JP2000258535A - Scintillation camera device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect a tomographic image where the prominent defect of each of step and continue modes by calculating the tomographic image of a subject from a plurality of projection data. SOLUTION: A detector 2 detects γ rays being emitted from an RI(radioactive isotope) in the body of a subject 1. A collection circuit 3 collects γ-ray signals from the detector 2 and integrates a number of γ rays to obtain the projection data of an RI distribution in the body of the subject 1. A CPU 4 controls the image collection operation of the collection circuit 3. A detector gantry 5 rotates the detector 2 in the direction of a periphery A of the subject 1, moves the detector 2 in a direction B for bringing it closer to or away from the subject 1, or moves the detector 2 in a horizontal direction C for the subject 1. Also, a top bed 6 supports or moves the subject 1 in the direction of a height D from a floor surface. The operation of the detector gantry 5 and the top bed 6 is controlled by the CPU 4 via a gantry control circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for projecting radiation from various directions around a subject while rotating a detector around the subject to which a drug containing a radioisotope (RI) is administered. These projection data are reconstructed and computed tomographic images (single photon emission,
The present invention relates to a scintillation camera device for obtaining a computer tomography (SPECT) image.

[0002]

2. Description of the Related Art A conventional scintillation camera device is
As disclosed in Japanese Patent Application Laid-Open No. 10-268054, radiation such as γ-rays emitted from a drug containing RI administered to a subject is detected, and a distribution image of RI in the subject is obtained. It is a medical diagnostic device. In such a scintillation camera device, a detector is rotated around a subject, and a SPECT image is obtained using the principle of an X-ray CT device. This data collection method is roughly classified into the following two types.

[0003] A first acquisition method is a method called a step (STEP) mode, in which a detector is rotated around a subject by a certain angle and image data is acquired when the detector is stopped. is there. This collection method is, for example, 2
This is a method suitable for obtaining a high-definition SPECT image even over a time period of 0 to 30 minutes. The second acquisition method is a method called a continuity (CONTINUE) mode in which the detector is rotated around the subject at a constant speed to obtain a distribution image for each angle range. This collection method
This is a method suitable for obtaining a SPECT image even if fineness is somewhat sacrificed within a short time of, for example, 5 minutes or less.

[0004]

However, there is a problem in that one step mode is high definition but requires an acquisition time, and the other continuous mode does not require an acquisition time but lacks image definition. Was. The purpose of the present invention is
An object of the present invention is to provide a scintillation camera device capable of performing a method of acquiring a SPECT image in which a noticeable drawback of each of the step and continue modes is improved.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a detector which administers a drug containing RI into a subject and collects radiation emitted from the drug as projection data. A scintillation camera device having a gantry section that alternately rotates and stops around a person, the first projection data collected while the detector is stopped, and the second projection data collected while the detector is rotated. And a means for calculating a tomographic image of the subject from the first projection data and the second projection data.

[0006] Further, the detector gantry section includes the first gantry.
And the second projection data are controlled so as to have an area overlapping in the rotation direction. Specifically, in the step mode acquisition method, radiation is detected during at least one of the rotation operations immediately before or immediately after a detector that has not conventionally acquired an image, and these detected radiation and the conventional radiation are detected. The radiation detected in the step mode is obtained as projection data, and S
This is achieved by calculating a PECT image.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the scintillation camera device of the present invention will be described with reference to the drawings. FIG.
1 is a block diagram of a scintillation camera device of the present invention.

[0008] The scintillation camera device includes a detector 2 which is arranged to face a subject 1 who has administered a drug containing RI.
A collecting circuit 3 electrically connected to the detector 2, a CPU 4 electrically connected to the collecting circuit 3, a detector gantry 5 rotatably supporting the detector 2, and a subject 1. A gantry control circuit 7 is provided which is electrically connected to the top bed 6 and the detector gantry 5.

[0009] The detector 2 detects γ-rays emitted from the RI in the subject 1. The collection circuit 3 collects γ-ray signals from the detector 2 and integrates many γ-rays to obtain projection data of the RI distribution in the subject. CPU
Reference numeral 4 controls the image acquisition operation of the acquisition circuit 3. That is, the detector gantry 5 rotates the detector 2 in the direction (A) around the subject 1 and moves the detector 2 in the direction (B) approaching or moving away from the subject 1, or The detector 2 is moved in the horizontal (C) direction with respect to the examiner 1. Further, the top bed 6 supports and moves the subject 1 in the height (D) direction from the floor surface. The operations of the detector gantry 5 and the top bed 6 are controlled by the CPU 4 via the gantry control circuit 7.

[0010] In such a scintillation camera device, projection data from each direction around the subject is collected and reconstructed in the same manner as an X-ray CT device, so that the distribution of RI in the subject can be obtained by a SPECT image. Can be obtained as
In the SPECT image collection operation, as shown in FIG. 3, the detector 2 is rotated around the subject 1 at a constant angular interval k to collect projection images from each direction.

For example, when obtaining a projection image in 64 directions around the subject, the angular interval is k = 360 ÷ 64 = 5.625.
It rotates sequentially every degree. The number of direction divisions is not necessarily limited to 64, but may be 92, 128, 60, 120 or the like. The acquired projection data from each direction is sent from the acquisition circuit 3 of FIG. 1 to the CPU 4, and the data processing device performs SPECT by a well-known reconstruction operation process of the X-ray CT device.
An image is obtained.

FIG. 2 is a time chart showing the operation, angle and projection data acquisition of the detector 2 in the SPECT image acquisition method according to the present invention. In this data collection method, the i-th projection data (data (i)) is collected in the following three steps. (A) The detector 2 has an angle range θ (i) −k / 2−θ (i)
The projection data is collected while rotating at. (B) The detector 2 stops at the angle θ (i), and for a certain time To
During this time, projection data is continuously collected. (C) The detector 2 is in the angular range θ (i) to θ (i) + k / 2
The projection data is collected in the state of rotating at.

Here, the projection data (data (i)) is
In addition to the collection of projection data in the conventional step mode shown in (b), the collection of projection data at the end of rotation shown in (a) and the collection of projection data at the start of rotation shown in (c) are performed. Will be

More specifically, when i = 1, the projection data (data (1)) obtains the projection data of the above (b) at an angle of 0 degree, and then the angle range of the detector 2 ranges from 0 to k. At / 2 degrees, the projection data of (c) is obtained. The projection data of (c) also serves as the projection data of (c) of the data (2). As described above, after the angle k / 2, projection data is collected while repeating rotation or stop until the next projection data (data (2) to data (N) closest to the angle of 360 °). Finally, the projection data obtained at the time of rotating around the subject by 360 ° and returning to the position of the projection data (data (1)) is collected as the above (a) of the data (1).

Here, the overlap between the projection data at the time of stop and the projection data at the time of rotation is set to の of the radiation incidence surface of the detector 2.
It was decided to set as. By setting the overlap of these projection data as の of the radiation incident surface of the detector 2, it is suitable for reducing the blur of the projection data.
This is because the projection data of (a) and the projection data of (c) have the same contribution.

With the above operation, SPECT image acquisition can be performed by effectively using the time during which no acquisition is performed in the conventional step mode. For example, the stop time To of the detector 2 in each direction is To
Is 10 seconds, the time required for rotation in each direction is 1 second, and the number of direction divisions is 64, the total time required for SPECT image acquisition is 10 × 64 + 64 = 704 seconds = 11 minutes and 44 seconds.

Since the projection data is collected even during the rotation of the detector, the collection time in each direction is 10 + 1 = 11.
Seconds. The time during which the detector is rotating is 1 second among the 11 seconds of the acquisition time, so the contribution of the collected data when the detector is operating is smaller than the contribution of the collected data when the detector is stopped. Blur in a SPECT image can be eliminated.

As described above, according to the present embodiment,
While minimizing blurring of the image due to the rotation of the detector,
SPECT image acquisition with improved acquisition efficiency can be performed. Also,
The overlap of the projection data at the time of stop and the projection data at the time of rotation,
The example in which the radiation incidence surface of the detector 2 is set to １ ／ of the radiation incidence surface has been described.
Needless to say, a T image is obtained.

As described above, the invention made by the present inventor is:
Although specifically described based on the embodiment of the present invention, the present invention is not limited to the embodiment of the present invention,
It goes without saying that various changes can be made without departing from the gist of the invention.

[0020]

The present invention has the effect of providing a scintillation camera device capable of performing a method of acquiring a SPECT image in which the remarkable drawbacks in each of the step and continue modes are improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a scintillation camera device of the present invention.

FIG. 2 is a time chart showing the operation of the detector of the present invention.

FIG. 3 is a principle diagram of SPECT image acquisition.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Examinee 2 Detector 3 Collection circuit 4 CPU 5 Detector gantry 6 Top bed 7 Gantry drive circuit

Claims (1)

[Claims] 1. A detector for administering a drug containing a radioisotope into a subject, collecting radiation emitted from the drug as projection data, and alternately arranging the detector around the subject. In a scintillation camera device provided with a gantry unit for rotating and stopping, first projection data collected when the detector is stopped and second projection data collected while the detector is rotated are respectively used. A scintillation camera apparatus comprising means for collecting and calculating a tomographic image of a subject from the first projection data and the second projection data.