JP2010190669A - Nuclear medicine diagnostic device and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain measurement accuracy by performing detailed sampling while preventing images from deteriorating owing to statistical noise. <P>SOLUTION: This nuclear medicine diagnostic device is for detecting gamma rays as projection data by a detector 30, with the gamma rays emitted by a nuclide given to an inspected body M, to obtain an image showing the distribution of the nuclide in the interior of the inspected body M. This diagnostic device includes a data collector 61 for collecting projection data at regular time intervals, a data accumulator 62 for accumulating the collected projection data in the data collector 61, and an image data preparer 63 for preparing image data based on projection data corresponding to a prescribed period of time out of the projection data accumulated in the data accumulator 62. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a nuclear medicine diagnostic apparatus and an image processing apparatus such as a gamma camera apparatus that detects radiation emitted from a nuclide (radioisotope: RI) administered to a subject and images an RI distribution from the detection information. In particular, it relates to an improved collection method for measuring temporal changes in the distribution of radiopharmaceuticals.

  Conventionally, a drug labeled with a radioisotope (hereinafter referred to as “RI”) is administered into a subject, and a gamma ray emitted from the RI is detected and measured. There has been provided a nuclear medicine diagnostic apparatus that images the state of distribution in a specimen (for example, see Patent Document 1).

  The main methods of nuclear medicine examination include a planar method (capturing a still image of a subject from a certain direction) and a SPECT method (single photon emission computed tomography: SPECT).

  In the case of nuclear medicine examination, it usually takes several minutes to several tens of minutes to collect the projection data. A dynamic acquisition method is known as a method of photographing such a dynamic (time change) distribution of RI. The dynamic acquisition method is a method of imaging an RI distribution that changes with time by acquiring images (frames) continuously in time. This makes it possible to measure the time change of the RI distribution.

FIG. 4 is an explanatory diagram showing the principle of the dynamic collection method. In order to observe the function of the heart H, RI can be administered, and the heart H can be diagnosed by detecting temporal changes in the intensity of gamma rays incident from the RI. At this time, in order to detect a change in time, a general observation time (for example, 100 seconds) is equally divided by a predetermined number of samplings (for example, 10), and incident within an equally divided collection time (for example, 10 seconds). The time change is obtained based on the collection count of gamma rays.
JP 2003-121549 A

  The nuclear medicine diagnostic apparatus described above has the following problems. That is, as the acquisition time of one image (frame) in the dynamic acquisition is shorter, it is possible to measure the temporal change of the RI distribution with fine sampling. However, since the collection time per image (frame) is shortened, there is a problem that the collection count is lowered and the statistical noise is increased.

  Conversely, if the acquisition time of one image (frame) is lengthened, the statistical noise is reduced, but there is a problem that the sampling becomes rough and the measurement accuracy of the time change of the RI distribution deteriorates.

  Accordingly, an object of the present invention is to provide a nuclear medicine diagnostic apparatus and an image processing apparatus that can maintain measurement accuracy by performing fine sampling while preventing image deterioration due to statistical noise.

  In order to solve the above problems and achieve the object, the nuclear medicine diagnostic apparatus and the image processing apparatus of the present invention are configured as follows.

  In the nuclear medicine diagnostic apparatus, the radiation emitted from the nuclide administered into the subject is detected as projection data by a radiation detector, and an image showing the distribution of the nuclide in the subject is obtained based on the projection data. A data collection unit that collects data, a data accumulation unit that accumulates projection data collected in the data collection unit, and projection data for a predetermined time among projection data accumulated in the data accumulation unit And an image data creation unit for creating image data.

  In an image processing apparatus that creates an image of a subject with time change, a data collection unit that collects basic image data of the subject at regular time intervals, and basic image data collected in the data collection unit is stored A data storage unit and an image data generation unit that generates image data based on basic image data for a predetermined time among the basic image data stored in the data storage unit are provided.

  According to the present invention, it is possible to maintain measurement accuracy by performing fine sampling while preventing image degradation due to statistical noise.

  FIG. 1 is an explanatory diagram showing a configuration of a gamma camera device 10 according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the principle of the gamma camera device 10, and FIG. 3 is an explanatory diagram showing an image reconstruction process. is there. Since the image processing apparatus is one form of the gamma camera apparatus 10, only the gamma camera apparatus 10 will be described here.

  The gamma camera device 10 includes a gantry 20 installed on the floor, a couch device 50 installed in the vicinity of the gantry 20, and a control device 60 connected to the gantry 20 and the couch device 50.

  The gantry 20 is provided with a tunnel portion 21 so that the subject M can be inserted. A detector 30 is disposed in front of the tunnel portion 21. The detector 30 includes a pair of camera heads 31 and 32 facing each other. The camera heads 31 and 32 may be any of the conventional anger type and the semiconductor array type that has been practically used in recent years. In the case of the unger type, a scintillator that generates flash by receiving gamma rays is placed behind the collimator that limits the incident direction of gamma rays, and a plurality of photomultiplier tubes are placed behind the scintillator with a light guide in between. It is the structure arranged densely. In the case of a semiconductor array type, semiconductor elements that detect incident gamma rays as electrical signals having an amplitude corresponding to the energy are arranged two-dimensionally behind the collimator.

  The camera heads 31 and 32 are arranged around the subject while maintaining the positional relationship so that an arbitrary positional relationship such as a position facing the subject M and a position shifted by 90 ° can be taken. It can be rotated.

  The outputs of the camera heads 31 and 32 are input to the control unit 64, and the position where the gamma rays are incident and the energy of the gamma rays are calculated.

  The couch device 50 includes a couch 51 fixed to the floor, and a couch top plate 52 provided on the couch 51 and inserted into the tunnel portion 21 of the gantry 20. The bed top plate 52 moves in a direction penetrating the tunnel portion 21, and the subject M is laid thereon.

  The control device 60 includes a data collection unit 61 that collects projection data detected by the detector 30 at regular intervals, a data accumulation unit 62 that accumulates projection data collected in the data collection unit 61, and a data accumulation unit. 62 includes an image data creation unit 63 that creates image data based on projection data for a predetermined time out of the projection data stored in 62, and a control unit 64 that controls these and sets various parameters. .

  The gamma camera device 10 configured as described above creates an image as follows. Here, for example, a case where a planer image is created using the heart H as a target organ will be described. First, collection parameters such as collection time T and overlap time P are set (ST10). Then, a drug RI labeled with a radionuclide that emits gamma rays is administered to the subject M. Next, the subject M is laid on the couch top 52. Then, the couch device 50 is driven, and the couch top plate 52 is moved to a position where the 3D image collection area 43 faces the measurement target, for example, the heart H.

  Next, data collection is started. The data collection method uses list mode collection that collects detected signals (incident gamma rays) one by one. That is, a data collection start signal is output from the control unit (timing generation unit) 63 at a predetermined timing, and each time the data collection start signal is detected, the data collection unit 61 collects projection data for a predetermined collection time T. A data group is created (ST11) and stored in the data storage unit 62. Note that one piece of projection data includes information on a gamma ray incident position (two-dimensional coordinates) and an incident time.

  Next, the image data creation unit 63 creates an image (frame) by post-processing based on the collection time, image size, and the like set for this data group. At this time, images (frames) are created so as to overlap for the designated overlap time P (ST12).

  For example, when the collection time T is 10 seconds and the overlap time P is 5 seconds, when the total observation time is 100 seconds, the first frame (0 to 10 seconds), the second frame (5 to 15 seconds), ..., 19 images (frames) of the 19th frame (90 to 100 seconds) are obtained. Since the collection time T of each image (frame) is 10 seconds, the sampling interval is halved to 5 seconds without changing the influence of statistical noise. Therefore, it is possible to prevent image degradation due to statistical noise, and it is possible to maintain image measurement accuracy by performing fine sampling.

  The image (frame) created in this way is stored as data on an external disk or the like (ST13). The data is subjected to application analysis (ST14), and the heart H is diagnosed.

  The collection time T and the overlap time P are preferably changed as appropriate depending on the observation target and the type of RI.

  As described above, according to the gamma camera device 10 according to the present embodiment, it is possible to maintain measurement accuracy by performing fine sampling while preventing image degradation due to statistical noise.

  The present invention is not limited to the above embodiment. For example, although a gamma camera device has been described as an example of a nuclear medicine diagnostic device, it may be applied to a PET device. Moreover, you may make it use for image processing apparatuses other than a nuclear medicine diagnostic apparatus. Of course, various modifications can be made without departing from the scope of the present invention.

Explanatory drawing which shows the structure of the gamma camera apparatus which concerns on one embodiment of this invention. Explanatory drawing which shows the image reconstruction principle in the same gamma camera apparatus. Explanatory drawing which shows the image reconstruction process in the same gamma camera apparatus. Explanatory drawing which shows the image reconstruction principle in the dynamic acquisition in the conventional gamma camera apparatus.

  DESCRIPTION OF SYMBOLS 10 ... Gamma camera apparatus, 20 ... Stand, 30 ... Detector, 50 ... Bed apparatus, 60 ... Control apparatus, 61 ... Data collection part, 62 ... Data storage part, 63 ... Image data creation part, 64 ... Control part.

Claims (4)

In a nuclear medicine diagnostic apparatus that detects radiation emitted from a nuclide administered into a subject as projection data by a radiation detector, and obtains an image showing the distribution of the nuclide within the subject based on the projection data.
A data collection unit for collecting the projection data;
A data storage unit for storing the projection data collected in the data collection unit;
A nuclear medicine diagnosis apparatus, comprising: an image data creation unit that creates image data based on projection data for a predetermined time among projection data stored in the data storage unit. In a nuclear medicine diagnostic apparatus that detects radiation emitted from a nuclide administered into a subject as projection data by a radiation detector, and obtains an image showing the distribution of the nuclide within the subject based on the projection data.
A timing generator that outputs a data collection start signal at a predetermined timing;
A data collection unit that collects the projection data for a predetermined collection time each time a data collection start signal from the timing generation unit is detected;
The nuclear medicine diagnosis apparatus, wherein the data collection start signal is generated at an interval shorter than the predetermined collection time. In an image processing apparatus for creating an image of a subject with time change,
A data collection unit for collecting basic image data of the subject at regular intervals;
A data storage unit for storing basic image data collected in the data collection unit;
An image processing apparatus, comprising: an image data creation unit that creates image data based on basic image data for a predetermined time among the basic image data stored in the data storage unit. In an image processing apparatus for creating an image of a subject with time change,
A timing generator that outputs a data collection start signal at a predetermined timing;
A data collection unit that collects image data for a predetermined collection time each time a data collection start signal from the timing generation unit is detected,
The image processing apparatus, wherein the data collection start signal is generated at an interval shorter than the predetermined time.

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