KR101358468B1 - Target volume verification phantom - Google Patents

Abstract

The present invention relates to a phantom for verifying a volume and a position of a lesion, capable of comparing volumes of the lesion with one another and verifying them according to imaging apparatuses, imaging conditions and variations in contrast enhancement of each contrast agent with respect to the same lesion positioned within the cranium of a patient who is to undergo stereo-tactic radio surgery and radiation therapy The phantom comprises a cylindrical phantom body forming a space for accommodating water; a plurality of fixed rods arranged in parallel with a longitudinal direction within the phantom body and fixed between top and bottom plates; and a plurality capsules concentrically fixed on the fixed rods respectively and including one or more capsules which are filled with a mixed solution of a CT contrast agent and an MRI contrast agent. The capsules are arranged to be regularly distributed over the entire height of the phantom body.

Description

Phantom for volume and location verification of lesions {Target volume verification phantom}

The present invention can compare and verify the image capturing equipment and imaging conditions for the same lesion located in the two heads of the patients undergoing stereotactic radiosurgery and treatment, and the volume of the lesion according to the change in contrast enhancement of each contrast agent. To a phantom for verifying the volume and location of the lesion.

Stereotactic radiosurgery and radiation therapy is a surgical procedure that involves irradiating high doses of radiation to small lesions in the cranial follicles at a time, with minimal dose reaching the surrounding normal tissue.

The characteristic of radiation distribution in cerebral stereotactic radiosurgery and treatment is the physical property that the dose is sharply reduced even a few millimeters away from the set point. The condition required for such radiosurgery is that the stereotactic instrument must first be firmly attached to the patient's skull, the position of the target target point must be accurately determined in three-dimensional space, and the planned dose must be accurately transmitted to the target point.

Above all, it is an important prerequisite to accurately determine the location of small lesions within the patient's skull in three dimensions. To this end, a computer tomography device (hereinafter referred to as CT device) or Magnetic resonance imaging apparatuses (hereinafter referred to as MRI apparatuses), nuclear medical imaging apparatuses (hereinafter referred to as SPECT apparatuses) and positron emission tomography apparatuses (hereinafter referred to as PET apparatuses) may be utilized.

Since the photographing apparatus has different advantages and disadvantages, the photographing apparatus is used to select the photographing apparatus that provides the most accurate and clean images according to the purpose of diagnosis. The photographing apparatus is the most widely used photographing apparatus with high frequency of use and relatively low photographing cost. Examples include CT devices and MRI devices.

The CT device obtains an image using the difference in X-ray attenuation coefficient according to the change of electron density as an expression mechanism, and provides a 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 apparatus obtains an image by using the frequency conversion signal in the magnetization and relaxation process 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 the magnetic field and various influences.

Therefore, in order to make use of the advantages and disadvantages of each of the above CT device and MRI device, the clinic uses MRI image and CT image for cerebral stereotactic radiosurgery and treatment. Because of these differences and the composition of contrast agents used to identify the lesions, there may be differences in the volume and shape of the lesions after image fusion.

If the volume and shape of the lesion is different, the possibility of later recurrence of the lesion may be determined by over-treatment by misdiagnosing normal tissue as the lesion according to the images used in the treatment plan during radiation surgery and treatment, or by performing surgery and treatment smaller than the actual lesion size. Left.

Therefore, the need for measuring and evaluating the reliability of image fusion is highly demanded by developing phantoms that can compare and verify the imaging equipment and imaging conditions for the same lesions, and the volume of lesions according to the contrast enhancement of each contrast agent. have.

As a phantom associated with stereotactic radiosurgery and treatment, Korean Patent Laid-Open Publication No. 2012-0011575 discloses a device for verifying a target point and radiation distribution of cerebral stereotactic radiosurgery.

Korean Laid-Open Patent No. 2012-0011575 fills the cavity of a phantom shaped to the head of a human body with a liquid filling material, and arranges it to correspond to the verification target position, so as to simulate each lesion (tumor) in a gel state. By providing a plurality of gel measuring instruments made of muscle equivalents, it is configured to be used as a three-dimensional verification tool of the radiosurgical plan before treatment by confirming the three-dimensional radiation distribution of the tumor that is the target of the actual radiation surgery.

However, since the above prior art can only confirm the three-dimensional radiation distribution of the tumor that is the target of the actual radiation surgery, the imaging equipment and imaging conditions for the same lesion, the lesion according to the contrast enhancement of each contrast agent. There is still a need for the development of new phantoms that allow for volume comparison and verification.

Korean Laid-Open Patent No. 2012-0011575

The present invention relates to the volume of lesions that can be used to evaluate the accuracy and reliability of lesion volume composition for various types of treatment planning programs (gamma knife, Novalis, cyber knife, linear accelerator, etc.) used in clinical practice. The purpose is to provide a phantom for position verification.

In addition, the present invention is for verifying the volume and location of lesions that can be used for quality control of the imaging device by comparing the image quality of the CT device and the MRI device with or without contrast and contrast-enhanced image quality according to the contrast agent. Another purpose is to provide phantoms.

The volume and position verification phantom of the lesion according to the present invention includes a cylindrical phantom body having a space accommodating water therein; and arranged in parallel in the longitudinal direction inside the phantom body, between the upper plate and the lower plate. A plurality of fixing rods fixed; And a plurality of capsules fixed on the fixing rods so as to be concentric with the fixing rods, the capsules including at least one capsule filled with a mixture of CT contrast medium and MRI contrast medium therein. It is characterized in that it is arranged to be evenly distributed throughout the height of the phantom body.

Here, the plurality of fixing rods includes at least one row arranged along the circumference of the same radius on a plane perpendicular to the longitudinal direction of the phantom body.

And, it is preferable that at least two rows are included, and any capsules included in each row do not overlap radially on a plane perpendicular to the longitudinal direction of the phantom body.

The rows may consist of three rows of first to third rows starting from the outer side of the phantom body, and the first to third rows are arranged at equal intervals along the radial direction.

In addition, the capsules included in each row may be sequentially distributed over the entire height of the phantom body along adjacent fixing rods to form a spiral in the circumferential direction.

In an embodiment of the present invention, the row consists of three rows of first to third rows starting from the outside of the phantom body, the first row includes 12 capsules, the second row and the third row Each contains six capsules.

In addition, two capsule groups consisting of a series of six capsules among the twelve capsules included in the first row are arranged to form a spiral on a semi-circle.

In particular, the two capsule groups are preferably in the same spiral direction.

On the other hand, one of the plurality of fixing rod is a central rod disposed along the longitudinal center axis of the phantom body, a plurality of capsules may be fixed to the central rod.

Here, it is preferable that the plurality of capsules fixed to the center rod form an equal interval, and in the embodiment of the present invention, the number of the plurality of capsules fixed to the center rod is three.

The phantom for verifying the volume and location of the lesion according to the present invention provides a standard for evaluating the accuracy and reliability of the volume composition of the lesions in the treatment planning program of each type of radiotherapy device used in the clinic. By misdiagnosing the lesion as an overtreatment or performing surgery and treatment smaller than the actual lesion size, the possibility of later recurrence of the lesion can be reduced.

In addition, by utilizing the phantom of the present invention, it is possible to use the quality control of the photographing apparatus by comparing the image quality of the CT apparatus and the MRI apparatus without the image distortion and the contrast agent or the contrast-enhanced image quality between the imaging apparatuses.

1 is a view showing the overall structure of the phantom according to the present invention.
2 is a view showing the arrangement of the fixing rods of the first row included in the phantom of the present invention.
3 is a view showing the arrangement of the second row of fixed rods included in the phantom of the present invention.
4 is a view showing the arrangement of the third row of fixed rods included in the phantom of the present invention.
5 is a view showing a central rod included in the phantom of the present invention.
Figure 6 is an image taken after fixing the phantom of the present invention to the head position of the patient in the same setting conditions for each of the CT device and MRI device.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the phantom 10 for verifying the volume and position of the lesion according to the present invention will be described in detail. The present invention is not limited to the embodiments described below, but may be implemented in various other forms, and the present embodiment is not intended to be exhaustive or to limit the scope of the present invention to those skilled in the art. .

1 is a view showing the overall structure of the phantom according to the present invention, Figures 2 to 4 are views showing the arrangement of the fixing rods of the first row to the third row included in the phantom of the present invention, Figure 5 is the present invention Figure 6 is a view showing a central rod included in the phantom of, Figure 6 shows the image taken after fixing the phantom of the present invention to the position of the head of the patient in the same setting conditions for each of the CT device and the MRI device.

Phantom for verifying the volume and position of the lesion according to the present invention (hereinafter, simply referred to as 'phantom') is a kind of water phantom, and has a cylindrical phantom body 100 having a space for receiving water therein, The phantom main body 100 includes a plurality of capsules 300 filled with a plurality of fixing rods 200 arranged in parallel in the longitudinal direction, and a mixed solution 310 of CT contrast medium and MRI contrast medium.

The overall configuration of the phantom according to the present invention is shown in FIG. 1, and the phantom of the present invention will be described in detail with reference to FIG. 1.

The phantom body 100 has a cylinder shape in which a water receiving space is formed therein as shown, and has a structure in which circular upper and lower plates 110 and 120 are assembled on both sides to close the inside.

In addition, a plurality of fixing rods 200 are provided and arranged in parallel in the longitudinal direction in the phantom body 100, and are fixed by being inserted into insertion holes 130 formed in the upper plate 110 and the lower plate 120, respectively. .

The stationary rod 200 as described above is for fixing a plurality of capsules 300 including at least one capsule 300 filled with a mixed solution 310 of CT contrast medium and MRI contrast medium in place. The capsule 300 may be referred to as a reference object for simulating the location and shape of a lesion that is a target of radiation surgery and treatment, and among them, the location and volume of a lesion obtained between a CT device and an MRI device, which are representative radiographic apparatuses, may be used. The capsule 300 is filled with a mixed solution 310 of CT contrast medium and MRI contrast medium so as to be compared with each other. Of course, if the radiography device is changed, the contrast medium mixed accordingly will be different.

The plurality of capsules 300 should be arranged to be evenly distributed throughout the height of the phantom body 100, which is spatially plural in the interior of the phantom body 100 to simulate the position and volume of the lesion having any shape This is because the three capsules 300 need to be distributed as uniformly as possible without being biased.

In addition, the fixed position of the capsule 300 must be maintained in the exact position according to the pre-designed specifications to compose the image three-dimensionally based on the capsule 300 image shown in the CT image or MRI image and to calculate the volume and position comparison The results of the analysis become reliable.

To this end, the capsule 300 is fixed in the middle of the fixing rod 200 to be concentric with the fixing rod 200, the two pieces having a length corresponding to the height of the phantom body 100 by adding the length of the capsule 300 It is possible to take the configuration to provide a fixed rod 200 and to fix the capsule 300 therebetween. According to this configuration, by changing the length of the two pieces of fixing rod 200 (the total length is constant), it is possible to arbitrarily adjust the fixed position (height) of the capsule 300. In the exemplary embodiment of the present invention, the capsule 300 has a cylindrical outer shell and has a space in which a space in which the mixed solution 310 of the contrast agent is filled is formed, and the insertion protrusion is formed at the end of the fixing rod 200. 205 is formed so that the insertion protrusion 205 can be inserted into the insertion hole 320 at both ends of the capsule 300 so as to be fixed while forming concentrically (see the partial enlargement included in FIG. 1). That is, the insertion protrusion 205 formed on the fixing rod 200 serves as a stopper to prevent leakage of the mixed solution 310 of the contrast agent filled in the capsule 300. In addition, in the embodiment of the present invention, the capsule 300 is made of acrylic material having strong chemical resistance and easy processing for the mixed solution 310 of the contrast agent.

On the other hand, the plurality of fixing rods 200 may be arranged to include at least one row arranged along the circumference of the same radius on a plane perpendicular to the longitudinal direction of the phantom body 100. When the fixing rod 200 to which the capsule 300 is fixed forms a row along the circumferential direction, it becomes easy to construct the capsule 300 spatial distribution uniformly and symmetrically, and the symmetry is based on the image of the capsule 300. This is desirable because it makes it easy to construct an image in three dimensions and to calculate volume and position.

At least two rows of the fixing rods 200 may be included, wherein no capsules 300 included in each row do not overlap in a radial direction on a plane perpendicular to the longitudinal direction of the phantom body 100. This is good because it is more advantageous in terms of simulating the position and volume of a lesion having any irregular shape by using a plurality of capsules 300 fixed at a predetermined position.

The row may be formed of three rows of first rows 210 to third columns 230 starting from the outside of the phantom body 100, and also the first rows 210 to third columns 230. Are arranged at equal intervals along the radial direction. Here, in FIG. 1, it may be confusing to show a plurality of rows on a perspective view, so only the outermost first row 210 and the central rod 240 to be described later are shown.

In addition, the capsules 300 included in each row may be sequentially distributed over the entire height of the phantom body 100 along the adjacent fixing rod 200 to form a spiral in the circumferential direction.

In the embodiment of the present invention, the row of the fixing rod 200 consists of three rows of the first row 210 to the third row 230 starting from the outside of the phantom body 100, the first row 210 ) Includes 12 capsules 300, and the second row 220 and the third row 230 include six capsules 300, respectively.

FIG. 2 is a view illustrating an arrangement of the fixing rod 200 and the capsule 300 included in the first row 210. The outermost first row 210 includes a total of twelve fixed rods 200 arranged at equal angles and twelve capsules 300 fixed one by one on each fixed rod 200. 2 shows the order of 1-1 to 1-12 for the 12 fixed rods 200 of the first row 210. As shown, the 12 capsules included in the first row 210 ( 300 includes two capsule groups 300 ', 1-1 to 1-6 and 1-7 to 1-12, which consist of a series of six capsules 300, each of which is 6 in each capsule group 300'. The dog capsules 300 are each arranged to spiral on a semicircle. Here, instead of forming a single spiral on the circumference of the 12 capsules 300, two distinct groups 300 ′ each constitute a spiral on a semicircle, and when the CT or MRI imaging is performed, The position is not to be confused with each other and to facilitate the distinction.

Based on one capsule group 300 ′ in the first row 210, six capsules 300 are sequentially arranged at equal intervals along the height direction, and the two capsule groups 300 ′ are identical to each other. It is arranged so that the fixed position of each capsule 300 gradually increases from below to upward (based on the drawing) so as to form a spiral direction. Then, the capsule 300 forming one spiral is preferably disposed evenly so as not to overlap each other on the height.

3 and 4 illustrate an arrangement of six fixing rods 200 and capsules 300 included in the second row 220 and the third row 230, respectively. In the fixing rod 200 of the second row 220, the order of 2-1 to 2-6 is shown, and the order of 3-1 to 3-6 is shown in the third row 230. The relative positions of the capsules included in 210), 1-1 to 1-12, are also displayed.

The configuration of the second row 220 and the third row 230 is almost the same as one capsule group 300 ′ included in the first row 210, and only the second row 220 and the third row ( Since the 230 is arranged at an isometric angle on the circumference, the difference between the adjacent fixing rods 200 is 60 °, which is twice as large as that of each capsule 300 included in the first row 210.

As described above, the capsules 300 included in each of the first row 210 to the third row 230 may not overlap in a radial direction on a plane perpendicular to the length direction of the phantom body 100. You can see that they are staggered.

In addition, one of the plurality of fixing rods 200 may be included as a central rod 240 disposed along the longitudinal center axis of the phantom body 100, the plurality of capsules 300 may be fixed to the central rod 240 have. The capsule 300 included in the central rod 240 may be used as a reference point for more easily determining the relative position of the other capsule 300 arranged in the circumferential direction.

Here, it is preferable that the plurality of capsules 300 fixed to the central rod 240 form an equal interval, and in the embodiment of the present invention, the number of the plurality of capsules 300 fixed to the central rod 240 is three, 5 is shown in order of 4-1 to 4-3. And, as the three capsules 300 indicated in the order of 4-1 to 4-3 are fixed, the central rod 240 is made of a structure that is divided into four pieces.

6 is an image taken after fixing the phantom of the present invention to the position of the head of the patient in the same setting conditions for each of the CT device and the MRI device. In FIG. 6, the round circle that appears white in the upper CT image is a cross-sectional image of the capsule 300 filled with the mixed solution 310 of the CT contrast agent and the MRI contrast agent, and it can be seen that the corresponding circle is shown in the lower MRI image. have. The ring around the circle in the MRI image is the container portion of the capsule 300 of acrylic material, the acrylic material appears in the form of a black ring in the MRI image.

The two-dimensional image as shown in FIG. 6 is continuously photographed. When the two-dimensional image is reconstructed in three dimensions by using each consecutive two-dimensional image, the position and volume of the capsule 300 may be compared and measured. In other words, a digital image and communication in medicine (DICOM) image of consecutive CT and MRI is loaded from the treatment plan program of each radiosurgery / radiation treatment device and reconstructed into three-dimensional volume, whereby a mixture of CT contrast agent and MRI contrast agent is used. Comparing the location of the lesion and the volume of the three-dimensional shape simulated by the capsule 300 filled with the 310 is to be able to measure the reliability.

Table 1 below shows a total of 27 capsules calculated using Brainscan, Leksell GammaPlan, and MultiPlan, which are radiation planners of Novalis, Gammaknife, and Cyberknife. This is a table comparing the average value of the volume for 300).

Modality
Surgical Equipment CT
(mean ± SD ㎣) MRI
(mean ± SD ㎣) Novalis
Brainscan
2224 ± 73
2080 ± 57 Gammaknife
(Leksell GammaPlan)
2129 ± 72
1940 ± 50 Cyberknife
(MultiPlan)
2239 ± 95
2151 ± 75
Overall average
2198 ± 93
2057 ± 106

And, Table 2 evaluates the difference between CT devices and MRI devices in the above three specifications at 95% confidence intervals through the Wilcoxon matched-pairs sign-rank test. It is.

CT ₁ -CT ₂ CT ₁ -CT ₃ CT ₂ -CT ₃ MRI ₁ -MRI ₂ MRI ₁ -MRI ₃ MRI ₂ -MRI ₃ T + 23 12 4 27 4 0 T- 3 14 23 0 22 27 T One 2 0 0 0 0 result CT ₁ > CT ₂ n.s CT ₂ <CT ₃ MRI ₁ > MRI ₂ MRI ₁ <MRI ₃ MRI ₂ <MRI ₃ Volume difference 95 ± 79 -15 ± 66 -110 ± 99 139 ± 68 -71 ± 94 -210 ± 87 Probability of approximate reason p < 0.001 p = 0.316 p < 0.001 p < 0.001 p = 0.001 p < 0.001

CT ₁ , MRI ₁ : Novalis (Brainscan)

CT ₂ , MRI ₂ : Gammaknife (Leksell GammaPlan)

CT ₃ , MRI ₃ : Cyberknife (MultiPlan)

T +: The sum of the ranks of positive difference

T-: The sum of the ranks of negative difference

T: The sum of the ranks of equal

n.s: No significantly difference

p-value: The differences are significant in 0.05 level (both sides)

Analyzing the results in Table 2 above, the 95% confidence interval of the Wilcoxon code rank test showed that there was a statistically significant difference in CT images obtained from Novalis and Cyberknife, but there were no significant differences in the other images. It was confirmed that.

Therefore, it is necessary to set the clinical tolerance for CT images acquired from Novalis and CyberKnife.

As described above with reference to the drawings illustrated for the volume and position verification phantom 10 of the lesion according to the present invention, the present invention is not limited by the embodiments and drawings disclosed herein, the present invention Of course, various modifications can be made by those skilled in the art within the scope of the technical idea.

10: phantom 100: phantom body
110: upper plate 120: lower plate
130: insertion hole 200: fixed rod
205: insertion hole 210: first row
220: second row 230: third row
240: center rod 300: capsule
300 ': capsule group 310: contrast medium mixture
320: insertion groove

Claims (12)

A cylindrical phantom body having a space accommodating water therein;
A plurality of fixing rods arranged in parallel in the longitudinal direction inside the phantom body and fixed between an upper plate and a lower plate; And
A plurality of capsules each fixed on the fixing rods so as to be concentric with the fixing rods and including at least one capsule filled therein with a mixed solution of CT contrast medium and MRI contrast medium;
And the plurality of capsules are arranged to be evenly distributed throughout the height of the phantom body. The method of claim 1,
The plurality of stationary rods are phantom for verifying the volume and position of the lesion, characterized in that it comprises at least one row arranged along the circumference of the same radius on a plane perpendicular to the longitudinal direction of the phantom body. 3. The method of claim 2,
At least two rows are included, and none of the capsules included in each row are overlapped in a radial direction on a plane perpendicular to the longitudinal direction of the phantom body, wherein the phantom for verifying volume and location of the lesion is phantom. The method of claim 3,
The row is phantom for verifying the volume and position of the lesion, characterized in that consisting of three rows of first to third rows starting from the outside of the phantom body. 5. The method of claim 4,
The first to third rows are phantom for verifying the volume and position of the lesion, characterized in that arranged at equal intervals along the radial direction. 6. The method according to any one of claims 2 to 5,
The capsules included in each row are sequentially distributed throughout the height of the phantom body along adjacent fixing rods to form a spiral in the circumferential direction as a whole. The method according to claim 6,
The row is composed of three rows of rows 1 to 3 starting from the outside of the phantom body, the first row includes 12 capsules, and the second row and third row each contain six capsules. Phantom for verifying the volume and location of the lesion, characterized in that. The method of claim 7, wherein
Two capsule groups consisting of a series of six capsules of the 12 capsules included in the first row are each helical in a semicircle, the volume and location verification phantom of the lesion. 9. The method of claim 8,
The two capsule groups are in the same spiral direction, the volume and position verification phantom of the lesion. The method of claim 7, wherein
One of the fixing rods is a central rod disposed along the longitudinal center axis of the phantom body, wherein the plurality of capsules are fixed to the central rod. 11. The method of claim 10,
Volume and location verification phantom of the lesion, characterized in that the plurality of capsules are fixed to the center rod to form an equal interval. 12. The method of claim 11,
Phantom for verifying the volume and location of the lesion, characterized in that the plurality of capsules are fixed to the central rod three.

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