KR20090074399A - Body shape phantom for accuracy evaluation of image registration - Google Patents

Abstract

A body shape phantom for evaluating image registration is provided to simplify an internal structure by detachably arranging an external target in a predetermined point of a phantom body. A body shape phantom(10) for evaluating image registration includes a phantom body(16), a plurality of external targets(24) and a frame(12). The phantom body copies the appearance of the human body. The phantom body has an internal space for accommodating the water. The external target is detachably mounted in the outside of the phantom body. An external target has a sealing space for accommodating the water. The external target includes a target body and an airtight plug. The target body is made of acryl. An outlet is formed in one side of the target body to open the internal space. The airtight plug opens and closes the outlet. The frame supports the phantom body.

Description

Body shape phantom for accuracy evaluation of image registration}

The present invention relates to a human simulation phantom for image registration evaluation.

With the rapid development of science and technology, medical equipment has also been advanced, and various procedures and diagnostics, which were not possible in the past, have become possible one by one. Among such medical devices, there are imaging devices that allow the internal condition of the human body to be observed in more detail.

The imaging apparatus includes, for example, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medical imaging (SPECT), positron emission tomography (PET) and the like to diagnose and treat various tumors It plays an important role.

The computed tomography apparatus (hereinafter referred to as CT apparatus), magnetic resonance imaging apparatus (hereinafter referred to as MRI apparatus), nuclear medicine imaging apparatus (hereinafter referred to as SPECT apparatus), or positron emission tomography apparatus (hereinafter referred to as PET apparatus) Since each has different strengths and weaknesses, it is necessary to select and use the most accurate and clear image taking device according to the purpose of diagnosis.

For reference, the CT device obtains an image by using the difference in X-ray attenuation coefficient according to the change of electron density as an expression mechanism, and provides good anatomical image information with little distortion of the image. In particular, it is excellent for photographing bone tissue, and the electronic density information can be directly used for dose calculation, so it can be used as a reference image in radiotherapy planning.

In addition, the MRI device obtains an image by using the frequency conversion signal during the magnetization and relaxation of hydrogen atoms in the human body as an expression mechanism, and provides excellent anatomical image information by showing excellent soft tissue contrast. However, there is a possibility of distortion of the image due to the uniformity of magnetic field and various effects.

The SPECT device is a device for obtaining an image by injecting a reagent including a radionuclide that emits gamma rays into the human body, and then generating an image by using gamma rays emitted from a radionuclide located in a region of interest to be diagnosed as an expression mechanism. This is mainly used to analyze the metabolic and neurological functions of the diagnosis target area, but the disadvantage is that it is difficult to obtain anatomical information due to the low resolution of the image.

In addition, the PET device is a device that can be confirmed on the screen by using the fact that when the malignant tumor occurs in the human body consumes more glucose than other parts. It shows the degree of metabolic activity of sugars, oxygen and proteins that cause changes in the body, so it can catch abnormal signs early, but it is vulnerable for doctors to know exactly how large the tumor is in what area for surgery.

As described above, each photographing apparatus has its own advantages and disadvantages, so that more accurate diagnosis and treatment can be performed by analyzing as many images as possible and comparing images obtained through photographing.

On the other hand, for accurate comparison and analysis of photographing contents obtained from different photographing apparatuses, image registration for placing the photographing contents with each photographing apparatus at the same coordinates is essential. The image registration means to obtain a cross-sectional shape of a region of interest among the image contents acquired by different photographing apparatuses, and to move them to one reference coordinate to overlap each other. By overlapping the analysis of the images in this way it is possible to increase the accurate diagnosis and treatment effect.

On the other hand, the software used for image registration (that is, the image registration tool) is used to precisely match the images captured by each photographing device to a single coordinate, so if the accuracy of the image registration tool is not guaranteed, accurate image registration is performed. It can't be proved, and therefore can't be diagnosed and treated correctly.

Accordingly, researches on image matching continue to be conducted, and more accurate and convenient image matching tools are being developed based on the research results.

On the other hand, the image registration tool needs a phantom to enable multiple image acquisition and easy error analysis of the matching result in order to verify its performance suitability and precision. The phantom is a photographing target photographed by each photographing apparatus. That is, the phantom is a tool that enables the matching between the acquired images and other necessary operations by allowing their shape to appear in the image obtained through the photographing.

As a phantom for achieving the above object, there is a phantom (patent registration number 517889) (hereinafter, referred to as "priority data") for evaluating image registration accuracy filed and patented by the inventor of the present invention.

By the way, the phantom disclosed in the above-described prior material is a method of receiving a long-term mimetic body in a cylindrical casing having a certain diameter, so that it is difficult to accurately determine the orientation of the phantom in a tomography image. More than one reference point was necessary to exactly overlap the image obtained by the imaging device with one coordinate. That is, a separate target to be used as a reference point for image registration was to be installed inside the casing.

The target takes the form of a rod and does not occupy a large area on the tomography plane, but complicates the internal structure of the phantom, and in particular, the target located in close proximity to the mimetic makes the tomography image messy and rather disturbs the image registration. Sometimes.

Because of this problem, so-called external targets that can be fixed outside the phantom are required, but the fixed targets of the external targets for the phantom and the robustness of the target itself are not applied.

The present invention has been created to solve the above problems, and provided with a solid target and detachable external target that provides a standard for image registration at a certain point outside the phantom body that simulates the appearance of the actual human body, the target inside the phantom body There is no need to install a ruler, so the internal configuration is simple, and the purpose is to provide an phantom simulation phantom for image registration evaluation that can determine the inclination of the image through the analysis of the captured image.

In order to achieve the above object, the present invention provides a medical imaging, including a computed tomography (CT), magnetic resonance imaging (MRI), nuclear medical imaging (SPECT) or positron emission tomography (PET) It is taken by the device, and it is possible to judge the accuracy of the image registration tool by matching the images obtained through the image through the image registration process using the image registration tool, and to simulate the appearance of the human body. A phantom body having an inner space for hermetically receiving water; A plurality of external targets detachably mounted on the outside of the phantom main body and having a sealed space for accommodating water therein, the appearance of which appears in an image through photographing; And a frame supporting the phantom body so that the phantom body can be positioned at the photographing position of the photographing apparatus.

In addition, the external target; It is made of acryl and has a spherical inner space and one side of the target body is provided with an outlet opening for opening the inner space to the outside, characterized in that it comprises a sealing plug for opening and closing the outlet opening.

In addition, for the coupling of the phantom body and the target body, the phantom body is formed with a plurality of female threaded or connected male thread, the target body has a coupling thread or female threaded screw threaded to the female threaded or connected male thread Characterized in that provided.

In addition, a plurality of display bars are provided inside the phantom main body to provide a reference for identifying a cross-sectional shape of the phantom main body corresponding to the cross-sectional shape of the image obtained by the photographing apparatus. Characterized in that provided.

In addition, the display bar; Four display bars that are parallel to each other and are paired two by two, and that virtual planes including two paired display bars are arranged to cross at right angles to each other, and between one pair of display bars of the two pairs of display bars. It is located in, the lower end is characterized in that made of one display rod is inclined so that the upper end is in close proximity to the lower end of the display bar on one side.

In addition, the display bar; And an acryl tube extending in the longitudinal direction and fixedly supported by the phantom body, one end of which is extended to the outside of the phantom body, and a sealing cap provided at an extended end of the acryl tube and opening and closing an inner space of the acryl tube. It is done.

In addition, the inner space of the acrylic tube, characterized in that the insertion rod which the cross-sectional shape appears in the image obtained through the imaging device is further provided.

The present invention made as described above is provided with a solid and detachable external target that provides a reference for image registration at a certain point outside the phantom body that simulates the appearance of the actual human body, it is necessary to install the target inside the phantom body Since the internal structure is simple, and it is possible to grasp the inclination of the corresponding image by analyzing the captured image.

Hereinafter, one embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view illustrating a human body phantom for image registration evaluation according to an embodiment of the present invention, Figure 2 is a side cross-sectional view of the human body phantom shown in Figure 1, the XYZ coordinate axis is added to the side Represented by.

Basically, the human simulation phantom 10 for image registration evaluation according to the present embodiment is a photographing target photographed by two or more photographing apparatuses of a CT apparatus, an MRI apparatus, a SPECT apparatus, or a PET apparatus. A plurality of images obtained through the photographing is matched using an image matching tool to determine the accuracy of the image matching tool.

In any case, the phantom 10 according to the present embodiment includes a phantom body 16 having a head shape of a human body, and a plurality of external target deficits that are detachably provided on the outside of the phantom body 16 ( 24 and a frame 12 for receiving and supporting the phantom body 16.

The phantom body 16 is made of acrylic resin and has a predetermined thickness. In particular, the contour is very similar to the human head, and the eyes, nose and mouth are represented. This feature contrasts with the simple cylindrical casing of conventional phantoms.

The inner space of the phantom body 16 is sealed to accommodate water, and an outlet opening 16b is formed at the bottom portion 16c in contact with the first support plate 12a of the frame 12. The outlet inlet 16b is a passage provided for supplying water into the phantom body 16 or discharging water supplied to the phantom body 16 to the outside, and a female screw thread is formed on an inner circumferential surface thereof. For reference, when the Phantom 10 is photographed by a CT device or an MRI device, only water is injected, and when a PET device or a SPECT device is photographed, an additional contrast agent is injected together with water.

The outlet 16b is sealed by a sealing plug 12e to be described later. The sealing plug 12e is coupled to the outlet inlet 16b to seal the internal space of the phantom body 16 or is separated from the outlet inlet 16b to open the internal space.

In addition, a plurality of female threaded holes 16a are provided on the outer surface of the phantom body 16. The female threaded ball 16a is a groove in which a female thread is formed on the inner circumferential surface thereof, and is located in five places in this embodiment. The female threaded ball 16a is disposed horizontally on the forehead portion of the phantom body 16 and is positioned at the same height from the bottom portion 16c in the drawing.

In addition, five display bars 20 are provided in the phantom main body 16. The display rod 20 has the same configuration as the members whose cross-sectional shapes are represented by dots during the Z-axis tomography imaging of FIG. 2.

The display rod 20 includes an acrylic tube 20a having a lower end thereof embedded in the bottom portion 16c and extending upward to pass upward through a parietal portion of the phantom body 16, and the acrylic tube 20a. Insertion rod 20d is inserted into the interior of the acrylic tube 20a and screwed to the upper end of the sealing cap 20c for sealing the inner space of the acrylic tube 20a.

The lower end of the acrylic tube 20a is blocked so that the insertion rod 20d housed therein does not contact the bottom 16c. In particular, as shown, the lower end of the insertion rod 20d is located on the same plane as the bottom portion 16c. In addition, a female screw portion 20b is formed on the inner circumferential surface of the upper end of the acrylic tube 20a to which the sealing cap 20c is screwed.

In particular, in the phantom body 16, a seal (not shown) is applied to a portion where the acrylic tube 20a passes upward to prevent water from leaking. When the seal is not applied, a portion through which the acrylic tube 20a passes may be sealed with an adhesive.

Since the sealing cap 20c is screwed to the acrylic tube 20a as described above, the inner space of the acrylic tube 20a can be opened to the outside by opening the sealing cap 20c if necessary. That is, if necessary, the insertion rod 20d can be inserted into or taken out of the acrylic tube 20a.

The material of the insertion rod 20d depends on the type of imaging device. For example, when photographing the phantom 10 with a CT device, an aluminum rod may be applied, and when photographing with a SPECT device or a PET device, a brass bar may be used. In addition, when photographing with an MRI device, the acrylic tube 20a is left empty without applying the insertion rod 20d.

Four of the five display bars 20 are arranged vertically and the other is kept inclined. That is, the four display bars 20 are parallel to each other and are paired two by two, and a virtual plane including two pairs of display bars is intersected at right angles to each other.

In addition, the inclined display bar 20 is positioned between the pair of display bars of the two pairs of display bars, with the lower end thereof proximate the lower end of one display bar and the upper end proximate the upper end of the other display bar. Is located. By the inclined display bar, three display bars (as shown in Fig. 2) take the form of N characters.

On the other hand, the frame 12 is the first support plate 12a in contact with the bottom portion 16c of the phantom body 16, the second support plate 12b located on the phantom body 16 and the first It consists of the connecting plate 12c which connects the 1st support plate 12a and the 2nd support plate 12b. The first and second support plates 12a and 12b form a right angle with the connecting plate 12c.

Basically, the frame 12 is for laying the phantom body 16 vertically or horizontally as shown in FIG. 2. The frame 12 is applied because there is no flat portion on the outer surface of the phantom body 16 and cannot be positioned vertically or horizontally.

An outlet inlet 12d is provided at the central portion of the first support plate 12a. The oil inlet and outlet 12d has an outflow of the phantom body 16 (when the phantom body 16 is seated on the first support plate 12a). As the hole fits into the inlet 16b, it passes through the male screw portion of the sealing plug 12e so that the sealing plug 12e can be screwed into the outlet inlet 16b of the phantom body 16.

The sealing plug 12e is screwed to the outlet inlet 16b in a state spanning the first support plate 12a, thereby fixing the phantom body 16 to the first support plate 12a and at the same time of the phantom body 16. Seal the interior space. Reference numeral 12g is an O-ring for the seal. Reference numeral 12f is a groove in which the O-ring 12g is accommodated.

In addition, five supporting holes 12k are formed in the second supporting plate 12b. The support hole 12k is a hole for passing the display rod 20 upward. The upper end of the display bar 20 protrudes upward through the support hole 12k to the second support plate 12b and is coupled to the sealing cap 20c.

Since the display rod 20 passes through the support hole 12k in this manner, the phantom body 16 may be shaken with respect to the second support plate 12b as long as the display rod 20 is inserted into the support hole 12k. none.

On the other hand, the external target 24 is a spherical member that is screwed to the female threaded ball (16a). The outer target 24 is made of acrylic, like the phantom body 16.

The external target member 24 is a target body 24a having a spherical inner space and a coupling thread 24c fixed to one side of the outer circumferential surface of the target body 24a and screwed to the female threaded mouth 16a. Has In addition, the inner space of the target body 24a is opened to the outside through the outlet opening 24b, and the outlet opening 24b is opened and closed by the sealing plug 24d.

As described above, the female threaded ball 16a is formed at a predetermined position of the phantom main body 16, and the external target 24 is screwed to the female threaded ball 16a, so that the reproducibility of fixing the external target is sufficient. Of course, the coupling of the external target 24 to the phantom body 16 can be securely maintained.

As such, reproducibility and robustness are guaranteed, the external target 24 itself may serve as a reference coordinate system.

The outlet inlet 24b is a passage for injecting water into the target body 24a or for discharging the injected water to the outside, and a female thread is formed on the inner circumferential surface thereof. The sealing plug 24d seals the internal space of the target body 24a by screwing into the outlet opening 24b.

In addition, like the phantom main body 16, when the phantom 10 is photographed by the CT device or the MRI device, only water is injected into the target body 24a, and when the PET device or the SPECT device is photographed, the contrast agent is injected together with the water. .

FIG. 3 is a view schematically showing an image of a tomography plane R among a plurality of tomography images obtained when the phantom 10 shown in FIG. 2 is tomographically photographed in the Z direction. In addition, FIG. 4 illustrates the principle of determining the height of the tomographic plane R of FIG. 3 from the bottom portion 16c by using the distance between the fixed points A1 and A3 and the moving point A2 shown in FIG. 3. Figure is shown.

Referring to FIG. 3, it can be seen that the cross section of the display rod 20 is shown as a dot in the image of the tomography plane R of the phantom body 16. The point consists of four fixed points A1, A3, A4 and A5 and one moving point A2.

In particular, the positional information of the fixed points A1 and A3 and the moving point A2 is used to determine the distance from the bottom surface of the tomography point, that is, the Z-axis distance H2 of the corresponding tomographic image, that is, the bottom portion 16c.

The fixing points A1 and A3 are always fixed to form a fixed point and spaced apart by a constant interval w regardless of the photographing position in the Z-axis direction. On the other hand, the moving point A2 moves between the fixed points A1 and A3 according to the photographing point in the Z-axis direction and approaches the fixed point A1 side or the other fixed point A3 side.

Meanwhile, the height of the axial direction of the image can be calculated by finding the distance S between the moving point A2 with respect to the fixed point A3. That is, it can be seen by examining the distance of the moving point with respect to the fixed point whether the current image is the image of the cross section corresponding to what height from the bottom 16c. The interval S can be known through the corresponding video material.

As shown in Fig. 4, the distance H2 in the Z-axis direction of the image R when the distance between the fixed points A1 and A3 is W and the moving point A2 is separated by S from one fixed point A3 is the insertion rod ( 20d) becomes the length H1 * S / interval W between fixed points.

That is, H2 = (H1 * S) / W.

After the tomography of the phantom 10, when the image of the required cross-section is imported to the computer monitor, the height of the axial direction of the imported image is obtained by only grasping the interval between the fixed points A1 and A3 and the moving point A2. Can be calculated.

On the other hand, by determining the interval of the display rod appearing in the image acquired through Z-direction tomography, it is possible to determine whether the acquired image is an abnormally tilted image that is not orthogonal to the Z-axis and how inclined.

5 to 7 is a method of determining the degree of inclination of the acquired image through the amount of change in the interval of the display rod appearing in the image obtained by the tomography in the Z-axis in the human body phantom 10 shown in FIG. Figure is for explaining.

FIG. 5A illustrates that the display rod 20 is parallel to the Z-axis when the phantom 10 is tomographically photographed in the Z-axis direction, and FIG. 5B illustrates an image obtained by the tomography.

As shown in FIG. 5B, for example, when the distance between the fixed point A1 and A3 in the tomography image floated on the monitor is equal to the distance D1 (which is a known value) of the actual display bar 20, the floating point is displayed on the current monitor. The true image is orthogonal to the Z-axis and based on this, it can be determined that the tomographic image is normal.

However, when the image uploaded on the monitor is the same as that of FIG. 6B, that is, when the distance D2 between the fixed points A1 and A3 is larger than the distance D1 of the actual display bar 20, the corresponding image being displayed on the monitor is normal tomographic plane ( A plane of the photographing surface S1 inclined by θ1 of FIG. 6A from a plane perpendicular to the Z axis). The incorrect image is corrected through the correction software, and then image registration is performed.

In addition, in the tomography image uploaded on the monitor as shown in FIG. 7B, when the distance D4 between the fixed points A4 and A5 is larger than the distance D1 of the actual display bar 20, the image on the monitor is normal tomographic plane Z. It can be seen as an image of the photographing surface S2 inclined by θ2 of FIG. 7A from a plane perpendicular to the axis). This incorrect image is corrected by the correction software and then used for image registration.

As described above, since the three-dimensional image registration is possible through the so-called rotation correction using the display bar 20 before the image registration, the accuracy of the image registration tool can be sufficiently evaluated.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to the said Example, A various deformation | transformation is possible for a person with ordinary knowledge within the scope of the technical idea of this invention.

1 is an exploded perspective view illustrating a human body phantom for image registration evaluation according to an embodiment of the present invention.

2 is a cross-sectional view of the human body phantom shown in FIG.

FIG. 3 is a view schematically illustrating an image of a tomography plane R among a plurality of tomography images obtained when the phantom shown in FIG. 2 is tomographically photographed in the Z direction.

FIG. 4 is a view for explaining the principle of grasping the height of the tomographic plane R using the distance between the fixed points A1 and A3 and the moving point A2 shown in FIG. 3.

5 to 7 are views illustrating a method of determining the degree of inclination of the acquired image based on the interval of the display rods shown in the image obtained through the tomography in the Z-axis in the human body phantom shown in FIG. It is shown for the sake of simplicity.

<Explanation of symbols for the main parts of the drawings>

10: Phantom 12: Frame

12a: first support plate 12b: second support plate

12c: connecting plate 12d: outlet

12e: Airtight plug 12f: Groove

12g: O-ring 12k: support hole

16: phantom body 16a: female thread

16b: Outlet 16c: Bottom

20: display bar 20a: acrylic tube

20b: Female thread 20c: Airtight cap

20d: Insertion Rod 24: External Target

24a: target body 24b: outflow

24c: Male thread 24d: Sealed plug

Claims (7)

It is taken by a medical imaging device, including a computed tomography (CT) or magnetic resonance imaging (MRI), or a nuclear medical imaging (SPECT) or a positron emission tomography (PET) device. By comparing the images through the image matching process using the image matching tool and comparing them with each other, it is possible to determine the accuracy of the corresponding image matching tool. A phantom body having an internal space that mimics the appearance of a human body and seals water therein; A plurality of external targets detachably mounted on the outside of the phantom main body and having a sealed space for accommodating water therein, the appearance of which appears in an image through photographing; Human body phantom for image registration evaluation, characterized in that it comprises a frame for supporting the phantom body so that the phantom body can be positioned at the shooting position of the imaging device. The method of claim 1, The external target; A target body made of acryl and having a spherical inner space and having an outlet opening at one side thereof to open the inner space to the outside; Human simulation phantom for the image registration evaluation, characterized in that it comprises a sealing plug for opening and closing the outlet. The method of claim 2, For coupling the phantom body and the target body, the phantom body has a plurality of female threaded or threaded male threads, and the target body has a threaded or female threaded screw threaded to the female threaded or male threaded thread. Human simulation Phantom for image registration evaluation. The method according to any one of claims 1 to 3, Inside the phantom main body, a cross-sectional shape appears in an image obtained by capturing the photographing apparatus, and a plurality of display bars are provided to provide a criterion for determining whether the image is a cross-sectional image corresponding to a point of the phantom main body. Human simulation phantom for image registration evaluation, characterized in that. The method of claim 4, wherein The display bar is; Four display bars parallel to each other and arranged in pairs, and arranged so that an imaginary plane including two pairs of display bars intersects at right angles to each other; It is positioned between the pair of display bar of the two pairs of display bars, the lower end is formed of one display bar inclined so as to be in close proximity to the lower end of one display bar and the upper end to the upper end of the other display bar. Human Phantom for Image Registration Evaluation. The method of claim 4, wherein The display bar is; An acrylic tube extending in a longitudinal direction and fixedly supported by the phantom body and having one end extending outward of the phantom body; The human body phantom for image registration evaluation, characterized in that it is provided at the extended end of the acrylic tube and comprises a closed cap for opening and closing the inner space of the acrylic tube. The method of claim 6, In the internal space of the acrylic tube, the human body simulation phantom for image registration evaluation, characterized in that the insertion rod which the cross-sectional shape appears in the image obtained through the imaging device is further provided.

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