JP5011250B2 - Radiation imaging apparatus and image information creation method - Google Patents

Description

  The present invention relates to a method for creating image information of a radiation imaging apparatus and a radiation imaging apparatus.

  In Patent Document 1, global positioning of each part in the first X-ray CT image in the respiratory stopped state and the second X-ray CT image in the respiratory state is performed, and the image of the blurred part in the second X-ray CT image is corrected. Thus, it is described that an image of a non-blurred part such as a first X-ray CT image is used.

JP 2003-232855 A

  In the above-mentioned Patent Document 1, image position correction is performed when correcting a PET image excluding wobble due to respiration, but the quantitativeness of the image is not taken into consideration. The imaging range is corrected for the entire image, the case where the image is lost is not considered, and the problem of the imaging range is not considered.

  In general PET imaging, the following items are particularly problematic in follow-up observation using a PET apparatus.

(1) Image quantification (2) Imaging range The purpose of this study is to maintain the quantification in follow-up observation using images and to obtain images with a wide imaging field of view. An object of the present invention is to provide a method for creating image information of a radiation imaging apparatus capable of acquiring data with high accuracy and a wide imaging field of view.

  A bed on which the subject is placed, a plurality of radiation detectors arranged around the longitudinal axis of the bed and outputting a signal corresponding to the energy of the radiation, and between the radiation detector and the bed, the radiation detector The radiation generating means for emitting a second radiation having a different energy from the first radiation emitted from the subject, rotated along the inner circumference of the subject, and data processing for creating an image by the first radiation and the second radiation And a display device that displays an image of the first radiation and the second radiation, and the data processing device receives information obtained from a region different from the region common to the plurality of images of the second radiation from the other Provided is a radiation imaging apparatus including a corresponding region processing unit applied to an image by second radiation.

  In follow-up observation using images, high-accuracy and wide-viewing field of view data can be collected, and an emission image that can withstand follow-up observation can be acquired.

  Embodiments will be described below with reference to the drawings.

  This embodiment will be described using a PET apparatus.

  In recent years, PET apparatuses have been heavily used mainly for the purpose of tumor diagnosis in the medical field. The PET device measures radiation (γ rays) derived from the radiopharmaceutical injected into the subject who is the subject and released from the subject's body, and the radiopharmaceutical in the subject's body is measured from the measurement data. The distribution of is imaged. Such a PET apparatus is used for diagnosis of metabolic function and physiological function. An X-ray CT apparatus is a representative example of a radiological image diagnosis apparatus that applies a radiation measurement technique and obtains an image inside a subject in a non-invasive manner.

Diagnosis of a malignant tumor or the like using a PET apparatus is performed as follows. First dose, labeled with positron emitting radionuclides ^{(15 O, 13 N, 11} C, 18 F , etc.), radioactive agents that specifically accumulates in a particular site in the body (hereinafter, referred to as PET agent) is the subject Is done. The positrons released from the PET drug in the body of the subject combine with the electrons in nearby cells and disappear. At the time of annihilation, a pair of γ rays having energy of 511 KeV (hereinafter referred to as pair γ rays) are emitted. Since each pair of γ-rays is emitted in directions almost opposite to each other, it is possible to determine on which straight line in the body the positron annihilation event has occurred by simultaneously measuring both γ-rays. These gamma rays are detected by a radiation detector. After detecting a statistically sufficient number of γ-rays, by using an image reconstruction algorithm such as a filtered back projection method, the frequency distribution of γ-rays, that is, the PET drug in the subject's body Can be imaged. The measurement of γ-rays caused by the PET drug in the body is emission measurement (hereinafter referred to as E measurement), and the image information reconstructed based on the γ-ray detection signal obtained by the emission measurement is emission image information ( Hereinafter referred to as E image information). The E image information is generally simply referred to as a PET image, but is referred to as E image information in this specification in order to distinguish it from transmission image information (hereinafter referred to as T image information) described later. A series of processes from E measurement to reconstruction is collectively referred to as emission imaging.

  In an examination using such a PET device, for example, when a PET drug called FDG (Fluoro-2-deoxyglucose), which is an analog of sugar (glucose), is administered to a subject, it is compared with a normal site. PET drugs accumulate in malignant tumors (cancer) with large glucose metabolism. This makes it possible to diagnose functions such as the position, shape, and cell activity of malignant tumors.

  By the way, in PET inspection requiring quantitativeness, measurement called transmission (transmission measurement, hereinafter referred to as T measurement) using a γ-ray source which is a transmission source provided in the PET apparatus is performed separately from E measurement. The attenuation of γ rays in PET measurement is a phenomenon that is not detected as simultaneous measurement data effective for imaging as a result of interaction with substances in the body before γ rays derived from radiopharmaceuticals go out of the subject's body. Point to. This process of correcting the attenuation of γ rays is called attenuation correction and is currently performed in most PET examinations.

The attenuation correction is usually performed using data obtained by T measurement. That is, the subject is irradiated with γ-rays (radiation) emitted from the γ-ray source by turning the γ-ray source around the subject on the bed. The respective radiation transmittances in various directions through which the γ rays pass through the subject are obtained. Data obtained by the E measurement is corrected using these radiation transmittance data. A radioisotope (Radio-Isotope; hereinafter referred to as “RI”) such as ⁶⁸ Ge— ⁶⁸ Ga or ¹³⁷ Cs is usually used as the γ-ray source. Instead of the γ-ray source, it is also possible to use an X-ray source as described in JP 2006-231083 A. If necessary, the tomographic image information of the subject is reconstructed based on the data obtained by T measurement. This tomographic image information is morphological image information and is hereinafter referred to as T image information. The T image information represents the distribution of radiation attenuation in the body of the subject. If necessary, the attenuation rate for each projection direction can be obtained again based on the image information, and these attenuation rates can be used for attenuation correction.

  In recent years, as described in pages 4S to 14S of The Journal of Nuclear Medicine, Vol. 45, No. 1, a combined PET / CT apparatus in which an X-ray CT apparatus is arranged in parallel with a PET apparatus. Is popular. In these composite PET / CT apparatuses, attenuation correction is performed using tomographic image information obtained by an X-ray CT apparatus. Japanese Patent Laid-Open No. 2006-231083 proposes a PET apparatus having a structure in which an X-ray source is turned inside a plurality of radiation detectors arranged in an annular shape. This PET apparatus also performs attenuation correction using tomographic image information reconstructed by using an X-ray detection signal emitted from an X-ray source and transmitted through a subject.

  Attention is paid to follow-up observations for the purpose of determining the therapeutic effect and prognosis by performing PET imaging for tumor diagnosis as described above before and after treatment (for example, radiotherapy, chemotherapy, etc.). Has been. Conventionally, follow-up has been performed using diagnostic imaging modalities such as X-ray CT and nuclear magnetic resonance imaging (hereinafter referred to as MRI). However, X-ray CT and MRI are called so-called morphological images, and only their shapes, sizes, etc. are evaluated. On the other hand, the PET image is called a function image because it functions as a function of cell activity as described above. Therefore, information possessed by a PET image is information that cannot be obtained by CT or MRI. Moreover, the functional change of the degree of activity of the tumor obtained by PET imaging is observed earlier than the morphological change such as shape and size, and is expected as an effective means of follow-up observation.

What is important when performing follow-up observation using a PET image is the quantitativeness of the PET image. If the quantitative value of the function information is not correct, the images before and after treatment cannot be compared, and it is difficult to follow up. The attenuation correction is a major factor for the quantitativeness of the PET image. As described above, the amount by which the γ-rays derived from the radiopharmaceutical are attenuated before coming out of the body can be calculated as follows. Assuming that an emission intensity I is obtained when a substance having an attenuation coefficient μ is transmitted by a distance L at an incident intensity I ₀ , the attenuation amount is expressed by the following equation.

I / I ₀ = exp (-μL)
Since the component constituting the human body can be considered to be almost water, the amount of attenuation that the 511-keV γ-ray receives when passing through the distance L = 10 cm is the attenuation coefficient μ = 0.095 / cm (511 keV). If it is used, I / I ₀ = 0.387, which is attenuated to about 40%. For this reason, the true γ-ray flying amount, that is, the radiopharmaceutical distribution amount cannot be measured only by E measurement, and T-measurement for correcting the attenuation amount of γ-ray is essential. Thus, T measurement and attenuation correction are important in quantitative properties of PET images.

  As described above, as a method of collecting and correcting attenuation correction data, there are usually methods using a γ-ray source in a PET apparatus and an X-ray source in a PET / CT apparatus, and both of these use a radiation source. It is common to measure the attenuation distribution in the body and to perform the E measurement together with the PET apparatus at the same time. On the other hand, a method for performing attenuation correction using an image captured by another image diagnostic apparatus has been proposed. In pages 937 to 948 of Medical Physics, Vol. 30 (5), an image captured by an MRI apparatus is converted into attenuation correction data, and a method for attenuation correction based on the data is proposed. In this method, attenuation correction is performed using an image processing method without using a radiation source and simultaneously with PET imaging. Note that pages 712 to 720 of IEEE Transactions on Medical Imaging, Vol. 18, No. 8 disclose a non-linear image registration method (non-rigid image registration method) of two pieces of image information.

  In general PET imaging, the following items are particularly problematic in follow-up observation using a PET apparatus. (1) Image quantitativeness, (2) imaging range.

  Regarding (1), in the case of conventional PET imaging using tumor diagnosis as an example, the presence or activity of a tumor was determined by looking at the distribution and accumulation of radiopharmaceuticals within one imaging. Therefore, the standard uptake value (hereinafter referred to as SUV) value, which is an index standardized with respect to the normal radiopharmaceutical distribution region, is also compared only within the single imaging. However, when multiple imaging such as follow-up is considered, if the accuracy of T measurement to be imaged each time varies and the attenuation correction data is not constant, the value of the normal radiopharmaceutical distribution region changes, Since the SUV value also changes, it cannot be directly compared. Image quantification is also related to the problem of subject exposure. In recent years, it has become common to use a PET / CT apparatus for PET imaging, but when considering the follow-up observation, the subject must perform CT imaging every time to perform T measurement, so the exposure dose Will increase. In 2004, an article entitled “Risk of cancer from diagnostic X-rays” was published in the English medical journal “Lancet”, and 3.2% of cancers in Japan were estimated to be due to radiation exposure. Thus, the subject's exposure problem is very serious, and it is desired to reduce the exposure by CT imaging for T measurement. However, if the X-ray dose is simply lowered, the statistical accuracy of the T measurement data is deteriorated and the quality is lowered, and as a result, the quantitativeness of the image is lowered. As described above, the image quantitativeness is closely related to the exposure amount.

  As a method of reducing the exposure dose, T measurement data is acquired with high dose γ-rays or X-rays in the first PET imaging in the follow-up process, and in subsequent PET imaging, the T measurement data is obtained. If the method used to correct the attenuation of E measurement data is the same subject, it is considered possible in principle. Thereby, it is not necessary to always perform T measurement in the course of follow-up observation, and the exposure dose can be reduced. However, if the E measurement and the T measurement are not performed at the same time, the position and orientation of the subject on the image are different for each PET imaging, so that they need to be aligned. Assuming that the images are aligned using a non-linear superposition technique of two images as shown on pages 937 to 948 of Medical Physics, Vol. 30 (5), local alignment is possible. However, it is difficult to match the position and posture of the whole body, and as a result, the accuracy of attenuation correction is reduced.

  The problem (2) will be described. Further, the T measurement data collected once is not always in the same imaging range as the E measurement data. On the other hand, in all PET imaging in the follow-up home, it is difficult to always take E measurement data and T measurement data collected once in the same imaging range. This is the problem (2). This problem can be solved if the T measurement once imaged is always measured in a form that includes the E measurement data. However, such a measurement is required when the movement range is limited as in a head-only PET apparatus. I can't. In particular, when a point source is used as a γ-ray source used for T measurement in recent years, these are remarkable. As shown in FIG. 1, the imaging region using the point source is a shaded portion, and it is not possible to collect T measurements of the entire imaging range that can be collected without moving the subject by E measurement. Even if T measurement is performed for the part lacking data, the dedicated PET device for heads has a small opening diameter, so the subject's shoulder interferes with the opening and cannot be inserted deeper, so T measurement cannot be performed. . An area in which T collection cannot be performed cannot be imaged even if E collection is possible, and PET in a sufficient range cannot be performed in the first place. Even in other image diagnostic apparatuses, for example, a method of creating attenuation correction data by image processing using MRI, the MRI image is mainly imaged by proton distribution, and by γ-ray attenuation distribution Absent. Therefore, in order to convert to an attenuation distribution, the MRI image is divided into regions and a known value is assigned as an attenuation coefficient. However, since there is an individual difference in the attenuation distribution value, a true attenuation distribution value cannot be obtained. Thus, the problem of the imaging region due to the inability to collect T is an important issue in PET imaging.

  In general, in a PET apparatus or a PET / CT apparatus, E image information for obtaining a radiopharmaceutical distribution and a radiopharmaceutical quantity in the body cannot be imaged with the correct distribution and quantity unless attenuation correction is performed. That is, in order to improve the quantitativeness of E image information, it is important to improve the accuracy of T image information that is attenuation correction data, and conversely, by improving the accuracy of T image information, E image It is possible to improve the accuracy of information. In the PET apparatus or PET / CT apparatus, a γ-ray source or an X-ray source is used as an external radiation source for collecting T image information. The accuracy of T image information can be improved by increasing the radiation intensity from these external radiation sources. However, it is often regarded as a problem that the amount of exposure to the subject is often large particularly in the case of an X-ray source. In particular, when performing multiple PET imaging such as follow-up observation, the number of exposures increases. Therefore, it is essential to reduce the exposure from external radiation sources.

  The present inventors do not need to acquire T image information at a high radiation intensity every time when PET imaging of the same subject is performed a plurality of times as in follow-up observation, and acquire highly accurate T image information once, Subsequent T image information obtains the body contour and position of the subject, and by correcting the T image information with high accuracy T image information, high accuracy T image information can be obtained every time. I thought it could be reduced.

  FIG. 2 shows the flow of image data processing. The form for carrying out the above-described means for images A and B, which are attenuation correction data obtained by imaging the same subject multiple times with the same image diagnostic apparatus or different image diagnostic apparatuses, is as follows. Become. Even if the same subject is captured by the same diagnostic imaging device, if the imaging subject is captured at different time points or by different diagnostic imaging devices, the imaging range and the position of the subject in the image are different. The alignment with the image A and the image B is performed using the alignment method or the nonlinear alignment method. In this alignment, both images may be displayed on the image display device, and the position may be adjusted by a person. In addition, in order to eliminate the need for position adjustment, a standard is provided so that the position and size of images captured by various types of devices fall within a predetermined range, and each image is assigned to the standard. If you save it according to the standard, you do not need to adjust the position.

  In the aligned image A and image B, either image is divided into two or more regions (here, an example in which the image B is divided into regions will be described). Although division is not always necessary, it is possible to confirm whether the area that is not common to the common area is correct by dividing.

  FIG. 3 shows the correspondence classification of comparative images by area division. How the area in the image B corresponding to the image A and each of the divided areas corresponds on the image can be classified into the following profiles on the image, which is an outline of the following three types of states. However, this classification is not always necessary.

Profile (1) Both image A and image B can be identified as the same area Profile (2) Image A can be identified as an area, but image B cannot be identified Profile (3) Image A cannot be identified as an area, but image B Discrimination is possible In each region corresponding to each image, the corresponding pixel value of each image is calculated and stored as correspondence information. Further, in each image, a continuous distribution having the same pixel value is obtained, and the continuous area distribution of each image and its correspondence are calculated as correspondence information and stored. Further, when it is desired to obtain attenuation correction data in a wide imaging range, not in the same imaging range, the images A and B use the correspondence information obtained above and data of a non-common part of an image having a wide imaging range. To create attenuation correction data for the shortage.

  FIG. 4 shows a processing procedure when the features of the images to be compared are the same and a method of estimating μ-Map from the common area and non-common area of the images. The image data processing method shown in FIGS. 2 and 3 will be described in detail below using actual image information. First, FIG. 4 shows an example in which the images A and B are acquired using an external radiation source of a PET apparatus or a PET / CT apparatus. When images A and B are acquired using a γ-ray source as an external radiation source, first, image A and image B are aligned and region division is performed. Since the images A and B are images having the same information, the classification corresponding to the region of the common portion in the images A and B is only the profile (1) among the profiles (1) to (3). . In this case, new attenuation correction data can be created using either pixel value of image data with higher statistical accuracy. Further, even when it is desired to acquire the same imaging area as that of the image B, attenuation correction data can be created by using the lacking area as it is. The same applies to the case where an X-ray source is used. Even if one of image A and image B is a γ-ray source and the other is an X-ray source, the properties of the obtained image are common because a radiation source is used, and high-precision attenuation correction is achieved by the above method. Data can be acquired. In addition to attenuation correction data, correction information for internal scattering may be used.

  In this way, the radiation imaging apparatus records the image of the first radiation and the image of the second radiation having different energy from the first radiation, and from the region different from the common region among the plurality of images from the second radiation. An image information generation method for applying the obtained information to an image of the other second radiation, correcting the image of the first radiation using information obtained from an area different from the common area, and displaying the corrected image Therefore, it is possible to acquire data with high accuracy and a wide imaging range. Further, in follow-up observation using a PET image, high-accuracy and wide-viewing visual field data can be collected, and an emission image that can withstand follow-up observation can be acquired.

  FIG. 5 shows a processing procedure according to the present invention and a method of estimating μ-Map from the common area and non-common area of the image when the characteristics of the images to be compared are different. Next, FIG. 5 shows an example in which images A and B are acquired by using one of the external radiation sources of the PET apparatus or the PET / CT apparatus and the other by another image diagnostic apparatus (for example, MRI). However, the images A and B need to include a common imaging region. An image by MRI is a morphological image and is an image having substantially body contour information. Image A and image B are aligned and divided into regions. Since the image information possessed by each of the images A and B does not have the same property, the feature of the pixel value in the common area is classified into any one of the above (1) to (3). The corresponding pixel value of the area and the information of the continuous area are acquired from the common area of these images A and B, and these are held as data as shown in FIG. The data of FIG. 5 is input if there is data of image A and image B. When there is no data, a portion where the data is insufficient is displayed on the screen, and the data is input by a person referring to the images A and B. On the other hand, in the non-common area included only in the image B, the corresponding pixel value in the common area and the information on the continuous area can be applied to the corresponding pixel value in the continuous area. By using the information of the continuous area, the appropriateness of the information applied to the non-common area increases, and the accuracy of the image is improved. Even if it is not a continuous area, if there is a pixel value of the image A corresponding to the pixel value of the image B using the information acquired in the common area, it can be estimated using the correspondence. When it is difficult to estimate the pixel value of the image A corresponding to the pixel value of the image B in the non-common part, it is possible to create a μ-Map by setting a predetermined pixel value and then correct it And

  In this way, the radiation imaging apparatus captures at least a part of the common area with the image by the first radiation, the image by the second radiation having an energy different from the first radiation, and the tomographic image by the second radiation, and the substantially contour information The information obtained from the area different from the common area of the image with the second radiation and the image having the approximate body contour information is applied to the other image, and from the area different from the common area. By using the obtained information, the image by the first radiation is corrected, and the image information creation method for displaying the corrected cut-off image can acquire data of a wide imaging range with high accuracy. Further, in follow-up observation using a PET image, high-accuracy and wide-viewing visual field data can be collected, and an emission image that can withstand follow-up observation can be acquired.

  As described above, in the two images A and B, when the properties of the image information are the same or different, it is possible to acquire the data of the wide imaging region with high accuracy in either case.

  A positron emission tomography apparatus (PET apparatus), which is a preferred embodiment of the present invention, will be described with reference to FIG. FIG. 6 shows a data flow in which the same subject is imaged a plurality of times in the PET apparatus of the present embodiment, and the T image information obtained there is processed. The PET apparatus of FIG. 6 performs the image processing of FIG. The process of obtaining E image data and T image data or CT image data from the PET or PET / CT apparatus 1 is the same as that of a general PET apparatus or PET / CT apparatus.

  The PET apparatus 1 includes an external radiation source 2 that irradiates a subject with radiation, a detector ring 3 (a plurality of radiation detectors) having a plurality of detectors, a bed 4 on which the subject can sleep, and a PET apparatus 1. And an image display device 5 for displaying the image picked up in (1) and a data processing device 6 (only connected to the PET device) picked up by the PET device 1 and displayed on the image display device.

  The PET apparatus 1 obtains E1 data and T1 data in the first imaging, and obtains E2 data and T2 data in the second imaging. The T1 data or T2 data need not have the same statistical accuracy, and the exposure dose of the subject can be reduced by reducing the intensity of the external radiation source 2 and shortening the imaging. The T1 data and T2 data are aligned by the alignment unit. The region dividing unit divides the T1 data into i and T2 data into j (i = 4 and j = 5 for the sake of explanation). This area division processing can also be designated from the image display device 5. Thus, the areas constituting the T1 data and the T2 data can be represented by the following set.

T1 data: {(common) (V1 [T1], V2 [T1], V3 [T1], V4 [T1])}}
T2 data: {(common) (V1 [T2], V2 [T2], V3 [T2], V4 [T2]),
(Not common) (V1 [T2], V2 [T2], V3 [T2], V5 [T2])}
Since the corresponding region processing unit has pixel values having the same characteristics in the T1 data and the T2 data, the correspondence between the pixel values is one-to-one in the region where the imaging range is common, and either one of the corresponding statistical systems By using a high pixel value, it is possible to obtain a highly accurate μ-Map. Also in the non-common area, V1 [T2], V2 [T2], and V3 [T2] are continuous areas from the common part, and thus the values can be applied to μ-Map as they are. The V5 [T2] area is also an independent area, but the T1 data and T2 data have the same characteristics, and thus the pixel values can be used as they are. The resulting set of μ-Map is as follows (shows an example in which T1 data is used as highly accurate data).

μ-Map: {V1 [T1], V2 [T1], V3 [T1], V4 [T1], V5 [T2]}
Note that T2 data may be adopted as highly accurate data.

  As described above, a bed on which the subject is placed, a plurality of radiation detectors that output radiation detection signals, and between the radiation detector and the bed, are rotated along the inner periphery of the radiation detector, Radiation generating means for emitting a second radiation having energy different from the first radiation emitted from the examiner, a data processing device for creating an image by the first radiation and the second radiation, and the first radiation and the second radiation A display device for displaying an image, wherein the data processing device applies information obtained from a region different from the common region among the plurality of images by the second radiation to the other image by the second radiation. High-accuracy and wide-range imaging range data can be acquired by the radiation imaging apparatus including the processing unit. Further, in follow-up observation using a PET image, high-accuracy and wide-viewing visual field data can be collected, and an emission image that can withstand follow-up observation can be acquired.

  Moreover, it is obtained from each of the first radiation detection signals output from a plurality of radiation detectors surrounding the bed on which the subject is placed when the first radiation emitted from the subject due to the radiopharmaceutical is input. First tomographic image information is generated based on each first information, and is output from a plurality of radiation detectors surrounding the bed on which the subject is placed when inputting the second radiation emitted from the radiation source. Third tomographic image information obtained by creating second tomographic image information based on the second information obtained from the radiation detection signal, and imaging the subject at different points in time by the same method that created the second tomographic image information, or another device The third tomographic image information holding morphological information similar to the imaging region that is at least partially shared with the second tomographic image information taken in step 3 is acquired from the image holding device, and the third tomographic image information The layer image information is aligned, the second tomographic image information and the third tomographic image information are each divided into one or more regions, and in the common imaging region with the third tomographic image information aligned with the second tomographic image information The image calculated from either the second tomographic image information or the third tomographic image information with high accuracy, or from both the second tomographic image information and the third image information, for the part corresponding to the region of each image Information (hereinafter referred to as high-precision image information) is calculated and narrowed using tomographic image information having a wider imaging area in the non-common area with the third image information aligned with the second tomographic image information. Image information having a wide imaging area (hereinafter referred to as wide imaging area image information) obtained by complementing the form of tomographic image information having an imaging area is calculated, and high-precision image information is calculated for the complemented area. Apply The fourth tomographic image information obtained by fusing the high-accuracy image information and the wide imaging area image information is calculated, and the first tomographic image information is attenuated and corrected by the fourth image information, thereby ensuring high quantitativeness and a wide field of view. One tomographic image information can be acquired. A high-accuracy image can be created using the high-precision image information.

  Another embodiment will be described with reference to the drawings.

  The embodiment described above uses a PET apparatus or a PET / CT apparatus, but can be implemented by a combination of the PET apparatus and the image information holding apparatus 7. An example thereof will be described with reference to FIG. FIG. 7 shows a feature that is different from the T image information obtained by imaging the subject in the PET apparatus of the present embodiment and the T image information captured by an apparatus other than the apparatus (such as MRI image information) and stored in the image information holding apparatus 7. The data flow which processes the image information (henceforth M data) which has is shown. The PET apparatus in FIG. 7 executes the image processing in FIG.

  The data processing device 8 is connected to the PET device and the image information holding device 7, displays data captured by the PET device 1 on the image display device, and displays an image of the image information holding device 7 on the image display device.

  Similar to the above method, E data and T data are obtained from the PET apparatus 1, and M data is obtained from the image information holding apparatus 7. However, the M data imaging region is wider than the T data imaging range. The T data and M data are aligned. The T data is divided into i ways and the M data is divided into j ways (i = 4 ways and j = 5 ways for explanation). Thus, the areas constituting the T data and M data can be represented by the following set.

T data: {(common) (V1 [T], V2 [T], V3 [T], V4 [T])}
M data: {(common) (V1 [M], V2 [M], V3 [M], V4 [M]),
(Not common) (V1 [M], V2 [M], V3 [M], V5 [M])}
T data and M data have pixel values having different characteristics, but in an area where the imaging range is common, the pixel values have a one-to-one correspondence because they are aligned. Pixel value correspondence information can be obtained. Also in the non-common region, V1 [T], V2 [T], and V3 [T] are continuous regions from the common portion, and thus the above values can be applied to μ-Map as they are. Since the V5 [M] area is also independent of the pixel value correspondence information, V1 [T] set as the specified value is applied to μ-Map. V1 [T] set as the specified value has a function that can be confirmed and corrected by the operator using the image display device 5. The set of μ-Map obtained by this is as follows.

μ-Map: {V1 [T], V2 [T], V3 [T], V4 [T]}
Thus, attenuation correction data for a wide imaging range can be acquired using the present invention.

  The attenuation correction unit performs attenuation correction on the E1 data and E2 data using the obtained μ-Map data, and generates corrected E1 data and E2 data. These corrected E1 data and E2 data are output to the image display device 5.

  With the above-described positron emission tomographic imaging apparatus, it is possible to collect attenuation correction data with high accuracy and wide imaging visual field in follow-up observation using a PET image, and an emission image that can withstand follow-up observation can be acquired. In addition, the exposure dose of the subject can be reduced during the follow-up process.

  As described above, a bed on which the subject is placed, a plurality of radiation detectors that output radiation detection signals, and between the radiation detector and the bed, are rotated along the inner periphery of the radiation detector, Radiation generating means for emitting a second radiation having energy different from the first radiation emitted from the examiner, a data processing device for creating an image by the first radiation and the second radiation, and the first radiation and the second radiation A display device for displaying an image; and means for capturing at least part of a common area with a tomographic image by second radiation and capturing an image having substantially body contour information. A high-accuracy, wide imaging range is detected by a radiation imaging apparatus having a corresponding area processing unit that applies information obtained from an area different from the common area of the image from the means to the other image. Data is a possible acquisition. Further, in follow-up observation using a PET image, high-accuracy and wide-viewing visual field data can be collected, and an emission image that can withstand follow-up observation can be acquired.

  In each of the embodiments described above, for the μ-Map data, the data in the common area is processed by the corresponding area processing unit into the data in the non-common area. Can be applied to data.

  In each of the embodiments described above, a PET apparatus or a PET / CT apparatus is used. However, a PET / MRI apparatus that combines a PET apparatus and an MRI apparatus may be used. The image acquired from the image storage device is an actually captured image, but digital data that models a general human body may be used.

  In each of the embodiments described above, a PET apparatus or a PET / CT apparatus is used. However, a SPECT apparatus may be used instead of a PET apparatus, or a gamma camera that captures a planar image may be used. it can. Moreover, although the above-described embodiment has been described using the attenuation coefficient, correction information for internal scattering may be applied from a common area to a non-common area.

An imaging area when a point source is used as an external radiation source. Flow of image data processing according to the present embodiment. Corresponding classification of comparative images by area division according to this embodiment. Processing procedure according to this embodiment when the features of the images to be compared are the same, and μ-Map estimation from the common area and non-common area of the image. Processing procedure according to the present invention when the features of images to be compared are different, and μ-Map estimation from common regions and non-common regions of images. The system structure by this invention in case the characteristics which the image to compare has are the same. The system structure by this invention when the characteristics which the image to compare has differ.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PET apparatus or PET / CT apparatus 2 External radiation source 3 Detector ring 4 Bed 5 Image display apparatuses 6 and 8 Data processing apparatus 7 Image information holding apparatus

Claims (10)

A bed on which the subject is placed;
A plurality of radiation detectors for outputting radiation detection signals;
Radiation generating means that emits second radiation between the radiation detector and the bed and rotated along an inner circumference of the radiation detector and having energy different from the first radiation emitted from the subject. When,
A data processing device for creating an image by the first radiation and the second radiation;
A display device for displaying an image of the first radiation and the second radiation,
The data processing apparatus as one image having a region different from the common area in the image by a plurality of the second radiation, the information obtained from the different regions, no area different from the common area A radiation imaging apparatus comprising a corresponding region processing unit applied to an image of the other second radiation. A bed on which the subject is placed;
A plurality of radiation detectors for outputting radiation detection signals;
Radiation generating means that emits second radiation between the radiation detector and the bed and rotated along an inner circumference of the radiation detector and having energy different from the first radiation emitted from the subject. When,
A data processing device for creating an image by the first radiation and the second radiation;
A display device for displaying images of the first radiation and the second radiation;
Means for capturing at least part of the common area with the image of the second radiation and capturing an image having substantially body contour information;
The data processing apparatus, on one side, has an image having a region different from a common region among images having the outline information from the second radiation and the capturing means, and information obtained from the different regions , A radiation imaging apparatus comprising: a corresponding area processing unit applied to the other image that does not have an area different from the common area . The radiation imaging apparatus according to claim 1,
An alignment unit that aligns a plurality of images of the second radiation; and a region dividing unit that divides the region into a region different from the common region and the common region in the plurality of second radiation images. A radiation imaging apparatus. The radiation imaging apparatus according to claim 2,
A positioning means for aligning the image by the second radiation and the image from the capturing means; and an area dividing means for dividing the area into an area different from the common area. A radiation imaging apparatus. The radiation imaging apparatus according to claim 1 or 2,
The corresponding region processing unit uses information on a continuous region indicating that the common region and a region different from the common region are continuous, and is used for images of regions different from the common region. A radiation imaging apparatus characterized by applying information obtained from a region. An image of the first radiation and an image of the second radiation having an energy different from the first radiation are recorded,
Among images from the plurality of second radiations , an image having an area different from the common area is used as one side, and information obtained from the different area is converted into information on the other of the images not having the area different from the common area . Image information by a radiation imaging apparatus, which is applied to an image by two radiations, corrects the image by the first radiation using information obtained from an area different from the common area, and displays the corrected image How to make. An image of the first radiation, an image of the second radiation having an energy different from the first radiation, and an image of the second radiation and at least part of the common area are recorded, and an image having substantially body contour information is recorded.
One of the images of the second radiation and the image having the approximate body contour information is an image having an area different from the common area, and information obtained from the different areas is different from the common area. An image obtained by a radiation imaging apparatus, wherein the image is applied to the other image that is not applied, the image obtained from the first radiation is corrected using information obtained from an area different from the common area, and the corrected image is displayed. Information creation method. The image information creation method according to claim 6,
Aligning the plurality of images from the second radiation,
An image information generation method, wherein the common area and the common area are divided into different areas. The image information creation method according to claim 7,
An image information generation method comprising: aligning an image obtained by the second radiation and an image having substantially body contour information; and dividing the region into a region different from the common region and the common region . The image information creation method according to claim 6 or 7,
Apply information obtained from a common area to an image of a different area from the common area by using information on a continuous area indicating that the common area and a different area from the common area are continuous. An image information creation method characterized by:

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