DE102009018596A1 - Test specimen and method for evaluating radiological images of a specimen - Google Patents

Abstract

The invention relates to a test specimen, a method for the automatic evaluation of radiological recordings of a specimen and a computer program product. The test specimen, suitable for testing a radiological device on the basis of a radiographic image prepared by the specimen, comprises at least one structural element with predetermined absorption properties, wherein at least one structural element is provided on the specimen and has a contrast having a signal-to-noise ratio of ≧ 100 and / or ≰ 400 corresponds. Thus, a simple, very accurate, reproducible and cost-effective way is provided to automatically and automatically evaluate radiological images of a specimen.

Description

The Invention relates to a specimen, suitable to check one radiological device based on a radiological Recording, comprising at least one structural element with predetermined Absorption properties, in particular predetermined imaging properties.

The The invention also relates to a method for automatic evaluation from radiological images of a test specimen having at least one structural element with predetermined absorption properties, with absorption equivalents Numerical values from a digital radiological image of the specimen in a record is read out.

moreover The invention relates to a computer program product comprising a Code means which is suitable for running the steps of the method according to the invention is when it runs on a computer.

Of the Inventive test specimen is preferably in radiology, especially in the diagnostic Radiography, in digital tomography in general radiography, especially in digital volume tomography in dental radiography, and in tomosynthesis in mammography as well as in imaging Method of radiotherapy, as in verification shots or Irradiation planning used. The concept of "diagnostic Radiography " both tomographic procedures, such as computed tomography in general radiology or radiotherapy, the digital Volumetric tomography in dental radiography, tomosynthesis in mammography, but also projection radiographic methods.

The Radiology as a branch of medicine deals with the application of radiation for diagnostic, therapeutic and scientific purposes. Traditionally, X-rays are used in radiology. There Another important application is imaging, others are imaging techniques such as sonography and magnetic resonance imaging, hereafter also referred to as MRI, calculated for radiology, although no ionizing radiation is used in these processes come. Imaging procedures in diagnostic radiology include projection radiography and cross-sectional imaging techniques, such as X-ray computed tomography, Sonography and MRI. In all these methods, substances can be used be the representation and / or demarcation of certain structures facilitate and / or shed light on to give the function of a system. Such substances are called contrast agents designated. The choice of the method and the decision, contrast agent use, depend on the clinical issue and a cost-risk-benefit assessment. In the radiographic procedure, the patient's body or a Part of the body from one direction with X-rays irradiated. On the opposite side, the radiation is suitable Materials registered and converted into an image. this happens in an analogous manner also in tomographic methods.

The MRI is similar such as computed tomography, hereinafter also referred to as CT, different Advantages. Unlike the CT, it offers a better Soft tissue contrast, no ionizing rays, but on the other Page a higher one time and equipment and thus higher costs. In addition, will The MRI is usually less tolerated by the patient than CT. The digital volume tomography, also referred to below as DVT, is a three-dimensional, dental or orthodontic Imaging tomography method using X-rays. Similar to during CT or MRI the DVT the production of sectional images. A digital volume tomograph has a rotatable about a certain angle range around the head, coupled unit of x-ray tube and Detector, passing through the skull transmits transmitted radiation into images. In the image creation rotate x-ray tube and Detector around the fixed patient positioning, in other words around the axis of rotation. This is done per degree, in other words per increment, ever created a two-dimensional summation single image and from the ultimately obtained N images a three-dimensional model calculated. It will become preferably primarily transversal Layers produced whose layer thickness are freely chosen can.

In of radiology become a test of x-ray equipment Test specimen used, being checking a X-ray equipment based on a test specimen created X-ray photograph visually. In other words, the images of the specimen are preferably visually evaluated. These specimens are often described in standards and are constructed in such a way that they are in particular homogeneous diffuser have, as polymethylmethacrylate plates, as Plexiglas denoted, and their structural elements in a two-dimensional Structure plate included. This does not allow statements about the spatial transmission properties of the respective system, preferably a three-dimensional Record created. Typically, in English-speaking countries for a test specimen too the term "test phantom" is used.

A automatic evaluation of x-rays of a test specimen previously used only in CT and MRI. Through digitization recording systems and the development of new technologies are previously performed Quality checks on their limits. An essential quality parameter must be the assessment of the ratio of picture quality and allow dose. This is due to simple visual checks with sufficient accuracy not detectable, which is why quality checks nowadays reach their limits.

at analog systems and especially in systems where the primary information was recorded directly on film, so far by the exam the visual optical density and the visual resolution at least one safe estimation be made if the quality parameters are within a reasonable range lies. An example for Such an analog system are film-film systems in projection radiography. With digital systems, there is no easy way to get the quality parameter through a visual exam to determine, since the image brightness of that used in the recording Dose is decoupled.

In analog systems, the visual optical density is an essential License plate while this in digital systems the noise is. The resolution based to determine lead crystal scanning is used in digital systems significantly disturbed by artifacts, also known as alias artifacts, and the Noise in recordings can only be determined in time-consuming experiments but in acceptance or constancy tests according to the X-ray ordinance can not be applied because they require trained personnel and also digital tools Image processing. In addition, such tests are very time consuming and associated with high costs. For example, at DVT in dental radiography, at tomosynthesis in mammography or in digital tomography no test regulations, the special ones Consider problems with these procedures. For other procedures For the sake of simplicity, assume that the quality parameter within reasonable limits, although others usually Manufacturer specifications corresponding parameters in a given tolerance frame lie.

Next the absence of the quality parameters for the Diagnostic radiography evaluating exams, consists in radiotherapy also need for action. Through new planning systems, verification systems, like "electronic portal imaging devices ", also referred to as EPIDs, and therapy systems and / or concepts For example, planning data is collected on the CT. These data allow but no treatment planning showing the electron density in the target volume considered, because these data are not provided by the CT. Also the accuracy in determining the target volume to be irradiated is preferably determined by visual estimates from image data and is subject to considerable uncertainty. This uncertainty in the estimation the target volume is of particular importance when irradiations be made with high-dose procedures.

Thus, new methods are needed to more accurately determine the target volume, taking into account the transmission characteristics, in particular the spatial transmission properties, of the electron density systems used for planning, since Hounsfield data from a CT is not correlated accurately enough with the electron density. The linear absorption coefficient μ describes how strongly monochromatic X-ray radiation is attenuated when penetrating matter along the irradiated path. In the context of CT, it is particularly interesting to assign the attenuation of X-rays to certain tissues and to be able to detect pathological deviations from healthy tissue. Hounsfield has proposed the CT number to be independent of the energy-dependent attenuation coefficients. This is calculated for a particular material or fabric as follows:

air absorbs X-rays almost at all not and therefore has a CT number of -1000 HU, where the abbreviation HU for "Hounsfield Unit" (Hounsfield Unit) stands. Adipose tissue absorbs X-rays a little less than water and therefore has a CT count of about -50 HU to -100 HU. Water has according to the definition 0 HU. Depending on their density, bones have values from 500 HU to 1000 HU. The Hounsfield scale is theoretically open at the top, in practice has the range of -1024 HU enforced to 3071 HU.

In addition to the above-mentioned aspects, one of the important tasks in radiotherapy today is to develop methods with which the image data of different radiological imaging methods can be superimposed on each other. Such methods are also referred to as "matching methods". This concerns, for example, the matching of CT data and MRI data. Thus, the advantages of different tissue differentiation of both methods can be represented in an image data set. The methods used in the prior art do not provide one for highly accurate dose planning and dose irradiation sufficient accuracy.

Next Radiotherapy requires invasive procedures, for example Tissue excisions, punctures or punch biopsy, high accuracy the imaging process. Determining the location of a suspect Image structure with an imaging system, hereinafter also referred to as modality referred to, happens for example in mammography by several Projection radiographic images in different recording geometry, the visual evaluation of the recordings, invasive marking of the suspects Place, for example by setting wire loops and a subsequent Punch biopsy under radiographic control. Through a tomosynthesis in mammography, providing a three-dimensional dataset Procedure, in principle with a radiological, imaging Investigate the location of a suspect The site can be located precisely and the punch biopsy could be automated carried out become. The determination of local transmission properties in the entire recorded volume but can not or at least can not be tested with sufficient accuracy as a requirement for the automated examination, namely the exact determination the local transmission characteristics a system that is not met.

When Example of use are also operations on a patient to mention. Operations can be made and the location information can be through a fluoroscopy X-rays be obtained with a Projektionsradiographischem system. Also In this process, the sometimes considerable distortions of the Recording systems, such as vignetting and distortion, not quantitative, based on a three-dimensional body, evaluated and the surgeon Image offered in which the spatial Distortions are corrected. Examples of such systems are angiological or cardiological examinations with therapeutic intervention.

Out The prior art is therefore known that in technical tests of X-ray equipment The following problems exist: There are no possibilities in radiological Diagnostics, the quality parameter easy and reliable testing in digital systems. Further lack possibilities in radiotherapy in originally for the Diagnostics developed modalities to determine the electron density versus Hounsfield units and to determine the location information with high accuracy. Furthermore lack possibilities Matching procedure with perform sufficient accuracy, such as MRI and CT data records accurately to match. This happens, for example, by using test specimens with same geometry, but adapted to the respective modality Materials. Alternatively, this can also be done by using a test specimen, which can be used both in CT and in MRI. Further In the case of invasive surgery, the possibility of missing the location information is lacking with sufficient accuracy, for example in interventional procedures under radiological control.

in the Prior art, apart from CT and MRI, is not common for specimen recordings automated and machine evaluated, but the evaluation Occurs in the radiography visually, occasionally be with simple Grayscale image capture tools, distances become for example calculated with the ruler function and / or the magnifying glass function.

method for determining a nonlinear transmission of a three-dimensional body in the two- or three-dimensional image space or three-dimensional Distortions are not applied yet. The structure of the test specimen is tuned to a visual evaluation and preferably contains no structural elements, which allow the distorted image of a three-dimensional body capture. In radiographic systems, the electron density not recorded. Matching methods use methods which should be done manually Lean contouring in image processing. fully automatic Matching procedures are not to the best of the inventor's knowledge Application. It leaves thus hold that it is extremely complex, inaccurate and costly, x-rays or at all radiological images of a specimen automated and / or to evaluate by machine.

It The object of the invention is a simple, very accurate, reproducible and cost-effective possibility to provide radiological images of a specimen automated and machine evaluating.

These Task is solved by that a test specimen, suitable to check one radiological device based on a radiological Receiving, wherein the test body at least one structural element, preferably a plurality of structural elements, with predetermined Absorption properties, in particular imaging properties, comprising, wherein at least one structural element provided on the test specimen and has a contrast corresponding to a signal-to-noise ratio of ≥ 100 and / or ≦ 400. Preferably, the signal-to-noise ratio comprises the signal-to-noise power ratio. Especially Preferably, the signal-to-noise ratio corresponds to the signal-to-noise power ratio.

Prefers is a signal-to-noise ratio of ≥ 40 dB and / or ≤ 60 dB corresponding contrast provided by the structural element. Preferably has at least that provided on the specimen Structural element has a diameter less than or equal to one Image element of the radiological image of the specimen on. Thus, the signal-to-noise ratio is sufficiently high, such that a structural feature is detected with sufficient accuracy becomes. In other words, the signal-to-noise ratio is set or selected so that disturbing Image artifacts are prevented or minimized and / or the dynamic range of the detector is observed. Thus, the detector is not overdriven.

According to one preferred embodiment The invention is a Dirac pulse with at least one structural element generates and from the Dirac pulse a modulation transfer function, also as MTF, calculated. Preferably, the specimen has a Structural feature, the means of digital image processing is evaluated so that a Dirac pulse is derived or extracted. This is preferably done by the evaluation of an image of a Tube. Particularly preferred is a structural element provided on the test specimen from the plurality of structural elements clamped to the specimen or with suitable Attached fasteners, such as adhesives.

According to one another preferred embodiment The invention provides a plurality of structural elements and at least one structural element of the plurality of structural elements is provided orthogonal to the scanning direction. Preferably have at least two provided on the specimen Structural elements different materials with different Absorption properties, in particular different electron densities and / or proton densities. Preferably, at least two on the test specimen under a predetermined angle to each other provided structural elements a contrast corresponding to a signal-to-noise ratio of ≥ 10, preferably ≥ 100. Thus, the signal-to-noise ratio is chosen so that a sufficiently reliable detection, in other words a detection with sufficient accuracy. Preferably, the angle based on the geometry of the provided on the specimen structural elements established.

According to one another preferred embodiment The invention is at least a part of the plurality of structural elements two-dimensional or three-dimensional configured. Preferably is a structural element, particularly preferably the plurality of Structural elements, as a wire and / or as a thread and / or as a string designed.

Preferably comprises the material of a structural element, more preferably the material of the plurality of structural elements, plastic and / or Aluminum and / or tungsten and / or nylon. Particularly preferred Materials used in their absorption properties, in particular in their imaging properties, proton densities and other similar Properties, the natural Materials of a human body correspond. According to one another preferred embodiment The invention uses air as the medium with the lowest absorption and bones with the highest Absorption simulated by aluminum, in particular, this is intended for X-ray. Fatty tissue, glandular tissue and muscle tissue are preferably simulated by plastic. According to one another preferred embodiment The invention uses air as the medium with the lowest proton density and water as the medium with the highest Proton density simulated, in particular, this is provided in the MRI. According to one another preferred embodiment The invention comprises a hollow body filled with contrast agents, in particular filled with contrast agents of MRI, very high signal intensities. Preferably, a material is used to generate a Dirac pulse high radiopacity chosen and / or the diameter of the structural element is significantly smaller as the resolution, also as a pixel pitch designated, selected. In other words, a structural element is preferably used which allows the calculation of a Dirac pulse. For other structural elements, like nylon threads, Preferably, a diameter is selected which at least several Pixel covers. The effective size of this Structural elements preferably depend on the resolution or the Pixel pitch of the respective modalities.

Preferably is the specimen dependent on The radiological application device used differs. Especially Preferably, the specimen also Structural features that are the same for different radiological application devices or similar are pronounced.

According to a further aspect of the invention, the object is achieved by providing a method for automatically evaluating radiological images of a test specimen having at least one structural element with predetermined absorption properties. The method comprises reading absorption-equivalent numerical values from a digital radiological image of the test specimen into a data set, wherein a characteristic of the gray values as a function of the dose is determined by conversion into relative dose values, with an orthogonal to the scanning direction is seen, a Dirac pulse is generated, and by a corresponding signal processing, the modulation transfer function and / or the noise power density spectrum, suitable for determining a quality parameter, is determined. In this case, a "digital radiological recording" means that the recording takes place digitally and / or a part of the data or the entire data is digitized only after analog recording. Preferably, the quality parameter is proportional to the ratio of image quality and dose, but other quality parameters may be defined and used depending on the application and the need. It is known to those skilled in the art what is meant by the phrase "a Dirac pulse is generated with a structural element orthogonal to the scanning direction", namely that a structural element provides a means to create or cause a point interference and the effect of this point interference adjacent areas, especially in close proximity, to detect the point interference. In other words, this provides a way to determine the non-ideal transfer behavior of the system.

According to one preferred embodiment According to the invention, the signal processing comprises a circular integral formation around the the Dirac pulse generating structural element suitable for noise reduction and suitable for reducing a two-dimensional space into one one-dimensional space. The circular integral formation preferably takes place the structural feature of the structure element, from which a Dirac pulse derived or extracted. This will be the dimension of the record reduced and processing is easier and faster. Preferably Signal processing includes the application of a cosine filter to the record for smoothing of artifacts. The artifacts are made especially by discontinuities caused at the phase boundary, but also artifacts of others Cause to be reduced. This will reduce the influence of artifacts minimizes and increases the accuracy of the procedure. With the Dirac pulse thus obtained is preferably over further mathematical methods carried out a Fourier transformation. Preferably Thus, a function is obtained, usually as a modulation transfer function or also referred to as MTF. According to another preferred embodiment According to the invention, the signal processing comprises the determination of a Noise power spectrum in physically homogeneous areas, especially in without structural elements provided areas.

According to one another preferred embodiment According to the invention the signal processing comprises the application of a Fourier transformation on at least one ordinate of the data set, forming the amplitude square on at least one ordinate of the data set and the application of at least one ordinate as Function of the abscissa, in particular as a function of the spatial frequency. The data set is preferably multidimensional. Preferably comprises the data set at least one abscissa and at least one ordinate. In the representation of measured values as complex numbers are preferred used at least two ordinates. The abscissa is preferably scaled to spatial frequencies.

According to one another preferred embodiment The invention relates to the electron density of defined homogeneous structural elements taken from a predetermined table and with the image data set provided gray levels compared. These are the table preferably to an international table, the public accessible is. Preferably, the data sets of at least two radiological Superimposed recordings of the specimen and a location-based lookup table, especially a spatial lookup table, certainly. Preferably, a three-dimensional structure matrix for determining the position of the plurality of structural elements. Consequently a very accurate and reproducible measurement is possible.

According to one Another aspect of the invention, the object is achieved in that a computer program product comprising a code device provided becomes. The code facility is to run the steps of the method according to the invention suitable when running on a computer.

Of the Inventive test specimen is used in at least one of the following fields of application: radiology, in particular diagnostic radiology, especially in digital Tomography, especially in the DVT in dental radiography, and tomosynthesis in mammography and radiotherapy, in particular for the preparation of irradiation plans and / or for verification, especially with EPIDs.

Consequently becomes a simple, very accurate, reproducible and cost effective option provided radiological images of a specimen automated and machine evaluate.

following The invention will be described with reference to preferred embodiments with reference to the drawing further explained in detail.

1 shows a software-based implementation according to a preferred embodiment of the invention.

According to one first preferred embodiment The invention is characterized by the inclusion of structural elements, a orthogonal to the scanning direction tensioned tungsten wire with the lowest possible Diameter generates a Dirac pulse, which is used to determine the modulation transfer function, also called modulation transfer function (MTF) used becomes. The noise power density spectrum, also called Noise Power Spectrum (NPS) is determined on homogeneous image areas. Thereby becomes a size equivalent the Noise Equivalent Quanta (NEQ) and in relation to the dose set. Thus, a size is determined the the quality parameter clearly indicates and / or describes. For a known input spectrum becomes the detective quantum efficiency, also called detective quantum efficiency (DQE). An input spectrum applies known as the number and energy of the incoming quantum per unit area are known. The input spectrum becomes known X-ray device parameters and determined by determining the aluminum half-thickness layer thickness. The x-ray device parameters include anode material and angle, additional filter thickness, Material, charge and performance.

The inventive method becomes in the evaluation of the Prüfkörperaufnahmen is used and is preferably as software or as a computer program product realized. The gray values of the respective radiographic method be over the Determination of the characteristic, d. H. the characteristic including the gray values plotted as ordinate over the Dose as abscissa, converted into relative dose values. These values have a 16-bit depth. Such a characteristic is also called Opto Electronic Conversion Function (OECF). Preferably are used to determine the characteristic several shots with different Dose prepared, the evaluation of the corresponding radiological Recordings of the specimen takes place preferably manually and / or automatically.

A perpendicular to one or more provided in the test specimen structural element lying image plane, in particular one perpendicular to one or more clamped in the test specimen Tungsten wire lying image plane, has a Dirac pulse. With In other words, this allows the calculation of a Dirac pulse. According to the first preferred embodiment The invention is a radiographic system. According to other preferred embodiments In the invention, as in MRI, a plastic is used instead of tungsten. By a circular integral formation around the Dirac pulse, a noise reduction takes place and a reduction of a two-dimensional space into a one-dimensional space Room. The application of a cosine filter on the record avoids Problems with the following image processing. Because it is important that at the phase boundary the signal intensity is zero. In addition, the influence minimized by artifacts. On this record is a Fourier transform applied, and the amplitude square of at least one ordinate of the record formed. This ordinate will then be against the spatial frequency plotted as abscissa. The result is the MTF. Such Operation can be performed in different cutting planes and you get in this way, information about the MTF pictured throughout Body.

In the same image plane is cut around the Dirac pulse a homogeneous surface, which does not contain the information of the Dirac pulse, in other words that does not contain the Dirac pulse generating structure element. The Fourier transformation is performed and the frequency spectrum is obtained. To reduce the two-dimensional information in the one-dimensional Space is made the circle integral. The amplitude square of at least one Ordinate is plotted against the spatial frequency. This gives you that NPS in one-dimensional representation. Such an operation will preferably performed at the sites or areas which the MTF was determined. This gives you information about the picture quality throughout the entire body.

According to one second preferred embodiment The invention is characterized by the inclusion of different materials Electron density and attenuation characteristic in the test piece, for example in cake form, the transfer characteristic certainly. From the transfer characteristic the electron density and the gray values are determined. By the Inclusion of materials in addition to the maximum and minimum absorbance naturally Components, the dynamics are checked. According to other preferred embodiments In the invention, as in DVT, aluminum is used as a bone substitute and air as a sinus and sinus filling as Materials used. The electron density information is beside other physical information, such as proton density or mass attenuation coefficient, deposited in international tables. Based on these tables will the needed Information about the Extracted electron density. It is emphasized that depending on the scope suitable material combinations for test specimens are to be used.

According to a third preferred embodiment of the invention, test body materials are to be used whose electron density, such as X-ray attenuation coefficients, as in CT imaging, and their proton density, as in MRI imaging, must be known. As a result, a test specimen ent which can be used both on CT as well as in MRI, thus enabling an accurate automatic matching.

Around one possible high accuracy in the overlay The image data of various imaging modalities is the same Test specimen used. For every modality is formed a location-related lookup table, also referred to as LUT. Each primary generated voxels in three-dimensional processes, according to others preferred embodiments The invention relates to pixels in two-dimensional methods a correction vector for a recalculation of the image information is used. The corrected Data of two image data sets be automated on top of each other placed. An eternal blurring at the automatic overlay of patient data are then based solely on the motion blur, the caused by the patient. This will with high accuracy ensures matching.

According to one fourth preferred embodiment of the invention are in test specimens, the the respective institution in size and shape are adapted, wires curious under known angles. The material of these wires must be adapted to the respective recording technique. According to others preferred embodiments The invention, as in mammography, plastic wires and / or Threads used become. According to others preferred embodiments In the invention, as in CT, aluminum wires are used. The absorption of the wires is chosen that if possible no disturbing Reconstruction artifacts are generated, but still a detection the wires possible with high accuracy is.

The The combination of materials used is preferably as a function from the used X-ray tube voltage selected. For example, in mammography, a "soft" beam quality of about 30 kV, in the DVT a radiation quality of "medium hardness" of about 70 kV and in CT a relatively "hard" beam quality of about Used 125 kV. After the X-ray absorption or the photoabsorption proportional to the atomic number of the elements is, the result is preferably to be used material combination.

The Geometry of the test specimens passing through wires is designed so that by an angle to the scanning matrix an oversampling is possible. By oversampling can be a very accurate, in other words subpixel accurate, location information about the Location of the wires and other structural elements. In the radiography In the individual cutting planes, aluminum wires become orthogonal whose position in the pixel matrix is determined and compared with nominal values becomes. According to others preferred embodiments The invention, as in MRI, is nylon cords. Out there lets in one Determine shift vector. According to this fourth preferred embodiment The invention are in a sectional plane at least three truncated wires each have different displacement vectors.

Become Considered several levels with orthogonal sections of the wires, can be determine the plane in which a wire lies. This wire is then at a certain angle to the image matrix. By the provision this tilt angle can be made an oversampling, with which an accuracy is achieved that is subpixel accurate. For between The pixels which are precisely position-determining pixels become intermediate values for the shift vectors interpolated. If the image matrix is larger than the size of the test specimen, then also contour distortions of the specimen are used for the orientation.

1 shows a schematic block diagram of a software-based implementation according to a fifth preferred embodiment of the invention. According to this fifth preferred embodiment of the invention, the provided unit comprises 1 a processing unit 2 , also referred to as Processing Unit (PU), which is provided on a single chip or on a chip module. The processing unit 2 includes any processor unit or any computer unit that includes a controller that performs control using software routines of a control program, wherein the software routines are stored in a memory unit 3 , also referred to as memory (MEM), are stored. Program code instructions are issued by the MEM 3 brought and into the control unit of the PU 2 loaded to perform the individual steps of the method according to the invention. The processing steps of the blocks 1 and 2 may be executed on the basis of input data, also referred to as data input (DI), and may generate output data, also referred to as data output (DO), the input data DI corresponding to data or signals that have been communicated and / or detected, and the output data DO may correspond to data or signals to be communicated or communicated with other units.

In summary, the invention relates to a specimen, a method for automatically evaluating radiological images of a specimen and a computer program product. The inclusion of structural elements in the test specimen determines individual parameters by means of which the image quality can be determined. This is preferably determined via the MTF and / or via the Wieners spectrum or via the NPS. Thus, the quality parameter can be determined accurately and quickly. In addition to improving the spatial resolution, the determination of the correlation between gray value and electron density allows better consideration of the dose-response relationship in treatment planning. In addition, high precision matching can be achieved by using specimens in a specimen that is suitable for imaging in both CT and MRI. By a subpixel accurate position determination of all stationary structures or structural elements, which are provided on the specimen, and thus possible accurate registration and assignment of structures or structural elements of the specimen in space, a three-dimensional structure matrix is formed, with all distortions in space can be determined. As a result, all voxels are spatially corrected for radiographic images in the case of three-dimensional methods or pixels in two-dimensional methods. Thus, it becomes possible to assign a secure location information to all pixels or voxels. All radiological images of the test specimen thus obtained are evaluated automatically and by machine.

The Invention is preferably used in digital radiography or in digital radiography systems used. Some application areas are listed below: CT, MRI, DVT, tomosynthesis in mammography and radiation therapy Planning and verification systems. It is particularly advantageous that the treatment planning with far higher Accuracy feasible becomes. This concerns individual parameters such as the electron density or the location information.

With The method provided is the image quality, the image dynamics and the geometric distortion of radiographic modalities quantitatively determined. Furthermore are records at least two different imaging methods, such as CT and MRI, can be combined with each other in a location-specific manner. The provided test specimen is preferably used in the described methods. Especially It is advantageous that the requirements of radiological diagnostics and radiological radiotherapy can. Thus, with the test specimen according to the invention in principle Method for quantitative determination of image quality, image dynamics, the geometric distortion of radiographic modalities as well the reconciliation of CT and MRI data feasible. For example, thus could diagnostic information directly in therapeutic treatment planning incorporated.

Claims (15)

Test specimen, suitable to check one radiological device based on a radiological Recording, comprising: at least one structural element with predetermined absorption properties, in which at least one structural element is provided on the test body and a Contrast corresponding to a signal-to-noise ratio of ≥ 100 and / or ≤ 400. Test specimen after Claim 1, wherein at least the provided on the test specimen structural element a diameter smaller than or equal to that of a pixel of radiological recording of the specimen has. Test specimen after one of the preceding claims, wherein a plurality of structural elements is provided and at least a structural element of the plurality of structural elements orthogonal is provided for the scanning direction. Test specimen after one of the preceding claims, wherein at least two provided on the test specimen Structural elements different materials with different Absorption properties, in particular different electron densities and / or proton densities. Test specimen after one of the preceding claims, wherein at least two on the test specimen under a predetermined angle to each other provided structural elements have a contrast which corresponds to a signal-to-noise ratio of ≥ 10, preferably ≥ 100. Test specimen after Claim 5, wherein the angle based on the geometry of the provided on the test specimen Structural elements is set. Test specimen after one of the preceding claims, wherein a structural element as a wire and / or as a thread and / or designed as a cord. Test specimen after one of the preceding claims, wherein the material of a structural element plastic and / or aluminum and / or tungsten and / or nylon. Method for automatically evaluating radiological images of a test specimen having at least one structural element with predetermined absorption properties, whereby absorption - equivalent numerical values are read from a digital radiological image of the test specimen into a dataset, wherein a characteristic of the gray values as a function of Dose is determined by conversion into relative dose values, wherein with a provided orthogonal to the scanning direction structural element, a Dirac pulse is generated, and by a corresponding signal processing, the modulation transfer function and / or the noise power density spectrum, suitable for determining a quality parameter, is determined. The method of claim 9, wherein the signal processing a circular integral formation around the structure element generating the Dirac pulse suitable for noise reduction and suitable for reducing a two-dimensional Encompassing space in a one-dimensional space. Method according to one of claims 9 and 10, wherein the signal processing the application of a cosine filter to the record is suitable for smoothing Includes artifacts. Method according to one of claims 9 to 11, wherein the signal processing the application of a Fourier transform on at least one ordinate of the data set, forming the amplitude square at least an ordinate of the data set and the application of at least one Ordinate as a function of the abscissa, in particular as a function of Spatial frequency, includes. Method according to one of claims 9 to 12, wherein the data records least Two radiological images of the specimen are superimposed and a location-related Lookup table is determined and / or a three-dimensional structure matrix for position determination the plurality of structural elements is determined. Computer program product comprising a code device, which is suitable for running the steps of a method according to any one of claims 9 to 13 is when it runs on a computer. Use of a test specimen according to one of claims 1 to 8 in at least one of the following fields of application: - Radiology, in particular diagnostic radiology, especially in digital Tomography, especially in digital volume tomography in dental radiography, - Tomosynthesis in mammography, - radiotherapy, in particular for the preparation of irradiation plans and / or for verification, especially in "electronic portal imaging devices ".