JPH02253184A - Camera rotation type SPECT device - Google Patents

Abstract

PURPOSE:To improve the space resolution of a tomographic image by providing a means which detects the incidence position of radiant rays and pinhole type collimator means set to a detector. CONSTITUTION:A pinhole collimator 6 is formed to a cone as the whole and has one pin hole 61 at the apex. This pinhole collimator 6 is set to a detector 5, and the detector 5 is rotated around a body 1 to be examined and is stopped at every prescribed angle of rotation to gather data, and therefore, data related to radiant rays which are converged to the pinhole 61 and are made incident in radial directions is obtained at every prescribed angle of rotation. Since the pinhole collimator 6 is used, an angle theta of coverage of the pinhole 61 is different in each position of the detector, and the sensitivity is not uniform in respective positions. Therefore, the sensitivity is corrected in accordance with the difference of the angle theta. Data interpolated, rearranged, and subjected to sensitivity correction in this manner is sent to an image reconstituting device to obtain the tomographic image superior in space resolution.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a nuclear medicine diagnostic device, and in particular to a camera rotation type S P E CT (Single Photon
EmissionComputer Tomograp
hy) Regarding the device.

[Conventional technology]

The SPECT device uses a single photon-emitting nuclide, R1.
(radioisotope) is administered to a subject, such as a human body,
The distribution of RI inside the subject is photographed as a tomographic image, and camera rotation type SPECT equipment rotates a two-dimensional radiation incidence position detector, such as a gamma camera, around the subject. This is the type that obtains directional projection data. In conventional camera rotation type SPECT devices, a parallel collimator is generally attached to the front of the gamma camera.

[Problem to be solved by the invention]

However, when using a parallel collimator, there is a problem that the spatial resolution is not good. An object of the present invention is to provide a camera rotation type SPECT apparatus in which spatial resolution is improved by using a pinhole collimator in place of a conventional parallel collimator.

[Means to solve the problem]

In order to achieve the above object, the camera rotation type SPECT apparatus according to the present invention includes a detection means for detecting the incident position of radiation, a pin-pole type collimating means attached to the detector, and a collimating means attached to the detector. a rotation means for rotating the detected detection means; a means for collecting data output from the detection means; a means for rearranging the data so as to collect data in the same direction; It is characterized by being equipped with a correction means for correcting data at each position according to the viewing angle, and means for performing image reconstruction processing on the rearranged and corrected data.

[For production]

When a pinhole type collimating means is attached to the front of the detection means, the radiation passing through the pinhole will be incident on the detection means, so projection data of parallel radiation can be obtained from the detection means at a certain rotation angle. isn't it. Therefore, data obtained from detection means located at different rotation angles are selected and rearranged to convert them into projection data. Further, when the pinhole type collimating means is attached to the front surface of the detection means, the angle at which the pinhole is viewed differs depending on the position on the detection surface of the detection means, so the sensitivity will differ at each position. Therefore, this difference in sensitivity is resolved by correcting the data at each position according to the angle at which the pinhole is viewed from each incident position of the detection means. By performing image reconstruction processing using data rearranged in this manner and with sensitivity corrected, a tomographic image representing the distribution of RI can be obtained. In this case, the magnification function of the pinhole type collimating means provides expanded data regarding the distribution of RI, and the tomographic image is reconstructed from this, so that the spatial resolution of the tomographic image can be improved.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a subject 1 is lying on an ECT bed 2, and a detector 5 equipped with a pinhole collimator 6 is held by an arm 4 and rotated around the subject 1. It looks like this. The detector 5 is a so-called gamma camera that two-dimensionally detects the incident position of radiation. The arm 4 extends from the gantry 3, and the gantry 3 is provided with a rotation mechanism. In this embodiment, the pinhole collimator 6 has a conical overall shape, and has one pinhole 61 at its apex. In this way, the pinhole collimator 6 is attached to the detector 5, and the detector 5 rotates around the subject 1 and stops at every predetermined rotation angle to collect data. As shown in FIG. 3, data regarding the radiation incident in the radial direction that converges on the pinhole 61 is obtained. The position signal obtained from the detector 5 is recorded in a recording device 7, such as a magnetic disk device, together with the rotation angle signals obtained from the guns 1 to 3, as shown in FIG. When the detector 5 rotates once and data is collected, the computer 8 reads this data from the recording device 7 and sends it to the interpolator 9 for interpolation of the data in angular and linear directions. Then select parallel data (for example, P and Q in FIG. 3) from among the data collected by the parallelizing device 10 or by placing the detector 5 at various angles as shown in FIG. Arrange in a linear direction. In this way, projection data is created as if it were collected from various angles using a parallel collimator. Furthermore, the correction device 11 corrects non-uniformity in sensitivity due to the use of the pinhole collimator 6. That is, when the pinhole collimator 6 is used, the angle θ at which the pinhole 61 is viewed differs at each position of the detector 5, as shown in FIG. 4, so that the sensitivity becomes non-uniform at each position. Therefore, the sensitivity is corrected according to the difference in angle θ. The interpolated, rearranged, and sensitivity-corrected data are sent to the image reconstruction bag W12, and a tomographic image is reconstructed using an image reconstruction algorithm such as filter projection back projection. This reconstructed image is stored in the image memory 13 for display.
The tomographic image is sent to the display device 14 via the display device 14, and the tomographic image is displayed on the display device 14. Note that although the configuration described above is such that interpolation, rearrangement, sensitivity correction, etc. are processed using hardware, it is of course possible to process them using software. Further, the order of these processes does not have to be the above order. Furthermore, when using the pinhole collimator 6 having one pinhole 61 as described above, only a tomographic image on one plane created by the movement locus of the pinhole 61 can be obtained;
A multi-slice tomographic image may be obtained using a multi-hole pinhole collimator 62 as shown in FIG. In this multi-hole pinhole collimator 62, a large number of pinholes 61 are arranged on one straight line parallel to the rotation center axis 20, and are arranged inside so that the radiation passing through each pinhole 61 is separated from each other. The pinholes 61 are partitioned by a partition plate in the direction in which the pinholes 61 are arranged. If such a porous pinhole collimator 62 is used,
Tomographic images of the same number of slices as the number of pinholes 61 can be obtained simultaneously.

【Effect of the invention】

According to the camera rotation type SPECT apparatus of the present invention, it is possible to obtain a tomographic image with excellent spatial resolution, so it is particularly effective when obtaining an enlarged image of a small organ or the like.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a block diagram of the embodiment, Fig. 3 is a diagram for explaining data sorting, and Fig. 4 is a diagram for explaining sensitivity correction. Figure, 5th
The figure is a perspective view of another embodiment. 1... Subject, 2... Bed, 3... Gantry,
4... Arm, 5... Detector, 6... Pinhole collimator, 7... Recording device, 8... Computer, 9... Interpolation device, 10... Sorting device, 11.
...Correction device, 12...Image reconstruction device, 13...
Image memory, 14... Display device, 20... Rotation center axis, 61... Pinhole, 62... Porous pinhole collimator. So

Claims (1)

[Claims] (1) A detection means for detecting the incident position of radiation, a pinhole type collimating means attached to the detector, a rotating means for rotating the detection means to which the collimating means is attached, and an output from the detection means. means for collecting data in the same direction; means for rearranging the data so as to collect data in the same direction; and correction means for correcting the data at each position according to the angle at which the pinhole is viewed from each incident position of the detection means; A camera rotation type SPECT apparatus comprising means for performing image reconstruction processing on the rearranged and corrected data.