KR101937651B1 - Tomotherapy apparatus using phantom inserting phosphorescent plate - Google Patents

Abstract

Disclosed is a tomotherapy apparatus measuring three-dimensional dose distribution using a phosphorescence plate-inserted phantom The tomotherapy apparatus includes: a first transparent member; a second transparent member; the phantom including a phosphorescence plate which is located between the first transparent member and the second transparent member; a camera detecting visible light which is generated from the phosphorescence plate and storing an image; and an image processing unit processing the stored image in the camera and forming a three-dimensional image. Therefore, the three-dimensional measuring method can derive better result in radiation treatment by using the tomotherapy.

Description

TOMOTHERAPY APPARATUS USING PHANTOM INSERTION PHOSPHORESCENT PLATE [0002]

The present invention relates to a tomography apparatus, and more particularly, to a tomography apparatus for measuring a three-dimensional dose distribution using a phantom inserted with a phosphorescent plate.

Tomotherapy is a combination of intensity modulated radiotherapy and computed tomography (CT), which uses CT to identify the location and shape of the tumor during each treatment, as well as to treat more intense intensity modulated radiotherapy on the cancer site .

TomoTherapy treats the cancer to be treated with several layers and then irradiates hundreds of slender radiations in each direction from 360 degrees. It is unique in that the radiation is irradiated to the patient, so that the treatment of slice or helical, Also called treatment.

More specifically, the method of measuring the dose of spiral tomography differs from that of a conventional linear accelerator because of its unique shape, and its performance is also different. Dosimetry of tomotherapy is typically measured by ionizing using a phantom dedicated tomothecopy. In addition, during the dose measurement process, a special treatment planning device is used, which can predict the dose used in the actual treatment by reconstructing the calculated dose on the image obtained using the phantom for the treatment plan of the patient.

However, as for the conventional phantom for tomothe- phy which has been commercialized so far, it is impossible to measure the three-dimensional dose similarly to other phantoms. In particular, radiation therapy using tomography, which performs intensity-modulated radiotherapy with a helical beam, is more complex than conventional intensity-modulated radiation therapy, and so a true three-dimensional dose assurance method is more urgently needed.

Korean Patent Laid-Open Publication No. 10-2013-0078470 discloses a phantom device for measuring the amount of radiation to be irradiated to a specific position. The phantom device includes a cylindrical case having a receiving space therein and an open side; A body made of the same material as the case and detachably housed in the accommodation space; A measuring groove formed in the body and recessed in the longitudinal direction of the body; A plug member slidably coupled to the measurement groove portion and having a groove type sensor mounting portion for receiving a detector for measuring the amount of radiation irradiated to the body; .

However, the prior art does not disclose a configuration in contrast to the phantom device for measuring the amount of radiation irradiated to a specific position. Therefore, the prior art differs in that it does not disclose a point for accurately measuring the dose and a technique for image processing the obtained image in a progressive manner and then implementing it as a 3D stereoscopic image.

Korean Patent Publication No. 10-2013-0078470

It is an object of the present invention to solve the above problems and provide a tomography apparatus for measuring a three-dimensional dose distribution using a phantom having a phosphorescent plate inserted therein.

According to an aspect of the present invention, there is provided a tomography apparatus comprising: a first transparent member; A second transparent member; A phantom including a phosphorescent plate positioned between the first transparent member and the second transparent member; A camera which senses visible light generated from the phosphorescent plate and stores the image; And an image processing unit for processing the image stored in the camera to construct a three-dimensional stereoscopic image.

Here, the first transparent member and the second transparent member may be plastic.

Here, the phantom may be cylindrical.

Here, the phantom may be independent of movement of the patient table.

Here, the phantom can maintain the same position while the radiation is irradiated.

Here, the image processor may construct a three-dimensional stereoscopic image based on the pitch and time information on which the patient table is moved.

According to another aspect of the present invention, there is provided a tomography apparatus comprising: a first transparent member; A second transparent member; And a phantom including a phosphorescent plate positioned between the first and second transparent members, wherein the phantom is independent of movement of the patient table and remains in the same position during irradiation.

Here, the first transparent member and the second transparent member may be plastic.

Here, the phantom may be cylindrical.

Here, the tomography apparatus includes a camera for sensing an image of visible light generated from a phosphorescent plate and storing an image; And an image processor for processing the image stored in the camera to construct a three-dimensional stereoscopic image.

Here, the image processor may construct a three-dimensional stereoscopic image based on the pitch and time information on which the patient table is moved.

In the tomography apparatus according to the embodiment of the present invention as described above, it is possible to guarantee the dose of tomography by applying the epileptic dose guarantee phantom for measuring the three-dimensional dose distribution in real time.

In addition, since the patient's table has the characteristic of moving during treatment because of the spiral treatment of the tomothecia and the characteristic of having the pitch value per one wheel of the gantry, It is possible to continuously capture a two-dimensional image by continuously positioning the center of the gantry without moving, and acquire a three-dimensional dose distribution image by applying a pitch value per frame to the photographed image.

Therefore, the three-dimensional measurement method according to the present invention can enhance the result of radiation therapy using tomothecia.

FIG. 1 is a conceptual view for explaining a phantom inserted with a phosphorescent plate according to an embodiment of the present invention. FIG.
FIG. 2 is an exemplary view for explaining a phantom inserted with a phosphorescent plate according to an embodiment of the present invention. FIG.
FIG. 3 is an exemplary diagram showing the results of irradiating three types of imaginary targets of one point, C shape, and multi type, in order to evaluate the performance of the tomography apparatus according to the embodiment of the present invention.
FIG. 4 is an exemplary view showing a result of irradiating a cylindrical phantom according to a treatment plan using radiation tomography according to an embodiment of the present invention. FIG.
FIG. 5 is a view illustrating an example of a green phosphorescence generated when a phosphor plate is irradiated with radiation according to an embodiment of the present invention. FIG.
FIG. 6 is a conceptual diagram for explaining a two-dimensional measurement method and a three-dimensional measurement method according to an embodiment of the present invention.
FIG. 7 is an exemplary diagram for comparing results of a two-dimensional measurement method and a three-dimensional measurement method according to an embodiment of the present invention.
FIG. 8 is an exemplary view showing a dose distribution per slice of a spherical target using a tomography apparatus according to an embodiment of the present invention. FIG.
9 is a diagram illustrating dose distribution of a C-shaped target using a tomography apparatus according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

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

FIG. 1 is a conceptual view for explaining a phantom inserted with a phosphorescent plate according to an embodiment of the present invention, and FIG. 2 is an exemplary view illustrating a phantom inserted with a phosphorescent plate according to an embodiment of the present invention.

Referring to FIG. 1, a tomography apparatus according to an embodiment of the present invention includes a phantom 100, a camera 200, and an image processing unit (not shown).

More specifically, the phantom 100 includes a first transparent member 110, a second transparent member 120, and a phosphorescent plate 130 positioned between the first and second transparent members 110 and 120, . In addition, the phantom 100 may be formed in a cylindrical shape.

The phosphorescent plate 130 may be positioned between the first transparent member 110 and the second transparent member 120 to generate visible light 20 as the radiation 10 is incident thereon.

Here, the first transparent member 110 and the second transparent member 120 may be made of plastic, and the kind of the plastic is not particularly limited.

The camera 200 senses the visible light 20 generated by the phosphorescent plate 130 and stores the image.

The image processing unit processes the image stored in the camera 200 to construct a three-dimensional stereoscopic image. For example, the image processing unit may process the image stored in the camera 200 as a microprocessor to construct a three-dimensional stereoscopic image.

Figure 2 shows an exemplary configuration of a phantom according to an embodiment of the present invention.

Referring to FIG. 2, the two plastics corresponding to the first transparent member 110 and the second transparent member 120 may have a diameter of 250 mm and a thickness of 80 mm.

The phosphorescent plate 130 may be positioned between two plastics.

Further, it can be manufactured in a form to be fitted in a PVC pipe composed of two plastic and phosphorescent plates 130. Here, the PVC pipe having a length of 365 mm and a diameter of 265 mm can be utilized.

The condition of the phosphorescent plate 130 for measuring a real time dose should be small and the phosphorescence efficiency should be good. The photon absorption efficiency of the phosphorescent plate 130 may vary depending on the energy of the incident photon beam and the type and amount of the phosphorescent material.

The photoelectric effect is the main interaction with the phosphorescent plate 130 and x-rays. The photoelectric effect is maximized at higher energy than the K-edge, and the conversion efficiency is determined by the type of phosphor and the reflection layer.

Table 1 below shows the photon absorption rate according to the type of phosphorescent plate.

Screen X-ray (80 kVp) photon absorbtion (%) High-speed CaWO ₄ 38 Medium-speed CaWO ₄ 21 Lanex Fast 73 Lanex Fine 41

The following Table 2 shows the visible light generation efficiency according to the phosphorescent plate.

Screen Typical conversion efficiencies (%) CaWO ₄ 5 Lanex Fast 18

In addition, the phantom 100 according to the embodiment of the present invention can be designed so that the rear portion of the phantom 100 is designed to be transparent so that the laser, which appears at the back of the phantom 100, have. In addition, since the laser is turned off and covered with an opaque lid during shooting, it can be prevented from affecting the image.

Also, since the cylindrical phantom 100 according to the embodiment of the present invention must be positioned at the center of the tomography apparatus using a support stand or the like, it is necessary to be light in weight. Therefore, since the phantom 100 is difficult to reduce the diameter, it should be made to have a minimum length considering the side scatter.

By improving the Tomo Terror device, the existing spiral therapy function can be added by fixing the couch, and it is possible to place the phantom (100) on the couch and irradiate the beam according to the treatment plan.

In addition, in the latest tomothe equipment, the phantom 100 can be kept separated from the cowl, and there is no need for a support for fixing the phantom 100 to the center while the beam is irradiated.

More specifically, the tomography apparatus generally comprises a phantom 100 placed on a moving couch in a slit beam rotating at one position, or a phantom 100 moving in a human body at a constant speed while a beam is being irradiated, The radiation dose may be irradiated to make the intended dose distribution shape. Using this point, if the blackening is obtained as a moving image obtained by fixing only one position where the radiation is irradiated, the time may be the pitch at which the couch moves. In addition, it is possible to measure the three-dimensional blackening degree, that is, the three-dimensional dose distribution, and to set the focal distance according to the angle of view of the lens.

Correction data can be obtained for examining the characteristics of the phosphorescent plate 130 to be attached to the phantom 100 according to the embodiment of the present invention.

The radiation incident on the phosphorescent plate 130 generates visible light due to the photoelectric effect, and a blurring effect generally appears in this process. Accordingly, the photographed image by the camera 200 includes a blurring effect, and correction can be performed by obtaining a blur kernel and decoding it.

For example, in a treatment planning device, a treatment plan can be created to create a virtual target of three types of circles, C-shaped, and multiple targets and deliver 10 Gy of radiation to each target.

A cylindrical Phantom (100) can be placed on a tomotherapy treatment table and irradiated according to the treatment plan. When radiation is irradiated on the phosphorescent plate, visible light is generated in the phosphorescent plate 130, and the visible light can be captured by a CCD camera and stored as a moving image.

All frames photographed with a CCD camera are accumulated and each pixel can be converted to a dose and the image from the phosphorescent plate 130 can be compared with the dose distribution calculated in the treatment planning device. Here, a graph of the relationship between the dose rate and the pixel value may not be saturated up to a dose slope of 900 MU / min.

FIG. 3 is an exemplary diagram showing the results of irradiating three types of imaginary targets of one point, C shape, and multi type, in order to evaluate the performance of the tomography apparatus according to the embodiment of the present invention.

Fig. 3 (a) and Fig. 3 (d) show performance evaluation results when the target is one point, Figs. 3 (b) and 3 3 (c) and 3 (f) show performance evaluation results when the target is a multi-type.

More specifically, in order to evaluate the performance of the tomotape phantom according to the embodiment of the present invention, three types of imaginary targets of one point, C-shape, and multi-type are irradiated using tomothecopy.

The degree of blackening is immediately converted to a dose value and can be compared using the gamma indicator and the acceptance rate for each target. For example, 84.46% for one point, and 80.38% for C shape. Also, the multi-type target was 83,28% higher than expected.

FIG. 4 is an exemplary view showing a result of irradiating a cylindrical phantom according to a treatment plan using radiation tomography according to an embodiment of the present invention. FIG.

FIG. 4A shows a result of irradiating the cylindrical phantom when the target is a single point, FIG. 4B shows the result of irradiating the cylindrical phantom when the target is C-shaped according to the treatment plan, FIG. The result of irradiating the cylindrical phantom when the target is of the multi type according to the treatment plan.

For example, FIG. 4A shows a case where a virtual spherical target having a diameter of 10 cm is located at the center of a cylindrical phantom having a length of 60 cm and a diameter of 26.5 cm, and FIG. 4B shows a cylindrical shape having a length of 60 cm and a diameter of 26.5 cm This figure shows the case where a C-shaped target having an outer diameter of 10 cm and an inner diameter of 5 cm and popping one side is located at the center of the phantom. FIG. 4c shows three different sized virtual spherical shapes having diameters of 8 cm, 4 cm, and 2 cm [-6, -6, 0], respectively, based on a cylindrical phantom center having a length of 60 cm and a diameter of 26.5 cm. [10, 10, 1], [12, -12, -0.5].

In addition, all virtual targets can be designed to be reproducible in any system, so that VMAT (volumetric arc therapy) etc. can be measured later in a general line accelerator.

FIG. 5 is a view illustrating an example of a green phosphorescence generated when a phosphor plate is irradiated with radiation according to an embodiment of the present invention. FIG.

Referring to FIG. 5, when radiation is irradiated according to a treatment plan for three kinds of targets, green phosphors appearing on the phosphorescent plate can be seen, and clear light transmitted through the plastic can be seen. Here, light reflected on the cylindrical phantom wall surface is also seen, but can be excluded in the analysis.

FIG. 6 is a conceptual diagram for explaining a two-dimensional measurement method and a three-dimensional measurement method according to an embodiment of the present invention.

Fig. 6 (a) shows an example according to a two-dimensional measuring method, and Fig. 6 (b) shows an example according to a three-dimensional measuring method.

Referring to FIG. 6 (a), the patient table 400 moves with the phantom 100 during the spiral treatment, and only one slice can be measured. More specifically, according to FIG. 6 (a), since there is no mode for stopping the patient table 400, only the function of fixing the phantom 100 to the center of the gantry 300 is provided from the outside. That is, the phantom 100 moves during treatment with the patient table 400 in the form of being placed on the patient table 400, thereby allowing only a two-dimensional dose distribution to be identified.

Referring to FIG. 6 (b), it is possible to acquire images of all slices by fixing the phantom 100 in spite of treatment. More specifically, according to FIG. 6 (b), a fixing mode for the patient table 400 is added to solve the problem of fixing the phantom 100. That is, when the phantom 100 is separated from the patient table 400 and the patient table 400 is moved during treatment, the phantom 100 can be fixed to the center, and the same position can be maintained while the radiation is irradiated. Thus, all of the radiation data can be obtained, and the patient table 400 can be given a moving pitch and time information to obtain a three-dimensional dose distribution immediately.

According to Fig. 6 (b), the phantom 100 can be independent of the movement of the patient table 400 and can maintain the same position while the radiation is being irradiated.

In addition, the camera 200 can be positioned in the center of the front part that is not currently fixed but opened in the photograph and can be focused in the manual mode, and the setting of the camera 200 is set to white balance, ISO: 3200, progressive 30 fps, 1280 * 720 pixels and so on.

Accordingly, the image processing unit can construct a three-dimensional stereoscopic image based on the pitch and time information of the patient table 400 moved.

Here, the pitch value when irradiating the tomothec is 0.287, and the field width is 2.5 cm.

Referring to Equation (1), the couch movement may be 0.7175 cm per revolution of the gantry, and about 2.0 seconds may take about 12 seconds per revolution, and the total treatment time may vary depending on the dose and length in the longitudinal direction .

FIG. 7 is an exemplary view for comparing the results of a two-dimensional measurement method and a three-dimensional measurement method according to an embodiment of the present invention, and FIG. 8 is a graph showing the distribution of dose amounts per slice of a spherical target using a tomo- FIG. 9 is a diagram illustrating dose distribution of a C-shaped target using a tomography apparatus according to an embodiment of the present invention.

Figs. 7 (a), 7 (b) and 7 (c) show results of a two-dimensional measurement method according to Fig. 6 (a) 7 (f) shows the results according to the three-dimensional measurement method according to Fig. 6 (b).

Referring to FIG. 7, it can be seen that the results according to the two-dimensional measurement method and the results according to the three-dimensional measurement method are large even though they are the same treatment.

In the two-dimensional measurement method, the phantom 100, which is a measuring device, is moved at the same time as the movement of the patient table 400 is performed.

More specifically, Fig. 7 (a) shows the first part of the two-dimensional measurement, Fig. 7 (b) shows the middle part of the two-dimensional measurement and Fig. 7 (c) shows the end part of the two-dimensional measurement. Referring to FIGS. 7 (a), 7 (b) and 7 (c), it can be seen that the image is blurred because the first and last portions of the two-dimensional measurement method are near the margins of the field. That is, if all images are superimposed, only the distribution of one slice in two dimensions can be obtained.

In comparison, in the three-dimensional measurement method, since the phantom 100 is always located at the center of the gantry 300, it can be seen that the image is always clear. That is, since such an image includes all the slice information, if the pitch value is applied, the 3D measurement becomes possible as shown in Figs. 7 (d), 7 (e) and 7 (f).

More specifically, Fig. 7 (d) shows the first part of the three-dimensional measurement, Fig. 7 (e) shows the middle part of the three-dimensional measurement, and Fig. 7 (f) shows the end part of the three-dimensional measurement. Referring to FIGS. 7 (d), 7 (e) and 7 (f), since the first, middle, and end portions of the three-dimensional measurement method are located at the center of the field, . That is, since it has all the slice information, the 3D dose measurement becomes possible.

Referring to FIG. 8, the distribution of the doses by the various slices of the spherical target is shown. 8 (a) shows a case of slice -5.0 cm, Fig. 8 (b) shows slice -2.5 cm, and Fig. 8 (c) shows slice 0.0 cm. Therefore, it can be confirmed that the spherical target increases as the slice moves to the center, and the dose distribution of each slice and the dose distribution of all the slices can be confirmed through this.

Referring to FIG. 9, a qualitative comparison of the C-shaped target is shown. In the case of the C-shaped target, the calculated value and the measured value are similar although the dose distribution is clustered. More specifically, Fig. 9 (a) shows the measurement result of the dose distribution of the C-shaped target, and Fig. 9 (b) shows the calculation result of the dose distribution of the C-shaped target. In other words, it can be seen that the measurement result of the dose distribution of the C-shaped target is similar to the measurement result of the dose distribution of the C-shaped target.

The tomography apparatus according to the embodiment of the present invention can apply the epoch-making dose assurance phantom for real-time measurement of the three-dimensional dose distribution to enable the dose guarantee of the tomography.

In addition, since the patient's table has the characteristic of moving during treatment because of the spiral treatment of the tomothecia and the characteristic of having the pitch value per one wheel of the gantry, It is possible to continuously capture a two-dimensional image by continuously positioning the center of the gantry without moving, and acquire a three-dimensional dose distribution image by applying a pitch value per frame to the photographed image.

Therefore, the three-dimensional measurement method according to the present invention can enhance the result of radiation therapy using tomothecopy.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

10: radiation 20: visible light
100: phantom 110: first transparent member
120: second transparent member 130: phosphorescent plate
200: Camera 300: Gentry
400: patient table

Claims (11)

A first transparent member;
A second transparent member; And
A phantom including a phosphorescent plate positioned between the first transparent member and the second transparent member;
A camera that senses visible light generated from the phosphorescent plate and stores an image; And
And an image processing unit for processing the image stored in the camera to construct a three-dimensional stereoscopic image,
Wherein the phantom is independent of movement of the patient table, and wherein the phantom inserts a phosphorescent plate that maintains the same position during irradiation. delete delete delete delete The method according to claim 1,
Wherein the image processing unit constructs the three-dimensional image based on the pitch and time information of the patient table moved. The tomography apparatus using the phantom inserted with the phosphorescent plate. delete delete delete delete delete

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