JPS60106439A - Diagnostic apparatus and method by radiation permeation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radiographic diagnostic apparatus that diagnoses the body by transmitting radiation such as X-rays.

BACKGROUND OF THE INVENTION (Prior Art and its Problems) CT scanners have become an established technology for obtaining tomographic images of the interior of living body tissues or inanimate objects. The following three conditions are required for advanced CT scanners. (1) high stereoscopic resolution; (2) high contrast resolution for distinguishing tissue; and (3) for dynamic studies where several scans are obtained in rapid succession and eliminating blurring due to patient movement. It is a high-speed scan that is minimized. High 3D resolution is generally a characteristic of images obtained with translational and rotational CT scanners, and high-speed scanning is generally achieved with rotational CT scanners.
This is a characteristic of the T scanner.

The essential stereoscopic resolution of a CT scanner is fundamentally determined by two factors. (1) the effective beam width at the center of the object and (2) the sampling frequency. The effective beam width is a function of the focal spot size, the detector aperture width, and the magnification factor (defined as the X-ray tube object resolution versus the Xfiij! tube detector resolution). This is completely independent of whether the scanner operates in translational rotation or only rotation. Assuming the effective beam width is optimal, the sampling frequency is all important. Regarding the sampling frequency, the difference between data obtained by translation and rotation and data obtained by rotation only is important.

In the case of rotary scanners, the sampling frequency and effective detector aperture are constrained by the dimensions of the installed detector. This is due to the inherent geometry of rotary scanners.

Rotary scanners have a Xi source and a group of detectors fixed together so that they rotate together about the object. As a result, the geometry of the rotary scanner limits the minimum possible sampling distance to the distance between the detectors and limits the sampling frequency to 91 times per beamwidth. However, according to the Nyquist criterion, the sampling frequency must be at least twice the beam width, ie, two or more beam width measurements must be taken.

Because the geometry of rotary scanners does not satisfy the Nyquist criterion, high image contrast and high stereoscopic frequencies can produce aliasing artifacts that degrade image quality. To prevent aliasing artifacts, it is necessary to prefilter the data by combining measurements in adjacent detector channels, which allows high stereo frequencies with a period less than or equal to the width of the two beams to be filtered. Attenuate.

In this way, a new beam width is created that is twice the actual beam width and satisfies the Nyquist criterion. Therefore, when making measurements at this beamwidth, the essential stereoscopic resolution of the rotary scanner must be reduced by two factors to prevent aliasing artifacts.

In contrast, in the case of a translating and rotating scanner, the gantry that secures the Xa tube and detector is indexed to an amount less than or equal to half the beam width to satisfy the Nyquist criterion. In this way, aliasing artifacts are eliminated while retaining the essential stereoscopic resolution of the system.

Furthermore, in the case of rotary scanners, the above-mentioned lack of flexibility in adjusting the sampling frequency unnecessarily reduces beam width for subsequent patient collimation. This is because the distance between the detectors is constant. Also, a narrow beam does not improve the final stereoscopic resolution beyond the limit set by the sampling frequency.

In the case of translating-rotating scanners, post-patient collimation can be used to reduce beam width and improve stereoscopic resolution, which allows the gantry to be indexed to correspondingly smaller volumes. This is because it is possible to maintain a sampling frequency that is at least twice as large as the beam width.

To overcome the limitations in sampling frequency caused by the detector-to-x-ray relationship inherent in conventional rotary scanners, some rotary scanners use center-of-rotation offset techniques to increase the sampling rate. simulate. Using this technique, the center of rotation of the gantry (i.e., its co-center) is offset by a distance equal to the width of the effective beam width at the co-center, and two fields of view taken 180 degrees apart are separated by the detector pitch. Shift only A. It is clear that using this technique, after the gantry is rotated 180°, x-rays from diametrically opposed fields of view can be interleaved, effectively doubling the sampling density and improving the stereoscopic resolution. . However, this technique is effective only in ideal cases where the patient is immobile. During the few seconds required to rotate the gantry,
If the object to be scanned moves by a fraction of a tone, the match is lost and proper interleaving of the fields of view is no longer achieved. Such conditions may result in aliasing artifacts that degrade video quality. Therefore, even if this technique simulates doubling the sampling frequency at the center of the object, it does not free rotary scanners from the above-mentioned drawbacks due to the limited sampling frequency.

Another method of increasing sampling density is to collect data from the detectors at a given location and then shift the detectors laterally by an amount equal to the pitch between the detectors while the x-ray source remains in the same location. do. (or rotate the detector around the co-center). In this way, the first 180°
The data collected at 180° and the data collected at the next 180° are arranged alternately, effectively doubling the sampling frequency. These data are then processed in the usual manner (ie filtering and backglossion) to form a CT image.

However, the mechanism for moving the detector instead of the X-ray source during scanning as described above is inconvenient in the case of a rotary scanner, and this mechanism eliminates the advantage of a simple mechanism that characterizes a rotary CT scanner. It acts to make it happen.

U.S. Pat. No. 4,149,079 discloses a system with reduced detectors, which increases data density for more accurate reproduction in systems where the apex angle of the fan beam is smaller than the apex angle of the reduction mill. is disclosed. This US patent rotates or translates a fan beam about a fixed center of reduction, and during one complete revolution, a first data set is obtained and then a second data set is obtained. This system therefore has the disadvantage of requiring two separate rotations and also requiring mechanical means to shift the fan beam.

U.S. Pat. No. 4,266,136 discloses a CT system that uses a reduced group of detectors. Since the X-ray source in this case emits a fan beam of radiation with an apex angle smaller than the diameter of the reduction axle, it only irradiates a false slice of the object at any given time. The data produced by the detector is transformed by a processing unit into a rectified profile signal suitable for processing by conventional rectification algorithms. This system provides insufficient data density to satisfy the Nyquist criterion, and therefore only provides poor quality playback video.

These unacceptable sampling limitations of rotary scanners have led to the development of modified rotary fixed scanners with fixed detector groups. In such systems, the detectors are rigidly mounted in a circle around the patient. The X-ray source is placed inside or outside the area of the detector and data is acquired as the X1w source is rotated. Rotating fixed systems with fixed detectors achieve flexibility in sampling, but introduce new constraints. In the end, the essential stereoscopic resolution and overall clinical performance are only approximately equal to the original rotary version.

The most notable issue with rotary fixed systems is that of efficiency. That is, it is expensive because it requires a large number of detectors. Additionally, rotating and fixed systems suffer from structural difficulties in canceling out scattered radiation and associated background noise, and therefore have poor contrast resolution. Furthermore, with the conventional rotary fixed XM source mounted inside a ring-shaped detector, it is difficult to optimize the separation between the X-ray tube, object, and detector; This is because the ring of detectors arranged in a ring must be made as small as possible to avoid an excessive number of detectors, and the X-ray source and object must be confined within this ring. Another disadvantage of rotary fixed systems is the increased x-ray exposure due to the distance 21- between the x- and g-tubes and the object. These problems are caused by the X
This was sufficient to facilitate the development of scanners that rotate the source and optimize the distance between the x-ray tube, object and detector. However, such systems are significantly more complex mechanically, since the x-ray tube must be rotated to deliver an unobstructed beam to the detector on the opposite side of the scanned object. This is because the detector closest to the X-ray tube must be moved out of the rotating field during that time. This is achieved by causing the annularly arranged detector ring to undergo a head-turning motion.

OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a new and improved computerized tomography method and tomography apparatus which substantially obviates the above-mentioned drawbacks of the prior art.

DETAILED DESCRIPTION OF THE INVENTION The present invention solves the above-mentioned problems associated with improving the basic stereoscopic resolution in rotary scanners or similar scanners. Additionally, the present invention can improve stereoscopic resolution in translating and rotationally fixed fully fixed x-ray source scanners or other radiation source detectors in which the invention may be practiced.

The radiographic diagnostic apparatus of the present invention has at least two different point sources of radiation, a transmitting radiation source that transmits radiation to the body, a detection device that detects the radiation transmitted to the body, and a radiation emitted from the radiation source. and a device for causing radiation to be passed through a plurality of passages through the body to be detected by the detection device, and a device for alternately emitting radiation to the at least two different point sources of radiation. . The radiation source can be provided with a target electrode that emits radiation when struck by the electron beam and a deflection device that deflects the electron beam between at least two different focal points on the target electrode. As a further alternative, the radiation source is provided with an X-ray tube having at least two filaments, each filament being provided with a different point source of radiation. Alternatively, the radiation source may include at least two x-ray tubes, each x-ray tube having a different point source of radiation. The radiation source can also be provided with a fixed anode or a rotating anode.

A post-patient collimator may also be provided. This collimator is made into a high-resolution bin collimator. The radiation source and detector arrangement can be mounted on a rotating gantry. The detector arrangement may consist of a plurality of individual detectors arranged substantially uniformly along an arc on the gantry. The collimator device can be a plurality of corresponding collimators, with the center of each collimator aligned with the center of the detector. A device may be provided to offset the gantry co-center by a distance equal to the effective pitch of the detector at the gantry co-center. Alternatively, the center of each collimator can be offset from the center of the corresponding detector by the origin of the detector pitch, with a device that offsets the co-center of gantry rotation by a distance equal to the effective detector pitch at the co-center. can be provided.

In one embodiment of the invention, the radiation source is provided with a device for transmitting fan beams of radiation, and each transmitted fan beam is provided with an apex angle α that is smaller than the apex angle β forming the rectification circle. Preferably, the angle α is approximately A of the angle β, and this angle α is approximately in the range of 15 to 30°. A plurality of individual detectors are placed on an arc on the gantry spanning an apex angle α. One alternative is to place one of the individual detectors at the end of the group approximately diametrically opposite the radiation source on the gantry, with the detectors co-centered on the gantry. Position it asymmetrically.

In another alternative, a plurality of individual detectors can be placed approximately symmetrically about the joint center of the gantry. Apparatus may be provided to move a plurality of detectors relative to a common center of the gantry to provide a system that can operate in either mode of operation. In this embodiment, the radiation source and detector may be provided with a device to offset the co-center of the gantry by 25 pairs.

In another embodiment of the present invention, an apparatus for diagnosing the body by transmitting radiation such as X-rays includes a radiation source that transmits radiation to the body, a detection device for detecting the radiation transmitted to the body, and a radiation source. a device for passing radiation emitted from the body through a plurality of passages passing through the body and detecting it by a detection device;
The radiation source is characterized by comprising a shift device that shifts the radiation source with respect to the detection device.

According to the present invention, there is provided a radiation source for transmitting radiation to a substantially flat part of the body, a detection device arranged to detect the radiation after passing through the body, and a detection device for detecting the part of the body to be detected by the detection device. To improve the three-dimensional resolution of images reproduced by a rotary scanner having a device for rotationally moving a radiation source and a detector around the circumference of the body so that the radiation traverses a passage having a plurality of identical squares. The invention is characterized in that the sampling density is increased by continuously interleaving 26 radiation beams between adjacent radiation beams when rotating the radiation source and the detector arrangement around the body.

In summary, the present invention improves the sampling density available with conventional rotary scanners or similar scanners by at least 2
It has the advantage of doubling. As mentioned above, the present invention can be used to increase sampling density in translational rotation, rotational fixed, fully fixed source systems, or other tomographic systems. A preferred embodiment of the invention accomplishes this by providing an x-ray tube with two or more focal points that are preferably movable laterally relative to each other. When the gantry rotates by the angle pitch of the detector,
For example, in the case of an X-ray tube having two focal points, the movement between the focal points is determined so that the second focal point occupies approximately the same azimuthal position that the first focal point originally occupied. In this way, the radiation beam produced by the second focus is interleaved between adjacent beams emitted by the first focus, doubling the sampling density. The two focal points are operated in toggle mode with approximately 50% duty cycle. When using an X-ray tube with three focal points, the movement between the focal points is determined so that three samples of each beam width are obtained.

The ideal amount of movement between focal points can be calculated by the following formula:

A 8 = R8/Rd Defined detector pitch, n is the number of focal points and number of samples per beam width, and N is 011.2,
It is a number like... The amount of movement calculated using the above formula is optimal, but other amounts of movement may also be acceptable. As long as the displacement is close to the above calculated value, a substantial improvement in stereoscopic resolution is achieved. N=0, R8=630 key, P
= 1.6 mm, Rd = 400 degrees, and n = 2, ΔB'' is 1.26 ml.

According to a preferred embodiment in the case of two foci, the foci are switched alternately or sequentially with a period of approximately A to several tenths of a second. This switching speed virtually eliminates aliasing artifacts due to patient movement. This allows interleaved additional fields of view to be collected to correct for shear aliasing, an advantage over prior art techniques that require a 180° rotation of the gallitori, which typically takes several seconds.

Another advantage of the present invention is the use of a collimator to reduce detector aperture and improve stereoscopic resolution. On the other hand, as mentioned above, pin collimators are not useful in conventional rotary systems. If the detector aperture is reduced, for example, by half, there are two techniques to increase the sampling density and thus satisfy the Nyquist criterion. The first technique is to use an x-ray tube with three or more focal positions. There are four positions to satisfy the Nyquist criterion, but three foci provide some improvement. The second technique is to offset the center of rotation (i.e. co-center) of the IJ (gun) by 29- and use an x-ray tube with two focal points. Concentric offset geometry and high resolution pin collimation can be achieved by two different techniques. One technique aligns the center of a high-resolution collimator with the center of the detector and offsets the co-center by a fraction of the effective detector pitch at the co-center. The other technique is to offset the center of the high-resolution collimator from the center of the detector by an amount of the detector pitch and offset the co-center by the amount of the effective detector pitch at the co-center. In both techniques, 18
Fields taken 0° apart are interleaved to double the sampling density in the central area of the patient and satisfy the Nyquist criterion. The ability to use pin collimators and increased sampling frequencies to improve stereoscopic resolution means that stereoscopic resolution is significantly improved compared to conventional rotary scanners, which are limited by sampling density.

= 30 - Another advantage of the present invention is that instead of requiring detector groups along the entire detector arc, i.e. around 40-50° from the radiation source as in a conventional rotary CT scanner. An alternative method that requires a group of detectors installed along an arc extending the diameter of the entire rectification circle so that the fan-shaped beam can be received by the group of detectors, the arc having a center diametrically opposite the X-ray source. , a reduced arc of the detector, i.e. a detector on an arc smaller than the diameter of the rectification circle, can be employed, e.g. the detector group can receive a fan beam in the range of about 15 to 30'; The advantage is that the price can be lowered. In one embodiment,
The reduced detectors are arranged asymmetrically, with the detectors at one end of the arc diametrically opposite the x-ray source, and in other embodiments the reduced radiation sources are arranged symmetrically about a joint center. A bimodal system can be achieved by moving the half-detector groups on the gantry and providing a means for displacing them;
It is therefore possible to shift between an asymmetrical shape and a symmetrical shape. The number of detectors needed can be cut in half, or by as many as actually needed, and
An even more satisfactory stereoscopic resolution can be achieved by using an x-ray tube with two or more focal points.

A conventional rotary scanner can also reproduce a 360° image of data after reducing the number of detectors to A, but such a scanner has a reduced stereoscopic resolution. This is because in such scanners, the 3D resolution is determined by the sample frequency, and the gantry joint center cannot be A-offset, which requires the detector to be placed along the entire circular arc. be. However, if such a scanner is provided with an X-ray tube having two or more focal points that alternately emit radiation according to the present invention, the sampling frequency can be doubled and the stereoscopic resolution can be doubled. improves. However, a 360° scan is still required.

As mentioned above, the stereoscopic resolution of a scanner with a reduced number of detectors and a multifocal x-ray tube is twice as high as that of a conventional scanner with an arc-arranged detector and a conventional scanner with a single focus. It has a three-dimensional resolution comparable to that of an X-ray tube. A scanner according to the invention is substantially free of aliasing artifacts resulting from patient movement. This is because the duration between interleaved samples is a few tenths of a second, corresponding to the switching time between focal points, whereas the duration between interleaved samples in conventional scanners is long, on the order of seconds. The longest is the gantry's 180° alternating position to obtain additional data.
This is because it only occurs after rotation over a period of time. When using a reduced detector as in the present invention, unnecessary radiation doses can be reduced by providing a collimator between the X-ray source and the patient to reduce the apex angle of the fan beam transmitted to the patient. , the size of the detector group can be correspondingly reduced.

Embodiments of the invention will now be described with reference to the accompanying drawings.

(Embodiment) In FIG. 1, reference numeral 1 indicates a 33-transmission radiation source such as an X-ray source for transmitting radiation to a substantially flat body part, and reference numeral 3 indicates a rotatable substantially circular gantry 6. shows a plurality of detectors arranged substantially uniformly in an arc, the gantry being preferably mounted on a support member 16. (Gun) The detectors 3 are arranged near the periphery of the IJ, preferably at substantially uniform intervals in an arc shape. The gantry, the radiation source 1 attached to the gantry, and the detector 3 are continuously rotated and swept around the patient 50 times to obtain data. The center of rotation of the gantry, ie, the joint center, is designated r4J. Reference numeral 17 indicates a radiation beam emitted from the radiation source 1. Radiation beam 17 is shown as a fan-shaped beam of radiation on a generally flat portion of the body being examined. Each fan-shaped beam 17 emitted by the radiation source 1 substantially originates from a different point source within the radiation source 1 . Arrow C represents the direction of rotation of the system. As shown diagrammatically in FIG. 4, the radiation source 1 has at least two different point sources of radiation.

Reference numeral 31 in FIG. 1 is a device for rotationally moving a radiation source and a detector around the circumference of the body 5; To detect. The rotational movement device 31 consists of means for rotationally moving the gantry. Reference numeral 33 denotes an emitting device for emitting radiation alternately from at least two point sources of radiation, by means of two lines connecting the joint center of the gantry and the centers of adjacent detectors arranged on the gantry. The emitting device 33 is configured with means for emitting radiation alternately by a point source at a frequency whose period is equal to the time required to rotate the gantry by an angle equal to half the effective detector pitch at the joint center given by the formed angle. do. Alternatively, this period may be multiplied by N. Here N is equal to 2.4.8.16...

Reference numeral 35 indicates a gantry 6 for the radiation source 1 and the detector 3.
It is a center offset device that shifts the joint center "A" of.

Reference numeral 37 is a radiation source shifting device that shifts the radiation source 1 with respect to the detector 3. The radiation source and the detector are in the body 5
The radiation source shifting device may be provided with means for periodically shifting the radiation source between at least two different positions relative to the detector during rotational movement of the radiation source. Reference numeral 39 is a detector shift device that moves the detector on the gantry. The detector shifting device is provided with means for moving the detector between a first position in which the detector is disposed asymmetrically with respect to the common center and a second position in which the detector is disposed symmetrically with respect to the common center. As will be explained in more detail below, this detector shifting device may be used with somewhat arranged detectors.

The geometry of conventional rotary scanners controls the minimum possible sampling distance to the distance between two instantaneously touching detectors, thus reducing the inherent stereoscopic resolution of such systems to the distance between the two detectors. Limit to 2x. In other words, this sampling distance effectively equalizes the beam width. As a result of this sampling frequency, the stereoscopic resolution of the rotary scanner is only half of what is theoretically possible. This is shown by Nyquist's theorem, which states that to obtain maximum stereoscopic resolution, the beam width must be at least 2
It is necessary to have several samples.

FIG. 2 shows why the Nyquist criterion causes a reduction in theoretical stereoscopic resolution by a factor of two in a conventional rotary CT scanner.

In this figure, "a" represents the beam width of the radiation beam transmitted by the X-ray source 1, and "b" represents the sampling distance or pitch. According to the Nyquist criterion, the sample spacing rbJ must be less than or equal to half the resolution or beam width raJ, ie, rbJ must be much less than or equal to half the resolution or beam width raJ. If “b” is a
If it is smaller than 4, the stereoscopic resolution is equal to raJ. If r
If bJ is larger than a4, the stereoscopic resolution must be reduced to prevent aliasing artifacts, and therefore the stereoscopic resolution will be larger than "a". When b=a, the stereoscopic resolution is approximately equal to 2b, as in a normal rotary CT scanner, and since b=a, the stereoscopic resolution is 2a.
is also equal to

37- Figure 3 shows a technique for shifting the detector by a pitch to increase sampling density.

The shifted detector is shown in dashed lines at 3.

In FIG. 3, a indicates the beam width and b' indicates the sampling distance or pitch. For Fig. 2, a' = a and sum i
= b4 = 84. Therefore, if the detector is shifted by pitch A, the Nyquist criterion is satisfied, so there is no aliasing, and the three-dimensional resolution is equal to raJ. The resolution is therefore twice that shown in FIG.

FIG. 4 shows the radiation source 1 in the form of an X-ray source with two different point sources 9.11. Point source 9.11 can be provided by a single X# tube with a pair of filaments. Alternatively, it can also be provided by a radiation source 1 comprising a pair of X-ray tubes, each with a different radiation source. As an alternative, as shown in Figure 15,
It can also be provided by deflection means for deflecting the electron beam between at least two different focal points on the target electrode. A device 33 is provided to cause radiation to be emitted alternately by different 38- point sources 9.11. It should be noted that the radiation source 1 may be provided with two or more different point sources, which alternately emit radiation. Within the X-ray source 1, place the radiation point source or focus at positions 9 to 11.
Increase the sampling density by alternating shifts up to . In FIG. 4, the X-rays are emitted from the focal point 9 and the detector 3 is positioned at the position 3. X-rays continue to be emitted from focal point position 9 as detector 3 reaches position 3 and the gantry rotates by the detector rotation angular pitch A until focal point 11 occupies the same position that focal point 9 originally occupied. . At this point, x-rays are emitted from the focal point 11 as the gantry continues to rotate through another A of the detector rotation angle pitch. After the gantry has rotated a full detector pitch, the x-rays are emitted once again from position 9. This cycle repeats throughout the scan.

When the detector is shifted by the detector pitch A, to achieve a second focus occupying the same azimuth position as occupied by the first focus, the required movement between the focus 9.11 is given by .

Δ, = Rs / Rd Detector pitch, defined as the distance between the centers of the detectors, and N = 0, Δ8 = R8/
N=0.1.2 for RdxP/2.

By providing multiple focal points as described above, the sampling frequency is at least doubled. This is because radiation beams 17 can be successively interposed between adjacent radiation beams 17 when the radiation source and detector rotate around the same center. Using a multifocal system, the interposition can be carried out independently of any change in the spatial relationship between the X-ray source 1 and the detector 3 on the gantry. This is because a constant relationship between is maintained throughout the entire 360° rotation of the gantry.

Additionally, when rotating the radiation source and detector around the patient,
Interleaving the radiation beams. Interleaving is accomplished by emitting radiation alternately from multiple point sources or focal points of radiation. Radiation is emitted alternately between the focal points at a frequency having a period preferably equal to the time required for the gantry to rotate the detector pitch. This period is N
It can be doubled, where N is 2.4.8.16...
·be equivalent to.

Alternatively, according to the invention, the radiation source shown in FIG. can be built. Detector 3
Preferably, this shifting device 37 is provided with means for periodically shifting the radiation source 1 between at least two different positions relative to the radiation source 1. This exposes each detector to radiation from multiple point sources as the gantry rotates. This shifting means can be implemented by conventional means for shifting the position of the radiation source 1 relative to the group of detectors 3.

The increased sampling density caused by the multiple focal points and the alternate data acquisition scheme can be understood with reference to Figures 5-9, which show the data in polar coordinates.

FIG. 5 shows the three-dimensional position of each X-ray measurement point using polar coordinates (r, θ) with respect to the common center "A".

For example, the line segment formed by the X-ray source 1 and the detector D1 can be expressed in polar coordinates (γ, θ), where γ is equal to the distance R1-0 and θ is θ1. The next line segment of the sector is formed by the X-ray source l and the detector D2 and is expressed in polar coordinates (γ, θ), where r is equal to the distance R2-0 and θ1 is θ2. Therefore, r is proportional to the number of detectors, and for a given sector, θ for each line segment increases by Δθ. Here, Δθ is an angle with the X-ray source 1 as its apex and the pitch of the detector.

Data collected by a conventional rotary CT scanner with a single x-ray source is shown in FIG. The data from each sector is located along the diagonal lines within this γ-〇 diagram. This is because both θ and γ change in proportion to the number of detectors. Location 42 - Data collected within a given sector is shown as an open or closed circle, this symbol alternating for successive sectors.

During data acquisition, the gantry is rotating so that each measurement extends over a small range of values of θ. The circle (open or closed) indicates the average value of θ, and the vertical line above or below the circle indicates the range of θ over which data are collected.

After acquiring the data, a “field of view” with a certain angle θ is
ws) The data may be combined into a new group defined as J. Therefore, the data in each set are essentially parallel lines. In the case shown in FIG. 6, the acquisition time Δt of each fan section is the time required for the gantry to rotate by Δθ.

Therefore, Δt is proportional to Δθ. In other words, Δt = Δθ, where 14 is proportional to the rotational speed.

Also, the angular sampling given by the angular distance between fields of view Δα is equal to Δθ. The minimum sampling interval is equal to the detector pitch, which reduces the stereoscopic resolution. This is because, as mentioned above, the Nyquist criterion is not satisfied.

An X-ray source having two foci, separated by a distance given by the above formula and emitting radiation alternately, is configured as shown in FIG.

The fan-shaped data collected by poems whose focus is at position X (branch) is shown as an open (closed) circle. By halving the integration time and alternating between focal points X and 7, the angular distance Δα = Δ
Data can be organized in fields of constant θ separated by θ. Most importantly, the sampling distance is made equal to the detector pitch, A, to satisfy the Nyquist criterion and significantly improve stereoscopic resolution.

Although this embodiment achieves a parallel field of view, satisfies the Nyquist criterion, and produces significantly improved stereoscopic resolution, it has a feature that reduces the data acquisition time Δt=(kΔθ)/2, which is because the gantry is This is because the focal point position changes every time the angle pitch rotates by half. This reduction in data acquisition time limits the amount of x-ray flux detected and reduces the signal-to-noise ratio, but requires a more expensive high-speed data acquisition system.

This drawback can be overcome by increasing the data acquisition time and sampling angular distance. A γ-θ diagram for a conventional rotary CT scanner with a single focus x-ray tube that rotates 2Δθ for each data acquisition is shown in FIG. Compared to FIG. 6, the integration time is doubled and the angular distance Δα is also doubled, so the overall field of view is A.

The minimum sampling distance is equal to the detector pitch as shown in FIG. 6, and does not improve stereoscopic resolution.

Furthermore, it is clear from FIG. 8 that it is not possible to organize the data into perfectly parallel fields of view with constant θ. Therefore, the loss in angular resolution is small, and the stereoscopic resolution at a distance of 200 m radius away from the co-center is slightly reduced. High stereoscopic resolution is not important at such locations;
CT scanners typically reduce resolution for other reasons. However, in this system, the 3D resolution does not decrease in the 45-center center.

Combining an x-ray source with two focal points with a longer data acquisition time produces the r-theta diagram shown in FIG. In this case, the longer data acquisition time Δt=2
Achieve Δθ.

This time is four times longer than the example of FIG. The sampling angle distance is also 4 times as Δα=4Δθ. Therefore, the total number of fields of view is A in the case of FIG. 7, which significantly reduces the computational burden of image reduction without sacrificing image quality.

As shown in FIG. 8, during data acquisition, the gantry rotates more than 30 degrees, so it is not possible to organize the data into a completely parallel field of view with constant θ. However, the slight reduction in image quality is limited to peripheral areas far from the co-center. By using two focal points x, y, the minimum sampling distance is equal to half the detector pitch, which satisfies the Nyquist criterion, and the stereoscopic resolution is considerably improved despite the long data acquisition time.

FIG. 10 shows the use of a high resolution collimator 13 to reduce the detector aperture and increase the volumetric resolution. In this preferred embodiment, pin collimator 13
This reduces the detector aperture and increases the stereoscopic resolution. In Figure 10, a is 50 of the value of a in Figures 4-6.
%, b = 2 a, and the required value for the sample pitch is 84. One solution to increasing sampling density is to use an x-ray tube with three or more focal positions.

Alternatively, an x-ray tube with two focal points can be used, with the joint center of rotation offset by a small distance,
The 180° fields of view can be interleaved to double the sampling density. The geometry of offsetting the concentric centers and the position of the high resolution pin collimator relative to the detector are implemented in two different embodiments of the invention.

In one embodiment, the center of the high-resolution collimator is aligned with the center of the detector, as shown in FIG.
approximately at the center of the detector 3 and offset the gantry co-center by an amount of the effective detector pitch at the co-center. In another embodiment, as shown in FIG. 11, the center of the high-resolution collimator 13 can be offset from the center of the detectors D□-Dn by an amount equal to the detector pitch, and the bin beam passing through the collimator 13 is offset from the center of the detectors D□-Dn. It hits the detector at a point offset from the center by approximately the detector pitch. The co-center is also offset by A, the effective detector pitch at the co-center. As shown in FIG. 11, the reference symbol "Δ" represents the offset of the center of the collimator with respect to the center of the detector. The amount of this offset can be any practical amount desired, but is preferably 14 or more of the detector pitch. The reference Δ indicates the offset of the gantry co-center relative to the effective detector pitch at the co-center.

The amount of this offset can be any practical amount desired, but is preferably in terms of the beam width at the co-center. For post-patient collimation, which reduces the detector aperture by 50%, two focal points (2
Achieve the required four-fold increase in sample frequency by double the sampling frequency) and pseudo-X-ray offset (double the sampling frequency).

FIG. 12 shows another embodiment of the invention that utilizes a reduced group of detectors. In FIG. 12, the detector 3 is formed by a plurality of individual detectors designated D1 to DIO. X
The source 1 has two different point sources of radiation, but may also have many point sources. A group of reduced detectors 3 is mounted, preferably approximately along an arc with an X-ray source 1 in the center.

In FIG. 12, reference numeral 15 designates a reduction mound associated with a fan-shaped beam having an apex angle equal to β. Here, the apex angle is the angle between the line segments at both ends of the fan-shaped beam. The width of the detector group corresponding to such a fan-shaped beam is shown by a broken line on the left side of the detector group 3.

As shown in the drawing, such a fan-shaped beam has an intermediate beam and a fixed co-center "A" 49- around which the X#J source and detector 3 rotate in the plane of the detector. The intermediate beam passes through. During one complete rotation of this X-ray source and detector assembly, the X-ray source moves in a circle centered on a fixed co-center "A" and the fan beam with apex angle β lies in the plane of the detector. The area contained within circle 15 is swept. The center of the circle 15 coincides with the common center "A", and the beam constituting the periphery of the fan-shaped beam occupying the above-mentioned center and having the apex angle β with respect to the common center is tangent to this circle 15. For a given scanner, the diameter of the reduction mill is directly related to a multiple of the apex angle of the fan beam.

The fan beam 17 shown in FIG. 12 has an apex angle α smaller than β. Beam 17 is matched to a reduced detector group 30, and a fan beam with apex angle β is matched to a full detector group extending as far as the dashed line in FIG. In Figure 12, the angle α is approximately 20~2
5°, angle β is shown at approximately 40-50°. α and β may be any other desired practical angular values;
It is best to set it within a range of 30 degrees and make it almost suspicious of β. Section 50 - By changing the associated collimator or X-ray source,
The apex angle of the fan beam can be changed.

It is clear that the arc containing the group of reduction detectors 3 extends smaller than the diameter of the reversal 15. The detector group is X-ray source 1
This forms the apex angle α of the fan-shaped beam 17 emitted from.

This arc extends approximately half the diameter of circle 15, so that β is equal to about 40-50' and α is about 20-25'.
Equal to °. However, α can be any desired actual value. In contrast, the detector array of a typical rotary CT scanner is arranged along an arc that typically corresponds to a maximum fan beam of about 40-50° and spans the center angle across the diameter of the reduction mound. Ru. As shown in FIG. 12, the X-ray source 1 is placed approximately diametrically opposed to the leftmost detector D□ on the gantry. In a preferred embodiment, means are provided for offsetting the co-center of rotation of the gantry by a distance equal to the pitch of the detector at the co-center. In the case of the scanner shown in FIG. 12, the group of detectors 3 is arranged asymmetrically with respect to the joint center of the gantry with the end detector D1 diametrically opposite the radiation source 1.

When dealing with images of small-diameter objects such as the head, half of the detector groups in the device shown in Figure 12 are arranged approximately symmetrically with respect to the joint center "A" as shown in Figure 13. It can be shifted to a new position. Intermediate detector D
5. The midpoint between D6 is approximately diametrically opposite the X-ray source 1 as shown in the drawing. The fan-shaped beam 17 in FIGS. 12 and 13 does not extend all the way through the reduction mill 15, but extends approximately A on the circle 15.

When using reduced detector groups, a patient precollimator (not shown) can be provided to reduce the apex angle of the fan beam corresponding to the reduced detector group, eliminating unnecessary radiation. quantity can be avoided.

For high resolution scanning of small object fields using the scanner shown in FIG. 13, a post-patient high resolution bin collimator is used as shown in FIG. The geometry of offsetting the concentric centers and the position of this high resolution bin collimator relative to the detector can be provided in two different embodiments according to the invention.

In one embodiment, the center of the high resolution collimator is aligned with the center of the detector, and the co-center is offset by A, the effective detector pitch at the co-center. In other embodiments, the center of the high resolution collimator is offset from the center of the detector by the magnitude of the detector pitch, and the co-center is offset by the magnitude of the effective detector pitch at this co-center. In the case of post-patient collimation, which reduces the detector aperture by 50%, the required 4x increase in sample frequency is achieved by two focal points (2x sampling frequency) and an HX-ray offset (2x sampling frequency). achieved. In a preferred embodiment, the co-center of rotation of the gantry is offset by a distance equal to the effective detector pitch at the co-center, and the center of the collimator is offset from the center of the detector by the pseudo-detector pitch. Provide means.

The first one is equipped with a high-resolution bin collimator as described above.
The configuration shown in FIG. 3 is suitable for scanning a small object such as a head, and has the following advantages. First, higher sampling frequencies and increased stereoscopic resolution can be achieved compared to conventional scanners. Second, compared to traditional scanners, faster scanning can be achieved, which requires approximately 205° rotation, rather than 360° rotation.
That is, a rotation of 180° plus the angle of the fan beam (preferably about 25°) is sufficient. Third, high resolution bin collimators can be used to increase stereoscopic resolution.

As mentioned above, single focus X#i! In the case of conventional co-rotating scanners with tubes, bin collimators are not effective in increasing stereoscopic resolution. Fourth, the scanner is insensitive to patient movement. This is because additional fields of view to be interleaved can be obtained within a few tenths of a second, as opposed to the several seconds required for conventional scanners to rotate 180° to obtain such data.

Reference numeral 39 in FIGS. 12 and 13 indicates the detector 3 on the gantry.
It is a device that moves or shifts the This gives rise to bimodal functions, and the 12th and 13th
A single scanner can be operated alternately in the states illustrated in the figures. In FIG. 12, the detector 3 is shown in the first position where the detector is arranged asymmetrically with respect to the joint center "A", and the detector 3 is shown in the first position.
In Figure 3, the second detector is placed symmetrically with respect to the joint center.
The detector is shown in position.

If a patient precollimator is utilized to reduce the radiation dose to the patient by approximately halving the emitted fan beam, the precollimator is placed at different locations in FIGS. 12 and 13. This is because the detectors are at different locations. When shifting modes,
Two such collimators can be provided instead of manually, or alternatively an automatic shifting device can be provided for shifting the collimators.

x with at least two different point sources of radiation? fM
A satisfactory stereoscopic resolution is obtained with a CT scanner as shown in FIGS. 12 or 13 with a source 1 and a reduced group of detectors. That is, a satisfactory Nyquist criterion can be achieved.

This is because the X-ray source 1 can emit radiation alternately from its at least two different radiation point sources. This doubles the sampling frequency and has a single radiation point source combined with a reduced group of detectors.
The stereoscopic resolution can be improved by a factor of two compared to that achieved in conventional rotary CT scanners with line tubes. In other words, a conventional rotary CT scanner can reproduce an image across 3600 degrees of data even after reducing the number of detectors, but the image has a reduced stereoscopic resolution. This is because the stereoscopic resolution of such scanners is constrained by the sample frequency. Furthermore, traditional rotary scanners with reduced detector arcs cannot increase stereoscopic resolution by μ-offsetting the gantry co-center, since this offset technique typically provides a complete 6, which requires an arc-shaped detector. However, as mentioned above, it is further preferred according to the invention to provide the scanner with an X-ray source 1 having at least two different point sources of radiation, and to provide means for emitting radiation alternately by the different point sources of radiation. by providing means for offsetting the gantry co-center by a distance equal to the effective detector pitch at the co-center.
The sampling frequency can be doubled and the resolution can be doubled.

The scanner of FIGS. 12 or 13 therefore has a stereoscopic resolution equal to that of a conventional rotary scanner with a full arc of detectors, i.e. twice as many detectors, and a conventional X-ray tube with a single focal point. resolution can be achieved. These conventional rotary scanners and Xa tubes require 360° rotation to achieve the same stereoscopic resolution. Figure 12 5
7--The scanner shown in FIG. 13 has much less aliasing artifacts due to patient movement. This means that the duration between interleaved samples, ie the time between switching between different point sources of radiation, is only a few tenths of a second, whereas in conventional scanners the additional data is generated only after the gantry has rotated 180°. Because they are obtained for interleaving, the duration between interleaving samples requires several seconds.

FIG. 14 shows a system in which the gantry co-center is offset by a distance i equal to the effective detector pitch at the co-center. The one in FIG. 14 is similar to, but different from, that in FIG. is the center of the detector D□ (located approximately diametrically opposite the X-ray source 1 on the gantry),
Offset the joint center "A" by a distance equal to the beam width A at the joint center from the line rLJ formed by the midpoint between two different point sources of radiation in the X-ray source 1 or This is the point where the joint center 58-"A" is offset to the midpoint of several different point sources provided within the source 1. The position of the joint center of the scanner in Fig. 12 is shown in Fig. 14 [A], νIJ
It is clear that the group of detectors 3 is offset to the right from the position of the group of detectors 30 in FIG. 12 by a distance equal to the beam width A at the joint center. The same geometric relationships exist for the system with the gantry co-centers viewed and offset.

As used above, the "beam width" at the concentric center is defined as the width of the x-ray beam moving from the focal point to a given detector.

FIG. 15 shows an X-ray tube 10 with a deflection device for deflecting the electron beam from one cathode 15 with a single filament 29 to a rotating anode 19. The continuous or intermittent beam from the filament 29 can be switched between two or more suitably spaced focal points 21.23 on the rotating anode 19. This switching is performed by means of voltage controls that control the voltages applied to the deflection plates 25, 27. Switching between foci may be accomplished by other means and is within the scope of the present invention.

The preferred embodiment of the present invention is a rotating CT scanner that employs a rotating anode X-ray tube, but a fixed anode tube may also be used. Also utilized are x-ray tubes having two filaments each floating relative to a cathode cup, each filament being alternately and separately pulsed relative to the cathode, effectively shifting the apparent focus back and forth. can.

Also, multiple x-ray tubes can be used to create multiple focal points. 2 each also has grid control
X-ray tubes can be provided. The point source of radiation shown in Figure 4 9.11 can be combined into a single X
It may be a radiation source or a pair of Xi sources. Also, magnetic devices can be used to deflect the electron beam to achieve multiple foci.

Furthermore, the preferred use of the invention is in rotary scanners, and the invention can also be incorporated into other types or types of scanners, i.e. (with or without) can be incorporated into translation-rotation or rotationally fixed or fully fixed multi-source actuation systems to increase sampling density and improve stereoscopic resolution.

The foregoing has merely explained the basic characteristics of the invention, and the invention can be modified in various ways without departing from the scope of the invention.

[Brief explanation of drawings]

FIG. 1 shows a rotary CT scanner according to the present invention, FIG. 2 shows the resolution of a conventional rotary scanner showing why the theoretical stereoscopic resolution decreases to IA according to the Nyquist theorem, and FIG. Figure 4 shows the shift of the detector to increase the sampling density, Figure 4 shows the shift of the detector focus to increase the sampling density, and Figure 5 shows the geometry of the rotary scanner in polar coordinates. , Figure 6 shows the polar geometry of data collected by a conventional rotary scanner with a single x-ray source, and Figure 7 shows the polar geometry of data collected by shifting the focus to increase sampling density. 8 shows a polar diagram of data collected by a conventional rotary scanner by increasing the angular sampling distance and data acquisition time, and FIG. 10 shows the use of a high-resolution collimator to increase the stereoscopic resolution, and FIG. A second embodiment of the invention using a high-resolution collimator to increase spatial resolution is shown in Figure 62-12, in which a fan-shaped beam with an apex angle α smaller than an apex angle β constituting the reduction is used. FIG. 13 shows a CT scanner that employs a transparent, multifocal X-ray source; FIG.
Figure 14 shows a CT scanner with offset concentric centers, and Figure 15 shows the use of deflection electrodes to deflect the electron beam between alternating different foci on the target electrode. It is a diagrammatic cross-sectional view. 1... Radiation source 3... Detector 5... Patient 6... Gantry 9.11... Radiation point source 10... X-ray tube 13...
Collimator 15...Cathode 16...Support member 1
7...Radiation beam 19...-Anode 21.23.
... Focus 25.27... Deflection plate 29... Filament 31... Rotation movement device 33... Point source alternate emission device 35... Center offset device 37... Radiation source shift device 39. ...Detector shift device. 63- Smell 19 Diagram 6 Anal Healing Bi 1.7 Hands H] 翫小1) Ri T-Ring Dark Side Procedural Amendments September 1989 Year/Day 1, Incident Indication 1988 Patent Application No. 158523 No. 2, Title of the invention: Radiographic diagnostic device and method 3, Relationship with the person making the amendment: Patent applicant's name: Elcinto Limited 4, Agent: Showa Year, Month, Date, Procedural Procedure Neho (Method): % Formula % 1. Indication of the case Patent Application No. 158523 filed in 1982. 2. Name of the invention. Radiographic diagnostic apparatus and method. 3. Person making the amendment. Relationship to the case. Name of patent applicant. Address: Hayakawa Building, 5-14-7 Hakusan, Bunkyo-ku, Tokyo Phone: Tokyo 946-0531 (Representative) November 2, 1980
7th 6th, subject of correction

Claims (1)

[Claims] 1. In an apparatus for diagnosing the body by transmitting radiation such as X-rays, ' (a) a transmitting radiation having at least two different point sources of radiation and transmitting radiation to the body; (c) a device for passing the radiation emitted from the radiation source through a plurality of passages through the body and detecting it by the detection device; d) A device for alternately emitting radiation from said at least two different point sources of radiation. 2. A patent claim in which a rotatable gantry for attaching the radiation source and the detection device is provided, and the device for passing the radiation emitted from the radiation source through the plurality of passages is provided with a device for rotationally moving the gantry. Apparatus according to scope 1. 3. the detection device is constituted by a plurality of individual detectors arranged substantially uniformly along an arc on the gantry;
The apparatus for alternately emitting radiation to said at least two different point sources of radiation includes alternately emitting radiation to said point sources at a frequency having a period approximately equal to the time required to rotate said gantry by a detector pitch. 3. A device according to claim 2, further comprising means for emitting. 4. The above-mentioned gun) The above-mentioned detection device is constituted by a plurality of individual detectors arranged substantially uniformly along an arc on the IJ, and the device for alternately emitting radiation to the above-mentioned point source of radiation is arranged at a detector pitch. 2.4.8.16... configured to cause the point source to alternately emit radiation at a frequency having a period approximately equal to the time required to rotate the gantry by a value multiplied by N, such as 2.4.8.16... A device according to claim 2, wherein the device is a device. 5.Rs is the distance from the radiation source mounted on the IJ to the rotatable joint center, Rd is the distance from each detector to the joint center, P is the detector pitch, and n is the radiation The number of different point sources, N, is o, i, 2...
3. The apparatus of claim 2, wherein said at least two point sources of radiation are separated by a predetermined distance approximately equal to R8/Rd*P(N+1/rl). 6. Claim 1, wherein the radiation source is provided with a target electrode that emits radiation when excavated by the electron beam, and a deflection device that deflects the electron beam between at least two different focal points on the target electrode. Equipment described in Section. 7. The apparatus according to claim 1, wherein the radiation source is provided with at least two X-ray tubes, each X-ray tube comprising a different point source of radiation. 8. The apparatus of claim 1, wherein the radiation source is an X-ray tube having at least two filaments, each filament forming a different point source of radiation. 9. Apparatus according to any one of claims 6.7 and 8, wherein the radiation source is provided with a stationary anode. 10. The apparatus according to any one of claims 6.7 and 8, wherein the radiation source is provided with a rotating anode. 11. The apparatus according to claim 1, wherein the radiation source emits a fan-shaped beam of radiation, and a collimator device is provided for reducing the width of the radiation beam detected by the detection device. . 12. The device according to claim 11, wherein the collimator device is a high-resolution collimator device. 13. The device according to claim 12, wherein the high-resolution collimator device is provided with a pin collimator. 14. The apparatus of claim 11, wherein the radiation source is provided with at least three different point sources of radiation. 15. A rotatable gun for attaching the radiation source and the detection device) An IJ is provided, and the device for passing the radiation emitted from the radiation source through the plurality of passages is provided with a device for rotationally moving the gantry, The detection device is constituted by a plurality of individual detectors arranged substantially uniformly along an arc on the gantry, and a plurality of collimators are provided corresponding to the collimator device, and the center of each collimator is set to the center of the detector. 12. Apparatus as claimed in claim 11, including means for aligning the centers and further offsetting the co-centers of the gantry by a distance equal to 14 of the effective pitch of the detectors at the co-centers. 16. A rotatable gantry for attaching the radiation source and the detection device is provided, and the device for passing the radiation emitted from the radiation source through the plurality of passages is provided with a device for rotationally moving the gantry, and the gantry The detection device is constituted by a plurality of individual detectors arranged substantially uniformly along the upper arc, and a plurality of collimators corresponding to the collimator device are provided, and the center of each collimator is located at the effective detector. Claim 11, further comprising means for offsetting the center of said detector by a pitch of 14 from the center of said detector and further offsetting the co-center of rotation of the gantry by a distance equal to the width of the effective detector pitch at said co-center. Device. 17. In a device that diagnoses the body by transmitting radiation such as X-rays, (a) a radiation source that transmits radiation to the body; (b)
a detection device that detects the radiation that has passed through the body; (e) a device that causes the radiation emitted from the radiation source to pass through a plurality of passages passing through the body and be detected by the detection device; (d) the detection device A diagnostic apparatus using radiographic transmission, comprising a shift device for shifting the radiation source relative to the radiation source. 18. When rotating the radiation source and the detection device around the body, at least two
18. Apparatus according to claim 17, characterized in that the shifting device is provided with means for periodically shifting the radiation source between different positions. 19. The radiation source is provided with a device for emitting a fan-shaped beam of radiation from each of the at least two point sources of radiation;
3. The device according to claim 2, wherein the apex angle of each of the fan-shaped beams is an apex angle α that is smaller than an apex angle β constituting the reduction molar. 20. The apparatus of claim 19, wherein the angle α is approximately A of the angle β. 21. The device according to claim 19, wherein the angle α is approximately in the range of 15° to 30°. 22. The detection device is provided with a plurality of individual detectors arranged on an arc spanning an apex angle α, one of the detectors on each side of the end of the arc being connected to the radiation source on the gantry. 20. A device as claimed in claim 19, substantially diametrically opposed to. 23. The apparatus of claim 22, further comprising means for offsetting the joint center of rotation of the gantry with respect to the radiation source and the detector by a distance equal to the effective detector pitch at the joint center. . 24. causing said point source of radiation to alternately emit radiation at a frequency with a period approximately equal to the time required to rotate said gantry by a detector pitch; An apparatus according to claim 19, which constitutes an apparatus. 25. The detector pitch is N=2.4.8.16...
alternating said point source of radiation so as to cause said point source to alternately emit radiation at a frequency approximately equal to the time required to rotate said gantry by an amount multiplied by the value of N such that 20. The device according to claim 19, wherein the device is configured to emit radiation. 26, RB is the distance from the X-ray source mounted on the gantry to the rotatable common center, Rd is the distance from each detector to the common center, P is the detector pitch, n
is the number of different point sources of radiation, N is Oll, 2..., separating said at least two point sources of radiation by a predetermined distance approximately equal to R8/RdXP(N+/n). Apparatus according to paragraph 19. 27. Claim 19, wherein the radiation source is provided with a target electrode that emits radiation when struck by an electron beam, and a deflection device that deflects the electron beam between at least two different focal points on the target electrode. Equipment described in Section. 28. Providing the radiation source with at least two X-ray tubes;
20. The apparatus of claim 19, wherein each x-ray tube comprises a different point source of radiation. 29. Device according to claim 19, characterized in that the radiation source consists of an X-ray tube having at least two filaments, each filament forming a different point source of radiation. 30. The apparatus of any one of claims 27.28 and 29, wherein the radiation source is provided with a stationary anode. 31. The device according to any one of claims 27, 28 and 29, wherein the radiation source is provided with a rotating anode. 32. The detection device according to claim 19, wherein the detection device is constituted by a plurality of individual detectors arranged substantially symmetrically with respect to the common center of the gantry and arranged on an arc extending an apex angle α. Device. 33. The device according to claim 32, further comprising a collimator device for reducing the width of the radiation detected by the detection device. 34. The device according to claim 33, wherein the collimator device is a high-resolution collimator device. 35. The device according to claim 34, wherein the high-resolution collimator device is provided with a pin collimator. 36. The apparatus of claim 33, wherein the radiation source is provided with at least three different point sources of radiation. 37. The plurality of individual detectors are arranged substantially uniformly along the arc on the gantry, and a plurality of collimators l0- are provided corresponding to the collimator device, and the center of each collimator is set at the center of the collimator. , a device for aligning the centers of the detectors and further offsetting the co-centers of the gantry by a distance equal to A of the effective pitch of the detectors at the co-centers.
The device according to item 3. 38. The plurality of detection devices are arranged evenly along the arc on the gantry, and a plurality of collimators corresponding to the collimator device are provided, and the center of each collimator is set at 14 times the detector pitch. 34. The apparatus of claim 33, further comprising means for offsetting the co-center of rotation of the gantry by a distance equal to the effective detector pitch at the co-center. . 39. The detection device is provided with a plurality of individual detectors arranged on the gantry extending the apex angle α, and further provided with a detector shifting device for moving the plurality of individual detectors on the gantry. An apparatus according to claim 19. 40. The detecting apparatus includes a device for moving the detector between a first position in which the detector is disposed asymmetrically with respect to the common center and a second position in which the detector is disposed symmetrically with respect to the common center. Claim 39 provided in the device shift device
Equipment described in Section. 41. A radiation source for transmitting radiation to a substantially flat part of the body, a detection device arranged to detect said radiation after passing through the body, and a plurality of said parts of the body to be detected by said detection device. improving the three-dimensional resolution of an image reproduced by a rotary scanner having a device for rotationally moving the radiation source and the detector around the circumference of the body to cause the radiation to traverse a path having the same extent as the body; The resolution of the scanner is characterized in that the sampling density is increased by continuously interleaving radiation beams between adjacent radiation beams when rotating the radiation source and the detection device around the body. How to improve. 42. The method of claim 41, wherein the radiation source is provided with at least two different point sources of radiation and radiation is emitted alternately from the at least two point sources of radiation. 43. The detection device is provided with a plurality of individual detectors arranged substantially uniformly along an arc on the gantry, and necessary for mounting the radiation source on the gantry and rotating the gantry by the detector pitch. 43. The method of claim 42, wherein radiation is emitted alternately from the at least two point sources at a frequency with a period approximately equal to a time. 44. The method according to claim 43, wherein a value obtained by multiplying the period by a value of N such as N=2.4.8.16, etc. is used as the period.