Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/48—Diagnostic techniques
  • A61B6/482—Diagnostic techniques involving multiple energy imaging
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
  • A61B6/03—Computed tomography [CT]
  • A61B6/032—Transmission computed tomography [CT]
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
  • A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
  • A61B6/4233—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector using matrix detectors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/48—Diagnostic techniques
  • A61B6/481—Diagnostic techniques involving the use of contrast agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
  • A61B6/504—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for diagnosis of blood vessels, e.g. by angiography
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
  • A61B6/507—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for determination of haemodynamic parameters, e.g. perfusion CT
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/40—Arrangements for generating radiation specially adapted for radiation diagnosis
  • A61B6/4064—Arrangements for generating radiation specially adapted for radiation diagnosis specially adapted for producing a particular type of beam
  • A61B6/4092—Arrangements for generating radiation specially adapted for radiation diagnosis specially adapted for producing a particular type of beam for producing synchrotron radiation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
  • A61B6/58—Testing, adjusting or calibrating thereof
  • A61B6/582—Calibration
  • A61B6/583—Calibration using calibration phantoms

Definitions

• the present invention relates to an X-ray arrangement for image display of an examination object containing at least one X-ray contrasting chemical element by means of X-radiation, a use of the X-ray arrangement and an X-ray contrast imaging method on an examination subject, for example a mammal, in particular a human.
• X-ray medical diagnostics is a technically advanced field for the diagnosis of diseases, for example for the early detection, radiographic detection, characterization and localization of tumors, vascular diseases and other pathological changes of the human body.
• the technology is very powerful and has a high availability.
• X-ray tubes are available, for example, with W, Mo or Rh rotary anodes and Al, Cu, Ti, Mo and Rh filters. With suitable filtering, a portion of the bremsstrahlung is filtered out so that in favorable cases substantially the characteristic radiation exits the x-ray tube.
• the detectors used are either conventional X-ray films, imaging plates or digital flatbed detectors.
• Computer tomographs use one or more lines of detector. Also several detectors can be connected in parallel.
• Semiconductor detectors consisting of cadmium telluride (CT), cadmium zinc telluride (CZT), amorphous selenium, or amorphous or crystalline silicon (MJ Yaffe, JA Rowlands, "X-Ray Detectors for Digital Radiography ", Med. Biol., 42 (1) (1997) 1-39).
• An example of the construction of such detectors is given in US Pat. No. 5,434,417. In order to also enable an energy sensitivity of the detector, this is formed of several layers.
• X-ray radiation with different energy penetrates into this detector at different depths and generates in the respective layer by photoelectric effect an electrical signal which can be identifiably read out as a current pulse after the layer and thus according to the energy of the X-ray photons.
• Computed tomography has long been used as a routine procedure in everyday clinical practice.
• CT Computed tomography
• sectional images are obtained by the body, with which a better spatial resolution is achieved than with the conventional projection radiography.
• contrast agents are still needed to reliably detect many pathological changes. These improve the quality of the morphological information.
• the contrast agent on the one hand shows functional processes in the body (excretion, perfusion, permeability) and on the other emphasizes the morphology by creating contrasts (different contrast agent concentrations in different tissues).
• X-ray contrast agents have been developed which produce a high X-ray density in the tissue in which they accumulate.
• iodine, bromine, elements of atomic numbers 34, 42, 44-52, 54-60, 62-79, 82 and 83 are used as contrasting elements and the chelate compounds of elements with atomic numbers 56-60, 62-79, 82 and 83 proposed.
• iodine compounds for example, meglumine-Na or lysine diatrizoate, lothalamate, loxithalamate, lopromide, lohexol, lomeprol, lopamidol, ioversoi, iobitridoi, iopentoi, iotrolan, iodixanol and loxilane (INN) are used (EP 0 885 616 A1).
• DSA digital subtraction angiography
• Contrast mammogram then the patient a conventional urographic X-ray contrast agent rapidly i.v. inject and record a post-contrast mammogram for about 30 seconds to 1 minute after the end of the injection.
• the obtained data of the two images are then correlated with each other, preferably subtracted from each other.
• the characteristic radiation of the two X-ray anodes is matched to the absorption spectrum of the X-ray contrast agent: the emission energy of the first X-ray anode is slightly below the absorption energy of the contrasting element in the X-ray contrast medium and the emission energy of the second X-ray anode is slightly above the absorption energy of the contrasting element.
• a disadvantage of this method is that conventional x-ray tubes with only one x-ray anode must be replaced with bi-anode tubes.
• WO 2004/041060 A2 describes a device for the non-invasive in vivo determination of a chemical element in the prostate of a human, comprising a probe, an irradiation system with which the chemical element can be excited to emit radiation, a radiation detector within the probe with which the emitted radiation can be imaged and a signal recording, processing and display system with which the amount of the chemical element in the prostate can be reproduced at different locations corresponding to the image of the emitted radiation.
• the emitted radiation essentially consists of fluorescence radiation.
• the distribution of Zn in the tissue is preferably determined.
• Scattering coefficient for different momentum transfers from the measured values obtained for each pixel of the layer is determined.
• Quanwen Yu et al. "Preliminary Experiment of Fluorescent X-Ray Computed Tomography to Detective Dual Agents for Biological Study”: J. Synchrotron Rad. (2001), 8 1030-1034, has proposed the X-ray fluorescence method for determination This method can be used to obtain images that can simultaneously detect multiagents using the fluorescence K ⁇ line in a single study, such as brain blood flow and density In the presented study, images obtained by this method were compared with images obtained by X-ray transmission tomography.
• the present invention is therefore based on the problem to avoid the aforementioned disadvantages and in particular to find arrangements and methods with which recordings can be made with different X-ray contrasting chemical elements.
• the X-ray images should also be receivable in a simple, convenient manner, without incurring high costs.
• the technology should be available on a broad basis. Even smaller lesions in the examination subject should be able to be visualized with high spatial resolution with the lowest possible radiation dose. Motion artifacts should be avoided.
• emission and emit are used below in the description of the invention and in the claims, they are intended to include, for example, X-ray fluorescence, i. the emission of radiation after a
• Excitation of the irradiated matter by means of electromagnetic radiation, and on the other preferably Rayleigh scattering understood.
• the radiation is emitted again without momentum transfer from the irradiated matter, although the irradiation does not cause any excitation of sheath electrons in atoms of this material in excited states, as in fluorescence.
• the X-ray arrangement With the X-ray arrangement, X-ray radiation transmitted through and emitted by the examination subject is used for imaging.
• the X-ray arrangement according to the invention comprises:
• a. at least one substantially polychromatic X-ray emitting X-ray source b. a first detector or a first detector unit (consisting of a plurality of detectors connected in parallel and / or arranged) with which the values of a first intensity of the X-ray radiation transmitted through the examination object can be determined, c. a second detector or a second detector unit, with which or with the values of a second intensity of the X-radiation emitted by the examination object can be determined, d. at least one correlation unit, with which the first intensity values of the transmitted X-ray radiation can be correlated with the second intensity values of the emitted X-ray radiation pixel by pixel, and e. at least one output unit for displaying the examination subject from pixel signals obtainable by correlation of the first intensity values with the second intensity values.
• the transmitted X-radiation and the emitted X-radiation can be detected either simultaneously or sequentially.
• This X-ray arrangement can advantageously be used for imaging an X-ray examination object containing preferably at least one X-ray-contrasting chemical element.
• the X-ray contrasting chemical element is preferably introduced into the examination subject by means of an X-ray contrast agent and, for example, for this purpose administered to the examination subject, for example a human or an animal.
• the X-ray arrangement is used for carrying out the X-ray contrast method according to the invention.
• the method has the following procedural steps:
• a. Preferably administering at least one chemical element giving an X-ray contrast
• b. Radiating the examination object with substantially polychromatic X-ray radiation
• c. Determining values of a first intensity of the X-radiation transmitted by the examination subject
• d. Determining values of a second intensity of the X-radiation emitted by the examination subject, e.
• Correlating the first intensity values of the transmitted X-ray radiation pixel by pixel with the second intensity values of the emitted X-radiation f. Representation of the examination object from obtained by correlation of the first intensity values with the second intensity values
• the X-ray transmission tomography offers the advantage of a high achievable temporal and spatial resolution, so that in principle even the smallest lesions or other details can be resolved in an examined human body.
• the contrast obtained is often not sufficient to visualize these details as well. This applies in particular to examinations of lesions in the soft tissue.
• examinations of certain body regions with the TXCT method are also affected by the skeleton.
• the X-ray fluorescence tomography offers the advantage of an extraordinarily high-contrast representation, since only certain chemical elements emit electromagnetic radiation with suitable excitation of these elements, so that these elements located in the examination region (ROI) are suitable as extremely sensitive measuring probes.
• the FXCT method suffers from the disadvantage of a low spatial resolution, so that smaller lesions can no longer be displayed.
• the invention can be used in particular for human examination.
• the invention is for the production of radiographs for the representation of Masses, vessels and perfusions suitable, for example, the representation of the esophageal gastrointestinal passage, bronchography, cholegraphy, angiography and cardiograography, cerebral angiography and perfusion measurements, mammography and lymphography.
• the focus of the application technology of the invention lies in the
• Computed tomography MS-CT; ⁇ CT
• PET-CT positron emission tomography
• SPECT Single Photon Emission Computer Tomography
• sonography sonography and other methods of optical imaging.
• the invention can also be used for the investigation of non-living materials, for example in the field of material testing.
• the transmitted radiation is recorded by means of the first detector, which is located in the beam path of the x-ray tube which is attenuated by the examination subject.
• the emitted radiation is measured by means of the second detector, which is arranged outside this beam path, preferably at an angle of approximately 90 ° to the beam path.
• this second detector can also be arranged in any other angular position relative to the X-ray beam, for example 45 ° or 135 ° to the beam emanating from the X-ray radiation source, without however being detected by the beam passing through the examination subject.
• the second detector can be arranged in the 3 o'clock position and / or the 9 o'clock position. Both X-ray fluorescence and X-ray scattering (Rayleigh scattering, Compton scattering) can be recorded by means of this second detector.
• the emitted X-radiation can be measured in terms of its energy resolved. It is particularly advantageous, in the presence of a given emitting chemical element in Object to be examined to discriminate the X-ray received from the second detector, which originates from this contrasting element of other emitted X-rays, for example, scattered radiation (Compton, Rayleigh radiation) and derived from other chemical elements fluorescent radiation.
• This makes it possible to make certain areas (ROI) very selectively visible by utilizing, for example, the accumulation of contrasting chemical elements in certain organs of a human body, so that a particularly large contrast of the visualized tissue to surrounding tissue arises.
• the structure caused by the skeleton in an image representation also occurs in such a case compared to the representation of the tissue, so that the framework practically does not disturb the image representation.
• an energy-dispersive detector is preferably used for the detection and characterization of the emission radiation.
• Intensity values of the transmitted X-radiation can be applied with the first detector. Also in this case, a selective representation of the areas in the examination subject (ROI) is achieved, in which accumulate the contrasting chemical elements.
• soft tissue can be represented in high contrast, for example in humans.
• Contrast increase over conventional methods can be achieved.
• a normal, commercially available X-ray tube with a continuous spectrum for example a tube with a Mo, W or Rh anode.
• a voltage is applied which enables an emission of the continuous radiation in the range up to, for example, more than 100 keV.
• the X-ray radiation source can be operated without filtering the emitted radiation, so that polychromatic radiation impinges on the examination subject in the entire spectral range.
• an AI or a Cu filter is used, the energy in the range ⁇ 20 keV (soft radiation) filters out.
• the continuous spectrum is thus to be understood as meaning an X-ray emission in a range of ⁇ 0 keV, preferably ⁇ 15 keV, particularly preferably ⁇ 17 keV and most preferably ⁇ 20 keV, up to, for example, 100 keV, with no spectral range within these limits being highlighted over others or excluded.
• Emission spectrum is determined by the voltage applied to the x-ray anode.
• the low-energy region of the radiation is preferably filtered out in order to eliminate dose-relevant radiation for the human body.
• the examination object is examined with polychromatic X-ray radiation with a suitable detector.
• an energy dispersive detector can be used to determine the energy of the incident photons.
• Energy-dispersive detectors and detector units there are basically two versions available: a. Energy-dispersive detectors of the type of Cd (Zn) Te detectors, as described in the introduction to the description. With such a series of detectors, X-ray spectra of the emitted X-ray radiation can be measured pixel by pixel. b. Simple X-ray detectors are used. In front of the detector, a discriminator is arranged, which consists in the simplest case of a suitable filter combination. For energy selection but also monochromators can be used, which are set for example on the X-ray fluorescence of the administered contrast agent. c. It is technically quite possible to adapt the detector directly to the contrast agent. Thus, Gd (Zn) Te or Dy (Zn) Te detectors can be used.
• the detector is positioned as much as possible so that a minimum of Compton scattering is measured.
• the detected photons are divided into at least two different energy ranges, which contain, for example, the K 0 and the K ⁇ emission lines. If necessary, a Compton correction can be carried out to increase the element specificity. As the examples given below show, this is not always necessary.
• an X-ray contrast agent can be administered.
• the X-ray contrast agent can be administered, for example, enterally or parenterally, in particular by IV, im. or subcutaneous injection or infusion. Subsequently, the X-ray image is created.
• Suitable contrast agents which have high attenuation coefficients in the selected spectral range are suitable. Contrast agent whose absorbing element is the K edge of the absorption spectrum in the selected Spectral range is just as well suited.
• Such X-ray contrast agents contain contrasting chemical elements with an atomic number of 35 or greater than 35 - this is, for example, bromine-containing contrast agents -, with an atomic number of 47 or greater than 47 - this is iodine-containing
• Contrast agents - having an atomic number of 57 or greater than 57 - these are lanthanide-containing contrast agents, in particular gadolinium-containing contrast agents - or having an atomic number of 83 - these are bismuth-containing contrast agents -. Therefore, X-ray contrast agents containing contrasting chemical elements having an atomic number of 35 (bromine) to 83 (bismuth) are suitable. Particularly suitable are contrast agents with contrasting chemical elements with an atomic number of 53 (iodine) - 83 (bismuth).
• X-ray contrast agents with contrasting chemical elements with an atomic number of 57 or greater than 57 (lanthanides) - 83 (bismuth) and more preferably means with contrasting chemical elements with an atomic number of 57-70 (lanthanides: La, Ce, Pr, Nd , Pm, Sm, Eu 1 Gd, Tb, Dy, Ho, Er, Tm, Yb).
• Suitable iodine-containing X-ray contrast agents are, for example
• Urografin ® (Schering), Gastrografin ® (Schering), Biliscopin ® (Schering), Ultravist ® (Schering) and Isovist ® (Schering).
• Gd-DTPA Magneticnevist ® (Schering)
• Gd-DOTA Gadoterate, Dotarem
• Gd-HP-DO3A Gadoteridol, Prohance ® (Bracco)
• Gd-EOB-DTPA Gadoxetat , Primavist
• Gd-BOPTA Gadobenate, MultiHance
• Gd-DTPA-BMA gadodiamide, Omniscan ® (Amersham Health)
• Dy-DTPA-BMA diethylenetriaminepentaacetic acid
• DOTA 1, 4,7,10-tetraazacyclododecane
• HP-DO3A 10 (Hydroxypropyl) -1, 4,7,10-tetraazacyclododecan
• the X-ray contrast agents can be administered enterally and parenterally.
• the intravenous (i.v.) application is preferably selected.
• Preferred dosages in the iodine-containing nonionic contrast media are doses up to 0.75 g I / kg body weight. This corresponds to about 6 mmol I / kg body weight. The dose may further be preferred at 1.5 g I / kg body weight (corresponding to about 12 mmol I / kg
• Body weight and in exceptional cases up to 2 (corresponding to about 16 I) or 5 g I / kg body weight (corresponding to about 39 mmol I / kg body weight) can be increased.
• the preferred dose is 0.1 mmol / kg body weight.
• suitable and furthermore preferred are doses of up to 0.3 mmol / kg body weight or up to 1 mmol / kg body weight.
• the emission lines of gadolinium are at 43.0 and 48.7 keV, i. far above the emission lines of iodine, which are at 28.6 and 32.3 keV.
• the metal complexes may, for example, also contain all other lanthanides, such as lanthanum, dysprosium or ytterbium, instead of the gadolinium atoms.
• C (Z) T detectors i. Detectors consisting of a cadmium (zinc) telluride (C (Z) T) semiconductor.
• the penetration depth depends on the energy of the X-ray photons. With larger energy of the X-ray photons, the radiation penetrates deeper until it interacts with the detector material and generates a current pulse by a photoelectric effect, as at lower energy
• the current pulses can be derived in the individual segments of the detector by means of attached electrical contacts.
• the current pulses are processed with a preamplifier.
• the detector can be designed in the form of a flatbed detector.
• all pixels are detected simultaneously and forwarded to the correlation unit for evaluation.
• the detector in this case consists of a planar arrangement of individual detector sensors, preferably in a row and columns of such sensors having matrix.
• a detector unit which serves to determine the emitted X-ray radiation and, if appropriate, to receive a Emission image and this is designed with an X-ray optical module for energy selection.
• the flatbed detector it is also possible to use line detectors or a matrix of a plurality of detectors suitable for recording a single pixel.
• the X-ray radiation from the examination object is simultaneously conducted via X-ray light guides.
• a plurality of such optical fibers is combined to form an area detector.
• the detector can be designed to receive a single pixel and be movable to accommodate all pixels.
• the detector can only detect energy-dependent intensities in a single pixel during the measurement.
• the intensities of the individual pixels are detected in succession, for example line by line, and forwarded to the correlation unit for further processing.
• the detector can also have an array of detector sensors designed to receive one pixel each and can be moved to accommodate all the pixels.
• an array of detector sensors according to the present invention both a row of detector sensors and another arrangement, for example, a matrix-like arrangement, of detector sensors understood.
• the detector detects the intensity values in the individual pixels line by line or optionally also in blocks. To record all intensity values, the detector is preferably moved perpendicular to a main axis of the array during the measurement. The intensity values determined during the measurement are transmitted to the correlation unit.
• the second intensity values are first corrected taking into account the absorption of incident X-radiation and / or the inherent absorption of the emitted X-radiation in the examination subject, and the first and second intensity values are correlated with each other only after this correction, pixel by pixel.
• Such a correction can be carried out by means of numerical methods, taking into account the geometry of the examination subject and an at least approximate location-dependent radiopacity. To determine the location-dependent radiopacity, the images generated from the first intensity values can be used.
• the location-dependent radiopacity obtained from this measurement can be used as a first approximation because the absorption coefficients for the irradiated X-radiation are similar to those of the emitted radiation.
• the signal originating from the preamplifier is then passed into the at least one correlation unit with which the intensity of the transmitted X-ray radiation from a pixel of the examination object is correlated with the image of the emitted X-radiation (X-ray scattering and X-ray fluorescence) from the same pixel.
• the correlation unit may be a correspondingly programmed data processing system.
• a comparator and in the other case a divisional element can be used for pixel-by-pixel correlation.
• X-rays are performed by a pixel.
• the following devices are preferably provided which can be realized in a data processing system, namely:
• a first memory unit with which the first intensity values of the transmitted X-ray radiation can be stored pixel by pixel
• d2. a second memory unit, with which the second intensity values of the emitted X-ray radiation can be stored pixel by pixel
• an arithmetic unit which provides for a suitable correlation of the two generated image data sets and thus generates or calculates an image data set from the information of the transmission data set and the data from the X-ray emission, preferably X-ray fluorescence.
• an arithmetic unit which provides for a suitable correlation of the two generated image data sets and thus generates or calculates an image data set from the information of the transmission data set and the data from the X-ray emission, preferably X-ray fluorescence.
• each characteristic emission lines may be used for the emission imaging, wherein the measured data sets then correlated imagewise together and, alternatively, the respective intensity values are correlated pixel by pixel, and the obtained data are subsequently used for image presentation.
• the data obtained are transmitted pixel by pixel to an output unit which contains, for example, a monitor (CRT or LCD display) or a plotter.
• FIG. 1 shows an illustration of a test arrangement in a computer tomograph
• FIG. 2 shows a schematic representation of the arrangement for image acquisition or the experimental setup
• Fig. 3 a schematic representation of the experimental arrangement for
• FIG. 5 emission spectra of the phantom of FIG. 3 filled with water (FIG.
• FIG. 6 Intensity of the emission as a function of the position / displacement of the phantom from FIG. 3 in selected energy bands (corresponding to the K 0 and K 2 lines (iodine: FIG. 6 a, gadolinium: FIG. 6 b) Gadolinium: Fig. 6c)
• Fig. 7 CT sectional images (transmission images) of the phantom filled with Gd, an iodine / Gd mixture, iodine, air and water.
• FIG. 1 shows a photographic representation of a test arrangement in a computer tomograph with a rubber ball 1 which is fastened to a stand 2.
• the rubber ball is located in the center of the computer tomograph.
• the rubber ball was filled with air, water and different contrast agent solutions.
• the ball was between the CT tube (above the rubber ball, not shown) and a line detector (below the table visible under the rubber ball, not visible).
• a measuring chamber 3 for detecting the X-ray fluorescence was positioned.
• a contrast-filled tissue, tumor or the like was used as
• Object of examination simulated, which is examined in the computer tomograph. For this purpose, the object was scanned in layers and thereby measured the scattering spectra.
• the experimental setup used for this experiment is shown in detail in FIG.
• the diagram shown there shows the ball 1, which was located as a phantom in the isocenter of the gantry 4.
• the CT tube 5 was located at the 12 o'clock position and stood there.
• a CZT detector 6 with a 3 mm ⁇ 3 mm ⁇ 2 mm cadmium-zinc-telluride crystal and 100/400 ⁇ m pinhole diaphragms was used (Amptek Inc., USA).
• the data recorded by the fluorescence detector were forwarded by the detector via an amplifier 8 to a multi-channel analyzer 9 and then a
• Fig. 3 is a schematic representation of the experimental arrangement for
• the dashed lines mark the respective positions of the CT tube above the image section.
• the horizontal scale indicates the shift of the fan beam and thus indicates the respectively addressed cutting plane (excited layer) in the ball.
• the entire measurement setup was moved 10 mm further into the gantry (in the z direction) and the new spectrum was recorded. Layer by layer, different spectra were generated depending on the position of the ball in the beam or the ball geometry.
• the ball was filled with water and measured at 80 kV, 50 mA for every 80 s per position of the ball in the beam according to FIG. 3 (parameter: detector: XR-100.CZT (pinhole 0.1 mm), Distance ball - detector: 18.0 cm, distance ball - CT tube: 32.0 cm).
• FIG. 4a shows the scattered spectra of the water in the phantom for the different positions.
• bale parameter was filled with a solution of 50 mmol / l of iodine in water (Ultravist ®) and at 80 kV, 50 mA for each measured 80 seconds per position (: Detector: XR-100.CZT (pinhole 0 ,1 mm)
• the obtained emission spectra at the various positions are shown in Fig. 4b.
• the K 0 and K ⁇ lines of iodine (28.6 and 32.3 keV) are clearly visible.
• the graph shows a dependence of the measured intensity of the X-ray fluorescence on the geometry of the phantom. The larger the irradiated layer of the phantom, the higher the measured intensity.
• the ball parameter was filled with a solution of 50 mmol / l gadolinium in water (Gadovist ®) and at 80 kV, 50 mA for each measured 80 seconds per position (: Detector: XR-100.CZT (pinhole 0 ,1 mm)).
• the obtained emission spectra at the various positions are shown in Fig. 4c.
• the K 0 and K ⁇ lines of gadolinium (43.0 and 48.7 keV) are clearly visible. It showed that the intensity of measured emission radiation, in particular in the field of K-lines on the geometry of the ball in the radiation field is dependent.
• FIG. 5a shows the scattered spectra of the water in the phantom for the different positions.
• bale parameter was filled with a solution of 50 mmol / l of iodine in water (Ultravist ®) and at 80 kV, 50 mA for each measured 80 seconds per position (: Detector: XR-100.CZT (pinhole 0 ,1 mm)).
• the ball parameter was filled with a solution of 50 mmol / l gadolinium in water (Gadovist ®) and at 80 kV, 50 mA for each measured 80 seconds per position (: Detector: XR-100.CZT (pinhole 0 ,1 mm)).
• the intensity values of the fluorescence were determined and recorded as a function of the positioning of the ball in relation to the X-ray beam.
• the ball is filled with a solution of 50 mmol / l of iodine in water (Ultravist ®) and at 80 kV, 50 mA, each for 80 seconds per position measured.
• the ball is filled with a solution of 50 mmol / l gadolinium in water (Gadovist ®) and at 80 kV, 50 mA, each for 80 seconds per position measured.
• Gadovist ® a solution of 50 mmol / l gadolinium in water
• Fig. 6b the intensity of the fluorescence radiation is plotted against the position / displacement of the phantom in selected energy bands corresponding to the K ⁇ line of gadolinium at 43.0 keV and the K ⁇ line of gadolinium at 48.7 keV.
• the profile of the emission intensity caused by the shape of the ball can also be seen from this figure.
• the ball is filled with a solution of 25 mmol / l iodine (Ultravist ®) and 25 mmol / l gadolinium in water (Gadovist ®) and at 80 kV, 50 mA for each measured 80 seconds per position.
• Ultravist ® 25 mmol / l iodine
• Gadovist ® 25 mmol / l gadolinium in water
• the intensity of the fluorescence radiation is dependent on the position / displacement of the phantom in selected energy bands corresponding to the K ⁇ line of iodine at 28.7 keV, the Kp line of iodine at 32.3 keV, the K ⁇ line of gadolinium at 43.0 keV and the K ⁇ line of gadolinium at 48.7 keV.
• the ball profile is reproduced insufficiently in the direct application of the signal intensity as a function of position. This is due to the absorption on the excitation side and the self-absorption on the emission side, which falsify the image. lower
• Fig. 7 shows the CT sectional images taken on the foregoing examples of X-ray fluorescence. From top left to bottom right is the gadolinium, the mixture of gadolinium and iodine, the iodine, the pure water and the air-filled ball.
• the air-filled ball has the least noticeable X-ray attenuation, followed by the ball filled with water.
• a quantitative evaluation is by determining the Hounsfield units (HU) possible, but only the addition of X-ray fluorescence images allows a statement about the element-specific filling of the ball.

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