JP5398381B2 - Nuclear medicine imaging apparatus and image processing program - Google Patents

Description

  The present invention relates to a nuclear medicine imaging apparatus and an image processing program.

  Conventionally, nuclear medicine diagnostic apparatuses such as a gamma camera, a single photon emission CT apparatus (SPECT apparatus), and a positron emission CT apparatus (PET apparatus) are medical image diagnostic apparatuses capable of performing functional diagnosis on a living tissue of a subject. It is widely used in today's medical field (see, for example, Patent Document 1).

  The nuclear medicine diagnostic device detects gamma rays emitted from radiopharmaceuticals that are administered to a subject and selectively taken into the body tissue of the subject, and generates a nuclear medicine image from the detected dose distribution of the gamma rays. To do. Specifically, the SPECT device and the PET device generate projection data from the dose distribution of gamma rays detected by the detector, and back-project the generated projection data, so that the biopharmaceutical distribution of the radiopharmaceutical administered to the subject A nuclear medicine image (SPECT image or PET image) which is a tomographic image in which is drawn is reconstructed. That is, the SPECT apparatus and the PET apparatus reconstruct the nuclear medicine image in which the distribution of the tumor tissue incorporating the radiopharmaceutical is depicted, so that the function information on the biological tissue of the subject can be obtained from the doctor performing the image diagnosis. provide.

  The position resolution of the nuclear medicine image is a value determined by the system configuration of the nuclear medicine diagnosis apparatus such as the performance of the detector and the data collection method. Here, since the position resolution of a nuclear medicine image is generally a large value (for example, 1 cm), a phenomenon called a partial volume effect (PVE) may occur in the nuclear medicine image. Are known.

  In PVE, due to poor position resolution, the pixel values of nuclear medicine images are small (underestimated) in hot areas where radioactive materials are accumulated, and large (overexaggerated) in cold areas where radioactive materials are not accumulated. This is a phenomenon that becomes an evaluation. That is, in order to accurately measure the distribution of the radiopharmaceutical in the body, it is necessary to correct (PVE correction) a change in pixel value due to PVE in the nuclear medicine image.

  For this reason, a recovery coefficient for performing correction so that the pixel value of the hot area becomes a true value is calculated in advance from the volume of the area determined as the hot area in the nuclear medicine image and the position resolution. A technique for performing PVE correction by multiplying a pixel value by a recovery coefficient is known. However, PVE correction of nuclear medicine images using a recovery factor is effective when radioactive substances are accumulated only at one point in the body, but in fact, radioactive substances are accumulated only at one point in the body. Because it is impossible, it is not a practical correction technique.

  Therefore, a technique for performing PVE correction of a nuclear medicine image by a deconvolution method is known. As described above, the position resolution of the nuclear medicine image is known from the system configuration of the nuclear medicine diagnostic apparatus, and in the PVE correction of the nuclear medicine image by the deconvolution method, the deconvolution integration process is performed by the distribution function determined by the position resolution. It is.

JP 2007-107995 A

  However, the above-described deconvolution method has a problem that the PVE of the nuclear medicine image cannot be corrected accurately and easily due to the factors described below. That is, since the deconvolution method is a high-frequency enhancement filter, noise is emphasized, and in the PVE correction of the nuclear medicine image by the deconvolution method, the S / N ratio of the nuclear medicine image may be deteriorated.

  In addition, the deconvolution method is a correction process that is realized only in the case of infinitely fine sampling. However, in the PVE correction of the nuclear medicine image by the deconvolution method, the nuclear medicine is a finite sampling in units of pixels. In some cases, the S / N ratio of the image deteriorates.

  In addition, in the PVE correction of a nuclear medicine image by the deconvolution method, since a constraint condition in the correction process cannot be added, the amount of calculation required for the correction process may be enormous.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and a nuclear medicine imaging apparatus and an image processing program capable of easily and accurately correcting a partial volume effect of a nuclear medicine image. The purpose is to provide.

In order to solve the above-described problems and achieve the object, the present invention provides a nuclear medicine imaging apparatus for generating a nuclear medicine image by detecting radiation emitted from a nuclide administered to a subject, the nuclear medicine Maximum value extraction means for extracting the maximum value from the pixel values of the pixels constituting the region of interest set in the image, and extraction by the maximum value extraction means even if the pixel value decreases due to the position resolution of the own device the estimate the maximum value which is presumed to be obtained by an estimation value calculating means for calculating with a predetermined coefficient determined from the position resolution, the estimated value calculated by the estimated value calculation detecting means A plurality of images that are determined as a maximum value, a plurality of values obtained by dividing the maximum value by a predetermined number of divisions, and each of the determined plurality of values is a pixel value of each pixel constituting the region of interest The first picture Image quality degradation using a response function determined by the position resolution for each image of the first image group generation unit generated as a group and the first image group generated by the first image group generation unit By performing the processing, a second image group generation unit that generates a second image group, and each image of the second image group generated by the second image group generation unit and the region of interest And a corrected image selecting means for calculating difference information by subtracting pixel values of corresponding pixels between them and selecting an image that minimizes the calculated difference information as a corrected image in which the region of interest is corrected. It is characterized by that.

The present invention also provides an image processing program for causing a computer to execute an image processing method for performing image processing of a nuclear medicine image generated by detecting radiation emitted from a nuclide administered to a subject. The maximum value extraction procedure for extracting the maximum value from the pixel values of the pixels constituting the region of interest set in the medical image, and the pixel value decrease due to the position resolution of the nuclear medicine imaging apparatus that generated the nuclear medicine image occurs. However, the estimated value calculation procedure for calculating the estimated value estimated to obtain the maximum value extracted by the maximum value extracting procedure using a predetermined coefficient determined from the position resolution, and the estimated value calculation the estimated value calculated by the procedure exits as the upper limit value, determining a plurality of values obtained by dividing by the upper limit value preset division number, a plurality of values the determined said A first image group generation procedure for generating a plurality of images as pixel values of each pixel constituting the heart region as a first image group; and the first image group generated by the first image group generation procedure A second image group generation procedure for generating a second image group by performing an image quality deterioration process using a response function determined by the position resolution for each image of the image group, and the second image group The difference information is calculated by subtracting the pixel value of the corresponding pixel between each image of the second image group generated by the generation procedure and the region of interest, and an image in which the calculated difference information is minimized And a corrected image selection procedure for selecting the corrected region of interest as a corrected image.

  According to the invention of claim 1 or 4, it is possible to easily and accurately correct the partial volume effect of the nuclear medicine image.

FIG. 1 is a diagram for explaining a configuration of a SPECT apparatus according to the present embodiment. FIG. 2 is a diagram for explaining the configuration of the image processing unit. FIG. 3 is a diagram for explaining setting of a tumor region. FIG. 4 is a diagram for explaining the setting information storage unit. FIG. 5 is a diagram for explaining a maximum value extraction unit, an estimated value calculation unit, a first image group generation unit, and a second image group generation unit. FIG. 6 is a diagram for explaining the corrected image selection unit. FIG. 7 is a diagram for explaining the corrected SPECT image generation unit. FIG. 8 is a flowchart for explaining the image processing of the SPECT apparatus in this embodiment. FIG. 9 is a diagram for explaining a modification of the present embodiment.

  Exemplary embodiments of a nuclear medicine imaging apparatus and an image processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. Hereinafter, a case where the present invention is applied to a single photon emission CT apparatus (SPECT apparatus) which is a nuclear medicine imaging apparatus will be described.

  First, the configuration of the SPECT apparatus in this embodiment will be described. FIG. 1 is a diagram for explaining a configuration of a SPECT apparatus according to the present embodiment. As shown in FIG. 1, the SPECT apparatus according to the present embodiment includes a gantry device 10 and a console device 20.

  The gantry device 10 is a device that collects projection data by detecting gamma rays emitted from a radiopharmaceutical administered to the subject P and selectively taken into the living tissue of the subject P. The bed 12 includes a bed driving unit 13, a gamma camera 14, and a camera driving unit 15. As shown in FIG. 1, the gantry device 10 has a cavity serving as a photographing port.

  The top plate 11 is a bed on which the subject P lies, and is placed on the bed 12. The couch driving unit 13 moves the subject P into the imaging port of the gantry device 10 by moving the couch 12 under the control of the couch controller 23 described later.

  The gamma camera 14 two-dimensionally detects the intensity distribution of gamma rays emitted from a radiopharmaceutical nuclide (RI: Radio Isotope) that is selectively taken into the living tissue of the subject P, and detects the detected two-dimensional gamma ray intensity. For example, the distribution data is an apparatus that generates projection data by performing amplification processing and A / D conversion processing, and transmits the generated projection data to a data collection unit 25 described later. For example, the gamma camera 14 is a scintillator that converts emitted gamma rays into light having a peak in the ultraviolet region, and a photomultiplier tube (PMT) that is a semiconductor element array that multiplies light emitted from the scintillator and converts it into an electrical signal. Photomultiplier Tube). In this embodiment, a case where only one gamma camera 14 is installed will be described. However, the present invention is applicable even when a plurality of gamma cameras 14 are installed.

  The camera drive unit 15 is a device that moves the gamma camera 14 under the control of a camera control unit 24 described later. For example, the camera drive unit 15 drives the gamma camera 14 to rotate along the imaging port of the gantry device 10, whereby the gamma camera 14 rotates around the subject P to project projection data in a 360 degree direction. Is generated.

  The console device 20 accepts the operation of the SPECT device by the operator, and at the same time, a nuclear medicine image (SPECT) that is a tomographic image depicting the distribution of the radiopharmaceutical administered to the subject P from the projection data collected by the gantry device 10. Device).

  Specifically, as illustrated in FIG. 1, the console device 20 includes an input unit 21, a display unit 22, a bed control unit 23, a camera control unit 24, a data collection unit 25, and an image reconstruction unit 26. The image processing unit 27, the data storage unit 28, and the system control unit 29. The units included in the console device 20 are connected via an internal bus.

  The input unit 21 includes a mouse, a keyboard, and the like used by the operator of the SPECT apparatus for inputting various instructions and various settings, and transfers the instructions and setting information received from the operator to the system control unit 29.

  In the present embodiment, various instructions and various setting information received by the input unit 21 from the operator will be described in detail later.

  The display unit 22 is a monitor that is referred to by the operator, and displays a SPECT image or the like to the operator under the control of the system control unit 29 or various instructions and various settings from the operator via the input unit 21. For example, a GUI (Graphical User Interface) is received.

  The data collection unit 25 collects projection data transmitted from the gamma camera 14, and corrects each collected projection data by performing correction processing such as logarithmic conversion processing, offset correction, sensitivity correction, and beam hardening correction. Processed projection data is generated, and the generated corrected projection data is stored in the data storage unit 28.

  The image reconstruction unit 26 reads the corrected projection data from the data storage unit 28, and performs the back projection process on the read corrected projection data (for example, the corrected projection data for the 360 degree direction), thereby performing SPECT. Reconstruct the image. Then, the image reconstruction unit 26 stores the reconstructed SPECT image in the data storage unit 28.

  The image processing unit 27 reads the SPECT image from the data storage unit 28, performs image processing on the read SPECT image, and stores the image processed SPECT image in the data storage unit 28. The contents of the image processing executed by the image processing unit 27 of this embodiment will be described in detail later.

  The system control unit 29 performs overall control of the SPECT device by controlling the operations of the gantry device 10 and the console device 20. Specifically, the system control unit 29 controls the couch control unit 23 and the camera control unit 24 to execute the projection data collection process in the gantry device 10. Further, the system control unit 29 controls the entire image processing in the console device 20 by controlling the correction processing of the data collection unit 25 and the image generation processing of the image reconstruction unit 26 and the image processing unit 27. Further, the system control unit 29 controls the display unit 22 to display the images (SPECT image and image processed SPECT image) stored in the data storage unit 28.

  Here, the position resolution of the SPECT image, which is a nuclear medicine image, is a value determined by the system configuration of the SPECT apparatus, such as the performance of the gamma camera 14, the projection data collection method, and the SPECT image reconstruction method. In nuclear medicine images, it is known that a phenomenon called partial volume effect (PVE) occurs due to poor position resolution. PVE is a phenomenon in which the pixel value of a nuclear medicine image becomes a small value (underestimation) in a hot area where radioactive substances are accumulated, and a large value (overestimation) in a cold area where radioactive substances are not accumulated. In order to accurately determine the distribution of radioactive substances in the body, it is necessary to correct the PVE.

  Therefore, the SPECT apparatus according to the present embodiment is mainly capable of accurately and easily correcting the partial volume effect of the nuclear medicine image (SPECT) by the image processing of the image processing unit 27 described in detail below. There are features.

  This main feature will be described with reference to FIGS. 2 is a diagram for explaining the configuration of the image processing unit, FIG. 3 is a diagram for explaining the setting of the tumor region, and FIG. 4 is a diagram for explaining the setting information storage unit. FIG. 5 is a diagram for explaining the maximum value extraction unit, the estimated value calculation unit, the first image group generation unit, and the second image group generation unit, and FIG. 6 explains the correction image selection unit. FIG. 7 is a diagram for explaining the corrected SPECT image generation unit.

  As shown in FIG. 2, the image processing unit 27 in this embodiment includes a setting information storage unit 27a, a maximum value extraction unit 27b, an estimated value calculation unit 27c, a first image group generation unit 27d, and a second image. A group generation unit 27e, a correction image selection unit 27f, and a correction SPECT image generation unit 27g are included.

  First, in order to start processing by the image processing unit 27, the operator inputs a display request for a SPECT image to be corrected for PVE via the input unit 21. Then, the system control unit 29 reads the SPECT image (correction target SPECT image) corresponding to the display request transferred from the input unit 21 from the data storage unit 28 and displays it on the monitor of the display unit 22.

  Then, as shown in FIG. 3, the operator refers to the correction target SPECT image displayed on the monitor of the display unit 22 and sets a tumor region that is a region of interest for which PVE correction is performed. That is, the operator limits the PVE correction to the estimated tumor region in order to obtain an accurate distribution of the radiopharmaceutical in the tumor region estimated to be a tumor because RI is accumulated in the correction target SPECT image. And set it as a region of interest.

  In addition, although the present Example demonstrated the case where a tumor area | region was set with a correction object SPECT image, this invention is not limited to this, For example, it is X-ray in the same cross section as a correction object SPECT image. The case where the tumor region estimated by the operator to be a tumor by referring to the X-ray CT image obtained by imaging the subject P by the CT apparatus may be set as the tumor region in the correction target SPECT image. Moreover, the case where the image which estimates a tumor area | region may be a case where it is a MRI image which the MRI apparatus image | photographed the test subject P in the same cross section as a correction | amendment SPECT image.

  Further, the present invention reconstructs a SPECT image and an X-ray CT image obtained by photographing the same cross section of the subject P in a SPECT-CT apparatus in which a SPECT apparatus and an X-ray CT apparatus are integrated, and a correction target SPECT image At the same time, the tumor region estimated by the operator to be a tumor by referring to the reconstructed X-ray CT image may be set as the tumor region in the correction target SPECT image.

  Returning to FIG. 2, the setting information storage unit 27 a stores setting information used for processing of the estimated value calculation unit 27 c, the first image group generation unit 27 d, and the second image group generation unit 27 e. Specifically, as illustrated in FIG. 4A, the setting information storage unit 27a includes “recovery coefficient: R”, “number of divisions: n”, and “response function: h (t)”. Store as setting information. The setting information is input in advance by the operator via the input unit 21 and stored in the setting information storage unit 27a by the system control unit 29.

  Here, “recovery coefficient: R” is a numerical value determined from the position resolution of the SPECT apparatus. Specifically, as shown in FIG. It was assumed that the pixel value distribution that was spread due to the underestimation of the values and the overestimation of the pixel values of the RI non-integrated region was the pixel value distribution derived from the RI integrated at one point in the body. It is a value for correcting to be an ideal value in the case. For example, the recovery coefficient is set as a value that becomes an ideal value by multiplying the pixel value.

  The “response function: h (t)” is a function determined from the position resolution of the SPECT apparatus. Specifically, the true intensity distribution in the frequency (t) direction of the gamma ray is actually measured. Used to estimate the intensity distribution, for example, a function as shown in FIG. In other words, the true intensity distribution in the frequency direction of gamma rays becomes “blurred intensity distribution” due to position resolution when actually measured, but “response function: h (t)” is “blurred intensity distribution due to position resolution”. Is a function that is generally used in the convolution method. The “number of divisions: n” shown in FIG. 4A will be described in detail later.

  Returning to FIG. 2, the maximum value extraction unit 27b extracts the maximum value (Pmax) from the pixel values of the pixels constituting the tumor region set in the correction target SPECT image, as shown in FIG. To do.

  Returning to FIG. 2, the estimated value calculation unit 27 c recovers the recovery coefficient stored in the setting information storage unit 27 a to the maximum value (Pmax) extracted by the maximum value extraction unit 27 b as illustrated in FIG. An estimated value (Imax = Pmax × R) is calculated by multiplying (R). That is, when it is assumed that the RI accumulated in the tissue of the subject P corresponding to the tumor region is concentrated on one pixel constituting the tumor region, the estimated value calculation unit 27c “Imax = Pmax × R” is calculated as an estimated value for which it is estimated that “Pmax” can be obtained even if the pixel value decrease due to the position resolution occurs.

  Returning to FIG. 2, the first image group generation unit 27d uses the estimated value “Imax” calculated by the estimated value calculation unit 27c as an upper limit value, and the setting information storage unit 27a stores the upper limit value “number of divisions: “n values” divided by “n” are determined. For example, when the number of divisions is 100, the first image group generation unit 27d sets the upper limit value to “Imax” and the lower limit value to “0” as shown in FIG. , “100 values” are determined by dividing the value in the range of “0 to Imax” into 100 levels. The lower limit value is not limited to “0”, and may be set as a value corresponding to “0.5%” of the upper limit value, for example.

Then, the first image group generation unit 27d generates, as the first image group, a plurality of images in which each of the determined “n values” is the pixel value of each pixel constituting the tumor region. For example, as shown in (C) of FIG. 5, when the number of pixels constituting the tumor region is “k”, the first image group generation unit 27 d uses the determined “100 values” for each pixel. A first image group made up of “100 ^k ” images as pixel values is generated.

Returning to FIG. 2, the second image group generation unit 27e stores “response function: h” stored in the setting information storage unit 27a for each image of the first image group generated by the first image group generation unit 27d. A second image group is generated by performing a process using “(t)”. That is, as shown in FIG. 5D, the second image group generation unit 27e changes the image quality of each image in the first image group to the position resolution by “response function: h (t)” determined by the position resolution. By degrading (blurring) accordingly, a second image group consisting of “100 ^k ” images is generated. When the response function is processed, the position resolution of each image in the second image group is the same as the position resolution of each image in the first image group without decreasing.

  Returning to FIG. 2, the corrected image selection unit 27 f performs difference information by subtracting pixel values of corresponding pixels between the images of the second image group generated by the second image group generation unit 27 e and the tumor region. Is calculated. For example, as illustrated in FIG. 6, the corrected image selection unit 27 f calculates the average of each image in the second image group from the difference value of the pixel values of the corresponding pixels between each image in the second image group and the tumor region. Calculate the root mean-square error (RMSE).

  Then, as illustrated in FIG. 6, the corrected image selection unit 27 f selects an image that minimizes the calculated RMSE as a tumor region corrected image in which the tumor region is PVE corrected.

  Returning to FIG. 2, the correction SPECT image generation unit 27g generates a correction SPECT in which the correction target SPECT image is corrected by replacing the tumor region correction image selected by the correction image selection unit 27f with the tumor region. That is, as shown in FIG. 7, the corrected SPECT image generation unit 27g uses the tumor region correction image (see FIG. 6) selected by the correction image selection unit 27f as the correction target SPECT image. A corrected SPECT image is generated by replacing the region (see FIG. 3).

  Then, the system control unit 29 displays the corrected SPECT image generated by the corrected SPECT image generating unit 27g on the monitor of the display unit 22. Each of the corrected image selection unit 27f and the corrected SPECT image generation unit 27g stores the tumor region correction image and the corrected SPECT image in the data storage unit 28, and the system control unit 29 selects the correction image selection unit 27f. It is also possible to display the tumor region corrected image on the monitor.

  Next, image processing of the SPECT apparatus in the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart for explaining the image processing of the SPECT apparatus in this embodiment.

  As illustrated in FIG. 8, when the SPECT apparatus according to the present embodiment receives a correction request SPECT image display request from the operator via the input unit 21 (Yes in step S101), the system control unit 29 includes a data storage unit. The correction target SPECT image is read from 28 and displayed on the monitor of the display unit 22 (step S102).

  Then, the system control unit 29 determines whether or not a tumor region has been set by an operator who refers to the correction target SPECT image displayed on the monitor of the display unit 22 (step S103).

  When the tumor region is not set (No at Step S103), the system control unit 29 continues the determination process at Step S103.

  On the other hand, when the tumor region is set (Yes at Step S103), the maximum value extraction unit 27b is controlled from the pixel values of the pixels constituting the tumor region set in the correction target SPECT image by the control of the system control unit 29. A value (Pmax) is extracted (step S104).

  Then, the estimated value calculation unit 27c multiplies the maximum value (Pmax) extracted by the maximum value extraction unit 27b by the recovery coefficient (R) stored in the setting information storage unit 27a to estimate the value (Imax = Pmax × R) is calculated (step S105).

  After that, the first image group generation unit 27d sets the estimated value “Imax” calculated by the estimated value calculation unit 27c as an upper limit value, and sets the upper limit value to “number of divisions: n” stored in the setting information storage unit 27a. A plurality of divided values (n values) are determined (step S106).

  Subsequently, the first image group generation unit 27d generates a first image group including a plurality of images in which each of the determined plurality of values (n values) is a pixel value of each pixel constituting the tumor region. (Step S107).

  Then, the second image group generation unit 27e stores “response function: h (t)” stored in the setting information storage unit 27a for each image of the first image group generated by the first image group generation unit 27d. By performing the process using, a second image group in which each image of the first image group is “blurred” according to the position resolution is generated (step S108).

  After that, the corrected image selection unit 27f calculates RMSE between each image of the second image group generated by the second image group generation unit 27e and the tumor region (step S109).

  Subsequently, the corrected image selection unit 27f selects, as the tumor region corrected image, an image that minimizes the calculated RMSE in each image of the second image group (step S110).

  Then, the corrected SPECT image generation unit 27g generates a corrected SPECT image by replacing the tumor region correction image selected by the correction image selection unit 27f with the tumor region (step S111).

  After that, the system control unit 29 controls to display the corrected SPECT image generated by the corrected SPECT image generation unit 27g on the monitor of the display unit 22 (step S112), and ends the process.

  As described above, in the present embodiment, the maximum value extraction unit 27b extracts the maximum value from the pixel values of the pixels constituting the tumor region set in the correction target SPECT image, and the estimated value calculation unit 27c By multiplying the maximum value extracted by the maximum value extraction unit 27b by the recovery coefficient stored in the setting information storage unit 27a, the maximum value can be obtained even if the pixel value decreases due to the position resolution of the SPECT device. An estimated value for estimating is calculated.

  Then, the first image group generation unit 27d uses the estimated value calculated by the estimated value calculation unit 27c as an upper limit value, and determines a plurality of values obtained by dividing the upper limit value by the number of divisions stored in the setting information storage unit 27a. Then, a plurality of images in which the determined values are the pixel values of the pixels constituting the tumor region are generated as the first image group. The second image group generation unit 27e performs an image quality deterioration process using the response function stored in the setting information storage unit 27a on each image of the first image group generated by the first image group generation unit 27d. Thus, a second image group is generated.

  Then, the corrected image selecting unit 27f calculates and calculates difference information by subtracting the pixel values of the corresponding pixels between each image of the second image group generated by the second image group generating unit 27e and the tumor region. The image with the smallest difference information is selected as a tumor region corrected image in which the tumor region is PVE corrected. Then, the correction SPECT image generation unit 27g generates a correction SPECT image in which the correction target SPECT image is corrected by replacing the tumor region correction image selected by the correction image selection unit 27f with the tumor region.

  Therefore, the processing target is limited to a tumor region, a finite number of first image groups are generated from the tumor region, and a finite number of second image groups are generated by a convolution method for the finite number of first image groups. By selecting an image in which the PVE of the tumor region is corrected, correction processing can be performed with a finite number of processing without reducing the S / N ratio as in the conventional deconvolution method. As described above, the partial volume effect of the nuclear medicine image (SPECT image) can be corrected accurately and easily.

  In the above-described embodiment, a case has been described in which one tumor region to be corrected for PVE is set. However, the present invention is not limited to this, and there are a plurality of tumor regions to be corrected for PVE. It may be set. A modification in which a plurality of tumor regions are set will be described with reference to FIG. In addition, FIG. 9 is a figure for demonstrating the modification in a present Example.

  As shown in FIG. 9, in the modification, three tumor regions (tumor region 1, tumor region 2, and tumor region 3) are set by the operator in the correction target SPECT image. Then, the maximum value extraction unit 27b calculates the maximum value in each of the tumor region 1, the tumor region 2 and the tumor region 3, and the estimated value calculation unit 27c in the tumor region 1, the tumor region 2 and the tumor region 3 respectively. Calculate an estimate. Then, the first image group generation unit 27d generates a first image group for each of the tumor region 1, the tumor region 2, and the tumor region 3, and the second image group generation unit 27e generates the tumor region 1, the tumor region 2, and the tumor region. A second image group for each region 3 is generated.

  Then, the corrected image selection unit 27f calculates the RMSE using each image of the second image group of each tumor region and the corresponding tumor region, so that each tumor of the tumor region 1, the tumor region 2, and the tumor region 3 is calculated. The region correction image is selected, and the correction SPECT image generation unit 27g replaces each tumor region correction image selected by the correction image selection unit 27f with the corresponding tumor region to generate a correction SPECT image. Thereby, even when a plurality of tumor regions are estimated in the SPECT image, the partial volume effect of the SPECT image can be corrected accurately and easily.

  In this embodiment, the case where the position resolution in the SPECT image is constant in the image has been described. However, the present invention is applicable even when the position resolution in the SPECT image is different in the image.

  That is, when the position resolution in the SPECT image is different in the image, the operator stores the recovery coefficient and the response function determined from the corresponding position resolution in the setting information storage unit 27a for each position in the SPECT image. The processing unit 27 performs an estimated value calculation process and a second image group generation process by using a recovery coefficient and a response function corresponding to the set tumor region. Thereby, even if the position resolution in the SPECT image is different in the image, the image processing unit 27 can select the tumor region correction image and generate the corrected SPECT image.

  Further, in the present embodiment, the case where the SPECT image generated by the SPECT apparatus is a PVE correction target has been described. However, the present invention is not limited to this, and an image generated by a gamma camera, a SPECT image generated by a SPECT-CT apparatus, a PET image generated by a positron emission CT apparatus (PET apparatus), All of the nuclear medicine images, such as a PET image generated by a PET-CT apparatus in which a PET apparatus and an X-ray CT apparatus are integrated, can be the target of the PVE correction process described above.

  As described above, the nuclear medicine imaging apparatus and the image processing program according to the present invention are useful for generating a nuclear medicine image by detecting radiation emitted from a nuclide administered to a subject, and in particular, nuclear medicine. It is suitable for correcting the partial volume effect of an image accurately and easily.

DESCRIPTION OF SYMBOLS 10 Stand apparatus 11 Top plate 12 Bed 13 Bed drive part 14 Gamma camera 15 Camera drive part 20 Console apparatus 21 Input part 22 Display part 23 Bed control part 24 Camera control part 25 Data collection part 26 Image reconstruction part 27 Image processing part 27a Setting information storage unit 27b Maximum value extraction unit 27c Estimated value calculation unit 27d First image group generation unit 27e Second image group generation unit 27f Correction image selection unit 27g Correction SPECT image generation unit 28 Data storage unit 29 System control unit

Claims (4)

A nuclear medicine imaging device that detects radiation emitted by a nuclide administered to a subject and generates a nuclear medicine image,
Maximum value extraction means for extracting a maximum value from pixel values of pixels constituting a region of interest set in the nuclear medicine image;
Even if the pixel value is reduced due to the position resolution of the device itself, an estimated value estimated to obtain the maximum value extracted by the maximum value extracting means is used using a predetermined coefficient determined from the position resolution. Estimated value calculating means for calculating
Wherein the estimated value calculated by the estimated value calculation detecting means and the upper limit value, determining a plurality of values obtained by dividing by the upper limit value preset division number, a plurality of values each of the regions of interest and the determined First image group generation means for generating a plurality of images as pixel values of each pixel constituting the first image group;
A second image group is generated by performing an image quality deterioration process using a response function determined by the position resolution on each image of the first image group generated by the first image group generation unit. Second image group generation means for performing,
The difference information is calculated by subtracting the pixel value of the corresponding pixel between each image of the second image group generated by the second image group generation means and the region of interest, and the calculated difference information A corrected image selecting means for selecting an image that minimizes the region of interest as a corrected image in which the region of interest is corrected;
A nuclear medicine imaging apparatus comprising:   And a nuclear medicine correction image generation means for generating a nuclear medicine correction image in which the nuclear medicine image is corrected by replacing the correction image selected by the correction image selection means with the region of interest. The nuclear medicine imaging apparatus according to claim 1. The maximum value extraction means, when a plurality of regions of interest are set in the nuclear medicine image, extracts the maximum value of each of the plurality of regions of interest set,
The estimated value calculating means calculates an estimated value corresponding to the maximum value of each of the plurality of regions of interest extracted by the maximum value extracting means, using the predetermined coefficient,
The first image group generation unit generates a first image group of each of the plurality of regions of interest using the estimated value and the number of divisions of each of the plurality of regions of interest calculated by the estimated value calculation unit. And
The second image group generation means generates a second image group corresponding to the first image group of each of the plurality of regions of interest generated by the first image group generation means using the response function. Generate
The corrected image selection unit uses the second image group of each of the plurality of regions of interest generated by the second image group generation unit and the region of interest corresponding to each second image group, and Select a corrected image for each of multiple regions of interest,
The nuclear medicine correction image generation unit generates the nuclear medicine correction image by replacing the correction image of each of the plurality of regions of interest selected by the correction image selection unit with a corresponding region of interest. The nuclear medicine imaging apparatus according to claim 2. An image processing program for causing a computer to execute an image processing method for performing image processing of a nuclear medicine image generated by detecting radiation emitted from a nuclide administered to a subject,
A maximum value extraction procedure for extracting a maximum value from pixel values of pixels constituting a region of interest set in the nuclear medicine image;
The estimated value estimated that the maximum value extracted by the maximum value extraction procedure is obtained even if a pixel value decrease due to the position resolution of the nuclear medicine imaging apparatus that generated the nuclear medicine image occurs. An estimated value calculation procedure for calculating using a predetermined coefficient determined from the position resolution;
The estimates the estimated value calculated by the calculation out procedure and the upper limit value, determining a plurality of values obtained by dividing by the upper limit value preset division number, a plurality of values each of the regions of interest and the determined A first image group generation procedure for generating, as a first image group, a plurality of images that are pixel values of each pixel that constitutes
A second image group is generated by performing an image quality deterioration process using a response function determined by the position resolution on each image of the first image group generated by the first image group generation procedure. A second image group generation procedure,
Difference information is calculated by subtracting pixel values of corresponding pixels between each image of the second image group generated by the second image group generation procedure and the region of interest, and the calculated difference information A corrected image selection procedure for selecting an image that minimizes the region of interest as a corrected image corrected,
An image processing program for causing a computer to execute.

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