JP4408480B2 - Positron emission CT system - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a positron emission CT apparatus (hereinafter abbreviated as “PET”) that displays projection data, and more particularly to PET that efficiently displays a large amount of projection data obtained by a three-dimensional projection data collection method.
[0002]
[Prior art]
Conventional PET is disclosed in JP-A-7-229969.
[0003]
As described in the above publication, development of PET capable of obtaining projection data with extremely high resolution in the body axis direction of the subject has progressed, and the projection data includes not only a single-channel detector ring but also a plurality of projection data. Since it is generated for each opposed position of the detector ring group of the channel, its use has expanded from the conventional collection of two-dimensional projection data to the collection of three-dimensional projection data.
[0004]
Since the projection data is generated for each opposing position of the detector ring group, the number of projection data is the square of the number of detector channels (for example, 32 channels), and a large amount of projection data (for example, 1024). You will get
[0005]
In order to display such a large amount of projection data on a display device, for example, projection data of different channels are sequentially changed (hereinafter referred to as “scroll”) and displayed on the screen of the display device. A so-called scroll display is provided.
[0006]
[Problems to be solved by the invention]
However, the scroll display has a problem that it takes time to find interesting projection data such as an affected part in the projection data.
[0007]
An object of the present invention is to provide a PET that can quickly find projection data of interest.
[0008]
[Means for Solving the Problems]
The object is to provide a plurality of detector rings for detecting radiation emitted from a medicine containing a radioisotope disposed around a subject and administered to the subject, and detection values of radiation from the detector ring. Based on the projection circuit stored as projection data and the projection data stored in the counting circuit, either one of the pair of detection values counted simultaneously is assigned as R1 coordinate and the other is assigned as R2 coordinate, and the coordinate conversion is performed. A conversion table storage unit, means for reading out the total value of the detection values for each of the R1 and R2 coordinates, and an amount for correcting overflow of pixel data of projection data based on the total value of the read detection values Based on the output of the frequency divider circuit, the R1 coordinate and the R2 coordinate are arranged in a matrix, and the total value of the detected values is used as projection data for each square. Display means for displaying, wherein the display means further displays projection data of a predetermined area selected based on the displayed projection data in association with R1 coordinates and R2 coordinates. This is achieved by a positron emission CT device.
[0009]
Usually, because different from a projection data of the projection data and the lesion normal region, it is possible to quickly find a characteristic portion of the projection data of the lesion is in the normal region.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the PET of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is a block diagram showing an embodiment of PET according to the present invention, FIG. 2 is a diagram showing an example of displaying projection data on the monitor of FIG. 1, and FIG. 3 is projection data selected by the display of FIG. It is a figure which shows an example which displays.
[0012]
PET includes a plurality of detector rings 2a, 2b, ... For detecting radiation emitted from a radiation source in a subject 1 to which a drug containing a radioisotope is administered, and detection of radiation from these detector rings. counting circuit 3a for storing the value as projection data, and 3b · · ·, counting circuit 3a, a conversion table storage unit 4 for coordinate transformation at the time of being connected to 3b · · · displaying projection data, the conversion table storage unit 4 Is connected to the frequency dividing circuit 5 for correcting the overflow of the projection data read from the conversion table storage unit 2, the memory circuit 6 connected to the frequency dividing circuit 5 for storing the output of the frequency dividing circuit 5, and the memory circuit 6. an image processing device 7 for a so-called image processing to display the output of the memory circuit 6 downstream of the monitor 8, a monitor 8 for displaying an output of the image processing apparatus 7 connected to the image processing apparatus 7, The number circuit 3a, connected to each element of 3b · · · to monitor 8 and a CPU9 for controlling each of these elements. Here counting circuit 3a, the projection data stored in 3b · · · the detector ring 2a, and that of 2b · · ·.
[0013]
Based on the projection data stored in the counting circuits 3a, 3b,..., The conversion table storage unit 4 assigns and adds one of a pair of detection values simultaneously counted as R1 coordinates and the other as R2 coordinates. . The CPU 9 reads the total value of the detection values for each R1 coordinate (row) and R2 coordinate (column) . The sum value (projection data) of the read detection values often exceeds the bit width of the pixel data of the projection data, so-called overflow in many cases. In order to correct this overflow, the frequency dividing circuit 5 is used to correct the overflow so as to be within the bit width. The output of the frequency dividing circuit 5 is sent to the memory circuit 6 and displayed on the monitor 8 as shown in FIG.
[0014]
As shown in FIG. 2, the R1 coordinates and the R2 coordinates are arranged in a matrix, and the total value of the detection values obtained there is displayed on the monitor 8 as projection data on each cell. The operator looks at the display on the monitor 8 and selects projection data of an area that is a total value of characteristic detection values . Further, the projection data of the area may be selected by calculating the total value of the characteristic detection values by the CPU 9. The selected area is a portion surrounded by a thick frame in the figure. For example, it is assumed that the coordinates of the upper left corners of R1 and R2 are (10, 10), and the matrix 10 × 10 is an area of the sum of characteristic detection values . The projection data of the matrix 10 × 10 designated in the above area is displayed on the monitor 8 as shown in FIG. 3 through the frequency dividing circuit 5, the memory circuit 6, and the image processing device 7. Here, the frequency dividing circuit 5 does not perform frequency division, and the projection data is output as it is.
[0015]
As shown in FIG. 3, the coordinates of the upper left corners of R1 and R2 are (10, 10), and projection data of a matrix 10 × 10 is displayed on the monitor 8. This makes it possible to quickly find a region of interest that has been difficult with the conventional scroll display.
[0016]
The display data is registered in an external storage means such as a magnetic disk separately provided in the database in association with, for example, cases and projection data. Image diagnosis can be supported by comparing projection data registered in the database with projection data of the same case obtained in the past.
[0017]
The database can also be used for PET maintenance and inspection by registering test data using a single radiation source.
[0018]
According to the embodiment described above, it is possible to quickly find projection data in a three-dimensional measurement mode that occurs in large quantities, and it is possible to read the fluctuation of the projection data as a count value or a distribution pattern of the count value. .
[0019]
【The invention's effect】
The present invention has the effect of providing a PET that can quickly find projection data of interest.
[0020]
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of PET according to the present invention.
FIG. 2 is a diagram showing an example of displaying projection data .
FIG. 3 is a diagram showing an example of displaying projection data selected by the display of FIG. 2;
[0021]
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Subject, 2a, 2b Detector ring, 3a, 3b Count circuit, 4 Conversion table memory | storage part, 5 Frequency dividing circuit, 6 Memory circuit, 7 Image processing apparatus, 8 Monitor, 9 CPU

Claims (2)

A plurality of detector rings for detecting radiation emitted from a medicine including a radioisotope disposed around the subject and administered to the subject;
A counting circuit for storing detected values of radiation from the detector ring as projection data;
Based on the projection data stored in the counting circuit, a conversion table storage unit that performs coordinate conversion by assigning and adding one of a pair of detected values simultaneously counted as R1 coordinates and the other as R2 coordinates;
Means for reading the sum of the detected values for each of the R1 and R2 coordinates;
A frequency dividing circuit for correcting an overflow of pixel data of projection data based on the total value of the read detection values;
Display means for displaying the R1 coordinate and the R2 coordinate in a matrix, and displaying the total value of the detection values as projection data on each square based on the output of the frequency divider circuit;
With
The positron emission CT apparatus , wherein the display means further displays projection data of a predetermined area selected based on the displayed projection data in association with R1 coordinates and R2 coordinates .   2. The positron emission CT apparatus according to claim 1, wherein the projection data of the selected predetermined area is output without being divided by the frequency dividing circuit.

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