JPH02253183A - Spect device - 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] [Industrial application field]

The present invention relates to a nuclear medicine diagnostic device, and particularly to a ring type S
Regarding PECT equipment.

[Conventional technology]

In a ring-shaped SPECT device, a large number of radiation detectors are arranged in a ring shape, and a ring-shaped collimator is arranged concentrically inside the ring shape. This collimator is, for example, a so-called turbofan collimator, and has a large number of radiation incident direction defining holes at each position in the circumferential direction, and the direction of the holes is different at each position in the circumferential direction. When rotated concentrically within the shaped detector array, the direction of the radiation incident on each detector is scanned over the required range. Then, when a single photon radionuclide RI (radioisotope) is administered to a human subject, etc., and when it accumulates in a specific organ, etc., the ring-shaped arrangement of the detector and the ring-shaped collimator concentric therewith are activated. The subject is inserted inside and radiation from the RI is incident on each detector through a collimator to collect data. By performing image reconstruction processing on this data, RI inside the subject is
A tomographic image is created that shows the state of distribution in two dimensions. In such a ring-type SPECT device, various corrections such as linear interpolation and absorption correction are required, but conventionally, the data collected is processed later and these corrections are performed to create a sinogram. This is used to reconstruct images.

PROBLEM TO BE SOLVED BY THE INVENTION 1 However, in the conventional method of correcting a take once collected, the processing takes time and it takes a very long time to complete the image. SUMMARY OF THE INVENTION An object of the present invention is to provide a SPECT apparatus that can significantly shorten the time required to produce an image even when performing various corrections. [Means for Solving the Problems] In order to achieve the object stated in 1., SPECT according to the present invention
The device includes a number of radiation detectors arranged in a link shape, a ring-shaped collimator that rotates and is arranged concentrically inside the ring-shaped arrangement of the detectors, and a rotation angle signal of the collimator and a radiation incidence signal. a first conversion means that obtains a view number and a detector address in the linear direction based on a signal from the detector where an event has occurred; and storage means for adding up each take as one of the plurality of linear addresses for each event.

[For production]

It is known in advance at which position and in which direction the radiation incident direction defining hole is located in the circumferential direction of the ring-shaped collimator. Therefore, when a radiation incident event occurs in a certain detector and a signal is obtained from it, if the rotation angle signal of the collimator at that time is known, it can be determined in which direction the hole is located in the front of the detector. It becomes clear what happened. By this principle it is possible to obtain from the first conversion means a number representing the direction of the radiation and a detector address representing the position of the detector in a direction perpendicular to that direction (linear direction). In this way, when a detector address is obtained in response to a radiation incident event l- on a certain detector, the second conversion means converts multiple linear addresses on the cytogram corresponding to this detector address and those linear addresses. You can get a take. By determining the conversion contents of the second conversion means according to absorption correction, linear interpolation, etc., it is possible to obtain a corrected take for each event in real time and add it directly to the storage means. Therefore, the corrected data will be accumulated one after another in the storage means, and the corrected sinogram will be created directly in this storage means. Therefore, a corrected sinogram is completed as soon as the data is completed, and the time required for image reconstruction is significantly reduced.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows the present invention as a multi-slice type SPEC.
1 shows an embodiment applied to a T device, in which a subject 11 is inserted into a cylindrical array of a cylindrical collimator 13 and a radiation detector 14. In this embodiment, the cylindrical collimator 13 is a turbofan collimator that has a large number of radiation incident direction defining holes in the circumferential direction, and the direction of the holes gradually changes in the circumferential direction. They are stacked on top of each other to form a cylindrical shape as a whole. The detectors 14 are also arranged in a ring direction and also in an axial direction, so that it can be said that the link-shaped arrangement is stacked in multiple layers to form an overall cylindrical shape. Assume that radiation 12 as shown by the dotted line in FIG. 1 is emitted from the RI inside the subject 11, passes through the hole of the collimator 13, and enters one detector 14. Then,
A signal is generated from the detector 14, and this signal is sent to a position signal generation circuit 21 to obtain a circumferential position signal and a slice direction position signal indicating in which detector 14 an event has occurred. On the other hand, the cylindrical collimator 13 is rotating, and its rotation angle signal is obtained from the rotary encoder 22. In addition, the signals from the detector 14 are sent to an energy discrimination circuit 23, and when the energy is within a predetermined range, a gate signal is generated, and these signals include a circumferential position signal, a slice direction position signal, and a collimator rotation angle. The signal is transferred by gate 24. The thus transferred collimator rotation angle signal and circumferential direction position signal are input to the conversion table 25. This conversion table 25 is composed of a RAM and the like, and converts these input signals into a view number indicating the direction of the incident radiation 12 and a detector address indicating the detector position in a direction perpendicular to this direction (linear direction). (See Figure 2). For example, the detector address is 1.2, ..., 192.
It is output as a quantized number like . This detector address and view number are sent to a conversion table 27 composed of a RAM or the like. For example, the detector address is number j
If so, it is converted to number n as shown in FIG. 2 in the conversion table 27 according to the input detector address and view number. This number n indicates the linear address of the sinogram, and is a number from 1 to 64, for example. This detector address is also sent to the count up circuit 28, which sequentially generates a signal to increment the number n by one. Therefore, for each detector address that occurs in response to an event, n, n+1 . n+2. n
+3. A plurality of linear addresses like n+4 are sequentially output from the conversion table 27 and sent to the memory address generation circuit 29.
sent to. At the same time, weighted data such as 7.10.15.8.3 is generated for each of these five linear addresses. Further, when the count up circuit 28 sequentially generates a signal to increment the number n by 1, it simultaneously generates a write signal sequentially and sends it to the memory 30. On the other hand, the slice direction position signal passed through the gate 24 is RA
The memory 30 is stored in the memory 30 by the conversion table 26 composed of M, etc.
The offset signal is converted into an offset signal indicating where to write, and sent to the memory address generation circuit 29. Since the above-mentioned linear address and view number are sent to this memory address generation circuit 29, an address signal corresponding to these is generated, and the above-mentioned weighted data is transferred to the above-mentioned n, n+1, . n+2. n+3゜n−
Data will be sequentially written into sections corresponding to linear addresses 1-4. In this way, data is written to the memory 30 for each event 1, so that when the data collection time, which is performed while the cylindrical collimator 13 rotates, ends, a sinogram as shown in FIG. 3 is completed. Here, data is collected by distributing the information obtained from one event to multiple linear addresses of the sinogram using predetermined weights as shown in Figure 2, and these weights are used for desired purposes such as absorption correction and linear interpolation. Since it can be determined according to the processing, it is possible to directly create a sinogram while accumulating data processed in real time for each event. Therefore, once the data collection is completed, the desired processed sinogram is completed, and the time required for image reconstruction is significantly reduced. Specifically, the above weights are R constituting the conversion table 27.
Since it depends on the contents of the AM, it is easy to rewrite it, and it can easily correspond to various processes such as absorption correction and linear interpolation. This weight is actually the collimator 13
Determined by experiment etc. depending on the shape etc.

【Effect of the invention】

According to the SPECT apparatus of the present invention, data that has been subjected to predetermined processing is collected in real time for each radiation incident event, so a processed sinogram is completed at the same time as data collection is completed, and therefore it takes time to reconstruct the image. The time can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation, and FIG. 3 is a diagram showing a sinogram. DESCRIPTION OF SYMBOLS 11... Subject, 12... Radiation, 13... Cylindrical collimator, 14... Detector, 21... Position signal generation circuit, 22... Rotary encoder, 23...
Energy discrimination circuit, 24...gate, 25.26.2
7... Conversion table, 28... Count up circuit,
29...Memory address generation circuit, 30...Memory.

Claims (1)

[Claims] (1) A large number of radiation detectors arranged in a ring shape, a ring-shaped collimator that is arranged concentrically inside the ring-shaped arrangement of the detectors and rotates, and a rotation angle signal of the collimator and a radiation incident event. a first conversion means that obtains a view number and a detector address in the linear direction based on a signal from the detector in which a and a storage means for adding each data as data of the plurality of linear addresses for each event.
PECT device.