CN104337540B - X-ray unit with gap aperture - Google Patents

Abstract

The invention comprises an x-ray unit and a method for recording x-ray projections. The x-ray unit according to the invention is designed for moving the examination object along the longitudinal axis at a feed speed and further comprises a recording unit which is rotatable about the longitudinal axis. The recording unit includes an X-ray emitter for emitting X-rays in the form of X-ray beams and an X-ray detector for detecting X-rays. The inventors realized that a fixedly positioned first slit aperture having a first opening of width D_1 along the longitudinal axis designed for shaping an X-ray beam having a width DZ_1 at the level of the longitudinal axis and having a first aperture along the longitudinal axis A second slit aperture with a second opening of width D_2 on the longitudinal axis, designed for shaping an x-ray beam having a width DZ_2 at the level of the longitudinal axis, is sufficient to enable selective irradiation of the active volume in helical mode, wherein There is DZ_2<DZ_1.

Description

X-ray unit with slit aperture

technical field

The invention relates to an x-ray unit and a method for recording x-ray projections.

Background technique

Computed tomography is an imaging method that is mainly used in medical diagnosis and for material inspection. To record tomographic x-ray images, the x-ray emitter and the cooperating x-ray detector are rotated around the examination object. In helical mode, the examination object is moved along the axis of rotation while X-ray projections are recorded at different angular positions. After recording the x-ray projections in helical mode, the x-ray projections are processed in order to generate a three-dimensional tomographic x-ray image. The area of the examination object to be reconstructed is also referred to as effective volume. The recording of X-ray projections in helical mode is also called helical scanning.

In order to reconstruct a tomographic X-ray image, the set of X-ray projections recorded during the helical scan must be complete. If the tomographic x-ray image is to be reconstructed only from a limited effective volume within the examination object, a post-scan or pre-scan is required, wherein regions outside the active volume are usually also scanned. This post-scan or pre-scan is required due to the generally large width of today's x-ray detectors. This results in an unnecessary radiation load outside the effective volume of the examination object. This is particularly problematic in the medical field when the object of examination is a patient. This problem becomes more severe as the width or number of rows of modern X-ray detectors increases. One possibility of avoiding the unnecessary radiation burden caused by the post-scan or pre-scan in the helical scan is to shape the x-rays by means of an aperture such that only the active volume is actually irradiated.

A diaphragm arrangement is known from DE 10 2005 018 811 A1 for an x-ray device provided for scanning an object with at least two diaphragms, wherein for at least one scanning segment at least The radiation beam modulated by the first aperture is partially and dynamically shaded. Furthermore, it is known from the said publication that the remaining radiation beams only irradiate regions of the object which contribute to the reconstruction of the image. Also, the aperture may be a slit aperture.

Contents of the invention

The technical problem to be solved by the invention is to keep the radiation burden due to post-scanning or pre-scanning to be low in tomographic recording in helical mode by means of a technically simple arrangement of the aperture.

This technical problem is solved by the x-ray unit according to the invention and the method according to the invention.

The solution according to the invention to the technical problem with respect to the claimed device and with respect to the claimed method is described below. Features, advantages or alternative embodiments mentioned here can also be transferred to other claims, and vice versa. In other words, for example, a device claim may also be extended to have features described or claimed in conjunction with the method. In this case, the functional features of the corresponding method are formed by corresponding device modules.

The invention includes an x-ray unit and a method for recording x-ray projections. The X-ray unit according to the invention is designed to move the examination object along the longitudinal axis at a feed speed and further comprises a recording unit which is rotatable about the longitudinal axis. The recording unit includes an X-ray emitter for emitting X-rays in the form of X-ray beams and an X-ray detector for detecting X-rays. The inventors have realized that a first opening having a width D_1 along the longitudinal axis, designed to be formed at the level of the longitudinal axis A fixedly positioned first slit aperture with an x-ray beam of width DZ_1 and a second aperture with a second opening of width D_2 along the longitudinal axis designed to shape the x-ray beam with width DZ_2 at the level of the longitudinal axis A two-slit aperture is sufficient to enable selective illumination of the effective volume in a helical mode, where DZ_2<DZ_1. Because according to the invention only the second slit aperture is moved along the longitudinal axis according to the feed speed, so that the X-rays shaped by the slit aperture only irradiate the regions of the examination object that contribute to the reconstruction of the tomographic X-ray image, in the helical mode The radiation burden due to the post-scan or pre-scan is kept small in the tomographic recording.

The proposed aperture arrangement is technically particularly easy to implement since only a single aperture has to be arranged movably. Furthermore, the aperture is according to the invention a slit aperture, so that only one aperture as a whole has to be moved, instead of moving individual parts of the aperture or even multiple apertures relative to each other. Furthermore, a slit aperture can be manufactured easily and inexpensively compared to an aperture having a plurality of movable parts. In addition, the replacement of the slit aperture becomes relatively simple, so that apertures with openings of different widths can be used for the method according to the invention. The invention is thus technically simple, low cost and flexible.

According to another aspect of the invention, the object under examination is moved in a helical mode at a first feed rate during the pre-scan and at a second feed rate during the post-scan, wherein during the post-scan and pre-scan are respectively as follows The second slit aperture is moved in such a way that the X-ray beams shaped by the slit aperture each move along the longitudinal axis at the same speed as the object under examination.

According to a further aspect of the invention, the tomographic x-ray image is reconstructed on the basis of the x-ray projections recorded according to the invention, wherein the reconstruction includes a weighting according to the intensity of the x-rays shaped by the slot aperture. Because of the fact that the first slit aperture is fixedly positioned due to the fact that only the second slit aperture is moved, the illumination of the X-ray detector for almost every point in time of the pre-scan or post-scan is asymmetrical. If the detector elements are read during a helical scan, the asymmetry must be taken into account by weighting when reconstructing. The complete reading of the detectors and subsequent weighting is technically easy to implement.

According to another aspect of the invention, the weighting is done binary during the reconstruction. This method is particularly easy to implement.

According to another aspect of the invention, the weighting is performed proportionally to the intensity of the x-rays shaped by the slit aperture. This method is particularly accurate because partial occlusions are also taken into account. This is advantageous in particular in the case of particularly fast movements of the second slit aperture.

According to another aspect of the invention, said reconstruction is weighted filtered backprojection. Reconstruction algorithms based on filtered backprojection offer the advantages of relatively short runtime and relatively little computational overhead.

According to another aspect of the invention, said reconstruction is an iterative reconstruction by means of statistical weighting. The iterative reconstruction algorithm offers the advantages of high resolution (especially at edges) and less artifacts.

Description of drawings

The invention is described and explained in detail below with the aid of exemplary embodiments shown in the drawings. in:

Figure 1 shows an x-ray unit according to the invention in the form of a computed tomography machine,

Figure 2 shows a cross-section of a slit aperture arrangement according to the invention,

Figure 3 shows in diagram form the position according to the invention of the two slit apertures relative to the gantry during recording in spiral mode, and

FIG. 4 shows in diagram form the position according to the invention of the two slit apertures relative to the examination object during recording in spiral mode.

detailed description

FIG. 1 shows an x-ray unit according to the invention in the form of a computed tomography machine with a recording unit comprising an x-ray emitter 8 and an x-ray detector 9 . The recording unit rotates about the longitudinal axis 5 during recording of the X-ray projections, and the X-ray emitter 8 emits X-rays in the form of an X-ray beam during recording. In particular, the x-ray beam can be fan-shaped or cone-shaped. A computed tomography apparatus can also have more than just one x-ray emitter 8 and more than just one x-ray detector 9 in order to enable recording according to the so-called dual-energy method. In the example shown here, the x-ray emitter 8 is an x-ray tube. In the example shown here, the x-ray detector 9 is a line detector with a plurality of lines, for example with 128 lines or with 256 lines. However, the x-ray detector 9 can also be designed as a planar detector. The x-ray detector 9 is generally designed as a scintillation counter, which converts high-energy x-ray photons into spectrally low-energy photons by means of a scintillator and subsequently detects them by means of photodiodes. Alternatively, the x-ray detector 9 can be designed as a direct-conversion detector, which converts high-energy x-ray photons into an electrical signal flow by means of a semiconductor material directly through internal optical excitation, making full use of the photovoltaic principle.

During the recording of the x-ray projections, the patient 3 lies on a patient couch 6 , which is connected to a couch base 14 such that the couch base carries the patient couch 6 with the patient 3 . The patient couch 6 is designed to move the patient through the opening 10 of the recording unit at a feed speed along the recording direction. The recording direction is generally given by the longitudinal axis 5, which is also the axis of rotation of the recording unit. However, the longitudinal axis 5 can also be inclined relative to the recording direction along which the patient 3 is moved during the recording, for example by configuring the recording unit as part of a tiltable gantry.

By rotating the recording unit, the X-ray projections are recorded from different directions, which can be reconstructed into a high-resolution, spatially three-dimensional data set. According to the invention, the recording takes place in a helical mode, in which the patient 3 is moved continuously along the longitudinal axis 5 . As shown in FIG. 3, the recording according to the spiral mode is divided into three stages, ie, pre-scanning, scanning of the effective volume, and post-scanning. In order to avoid unnecessary irradiation of the patient 3 during the post-scan or pre-scan, according to the invention two slit apertures are provided as part of the recording unit. The slit apertures are both located on one side 8 of the x-ray emitter directly adjacent to the exit point of the x-rays. Both slit apertures are designed for shaping x-rays or x-ray beams by absorbing x-rays. Therefore, the slit aperture consists of a horizontally x-ray-absorbing material, which may contain, for example, tungsten, molybdenum, iron and other metals.

According to the invention, the first slit aperture 15 is fixedly positioned within the recording unit, whereas the second slit aperture 16 is movable along the longitudinal axis 5 according to the advancing speed of the patient 3 . The movement of the second slit aperture 16 can be realized by an actuator, such as a motor. In one embodiment of the invention, the recording unit therefore has only a single actuator, for example in the form of a motor, for moving the slit aperture, which makes the invention technically simple and cost-effective.

In the example shown here, the computed tomograph also includes a computer 12 , which is designed, for example, to control the computed tomograph and to store and process a large number of x-ray projections. The computer 12 is connected to an output unit 11 for, for example, an X-ray image for image output tomography. The output unit 11 is, for example, one or more LCD, plasma, or OLED screens. In addition, the computer 12 is connected to the input unit 13 . The input unit 13 is used, for example, to select parameters for processing x-ray projections. The input unit 13 is, for example, a keyboard, a mouse, a so-called touch screen or a microphone for speech input. The interface enables the computer 12 to communicate with the computed tomography imager and with the input unit 13 or the output unit 11 . The interface is a generally known hardware interface or software interface, for example a hardware interface PCI bus, USB or Firewire.

In a further embodiment of the invention, the x-ray unit has a reconstruction unit 4 . The reconstruction unit 4 can include both hardware and software. The reconstruction unit 4 may comprise, for example, an FPGA or a processor. In the example shown here, the reconstruction unit 4 is designed as a computer program, which can be loaded into the internal memory of the computer 12 . However, in an alternative embodiment, the reconstruction unit 4 can also be located on a separate computer which is not designed to control the computed tomography machine.

Figure 2 shows a cross-section of a slit aperture arrangement according to the invention. A first, fixedly positioned slit aperture 15 with a first opening of width D_1 along the longitudinal axis 5 is designed to shape an x-ray beam having a width DZ_1 at the level of the longitudinal axis 5 . A second slit aperture 16 with a second opening of width D_2 along the longitudinal axis 5 is designed to shape an x-ray beam with a width DZ_2 at the level of the longitudinal axis 5 , wherein DZ_2≦DZ_1. In an alternative specific embodiment DZ_2<DZ_1. Here, the width is measured in each case along the longitudinal axis 5 , below which the z-coordinate is also defined. The width at the level of the longitudinal axis 5 indicates the width of the x-ray beam along the longitudinal axis when projected onto the longitudinal axis 5 , as shown in FIG. 2 . The idea of the invention is that the radiation beam shaped by the two slit apertures can have at most a width DZ_2. The width DZ_1 therefore represents the width during the projection of the x-ray beam and the accompanying shaping thereof only by the first slit aperture 15 , ie without the effect of the second slit aperture 16 .

Strictly speaking, the width of the radiation beam is related to the position of the second slot aperture 16 along the longitudinal axis 5 . For simplicity, the effects of projection distortions due to different angles between the x-rays and the second slit aperture 16 are ignored here. The width DZ_2 of the second radiation beam represents the width when oriented centrally with respect to the first opening of the first slot aperture 15 . Alternatively, a central orientation relative to the x-ray emitter 8 can also be indicated.

In the embodiment shown here, the first slit aperture 15 is located closer to the x-ray source 8 than the second slit aperture 16 . In an alternative embodiment, the second slit aperture 16 is closer to the x-ray source 8 than the first slit aperture 15 . In addition, in the example shown here, D_2<D_1.

The x-ray radiation-absorbing portion of the second aperture aperture 16 must be large enough to completely close the opening of the first aperture aperture 15 by moving the second aperture aperture 16 along the longitudinal axis 5 . In other words, the second slit aperture 16 must be dimensioned, arranged and movable in such a way that the second slit aperture 16 is able to completely block the X-rays emitted by the X-ray emitter 8 from reaching the X-ray detector 9 or at the location of the X-ray emitter. 8 and the inspection object between the X-ray detector 9.

The slit aperture (in particular in the case of a spherical shape) can have a rectangular opening, which also extends perpendicularly to the width denoted here as D_1 or as D_2. In particular, the openings of the first and second slit apertures can each extend as far as possible perpendicular to the width indicated by D_1 or D_2 , so that they can fully illuminate the x-ray detector 9 in this direction. In other embodiments, the slit aperture is flat or cylindrical in shape.

The opening of the first slit aperture 15 is dimensioned such that the X-rays shaped by the first slit aperture 15 can illuminate the entire area of the X-ray detector 9 . In the embodiment shown here, the first slit aperture 15 is fixedly positioned within the recording unit such that its opening is also aligned centrally with respect to the x-ray detector 9 . This is illustrated in FIG. 2 by the first center position 17 , which indicates the center position of the x-rays shaped by the first slot aperture 15 . In contrast, the second central position 18 of the x-rays shaped by the second slit aperture 16 is movable because the second slit aperture 16 is movable along the longitudinal axis 5 and, in the example shown here, D_2<D_1 . According to the invention, the second slit aperture 16 is moved along the longitudinal axis 5 during the helical scan in such a way that the x-rays generated by the two slit apertures strike the x-ray detector 9 asymmetrically for most of the helical scan. Asymmetric irradiation means that the central position of the generated x-rays is not centered relative to the x-ray detector 9 .

In a further embodiment, the second slit aperture 16 has at least one further opening with a width D_3≠D_2 along the longitudinal axis 5 and is designed to be shaped at the level of the longitudinal axis 5 with a width DZ_3≠DZ_2 and DZ_3≦ X-ray beams of DZ_1 or DZ_3<DZ_1. In a variation of this embodiment, there is D_3≦D_1 or D_3<D_1. In this embodiment at least two openings of the second slit aperture 16 have to be mounted at a distance from each other so that the second slit aperture 16 can completely block the X-rays shaped by the first slit aperture 15 . In other words, the second slit aperture 16 must always have an x-ray-absorbing partial assembly between at least two openings wide enough to completely absorb the x-rays shaped by the first slit aperture 15 .

Figure 3 shows in diagram form the position according to the invention of the two slit apertures relative to the gantry during recording in spiral mode. Here, the time is plotted on the horizontal axis, denoted by "t", and the z-coordinate is plotted on the vertical axis, denoted by "z". In the following the time interval between t_0 and t_1 shall be referred to as dt_1, the time interval between t_1 and t_2 shall be referred to as dt_2, and the time interval between t_2 and t_3 shall be referred to as dt_3. A pre-scan of the helical scan is performed in time interval dt_1 and a post-scan is performed in time interval dt_3. During the post-scan or pre-scan, the x-ray detector 9 does not have to be completely illuminated in order to record the x-ray projections required for the reconstruction of the tomographic image. Rather, the irradiation of the examination object during the post-scan or pre-scan which corresponds to a complete irradiation of the x-ray detector 9 simply means unnecessary radiation exposure. In contrast, during the time interval dt_2 the examination object can be irradiated in such a way that it corresponds to a complete irradiation of the x-ray detector 9 since in this case only the effective volume lies on the radiation path. A post-scan or pre-scan is necessary due to the helical pattern and presents a problem mainly in the medical field as the width of the x-ray detector 9 increases, since it counteracts the pursuit of dose efficiency.

According to the invention, during the helical scan, the second slit aperture 16 is moved according to the advance speed of the examination object or patient table 6 along the longitudinal axis 5, so that the x-rays shaped by the slit aperture illuminate only the portion of the examination object that is imaged for the reconstruction tomography. Contributing regions of the X-ray image. In other words, the irradiation area 20 as shown in FIG. 3 is only an effective volume. The frame of reference selected there is based on the first slit aperture 15 . The second slit aperture 16 moves in the z direction during a post-scan or pre-scan at a first speed v_B1 and during scanning of the active volume at a second speed v_B2, wherein the speeds v_B1 and v_B2 are related to the feed speed of the examination object. In an embodiment of the invention, the second slit aperture 16 is moved according to the feed speed, so that in particular the pitch changes between different time intervals. In the helical mode, the pitch is defined as the ratio of the advance of the patient table 6 per revolution of the recording unit to the width of the probe 9 along the longitudinal axis 5 .

FIG. 4 shows in diagram form the position according to the invention of the two slit apertures relative to the examination object during recording in spiral mode. In the diagram shown here, the relative movement between the test object and the first slit aperture 15 due to the movement of the test object at the feed speed is visualized. The feed rate increases during the second time interval dt_2. The speed of the second slit aperture 16 is measured in the first and third time intervals in such a way that the X-ray beam shaped by the slit aperture moves at a corresponding feed speed. The second slit aperture 16 is then fixed relative to the examination object during the first and third time intervals. Only in the second time interval dt_2 does the feed speed differ from the speed of the x-ray beam. The ratio according to the invention of the movement of the second slit aperture 16 to the feed speed results in that only the active volume 19 is illuminated, while regions 21 a, b outside the active volume are not illuminated during a post-scan or pre-scan. In the conventional method with a stationary aperture, the regions 21 a, b outside the active volume are instead illuminated.

In one embodiment of the present invention, the inspection object moves at the first feed speed v_1 in the first time interval dt_1 and the third time interval dt_3 respectively, and at the second feed speed v_2>v_1 in the second time interval dt_2 Movement, wherein the second slit aperture 16 can be moved such that the area of the X-ray detector 9 irradiated by the X-rays expands from a minimum width to a maximum width along the longitudinal axis 5 during a first time interval, wherein the X-rays in the second A range of maximum width is illuminated during a time interval, wherein the area of x-ray detector 9 irradiated with x-rays is reduced from a maximum range to a minimum range during a third time interval.

In another embodiment of the invention, the second feed rate is given by v_2=v_1·(1+(DZ_1-DZ_2)/(L-DZ_2)), where L is the width of the active volume along the longitudinal axis 5 . Here, the second slit aperture 16 can move at the first aperture speed vB_1 respectively in the first and third time intervals, so that the speed of the X-ray beam is equal to v_1. In addition, the second slit aperture 16 can move at a second aperture speed vB_2 at a second time interval, so that the speed of the X-ray beam is equal to (DZ_1−DZ_2)/dt_2. The speed of the x-ray beam always represents the speed at the level of the longitudinal axis 5 .

In another embodiment of the invention, the velocity is given by the following relationship, where L gives the length of the active volume along the longitudinal axis 5 . The patient table 6 moves and thus the examination object located on the patient table 6 moves at the following speed:

-v_1, between time points t_0 and t_1=t_0+DZ_2/v_1;

- v_2=v_1·(1+(DZ_1-DZ_2)/(L-DZ_2)), between time points t_1 and t_2=t_0+L/v_1; and

- v_1, between time points t_2 and t_3=t_0+(L+DZ_2)/v_1.

The second slit aperture 16 is then moved such that the X-ray beam shaped by the two slit apertures moves along the longitudinal axis 5 at the following speed:

- v_1, between time points t_0 and t_1 and between time points t_2 and t_3; and

-(DZ_1-DZ_2)/(t_2-t_1).

In other variants of the embodiment described here, the velocity transitions between different time intervals for the velocity of the examination object and the velocity of the second slit aperture 16 are not discrete but continuous.

Corresponding to the described embodiment according to the invention, the central position of the X-rays generated during the helical scan is changed such that the X-ray detector 9 is illuminated asymmetrically during most of the helical scan. During the reconstruction of the tomographic x-ray image, it is thus necessary to weight the x-rays shaped by the x-ray detector 9 . This is especially true when the detector elements of the x-ray detector 9 are read as if the x-ray detector 9 is fully illuminated. Weighting during reconstruction always involves weighting the x-rays as if no examination object interfered with the radiation path. In this case, the purpose of the weighting is to take into account the intensity of the X-rays due to the movement or position of the slit aperture when reconstructing. Therefore, the intensity can be calculated from the known movement or position of the slit aperture, which can then be used for weighting. In order to calibrate the intensity values, the helical scan according to the invention can also be carried out without an examination object.

The weighting is performed, for example binary, according to the x-rays shaped by the slit aperture, since such a weighting is particularly easy to implement. Alternatively, the weighting is carried out proportionally to the intensity of the x-rays shaped by the slit aperture, since such a weighting is particularly precise, especially in the case of rapid movements of the second slit aperture 16 . The weighting proportional to the intensity of the x-rays shaped by the slit aperture also takes into account the effect of half-occlusion. In other embodiments, the weighting may follow other mathematical relationships, for example may relate quadratically or exponentially to the intensity value.

In an embodiment of the reconstruction according to the invention, weighted filtered back-projection is involved. Reconstruction algorithms based on filtered backprojection offer the advantages of relatively short runtime and relatively small computational overhead. In a further embodiment of the invention, the reconstruction is an iterative reconstruction by means of statistical weighting. The iterative reconstruction algorithm offers the advantages of high resolution (especially at edges) and less artifacts.

Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited to the disclosed examples and other variations can be derived therefrom by a skilled person without departing from the scope of protection of the invention.

Claims (12)

1. a kind of x-ray unit, the X-ray for recording the check object that can be moved along the longitudinal axis (5) with feed speed is thrown Shadow, including the recording unit that can be rotated around the longitudinal axis (5), wherein, the recording unit includes：

- X-ray emitter (8), for the X-ray of emitting x-ray form, and X-ray detector (9), for detecting State X-ray,

First gap aperture (15) of-stationary positioned, it has the first opening for D_1 along the width of the longitudinal axis (5), is designed For there is width D Z_1 X-ray beam for being formed in the level of the longitudinal axis (5),

- the second gap aperture (16), it has the second opening for D_2 along the width of the longitudinal axis (5), designed to be used shaping There is width D Z_2 X-ray beam in the level of the longitudinal axis (5),

Wherein, DZ_2≤DZ_1,

Wherein, can be according to the feed speed along mobile second gap aperture (16) of the longitudinal axis (5) so that by the One gap aperture (15) and the X-ray beam only examination object of the second gap aperture (16) shaping to reconstruction tomography The contributive region of radioscopic image,

Wherein, the check object is moved in helicon mode during prescan with the first feed speed, and in rear sweep time Between moved with the second feed speed, and wherein, second gap aperture (16) energy respectively during rear scanning and prescan Enough movements are to enable X-ray beam with mobile along the longitudinal axis (5) with the check object same speed.

2. according to the x-ray unit described in claim 1, in addition to reconstruction unit (4), it is designed to be used based on by institute The x-ray projection for stating x-ray unit record carrys out the radioscopic image of reconstruction tomography, wherein, described rebuild is included according to passing through The intensity of first gap aperture (15) and the X-ray of second gap aperture (16) shaping is weighted.

3. according to the x-ray unit described in claim 2, wherein, carry out the weighting binary system.

4. according to the x-ray unit described in claim 2, wherein, with passing through first gap aperture (15) and described second The intensity of the X-ray of gap aperture (16) shaping proportionally carries out the weighting.

5. according to the x-ray unit any one of claim 2 to 4, wherein, the reconstruction, which is that the filtering weighted is counter, throws Shadow.

6. according to the x-ray unit any one of claim 2 to 4, wherein, the reconstruction be by statistics weight into The reconstruction of capable iteration.

7. it is a kind of in helicon mode by the recording unit records x-ray projection that can be rotated around the longitudinal axis (5) method, its In, the recording unit includes：

- X-ray emitter (8), for the X-ray of emitting x-ray form, and X-ray detector (9), for detecting State X-ray,

First gap aperture (15) of-stationary positioned, it has the first opening for D_1 along the width of the longitudinal axis (5), is designed For there is width D Z_1 X-ray beam for being formed in the level of the longitudinal axis (5),

- the second gap aperture (16), it has the second opening for D_2 along the width of the longitudinal axis (5), designed to be used shaping There is width D Z_2 X-ray beam in the level of the longitudinal axis (5),

Wherein, DZ_2≤DZ_1,

Wherein, check object is moved with feed speed along the longitudinal axis (5),

Wherein, second gap aperture (16) is moved along the longitudinal axis (5) according to the feed speed so that by the first seam The X-ray to reconstruction tomography of gap aperture (15) and the X-ray only examination object of the second gap aperture (16) shaping The contributive region of image,

Wherein, the check object is moved during prescan with the first feed speed, and with the second feeding during rear scanning Speed movement, and wherein, it is respectively that second gap aperture (16) is mobile for so that X is penetrated during rear scanning and prescan Wire harness is always with mobile along the longitudinal axis (5) with the check object same speed.

8. it is a kind of based on the x-ray projection recorded in accordance with the method for claim 7 come the radioscopic image of reconstruction tomography Method, wherein, it is described rebuild include according to by first gap aperture (15) and second gap aperture (16) into The intensity of the X-ray of shape is weighted.

9. in accordance with the method for claim 8, wherein, carry out the weighting binary system.

10. in accordance with the method for claim 8, wherein, with passing through first gap aperture (15) and second gap The intensity of the X-ray of aperture (16) shaping proportionally carries out the weighting.

11. according to the method any one of claim 8 to 10, wherein, the reconstruction is the filtered back projection of weighting.

12. according to the method any one of claim 8 to 10, wherein, the reconstruction is to weight to carry out by statistics Iteration reconstruction.