from the input amplifier is sent to at least one correlated unit, and the intensity of the X-ray radiation detected from the pixel of the object under inspection is equal to the emitted X-ray radiation (X-ray scattering and X-ray fluorescence of the same pixel). ) Is correlated with the image. Correlated units may be correspondingly programmed data processing units.

In order to correlate the intensity values of photons of the two aspects (transmission image and emission image), the latter are correlated at one time with another pixel, preferably excluded from each other or separated from each other. In this case, in this case, a comparator can be used, and in other cases, separate terms can be used for the interrelationships performed pixel to pixel. Of course, mathematical calculations may also be performed to correlate the intensity values of the X-ray radiation transmitted and emitted from the image.

In order to process the intensity value of the measured pixel, the following apparatus is preferably provided that can be implemented in a data processing unit.

1. A first storage unit wherein the first intensity value of transmitted X-ray radiation can be stored pixel to pixel.

2. A second storage unit in which the second intensity value of the emitted X-ray radiation can be stored pixel-by-pixel (eg, with elements I, Gb and Yb).

3. A calculation unit that provides appropriate correlation to the generated two image data sets to generate or calculate image data sets from the transmission data set information and data from X-ray emission, preferably X-ray fluorescence.

As a result, the intensity values of all the transmitted and emitted pixels can be correlated with each other, so that the emitted image is adapted to be suitable for the contrast medium used over the particular emission line. Mixtures consisting of X-ray contrast media (Ultravist ^® and Gadovist ^® ) or materials containing both iodine and lanthanides (eg Gd or Dy) are used, in which the characteristic emission lines in each case are to be used as emission images. The measured data sets can then be correlated with each other by the pixels and used in a graphical display, or alternatively, each intensity value is correlated with each other pixel by pixel, so that the data obtained is then graphically Used as a display. Eventually, the obtained data is delivered one pixel at a time to an output unit, for example a monitor (CRT or LCD display) or a plotter.

In order to explain the invention in more detail, the following figures and examples are used. To provide a direct explanation of how the invention works, no effort is made to calibrate the X-ray spectrum as measured according to the absorption and self-absorption of the excitation beam.

1 shows an image of a computed tomography imaging test device.

2 is a schematic diagram of a visualization process of an image forming apparatus or inspection setup.

Figure 3 shows a test apparatus schematic visualization process for generating a first phantom measurement.

Figure 4 shows the emission spectrum of the phantom of Figure 3 filled with water 4a, Ultravist ^® (Figure 4b), Gadovist ^® (Figure 4c).

FIG. 5 shows the emission spectrum of the phantom of FIG. 3 filled with water 5a, Ultravist ^® (FIG. 5B), Gadovist ^® (FIG. 5C) and in each case a 5 cm thick PMMA disc is placed between the detector and the phantom. do.

FIG. 6 shows the phantom position / variation from FIG. 3 in the selected energy band (corresponding to the K _α and K _β lines of the iodine (FIG. 6A), gadolinium (FIG. 6B), mixture of iodine and gadolinium (FIG. 6C)). The emission intensity based on is shown.

Figure 7 shows a CT cross-sectional image (transmission image) of a phantom filled with Gd, iodine / Gd mixture, iodine, air and water.

In Fig. 1, a photographic visual image of a test apparatus of a computer tomography X-ray photographing apparatus having a rubber ball 1 fastened to the rack 2 is shown. The rubber ball is arranged in the center of the computed tomography X-ray photographing apparatus. In various tests, the rubber balls are filled with air, water, and different contrast medium solvents. The ball was between the CT tube (above the rubber ball, not shown) and the line detector (just below the table visible below the rubber ball, not shown).

At an angle of 90 ° with respect to the connecting line between the CT tube, the rubber ball and the detector, the measuring chamber 3 was positioned to detect X-ray fluorescence. With these experimental instruments, tissues or tumors, such as those filled with contrast media, were simulated as test subjects examined with a computed tomography X-ray apparatus. For this purpose, the object was scanned into layers, in which case the scatter spectrum was measured.

The experimental instrument used in this test is shown in detail in FIG. The schematic illustration shows a ball 1 marked phantom at an isocenter of a gantry 4. The CT tube 5 was arranged at the 12 o'clock position and was fixed at this position. The measuring chamber 3 consisting of a detector 6 and a lead tube 7 was oriented at a 90 degree angle to the X-ray cone beam projecting from the CT tube to the phantom (ball) (z-direction , See arrow).

In order to detect the X-ray irradiation, a CZT detector 6 having a 100/400 μm aperture with a 3 mm × 3 mm × 2 mm cadmium-zinc-tellide compound crystal was used [Amptek, Inc. ), United States of America]. The data recorded by the fluorescence detector is transferred from the detector through the amplifier to the multichannel analyzer 9 and then supplied to the PC 10 in a storage trade name Excel (Microsoft) sheet. Therefore, signal strength [SI = SI (E)] exists in digital form as a function of energy E.

In FIG. 3, a test apparatus for generating a first phantom measurement is shown as a schematic visible image. A portion of the measuring chamber for measuring fluorescence 3 can be seen on the left side of the visible image as a visible image, with the ball 1 shown in the center of the visible image. A separate partial plane perpendicular to Figure 3 where fluorescence enters the measurement chamber was generated by the X-ray fan beam projected from above. Dotted lines indicate the individual positions of the CT tubes above the image cutout. The horizontal scale represents the movement of the fan beam and therefore represents the partial plane processed in each case (excitation layer) in the ball.

Since "zero measurement" was made at +45 mm, it was made outside of the beam here.

After recording each spectrum, the entire measurement structure was shifted 10 mm further (in the Z direction) into the gantry, and a new spectrum was recorded. Therefore, various spectra were generated in layers based on the individual positions of the balls in the beam or the individual positions corresponding to the geometry of the balls.

With this measurement structure, X-ray fluorescence can be measured based on the topography of the phantom, at Z = -60 mm the layer closest to the detector is irradiated and at Z = 0 the layer farthest from the detector is irradiated. (The radiation self-absorption is minimal at z = -60, the maximum at Z = 0, and the absorption effect of irradiation is prominent at higher contrast medium concentrations due to the spherical geometry.

Example 1:

In the first measurement, the ball was filled with water and measured at 80 kv, 50 mA each 80 seconds per ball position in the beam corresponding to Figure 3 [parameter: detector: XR-100.CZT (diameter 0.1 mm), between ball and detector Distance: 18.0 cm; Distance between ball and CT tube: 32.0 cm].

In FIG. 4A, the dispersion spectrum of the phantom for water is shown for various locations.

In a second measurement, the ball was filled with 50 mmol / l of iodine solution (Ultravist ™) and measured at 80 kV, 50 mA each 80 seconds per position [parameter: detector: XR-100.CZT (diameter 0.1) mm)].

Emission spectra obtained at various locations were reproduced in FIG. 4B. The K _α and K _B lines of iodine are clearly visible. From the graph the dependence of the measured intensity of the X-ray fluorescence on the phantom geometry is evident. The larger the irradiated layer of phantoms, the higher the measured strength.

In a third measurement, the ball was charged with 50 mmol / l of gadolinium (Gadonist) solution and charged at 80 kv, 50 mA each 80 seconds for each position [parameter: detector: XR-100.CZT ( Bulb 0.1mm)].

Emission spectra obtained at various locations were reproduced in FIG. 4C. The K _α and K _B lines (43.0 and 48.7 keV) of gadolinium are clearly visible. In particular, it has been shown that the intensity of the emitted radiation measured in the K line range is independent of the geometry of the ball in the irradiation area.

Example 2:

In each measurement of this test, in each case a 5 cm thick PMMA disc was positioned as a filter between the detector and the model to simulate X-ray fluorescence self-absorption through the surrounding tissue.

In FIG. 5A, the dispersion spectrum of moisture in the model is shown for several locations.

In a second measurement, the ball was filled with water (Ultravist ^® ) with 50 mmol / l of iodine in water and measured at 80 mA, 50 mA every 80 seconds for each position [parameter: detector: XR-100.CZT ( Aperture 0.1 mm)].

Emission spectra obtained at various locations were reproduced in FIG. 5B. The intensity of fluorescence radiation was reduced due to the inserted PMMA discs. This proved that the thicker the disk, the lower the strength. However, even within the largest layer of (center) balls, the K line was still measurable.

In a third measurement, the balls were filled with water (Gadovist ^® ) with 50 mmol / l gadolinium in water and measured at 80 mA, 50 mA every 80 seconds for each position [parameter: detector: XR-100.CZT (opening 0.1 mm)].

Emission spectra obtained at various locations were reproduced in FIG. 5C. Here too, fluorescence emission was reduced due to the inserted PMMA disc. Since the K _α and K _B lines of gadolinium are approximately 43.0 or 48.7 KeV, a significant large fluorescence emission could be detected in the presence of a 5 cm-thick PMMA disc than in the case of the previous iodine emission. Thus, even in this case, K lines can still be measured within the largest layer of the (center) ball.

Example 3:

In another test, fluorescence intensity values were determined and recorded based on the positioning of the balls relative to the X-ray beam.

In a first measurement, the ball was filled with water (Ultravist ^® ) with 50 mmol / l of iodine in water and measured at 80 mA, 50 mA every 80 seconds for each position.

In FIG. 6A, the intensity of fluorescence radiation is shown based on the position / movement of the model within the selected energy band corresponding to the K _α line of iodine at 28.6 KeV and the K _β line of iodine at 32.3 KeV. The profile of the radiation intensity produced by the shape of the ball can be detected from this figure.

In a second measurement, the balls were filled with an aqueous solution (Gadovist ^® ) of 50 mmol / l gadolinium in water and measured at 80 mA, 50 mA every 80 seconds for each position.

In FIG. 6B, the intensity of fluorescence radiation is shown based on the position / shift of the model within the selected energy band corresponding to the K _α line of gadolinium at 43.0 KeV and the K _β line of gadolinium at 48.7 KeV. The profile of the radiation intensity produced by the shape of the ball can be detected from this figure.

In a third measurement, the ball is filled with an aqueous solution of 25 mmol / l of iodine in water (Ultravist ^® ) and 25 mmol / l of gadolinium in water (Gadovist ^® ) in water and measured at 80 mA, 50 mA every 80 seconds for each position. It became.

In FIG. 6C, the intensity of fluorescence radiation corresponds to the K _α line of iodine at 28.6 KeV, the K _β line of iodine at 32.3 KeV, the K _α line of gadolinium at 43.0 KeV, and the K _β line of gadolinium at 48.7 KeV Is shown based on the position / movement of the model within the selected energy band. As can be seen in FIG. 6C, the ball profile has been insufficiently regenerated within a direct view of a single intensity only as a function of position. This may be due to absorption on the excitation side and self-absorption on the emission side. Lower contrast medium concentrations, correction of absorption of the main beam and self-absorption of X-ray fluorescence resulted in graphical visualization of the balls in one dimension.

Example 4:

7 shows the CT cross-sectional images recorded in the previous examples of X-ray fluorescence. From the upper left to the lower right, you can see a ball filled with gadolinium, a ball filled with a mixture of gadolinium and iodine, a ball filled with iodine, a ball filled with pure water, and a ball filled with air. The air filled ball clearly has the smallest x-ray attenuation after the water filled ball. When using a ball with opaque element 50 mmol / l, X-ray attenuation is more pronounced than with water, and quantitative evaluation is possible through the measurement of Hounsfield unit (HU), but with X-ray fluorescence Only the addition of images allows evaluation of the element-specific filling of the balls.

Claims (37)

An X-ray apparatus for the graphical display of a subject under examination comprising at least one radiation opaque chemical element by X-ray radiation that passes through the subject under examination and radiates from the subject under examination, At least one X-ray radiation source emitting substantially polychromatic X-ray radiation, A first detector or first detector unit through which the first intensity values of the X-ray radiation transmitted through the object under examination can be determined; A second detector or second detector unit in which second intensity values of X-ray radiation emitted from the subject under examination can be determined; At least one correlation unit, wherein the first intensity values of the transmitted X-ray radiation may be correlated with the second radiation values of the transmitted X-ray radiation on a pixel-by-pixel basis, And at least one output unit for visualizing a subject under examination from pixel signals that can be obtained by a correlation of first intensity values and second intensity values. The method of claim 1, wherein the correlation unit, A first storage unit, wherein the first intensity value of the transmitted X-ray radiation can be stored pixel to pixel, A second storage unit, wherein the second intensity value of the emitted X-ray radiation can be stored pixel to pixel, And an arithmetic unit in which the first intensity value of the transmitted X-ray radiation can be correlated with the second intensity value of the emitted X-ray radiation on a pixel-by-pixel basis. The X-ray apparatus according to claim 1 or 2, wherein the second intensity value can be detected in a decomposed form based on the energy of the emitted X-ray radiation. The X-ray radiation emitted by the opaque chemical element contained in the object under inspection, using the second detector or the second detector unit, helps the energy of the X-ray radiation. X-ray apparatus that can be identified from other x-ray radiation emitted by the. The first intensity value and the second intensity according to any one of claims 1 to 4, in accordance with pre-calibration taking into account the absorption of the irradiated X-ray radiation and / or the self-absorption of X-ray radiation emitted to the subject under examination. X-ray devices in which intensity values can be correlated with each other pixel-by-pixel The X-ray apparatus of claim 1, wherein the first and / or second detector is a flat bed detector. The x-ray apparatus according to claim 1, wherein the first and / or second detectors are designed to pick up individual pixels and can be moved to pick up all pixels. The X-ray apparatus according to claim 1, wherein a detector unit designed using an X-ray optical module for energy selection is provided to determine emitted X-ray radiation. The X-ray of claim 1, wherein the first and / or second detector is designed to pick up a pixel in each case and has an array of detector sensors that can be moved to pick up all the pixels. Device. The method according to any one of claims 1 to 9, as well as other methods of optical imaging, such as positron-emitting x-ray tomography (PET) or single-photon-emitting-computer x-ray tomography (SPECT). X-ray apparatus in radiological discovery in combination with image forming methods. The method according to any one of claims 1 to 10, for a graphical display of a subject under examination, comprising at least one radiopaque chemical element transmitted by the subject under examination and emitted from the subject under examination. Use of X-ray Devices. The method of claim 11, Essentially irradiating the subject under examination with polychromatic X-ray radiation, Measuring a first intensity value of the X-ray radiation transmitted through the subject under examination; Measuring a second intensity value of the X-ray radiation emitted by the subject under test; Correlating the first intensity value of the transmitted X-ray radiation pixel-by-pixel with the second intensity value of the emitted X-ray radiation; Use of an X-ray apparatus in which steps of visualizing an object under inspection are performed from a pixel signal obtained by correlating a first intensity value with a second intensity value. 13. Use of an x-ray apparatus according to claim 11 or 12, wherein the second intensity value can be measured in disassembled form based on the energy of the emitted x-ray radiation. Use of an X-ray apparatus according to claim 11, wherein the X-ray radiation emitted from the opaque chemical element contained in the subject under test is identified from other emitted X-ray radiation with the aid of radiation energy. The first intensity value according to any one of claims 11 to 14, in accordance with pre-calibration taking into account the absorption of the irradiated X-ray radiation and / or the self-absorption of X-ray radiation emitted in the subject under examination. The use of an X-ray apparatus in which second intensity values are correlated with each other pixel by pixel. Use of an X-ray apparatus according to any one of claims 11 to 15, wherein a first and a second detector or a first and a second detector unit are provided. The use of an X-ray apparatus according to claim 16, wherein the first and / or second detector is a flat bed detector. The use of an x-ray apparatus according to claim 16, wherein the first and / or second detectors are designed to pick up individual pixels and are moved to pick up all pixels. The use of an x-ray apparatus according to claim 16, wherein the first and / or second detector has an array of detector sensors designed to pick up pixels in each case and are moved to pick up all pixels. The use of an X-ray apparatus according to claim 16, wherein a detector unit designed using an X-ray optical module for energy selection is provided to determine emitted X-ray radiation. The use of any of claims 11 to 20, wherein the opaque chemical element is selected from the group comprising bromine, iodine, lanthanide elements, bismuth. 22. The use of any one of claims 11 to 21 wherein the opaque chemical element is administered intranasally or parenterally. 23. Use of an X-ray apparatus for a graphic or quantitative display of a specific element of an inspection area in a subject under test, comprising any one of claims 11 to 22. 24. The method of any one of claims 11 to 23, as well as other methods of optical imaging, such as positron-emitting x-ray tomography (PET) or single-photon-emitting-computer x-ray tomography (SPECT). Use of X-ray Devices in Radiologic Discovery in Combination with Image Formation Methods. Essentially irradiating the subject under examination with polychromatic X-ray radiation, Measuring a first intensity value of the X-ray radiation transmitted through the subject under examination; Measuring a second intensity value of the X-ray radiation emitted by the subject under test; Correlating the first intensity value of the transmitted X-ray radiation pixel-by-pixel with the second intensity value of the emitted X-ray radiation; An image of the subject under examination by X-ray radiation transmitted by and emitted from the subject, comprising visualizing the subject under examination from a pixel signal obtained by correlating the first intensity value with the second intensity value Formation X-ray contrast method. 27. The method of claim 25, wherein at least one radiopaque first chemical element is administered to the subject under test before all the method steps are performed. 27. The method of claim 25 or 26, wherein the second intensity value can be measured in disassembled form based on the energy of the emitted X-ray radiation. 28. The method of any one of claims 25-27, wherein X-ray radiation emitted from the opaque chemical element contained in the subject under test is identified from other emitted X-ray radiation with the aid of radiation energy. 29. The method according to any one of claims 25 to 28, wherein the first intensity value is determined in accordance with pre-calibration taking into account the absorption of the irradiated X-ray radiation and / or the self-absorption of X-ray radiation emitted within the subject under examination. X-ray contrast method in which the second intensity values are correlated with each other pixel by pixel. 30. The method of any one of claims 25 to 29 wherein a first and a second detector or a first and a second detector unit are provided. 31. The method of claim 30, wherein the first and / or second detector is a flat bed detector. 31. The method of claim 30, wherein the first and / or second detector is designed to pick up individual pixels and is moved to pick up all pixels. 31. The method of claim 30 wherein the first and / or second detector has an array of detector sensors designed to pick up pixels in each case and are moved to pick up all pixels. 31. The method of claim 30, wherein a detector unit designed using an X-ray optical module for energy selection is provided to determine emitted X-ray radiation. 35. The method of any of claims 25-34, wherein the opaque chemical element is selected from the group comprising bromine, iodine, lanthanide elements, bismuth. 36. The method of any one of claims 25-35, wherein the opaque chemical element is administered intranasally or parenterally. 37. A method according to any one of claims 25 to 36, such as positron-emitting x-ray tomography (PET) or single-photon-emitting-computer x-ray tomography (SPECT) and ultrasound, as well as optical image forming methods. X-ray contrast method in radiological discovery in combination with other radiological imaging methods.

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