JPS5956181A - Ring type single photon ect device - Google Patents

Abstract

PURPOSE:To obtain different tomographic images without increasing the number of detector layers, by arranging a Hadamard mask on the radiant rays incidence side of each radiant rays detector, and reconstituting plural tomographic images at different positions at one-slot intervals of Hadamard masks. CONSTITUTION:Each radiant rays detector consists of a scintillator 11, light guide 12, and a photomultiplier 13. Many radiant rays detectors are arranged annularly in a ring type radiant rays detector array and Hadamard masks 14 serving as collimators are arranged inside of the array, i.e. on radiant rays incidence sides of scintillators 11. Those Hadamard masks 14 are moved, slot by slot, by one slot at right angles to tomographic images and a cyclic Hadamard matrix corresponding to the array order of the opening parts and shield parts of the Hadamard masks 14 is made to operate on detector outputs obtained at respective positions and also standardized to obtain data.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a ring type single phone ECT device.

As is well known, the ring-type single photon ECT device arranges a large number of radiation detectors in a single layer in a ring shape around the subject at one tomographic plane 1- of the subject. The radiation emitted from the radioactive diffraction element of the single photon-emitting nuclide contained in is incident on each radiation detector through a collimator, and the incident angle IJHη
By discarding the data regarding the number of incident radiations and processing this data with a computer, a tomographic image is constructed of an AJ image corresponding to the concentration of the radiation outer A* element in the tomographic plane of the object.

By the way, in a conventional ring-type single photon ECT device, when attempting to obtain multilayer tomographic images at the same time, it is necessary to configure it using a link-type radiation detector array with a number of layers equal to the number of layers. There is.

Each layer's ring-shaped radiation detector array obtains a tomographic image for each layer. However, in this configuration, even though a large number of radiation detectors for one layer is safe and expensive, it becomes increasingly expensive.

In view of (-), this invention is capable of obtaining multi-layer tomographic images with a radiation detector for one layer, and has no negative impact on sensitivity.
The purpose of the present invention is to provide a ring-type single photon ECT device that is a paper storage.

1 Please refer to the drawings for an embodiment of this invention! Explain while asking questions. In FIG. 1, the radiation detector consists of a scintillator 11, a light guide 12, and a light multiplier 13. ), and the scintillation light is emitted from this long scintillator 11.
(In order to guide the photoelectric current f l (i times fi'i' l 3), there is no optical coupling between the scintillator 11 and the photoelectric multiplication + i'i; t 3 by the light guide 12. Thus, the structure is A large number of radiation tIJtja detectors are arranged in a ring shape.A Hadamard mask 14, which also serves as a collimator, is arranged inside the ring-shaped radiation detector array, that is, on the radiation incident side of the wrench 1/-tor 11. Ru.

This Hadamard mask 14 is made of lead etc. Q) b
As shown in Figure 2, the fault thickness direction 11 is
For example, (1, 0, 1, 1, 1, 0, They are arranged periodically in the order of 0), and are moved in the direction of the fault thickness, that is, in the direction of the arrow in FIG. Therefore, the Hadamard mask 14 is safe for at least two cycles.

Here, the number of incident radiations is counted by the output of the radiation detector 111 at each position of movement for each l slot I-, and yl, y2 . y3. y4. y5. y6. y7
Suppose that the measured values of are obtained. The number of radiation incident on each l slot is XI number 6fi/41 as X =
If (x142.z3.++445.++64'?), then there is a relationship of (yl, y2.y3.y4.y5.yEl, y7)-that is, Y=MX. Here, M is actually NX where L and O circulate.
H mask matrix (N is 7 in this case).

Therefore, to find the unknown X from the l1llll constant value Y, NX
Create a cyclic Atamard matrix H1 of N, and perform ;+W of X=-(2/N+1)xIIY. Thus, the radiation for the feature layer plane for every l slot spacing of the Hadamard mask 14, -1 numerical matrix X = (zl, x243.g4.z54647)
+li appears. Note that -(2/N+1) is normalized '>'1. 'It's a number.

Therefore, in the ring-type single-phone ECT device of this embodiment, seven pieces of data can be obtained from different pieces of the device in the cross-sectional thickness direction, so even though the ring-type array of radiation detectors is in one layer, seven It is possible to configure 111 different tomographic images. Moreover, there are few kankaku low de. I mean,
1. Even if you move the mask instead of the Hadamard mask 14 as shown in the example below, which has an opening of only 1 front with the opening 11 and the other b front as a shielding part, seven tomographic images will be obtained in the same way. In this case, the opening u=j/
, is 1/7, so the sensitivity is significantly lower.
If you use Agemar Mask, the open 11 rate will be 1. This is because in the embodiment described above, the sensitivity is as large as 4/7, so that there are few low sensitivity waves.

In addition, in the embodiment described in I-, 1 of the Agemar mask 14
The period consisted of 7 fronts, and 7 tomographic images were obtained.
The number of melons in one cycle is not limited to this, and the number of tomographic images obtained is not limited to 1. Hadamard matrices other than 1-item can also be used. The radiation detector can also be a combination of a scintillator and a photoelectric detector (i"i/11).

In addition, instead of configuring the Agemar mask and collimator in one body as in Example 1-1, it is possible to configure them with separate body numbers.
[7] A Agemar mask may be placed between the collimator and the scintillator. In this case, the collimator 1
It is preferable that the opening n + l be equal to the interval of one front of the Agemar mask, or an integer fraction of this interval.

As described in Example 11 below, the ring-type single-photon ECT device according to the present invention allows different It is economical because a large number of fault images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view schematically showing an ECT device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram for explaining the operation of the same embodiment. 11...Scintillator 12...Light guide 13...Photomultiplier tube 14...Hadamard mask patent applicant Shimadzu Corporation

Claims (1)

[Claims] (1) A predetermined tomographic plane 1 of the subject using multiple radiation detectors:
is arranged in at least one layer in a ring shape around the subject, and the radiation emitted from the radioactive isotope of the single photon-emitting Inno-1 nuclide contained in the subject is incident on each radiation detector through a collimator. A ring-shaped single photon is used to reconstruct the out-of-concentration 4j image of radioactive elements in the tomographic plane of the object as a tomographic image by obtaining data on the number of incident radiation for each incident angle and processing this data with a computer. In the ECT device, a Hadamard mask is disposed on the radiation incident side of each of the radiation detectors, in which openings and shielding portions are periodically arranged in a predetermined order at intervals of one front in a direction perpendicular to the tomographic plane;
When this Hadamard mask is moved one slot at a time in a direction perpendicular to the tomographic plane and one period of movement is performed, the output of the radiation detector obtained at each position is determined by the open 1-1 portion of the Hadamard mask. applying and normalizing a cyclic Hadamard matrix corresponding to the arrangement order with the shielding part, and obtaining data for each interval in the direction perpendicular to the tomographic plane corresponding to one slot interval of the Hadamard mask;
A ring-type single photon ECT''J arrangement, characterized in that a plurality of tomographic images at different positions are constructed at an interval of one slot 1u of the Hadamard mask.