JP2006166968A - Medical image diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of position deviation of images by minimizing the position deviation and generating the position deviations similarly in both images while a top plate is bent into a cantilever state and the position deviation is caused at the time of inserting the top plate on which a subject is mounted into a tunnel part of the gantry of a nuclear medicine diagnostic apparatus and a tunnel part of the gantry of an X-ray CT apparatus. <P>SOLUTION: The tunnel part 21 of a PET gantry 20 and the tunnel part 31 of a CT gantry 30 are adjacently arranged side by side in parallel in a horizontal direction to the top plate 12 of a bed device 11 and also moved in the side arrangement direction as indicated by arrows A and B to the bed device 11, and the tunnel part 21 or the tunnel part 31 is positioned in front of the bed apparatus 11 as indicated in (a) or in (b), respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a medical diagnostic imaging apparatus suitable for early detection of cancer, tumor, etc., and in particular, a PET (positron emission computer tomography) apparatus, a SPECT (single photon emission computer tomography) apparatus, etc. The present invention relates to a medical image diagnostic apparatus that combines a nuclear medical diagnostic apparatus and an X-ray CT apparatus (CT scanner).

  In the PET apparatus, a drug having the property of gathering in cancer and tumor is labeled with a positron-releasing nuclide, and this drug is administered into the human body. Since gamma rays are emitted in the opposite direction of 180 ° when the positron disappears, a large number of radiation detectors arranged in a ring shape so as to surround the human body 360 ° capture the simultaneous incidence of the two gamma rays. From the relationship that the nuclide is located on the line connecting these incident positions, the number of simultaneous incidents is counted for a line (LOR: Line Of Response) connecting these incident positions. Such simultaneous counting is performed for each of a large number of LORs for a certain period of time to collect data and perform arithmetic processing to reconstruct the nuclide distribution image. This distribution image represents the nuclide concentration distribution on the tomographic plane where the plane on which the radiation detectors are arranged in a ring shape crosses the human body.

  In the SPECT apparatus, a single photon emitting nuclide is used instead of a positron emitting nuclide. In this case, since only one gamma ray is emitted from the nuclide, it is necessary to detect the incident direction of the gamma ray with a collimator or the like. However, the gamma ray incidence is counted for each combination of the detection position and the detection direction. To collect. Since the detection position needs to cover 360 ° surrounding the human body, a radiation detector arranged in a ring shape is used. Also in the case of this SPECT apparatus, the reconstructed nuclide distribution image represents the nuclide concentration distribution on the tomographic plane where the plane in which the ring detector array is located crosses the human body.

  However, since these PET images and SPECT images only represent the nuclide accumulation / distribution state, it is not necessarily clear where in the human tissue.

  On the other hand, in an X-ray CT apparatus, an X-ray tube and an X-ray detector are rotated around the body axis of the subject to scan the body of the subject with a X-ray on a tomographic plane perpendicular to the body axis. Thus, X-ray projection data (absorption distribution data) from each direction in the tomographic plane is collected, and an image (X-ray CT image) of the X-ray absorption rate distribution in the cross section is obtained by back projecting the projection data. Reconfigure. This X-ray CT image represents the tissue shape inside the human body on the tomographic plane.

  Therefore, in order to make a reliable diagnosis, conventionally, a nuclear medicine diagnosis apparatus such as a PET apparatus or a SPECT apparatus is combined with an X-ray CT apparatus, and a nuclear medicine examination and an X-ray CT examination are performed on the same patient. Diagnosis is made by using the PET image or SPECT image obtained in the above and an X-ray CT image in combination.

As a conventional medical image diagnostic apparatus combining a nuclear medicine diagnostic apparatus and an X-ray CT apparatus, for example, a combination of a PET apparatus and an X-ray CT apparatus as described in Patent Document 1 below is known. As described above, in the PET apparatus and SPECT apparatus, it is necessary to detect radiation in a 360 ° direction surrounding the human body. Therefore, a tunnel part is provided in the gantry, detectors are arranged in a ring shape around the gantry, and the human body is located in the tunnel part. The structure is inserted. Also, in the X-ray CT apparatus, in order to obtain projection data by detecting transmitted X-rays in the 360 ° direction of the human body, an X-ray tube and an X-ray detector are rotated around the tunnel portion of the gantry, The structure is such that a human body is inserted into the tunnel. Therefore, as shown in Patent Document 1 below, the PET gantry and the CT gantry are arranged in cascade so that the two tunnel portions communicate with each other, and one bed apparatus is commonly used for these.
Japanese Patent Laid-Open No. 7-20245

  This will be described in more detail with reference to FIG. 4. The PET gantry 20 is provided with a tunnel portion 21, and a large number of radiation detectors 22 are arranged around the tunnel portion 21 in a ring shape. In the CT gantry 30, the X-ray tube 32 and the X-ray detector 33 face each other around the tunnel portion 31 with the X-ray tube 32 and the X-ray detector 33 facing each other so as to sandwich the tunnel portion 31. It is made to rotate. As shown in the figure, the PET gantry 20 and the CT gantry 30 are arranged in a row so that the two tunnel portions 21 and 31 are continuous, and the subject 10 is inserted into the tunnel portions 21 and 31. One bed apparatus 11 that can move the top 12 on which the subject 10 is placed as shown by an arrow is arranged.

  Thus, by sharing the single bed apparatus 11 for the PET apparatus and the X-ray CT apparatus, the bed top plate 12 is moved as indicated by the arrow, and the subject 10 enters the tunnel portion 31 of the CT gantry 30. X-ray CT data collection in a positioned state and PET data collection in a state where the subject 10 is located in the tunnel part 21 of the PET gantry 20 can be sequentially performed. And since both the tunnel parts 21 and 31 communicate and it has taken the structure that the subject 10 is inserted in it, it is examined by controlling the movement position (delivery amount) of the bed top plate 12. A PET image and an X-ray CT image on the same tomographic plane of the person 10 can be easily obtained.

  If a PET image and an X-ray CT image can be obtained for the same tomographic plane of the subject 10, a fusion image in which these images are superimposed and synthesized can be obtained. This fusion image is very useful for accurate diagnosis because the nuclide concentration distribution image collected at a cancer lesion or the like is superimposed on an X-ray CT image representing human tissue.

  However, since the bed top 12 must protrude from the end of the bed apparatus 11 and the subject 10 is inserted into the tunnel portions 21 and 31, the bed top 12 is in a so-called cantilever state. In particular, when inserted into the tunnel portion 21 far from the bed apparatus 11, the length of the cantilever becomes large, and there is a problem that it is bent downward due to the weight of the subject 10 riding on the cantilever. That is, when inserted into the tunnel portion 31 on the side close to the bed apparatus 11, the length of the cantilever is short, the amount of bending is not large, and the central axis of the subject 10 is kept at the height H1. On the other hand, when it is inserted into the tunnel portion 21, the length of the cantilever is long and the top plate 12 is bent as shown by the dotted line in the figure, and the central axis of the subject 10 is height. It becomes H2.

  Thus, the center of the CT image is H1 and the center of the PET image is H2, which is different from that, and the centers of both images are shifted. This means that there is a positional shift between the CT image and the PET image that form the fusion image. That is, the problem arises that an accurate fusion image cannot be created.

  This invention is based on the bending of the top plate in a cantilever state when the top plate with the subject is inserted into the tunnel portion of the gantry of the nuclear medicine diagnostic apparatus and the tunnel portion of the gantry of the X-ray CT apparatus. It is an object of the present invention to provide a medical image diagnostic apparatus that solves the problem of image displacement.

  In order to achieve the above object, in the medical image diagnostic apparatus according to the first aspect of the present invention, the gantry of the nuclear medicine diagnostic apparatus having the tunnel part for inserting the subject, and the tunnel part in the horizontal direction with respect to the gantry An X-ray CT apparatus gantry having a tunnel part for inserting a subject, arranged adjacently in parallel, and a bed apparatus having a top plate for placing the subject and inserting it into the tunnel part of the gantry, The horizontal position of the bed apparatus with respect to the above two gantry in the direction of arrangement of the gantry arranged in parallel, the position where the top plate can be inserted into the tunnel part of one gantry and the position where it can be inserted into the tunnel part of the other gantry And a means for relatively moving between them.

  According to the medical image diagnostic apparatus of claim 1, the gantry of the nuclear medicine diagnostic apparatus and the gantry of the X-ray CT apparatus each having a tunnel part into which the subject is inserted are arranged such that the two tunnel parts are aligned in the horizontal direction. Are arranged adjacent to each other in parallel. Here, the subject is typically assumed to be a subject such as a patient, but includes small animals such as mice or other living bodies. The bed apparatus is provided with a top plate for inserting the subject placed thereon into the tunnel part of the gantry. The position of the bed apparatus is arranged in parallel as described above. The two gantry are moved relative to each other in the arrangement direction by moving on the two adjacent gantry sides or moving on the bed apparatus side. By this movement, the bed apparatus takes a position where the top plate can be inserted into the tunnel portion of one gantry and a position where the top plate can be inserted into the tunnel portion of the other gantry. .

  Thus, two gantry are arrange | positioned in parallel, and those tunnel parts do not cascade so that it may connect, but become a parallel thing. Therefore, whether the nuclear medicine examination or the X-ray CT examination is performed, the top plate is only inserted into the tunnel part of one gantry, and the length of the cantilever is not increased. The amount can be kept small. Since the amount of insertion into the tunnel portion is the same in either gantry, the length of the cantilever of the top plate is also the same, and the amount of bending thereof is also the same. Therefore, even if the positional deviation of the image due to bending occurs, the amount of positional deviation is the same between the nuclear medicine image and the X-ray CT image. Therefore, particularly when creating a fusion image that combines these images. It is effective for. That is, in this case, since the positional deviation occurs between both images, the positional deviation is not a problem, and an accurate fusion image can be created.

  Next, a medical image diagnostic apparatus embodying the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a medical image diagnostic apparatus according to an embodiment of the present invention. In this figure, a PET gantry 20 and a CT gantry 30 are the same as those described above with reference to FIG. 4, and tunnel portions 21 and 31 are provided, respectively. Although omitted in this figure, the PET gantry 20 has a large number of radiation detectors arranged in a ring shape so as to surround the periphery of the tunnel portion 21 as shown in FIG. Further, in the X-ray CT apparatus 30, an X-ray tube and an X-ray detector are arranged to face each other with the tunnel portion 31 interposed therebetween, and these are rotated around the tunnel portion 31.

  The difference from FIG. 4 is that the gantry 20, 30 is not arranged in a column so that the tunnel parts 21, 31 communicate with each other, but the gantry 20, so that the tunnel parts 21, 31 are arranged in parallel in the horizontal direction. , 30 are adjacently arranged in parallel. The gantry 20 and 30 are moved in the parallel arrangement direction as indicated by arrows A and B. Such a moving mechanism can be easily realized by installing a rail on the floor, providing wheels rotating on the rail in the gantry 20, 30 and sliding the gantry 20, 30 along the rail. The gantry 20 and 30 can be configured to move individually on the rail, or by mounting the two gantry 20 and 30 on one moving base, the two gantry 20 and 30 can be configured. It can also be configured to move together.

  On the other hand, the bed apparatus 11 and the console 41 are fixed on the floor. When the gantry 20, 30 moves in the horizontal direction as described above and performs the PET examination, the top plate 12 on which the subject of the bed apparatus 11 is placed is placed on the PET gantry 20 as shown in FIG. The position can be inserted into the tunnel portion 21. Further, when X-ray CT inspection is performed after the PET inspection is completed, both gantry 20 and 30 are moved in the direction of arrow A, and the top 12 is placed in the CT gantry 30 as shown in FIG. It is set as the position which can be inserted in the tunnel part 31. Thereafter, when PET inspection is performed again, both gantry 20 and 30 are moved in the direction of arrow B to the position shown in FIG.

  The console 41 performs control / calculation, image display, and input operation of the entire apparatus combining the PET apparatus and the X-ray CT apparatus. The operation on the console 41 is used to input conditions for PET inspection and X-ray CT inspection. A control device for controlling each part so that these inspections are performed is also housed in the console 41. An arithmetic unit that processes data collected by the PET gantry 20 and the CT gantry 30 to reconstruct an image is also incorporated in the console 41. A display device that displays the reconstructed image is also provided in the console 41.

  The horizontal movement of the gantry 20, 30 can also be controlled by an operation on the console 41. However, by providing an appropriate positioning tool such as a stopper on the rail or the like, FIG. It is also possible to manually move between the position (b) and the position (b).

  Next, with respect to the operation when the X-ray CT inspection and the PET inspection are sequentially performed on the same subject using the medical image diagnostic apparatus configured as described above, and a fusion image is obtained from these images, FIG. This will be described with reference to the flowchart of FIG. First, a drug labeled with a positron-emitting nuclide such as FDG is administered to a patient (subject). After administration of the drug, it waits for about 40 to 60 minutes until the drug is accumulated and distributed in the tumor (note that the waiting time is about the same when a small animal such as a mouse is used as the subject). Next, the patient is laid on the top plate 12 of the bed apparatus 11. First, the PET gantry 20 and the CT gantry 30 are moved and fixed so as to be in a position as shown in FIG. 1B, that is, a position where the top plate 12 can be inserted into the tunnel portion 31 of the CT gantry 30. At this position, the top plate 12 on which the patient is placed is inserted into the tunnel portion 31, and the top plate 12 is moved so that the whole body of the patient sequentially passes through the tunnel portion 31. The X-ray is scanned in a plane that crosses the patient's body by rotating the line detector, CT data is collected at each position in the body axis direction of the patient, and CT scan is performed on the whole body of the patient.

  When the patient's whole body CT scan is completed in this way, the PET gantry 20 and the CT gantry 30 are moved in the direction of arrow B, and the tunnel portion 21 of the PET gantry 20 is moved to the bed apparatus 11 as shown in FIG. Position it in front. In this state, the gantry 20, 30 is fixed, the top plate 12 on which the patient is placed is inserted into the tunnel portion 21, and the top portion 12 is moved so that the whole body of the patient sequentially passes through the tunnel portion 21, while the tunnel portion A radiation detector arranged in a ring shape around 21 performs simultaneous counting of gamma rays from the above-mentioned nuclide in the patient's body at each position in the patient's body axis direction, and collects PET data for the patient's whole body.

  During the PET data collection, the CT data collected as described above is processed to reconstruct a CT image at each position for the whole body of the patient. When the whole body PET scan is completed, the PET image reconstruction calculation is performed using the collected PET data, and the PET image at each position on the whole body of the patient is reconstructed. Then, a fusion image is created by superimposing and combining these CT images and PET images at the corresponding positions, and displayed on the screen of the image display device on the console 41.

  Here, the insertion distance to the tunnel portions 21 and 31 of the top 12 at the time of X-ray CT image acquisition and PET image acquisition is short in both cases, and the insertion distance is about the same in both cases. It has become. Thus, in any case, the short insertion distance means that the length of the cantilever of the top plate 12 is short, and as a result, the amount of bending can be suppressed. Further, the amount of bending is substantially the same because the length of the cantilever is the same. Therefore, even if the image is displaced due to the bending of the top plate 12, the CT image and the PET image are almost the same. Therefore, when creating a fusion image, it is possible to overlay and synthesize both images with accurate alignment without causing the problem of positional deviation between the two images.

  In addition, since the PET gantry 20 and the CT gantry 30 are arranged side by side in a so-called side-by-side state, the internal parts of the internal gantry 20 and 30 can be opened by opening the covers of the gantry 20 and 30 as compared with the conventional case. Maintenance work such as replacement and adjustment can be easily performed.

  FIG. 3 shows a second embodiment. In the embodiment shown in this figure, unlike the above-described first embodiment, the PET gantry 20 and the CT gantry 30 arranged side by side are fixed on the floor, and only the bed apparatus 11 is indicated by arrows A and B. In addition, the gantry 20 and 30 are horizontally moved in the horizontal direction. For this movement, for example, a mechanism is adopted in which a rail is laid on the floor and a wheel provided in the bed apparatus 11 rotates on the rail. Then, a motor or the like is built in the bed apparatus 11, and the bed apparatus 11 is moved by driving the motor in response to a command from the console 41. Or it can also comprise so that it may move manually, without using drive devices, such as a motor.

  In any case, when performing a PET inspection, the bed apparatus 11 is positioned at the position shown in FIG. 3A so that the top 12 can be inserted into the tunnel portion 21 of the PET gantry 20, and the X-ray CT inspection is performed. When performing the above, it is necessary to position the bed apparatus 11 at the position shown in FIG. 3B so that the top 12 can be inserted into the tunnel portion 31 of the X-ray CT gantry 30. For this reason, for example, in the case of motor drive or the like, the position of the bed apparatus 11 is detected and controlled so as to be securely fixed at each of the above positions. In the case of manual operation, a mechanical stopper or the like is provided to reliably stop at the stopper position. Like that.

  The other configurations are the same as those in FIG. 1, and the actions and effects can be said in the same way, so they will not be described again.

  Although the first and second embodiments have been described, it goes without saying that the present invention is not limited to these embodiments. In the above, a PET apparatus is used as the nuclear medicine diagnostic apparatus, but other nuclear medicine diagnostic apparatuses having a tunnel part for inserting a subject such as a SPECT apparatus can also be used. In addition, specific configurations and the like can be variously changed. Moreover, although it applies to a subject (human body) in the above, it can be applied to a subject such as a small animal such as a mouse or other living body in addition to the human body.

  According to this invention, the top plate in a cantilever state when the top plate on which the subject is placed is inserted into the gantry tunnel portion of the nuclear medicine diagnostic apparatus and the gantry tunnel portion of the X-ray CT apparatus. A medical image diagnostic apparatus that does not cause a problem of image displacement due to bending can be realized at a low cost with a relatively simple configuration. Further, this medical image diagnostic apparatus has improved maintainability.

1 is a perspective view schematically showing a medical image diagnostic apparatus according to one embodiment of the present invention. The flowchart for operation | movement description of the Example. The perspective view which shows typically the medical image diagnostic apparatus concerning another Example. The side view which shows a prior art example typically.

Explanation of symbols

10 ... Subject 11 ... Bed device 12 ... Bed top 20 ... PET gantry 21 ... Tunnel 22 ... Radiation detector 30 ... CT gantry 31 ... Tunnel 32 ... X-ray tube 33 …… X-ray detector 41 …… Console

Claims (1)

  A gantry of a nuclear medicine diagnostic apparatus having a tunnel portion for inserting a subject, and an X-ray having a tunnel portion for inserting a subject, which is adjacently arranged in parallel so that the tunnel portion is aligned in the horizontal direction with respect to the gantry. The horizontal position of the gantry of the CT apparatus, the bed apparatus having a top plate on which the subject is placed and inserted into the tunnel part of the gantry, and the horizontal position of the bed apparatus with respect to the above two gantry in the arrangement direction of the gantry arranged in parallel And a means for relatively moving the top plate between a position where the top plate can be inserted into the tunnel portion of one gantry and a position where the top plate can be inserted into the tunnel portion of the other gantry. apparatus.

Images