JP6446635B2 - Radiation therapy bolus manufacturing method and radiation therapy bolus - Google Patents

Description

  The present invention relates to a bolus manufacturing method and a bolus used in close contact with a human body to correct the distribution of absorption of the irradiated radiation in the human body in radiotherapy.

  FIG. 3A and FIG. 3B are schematic diagrams for explaining the general action of the bolus.

  As shown on the left side of the drawing in FIG. 3A, it is assumed that the body surface 101 is irradiated with radiation as indicated by an arrow y101 in order to treat the affected area 103 near the body surface 101. In this case, as indicated by a line L101 on the right side of FIG. 3A, the amount of radiation absorbed in the body first increases as it goes deeper from the body surface 101, and then reaches a peak (build-up point BP). It will decrease after passing. Therefore, as shown by drawing a dotted line from the affected part 103 to the line L101, if the affected part 103 is at a position shallower than the build-up point BP, the affected part 103 cannot efficiently absorb the radiation.

  Therefore, as shown in FIG. 3B, a bolus 105 made of a material having characteristics similar to that of the human body is arranged on the body surface 101. By doing so, the surface of the bolus 105 becomes an apparent body surface for radiation. As a result, the affected area 103 is positioned at the build-up point BP, and the affected area 103 can efficiently absorb the radiation.

  Various materials have been proposed as such bolus materials (for example, Patent Documents 1 and 2). Patent Document 1 proposes plastics, paraffin, synthetic rubber, silicone and water as conventionally used bolus materials, and proposes a gel containing water as a new bolus material. Patent Document 1 claims that it becomes possible to use disposable gels by using such a gel containing water. Patent Document 2 proposes an oily gel containing a thermoplastic elastomer as a bolus material.

Japanese Patent Laid-Open No. 11-255958 US Patent Application Publication No. 2008/0123810

  As will be described later, various properties are required for the bolus material. Accordingly, it is desirable to provide a method of manufacturing a bolus and a bolus having suitable characteristics when one characteristic is evaluated or when several characteristics are comprehensively evaluated.

  The manufacturing method of the bolus which concerns on 1 aspect of this invention is equipped with the process of producing | generating the material of a bolus by mixing the main ingredient containing a polyol and the hardening | curing agent containing polyisocyanate and diisononyl phthalate.

  In one example, the weight ratio of the main agent to the curing agent is 100: 40 to 100: 60.

  In one example, the weight ratio of the polyisocyanate to the diisononyl phthalate is 10:90 to 20:80.

  In one example, the polyisocyanate is of hexamethylene diisocyanate type.

  In one example, the curing agent includes hexamethylene diisocyanate.

  In one example, the bolus is a bolus for a head that surrounds at least the parietal portion of the head, and the manufacturing method performs a CT scan of the parietal portion to obtain three-dimensional tomographic image data; Based on the three-dimensional tomographic image data, generating three-dimensional coordinate data of the bolus having a uniform thickness in which the surface shape of the parietal portion is the shape of the inner surface, and based on the coordinate data Forming a master model of the bolus with a 3D printer; disposing an uncured mold material around the master model; and dividing a mold formed by curing the mold material. Removing the master model from the mold, placing the uncured bolus material in the mold, and curing the bolus material to form The bolus which has been having the steps of retrieving from the said mold.

  In one example, the bolus is a bolus for a head that surrounds at least the parietal portion of the head, and the manufacturing method performs a CT scan of the parietal portion to obtain three-dimensional tomographic image data; Generating, based on the three-dimensional tomographic image data, three-dimensional coordinate data of a type capable of forming the bolus having a uniform thickness in which the surface shape of the parietal portion is the shape of the inner surface; Based on the coordinate data, forming the mold with a 3D printer, placing the uncured bolus material in the mold, and curing the bolus formed by curing the bolus material into the mold Removing from the inside.

  In one example, the bolus is a bolus for a head that surrounds at least the parietal portion of the head, and the manufacturing method performs a CT scan of the parietal portion to obtain three-dimensional tomographic image data; Based on the three-dimensional tomographic image data, generating three-dimensional coordinate data of the bolus having a uniform thickness in which the surface shape of the parietal portion is the shape of the inner surface, and based on the coordinate data Forming the bolus with a 3D printer.

  In one example, in the step of generating the coordinate data, frontal data and occipital data are generated, and the subsequent steps are performed separately on the frontal and occipital sides.

  In one example, the bolus material is transparent to visible light.

  The bolus according to the present invention has as its main component a material in which a polymer compound in which a polyol and a polyisocyanate are urethane-bonded with diisononyl phthalate.

  In one example, the thickness is 3 mm or more and 20 mm or less.

  In one example, the hardness measured by an A-type hardness meter defined in JIS K 6253 is 0 or more and 10 or less.

  According to said procedure or structure, the bolus which has a suitable characteristic is obtained.

1 is an external perspective view showing a bolus according to an embodiment of the present invention. FIG. 2A to FIG. 2H are schematic views for explaining a manufacturing method of the bolus of FIG. FIG. 3A and FIG. 3B are schematic diagrams for explaining a general action of the bolus.

<Bolus configuration>
(Bolus shape)
The shape of the bolus with no external force (including gravity) applied may be a three-dimensional shape similar to the three-dimensional shape of the affected body surface, or may be a sheet having an appropriate planar shape. Good. In another aspect, the bolus may correspond to a specific affected area or may be versatile. The three-dimensional shape of the body surface of the affected part is, for example, a shape in a state where a posture and an external force (gravity may or may not be considered) are not applied. The affected part may be any part of the human body.

  FIG. 1 shows a head bolus 1 as an example of a specific affected bolus. Hereinafter, the configuration, manufacturing method, usage method, and the like of the bolus will be described by taking the head bolus 1 as an example. However, except for the shape suitable for the head, the following description of the bolus 1 also applies to other affected boluses or general-purpose boluses. Therefore, for example, in the following description, the word of the head may be appropriately replaced with another affected part.

  In general, the word of the head refers to the part where the brain is located above the eyes and ears (in the narrow sense) and in addition to the eyes, nose and mouth above the neck There are cases where it refers to the entire part (in a broad sense). In the description of the present embodiment, the word “head” is basically used in the latter sense. However, just because the bolus 1 is described as being for the head, the bolus 1 is not necessarily required to cover the entire head in a broad sense, and may be anything that covers at least a part of the head. .

  The bolus 1 has, for example, a front part 3 that covers the frontal head and the like, and a rear part 5 that covers the back of the head and the like. The bolus 1 can surround at least the parietal side portion of the head by combining both parts so that the front part 3 and the rear part 5 sandwich the head. In addition, since the top side part here is a part enclosed by the bolus (covered from front and rear, right and left), it is a hemispherical part above the height of the forehead, for example.

  The range that the bolus 1 can surround or cover may be set as appropriate. For example, it may be a part above the height of the forehead, a part above the eyes and ears, or a part above the nose and ears as in the example of FIG. Furthermore, the entire head above the neck may be used.

  The shape of the inner surface of the bolus 1 is formed to be substantially the same as the shape of the head of each individual patient. Thus, the bolus 1 fits the individual patient's head. Further, the bolus 1 has a substantially uniform thickness, for example. In another aspect, the shape of the outer surface of the bolus 1 is generally similar to the inner surface. In addition, when the thickness in an uneven | corrugated | grooved part is uniform, the shortest distance from each point of an inner surface to an outer surface is pointed out, for example. Moreover, even if the thickness is uniform, it is a matter of course that the thickness may vary due to the accuracy of manufacturing.

  In addition, the shape of the inner surface or the outer surface of the bolus 1 may include a portion that does not reflect the actual shape of the patient's head. For example, the details of the shape may be omitted depending on the purpose of treatment. More specifically, for example, in the case of the bolus 1 in the example of FIG. 1, when the ear is not included in the treatment target, the shape of the detail of the ear is used unless the bolus 1 covers the patient's ear. May be omitted. Further, for example, a hole for breathing the patient may be appropriately formed.

(Bolus thickness)
As understood from the bolus action described with reference to FIGS. 3 (a) and 3 (b), the thickness of the bolus (not limited to the head) is the depth from the body surface of the affected area 103 and It may be set as appropriate according to the depth of the build-up point from the surface of the bolus. For example, the thickness of the bolus is 3 mm or more and 20 mm or less. With such a depth, it is possible to match the depth of the affected area 103 with the depth of the build-up point.

  Further, for example, by preparing boluses with various thicknesses in advance, it is possible to perform treatments according to various sites of the affected area during radiotherapy. For example, thicknesses of 5 mm, 10 mm, and 15 mm may be prepared.

(Bolus material)
The bolus material preferably has the following characteristics.
1) A substance equivalent to human tissue 2) Good softness to skin and good adhesion 3) Good form preservation and uniform production 4) Toxicity Do not hold and do not cause damage such as inflammation even if it touches the skin 5) Does not change over time, such as discoloration or deformation 6) Does not contain bubbles 7) Excellent flexibility and elasticity 8) Transparency (transmittance to visible light)

  Here, “equivalent to human tissue” refers to having characteristics similar to those of human tissue with respect to absorption and / or scattering of radiation (for example, X-rays). In another aspect, the equivalent to a human tissue indicates that a CT (Computed Tomography) value is the same as or close to a value in a human body (a value in water may be substituted). A CT value close is, for example, a state where the difference from the CT value in the human body (water) is 80 or less, preferably 30 or less, more preferably 5 or less.

  As a result of intensive studies, the inventors of the present application have found that it is preferable to use polyurethane or a material mainly composed of polyurethane as the bolus material. The polyurethane referred to here is not only a polymer compound having a urethane bond (a narrow definition polyurethane), but also a customary product obtained by mixing various materials with a narrow definition polyurethane in order to adjust the properties of the material. In particular, what is called polyurethane (or urethane resin or urethane resin) is included. The same applies hereinafter unless otherwise specified. The main component is, for example, a component that exceeds at least 50 wt% of the material.

  By using polyurethane as the material for the bolus 1, for example, it is easy to achieve equivalence with the human body. In addition, for example, suitable characteristics are easily obtained in terms of corrosion resistance, flexibility, adhesion, and the like. For example, it is easy to impart transparency to the bolus.

  Moreover, the bolus 1 using polyurethane can be made sufficiently soft, for example. As a result, for example, the contact of the bolus 1 with the body surface of the patient is softened, the burden on the patient's mind and body is reduced, the adhesion of the bolus to the body surface is improved, and the accuracy of radiotherapy is improved. be able to. For example, the polyurethane constituting the bolus 1 has a hardness of 0 or more and 10 or less measured by an A-type hardness meter defined in JIS (Japanese Industrial Standard) K 6253.

  The specific composition or structure of the polyurethane may be various known ones. The polyurethane may be a one-component type that cures by reacting with oxygen or moisture in the atmosphere in the raw material stage (before curing), or a main component containing a polymer compound having a hydroxyl group and an isocyanate group. It may be a two-component type which is mixed with a curing agent containing a polymer compound having In addition to the main raw material for urethane bonding, the polyurethane may appropriately contain auxiliary raw materials or additives such as a catalyst, a crosslinking agent, a filler, and a stabilizer as necessary.

  In a two-component polyurethane, it is possible to adjust characteristics such as hardness by appropriately setting the weight blending ratio of the main agent and the curing agent. Although depending on the specific composition and structure of the main agent and curing agent, suitable characteristics can be obtained, for example, by setting the weight ratio of the main agent and the curing agent to 100: 40 to 100: 60.

  The specific composition or structure of the polymer compound having a hydroxyl group or the main component of a two-component polyurethane containing the polymer compound may be various known ones. For example, as a polymer compound having a hydroxyl group, a polyol is generally used. Examples of the polyol include polyether polyol, polyester polyol, and polymer polyol.

  The specific composition or structure of the curing agent of the polymer compound having an isocyanate group or the two-component polyurethane containing the polymer compound may be various known ones. For example, polyisocyanate is generally used as a polymer compound having an isocyanate group. Examples of the polyisocyanate include hexamethylene diisocyanate (HDI) polyisocyanate, tolylene diisocyanate (TDI) polyisocyanate, and diphenylmethane diisocyanate (MDI) polyisocyanate. Examples of HDI polyisocyanates include HDI homopolymers.

  The main component or curing agent of polyurethane and two-component polyurethane may contain a plasticizer for softening the polyurethane in an appropriate ratio. Examples of the plasticizer include diisononyl phthalate (DINP). The ratio of the plasticizer may be set as appropriate. For example, in the curing agent for polyurethane and two-component polyurethane, the weight ratio of polyisocyanate to diisononyl phthalate is 10:90 to 20:80.

  Taking a concrete material in consideration of the above, for example, as the polyurethane, a two-component type in which a main component containing a polyol and a curing agent containing polyisocyanate and diisononyl phthalate are mixed may be used. At this time, polyisocyanate is HDI type, for example. The curing agent may contain some hexamethylene diisocyanate (monomer). For example, the curing agent may contain hexamethylene diisocyanate at a ratio of 0.15 wt% or less. As such a two-component polyurethane, for example, “Polycrystal PC-00N” manufactured by Polysys Co., Ltd. can be used.

  In addition, it is preferable that a polyurethane is a medical grade thing. That is, the polyurethane is preferably manufactured in a factory that has received medical certification for the production process. The certification body may be, for example, in the country where the marker 1 is implemented.

<Bolus manufacturing method>
The bolus as described above may be manufactured by various manufacturing methods. Hereinafter, Examples 1 to 3 of the manufacturing method will be described. In the following description, as described above, a case where the bolus is the bolus 1 for the head in FIG. 1 is taken as an example.

(Outline of procedure of production method example 1)
FIG. 2A to FIG. 2H are schematic views for explaining Example 1 of the manufacturing method of the bolus 1. As indicated by arrows between the drawings, the manufacturing method proceeds in order from FIG. 2A to FIG. 2H.

  First, as shown in FIG. 2A, a CT scan of the patient 11 is performed by the CT apparatus 13, and three-dimensional tomographic image data (hereinafter referred to as “CT image data”) about the head of the patient 11 is generated. To do.

  Next, as shown in FIG. 2B, three-dimensional coordinate data (coordinate data 17) of the master model of the bolus 1 is generated based on the CT image data 15. In the figure, the shape of the head of the patient 11 held as information in the CT image data 15 and the shape of the master model held as information in the coordinate data 17 are schematically shown.

  Next, as shown in FIG. 2C, a master model 19 is created by a 3D printer based on the coordinate data 17.

  Next, as shown in FIG. 2D, an uncured mold material 21 is disposed around the master model 19.

  Next, as shown in FIG. 2E, the mold 23 formed by curing the mold material 21 is divided into a first mold 23a and a second mold 23b, and the master model 19 is taken out. Thereby, the cavity 25 having the same shape as the master model 19 is formed.

  Next, as shown in FIG. 2F, an uncured bolus material 27 (polyurethane) is prepared. In the illustrated example, the bolus material 27 is a two-component polyurethane, and a main agent 27a and a curing agent 27b are mixed.

  Next, as shown in FIG. 2G, a bolus material 27 is placed in the cavity 25 of the mold 23.

  Then, as shown in FIG. 2 (h), the bolus 1 formed by curing the bolus material 27 is taken out from the mold 23 that has been opened.

  Hereafter, each said procedure is explained in full detail.

(CT scan (FIG. 2A))
In a CT scan, the dose of radiation (eg, X-rays) emitted from a source and transmitted through a patient is detected by a detector. Thereby, projection data (raw data) is generated. Further, a plurality of projection data is obtained by rotating the radiation source and the detector around the patient's body axis. Then, image reconstruction is performed based on a plurality of projection data, and a tomographic image is obtained. Further, a tomographic image can be obtained three-dimensionally by moving the radiation source and the detector in the body axis direction with respect to the patient.

  As the CT apparatus 13, a known appropriate apparatus may be used. The detectors are preferably multi-row, but may be single-row. The scan method may be a non-helical scan (sometimes referred to as a conventional scan or an axial scan) or a helical scan. Parameters that affect the accuracy, such as pitch, may be set as appropriate. A contrast agent may or may not be used.

  The CT image data 15 is data including information on the three-dimensional tomographic image after the above reconstruction. The CT image data 15 includes, for example, information that can specify a coordinate and information that can specify a CT value at each coordinate. The format preferably conforms to a standard such as DICOM (Digital Imaging and Communication in Medicine), but may not conform. The coordinate information includes information that can specify coordinates in units of actual distance. For example, the CT image data 15 includes position information in units of detector and imaging pitch, and information such as a scale for converting the position information into actual length coordinates.

  The CT scan does not need to be performed only for creating the bolus 1, for example. For example, when performing radiotherapy, currently, CT image data of a patient is acquired by CT scan, and a treatment plan is made by looking at an image based on the CT image data. Therefore, CT image data acquired for such a treatment plan may be used to create the bolus 1. Of course, the CT scan may be performed only for creating the bolus 1.

(Creation of coordinate data (FIG. 2B))
The creation of the coordinate data 17 based on the CT image data 15 may be partly or entirely performed by the CT apparatus 13, or part or all of the coordinate data 17 may be performed by a computer that has acquired data from the CT apparatus 13. Good. Hereinafter, for convenience, a device that creates the coordinate data 17 is referred to as a data editing device.

  In creating the coordinate data 17, the coordinates of the patient's body surface are extracted from the CT image data 15. For example, the data editing device performs edge detection processing on the reconstructed image of each tomogram orthogonal to the body axis, and specifies the coordinates of the body surface in each tomography. Then, the data editing device specifies three-dimensional coordinates for the body surface by performing the specification of the coordinates for a plurality of slices in the body axis direction.

  The data editing device uses the coordinates of the body surface as the coordinates of the inner surface of the bolus 1 (master model 19 in another viewpoint) in the coordinate data 17. The data editing device calculates coordinates obtained by shifting the coordinates outward by a certain distance. Then, the data editing device uses the shifted coordinates as the coordinates of the outer surface of the bolus 1 in the coordinate data 17. In this way, coordinate data 17 of the bolus 1 having a uniform thickness that fits the head of the patient 11 is created.

  Note that the thickness of the master model 19 is set by, for example, a user (physician or the like; the same applies hereinafter) inputting the numerical value to the data editing device. In calculating the coordinates of the outer surface, an appropriate algorithm may be used so that the thickness of the bolus 1 is substantially uniform. The direction and / or amount to be shifted with respect to the individual coordinates of the inner surface may be set separately, or the direction and / or the amount to be shifted outward with respect to a certain number of coordinates on the inner surface are common. It may be set. For details and the like that do not affect the treatment, the coordinates may be corrected by an operation on the data editing device by the user.

  In addition, the data editing device extracts a target portion covered by the bolus 1 when the coordinate data 17 is created. This extraction is performed, for example, when the user designates a tomographic image or coordinates of the boundary between the extraction range and the non-extraction range to the data editing device. It should be noted that a graphic user interface for designating may be appropriately constructed. Further, the extraction of the target part may be performed based on the CT image data 15, or may be performed based on the body surface coordinates extracted from the CT image data 15.

  Further, the data editing device creates coordinate data of the divided bolus 1 (master model 19) corresponding to the bolus 1 having the front part 3 and the rear part 5. Thereafter, creation of the master model 19 (FIG. 2C), creation of the mold 23 (FIGS. 2D and 2E), arrangement of the bolus material 27 (FIG. 2G), and the bolus 1 The removal is performed separately for the front part 3 and the rear part 5. 2B to 2H, only the creation of the front part 3 is illustrated, but the creation of the rear part 5 is the same.

  The division position of the bolus 1 (master model 19) may be set automatically by the data editing device, or may be set by the user performing a predetermined operation on the data editing device. It should be noted that a graphic user interface for designating may be appropriately constructed.

  Further, the data editing device converts the data format of the CT image data 15 into a data format usable by the 3D printer when the coordinate data 17 is created. For example, the format of the CT image data 15 conforms to the above-mentioned standard widely used in the medical field called DICOM. The format of the coordinate data 17 is widely used in the field of 3D modeling such as a 3D printer, for example, an STL (Standard Triangulated Language) format. This data format conversion is easily performed.

(Create master model (Fig. 2 (c)))
The 3D printer that forms the master model 19 may be a commercially available one. For example, the 3D printer forms a three-dimensional shape by forming a cross-sectional shape of what is finally formed in a stacked manner. The method may be an optical modeling method in which an uncured photocurable resin is laminated with a layer cured by irradiating ultraviolet rays, or a heat-melting lamination method in which heat-melted resins are stacked. Alternatively, it may be a powder fixing method in which an adhesive is sprayed onto a powder resin, or an ink jet method in which ultraviolet rays are irradiated while injecting an uncured photocurable resin. Parameters that affect the accuracy, such as layer thickness, may be set as appropriate. The stacking direction with respect to the master model 19 may be set as appropriate.

  The material of the master model 19 may be a material generally used in a 3D printer and / or a material suitable for modeling by a 3D printer. Further, since the mold material 21 is disposed around the master model 19 to form the mold 23, it is preferable that the mold has a certain degree of rigidity. Examples of such a resin include ABS (acrylonitrile, butadiene, styrene) resin.

(Disposition of mold material (FIG. 2 (d)))
Before disposing the mold material 21 around the master model 19, an appropriate release coating may be applied to the surface of the master model 19. Thus, when the master model 19 is later taken out from the mold 23 (FIG. 2E), the master model 19 and the mold 23 are preferably separated from each other.

  The method of disposing the uncured mold material 21 around the master model 19 may be an appropriate method. For example, the mold material 21 may be arranged around the master model 19 by a hot melt lamination method, a powder fixing method or an ink jet method 3D printer, and the master model 19 is arranged in a box-shaped mold, An uncured mold material 21 may be poured into the mold.

  When a 3D printer is used for arranging the mold material 21, the 3D printer may also be used as a 3D printer that creates the master model 19. When the uncured mold material 21 is poured into the mold, defoaming may be performed as appropriate. For example, if the mold is open at the top, the mold may be placed in the vacuum chamber when and / or after pouring uncured mold material. Further, for example, if the mold has a sealed cavity, the mold material 21 may be injected after the cavity is evacuated.

  The mold material 21 may be an appropriate material. However, the mold material 21 preferably has a certain degree of rigidity after curing so that it functions as the mold 23 after curing. On the other hand, it is preferable that the mold material 21 can easily divide the mold 23. For example, the mold material 21 is a silicon resin.

(Division of mold (FIG. 2 (e)))
The division of the mold 23 is performed, for example, by cutting using a blade such as a knife. The cutting is preferably a method in which the volume of the mold 23 is not reduced or difficult to reduce during cutting.

  The division position may be set as appropriate. Moreover, it is not divided by one plane, but may be divided by a plurality of surfaces whose positions in the mold opening direction are different from each other. In the illustrated example, both the first mold 23a and the second mold 23b are formed with recesses, but one is a female mold in which only a recess is formed on the split surface, and the other is on the split surface. You may be made into the male type | mold in which only the convex part was formed.

(Preparation of bolus material (FIG. 2 (f))
The mixing of the main agent 27a and the curing agent 27b may be performed using various known devices or apparatuses. FIG. 2F illustrates a method of pouring the main agent 27a and the curing agent 27b into the container as the simplest example. In the illustrated example, the curing agent 27b is poured into the main agent 27a accommodated in the container, but both may be poured into the container at the same time, or the main agent 27a is poured into the curing agent 27b. Also good.

  The bolus material 27 made of two-component polyurethane can change its characteristics such as hardness depending on the mixing ratio of the main agent 27a and the curing agent 27b. Thereby, according to the site | part etc. which are covered with a bolus, the hardness of a bolus can be made appropriate. In the present embodiment, the main agent and the curing agent are weighed and mixed so as to obtain a hardness mixing ratio suitable for the head.

  Before mixing, during mixing and / or after mixing, the bolus material 27 may be defoamed by a vacuum apparatus. This is because if bubbles are included in the bolus 1, the radiation scattering characteristics and the like change from the intended ones. Specifically, for example, a container containing the mixed bolus material 27 is placed in a vacuum chamber, and the vacuum chamber is evacuated by a vacuum pump.

(Bolus material injection (FIG. 2 (g))
The bolus material 27 is injected into the cavity 25 by, for example, forming a passage (spool or the like) communicating the cavity 25 and the outside of the mold 23 in the mold 23 by cutting or the like, and then closing the mold in a closed state. It may be done through a passage. When the mold 23 is divided so that the mold 23 is composed of a male mold and a female mold, the bolus material 27 is poured into the female mold that is opened and the dividing surface is directed upward, and then the male mold is formed. You may put it on a female mold.

  Moreover, it is preferable that the injection of the bolus material 27 into the cavity 25 is performed gently. This is to prevent the bolus material 27 from entraining gas (for example, air). Alternatively, the bolus material 27 may be injected after the cavity 25 is evacuated.

(Removal of bolus (Fig. 2 (h))
The bolus 1 is taken out when the bolus material 27 is sufficiently cured. Whether or not it has been sufficiently cured may be determined, for example, based on whether or not a predetermined time has elapsed since the bolus material 27 was injected into the cavity 25.

  The removed bolus 1 has an unnecessary portion cut. For example, when the passage for injecting the bolus material 27 is formed in the mold 23 as described above, the hardened portion in the passage is cut. If there is a burr formed by the bolus material 27 entering the gap between the first mold 23a and the second mold 23b, the burr is cut. On the contrary, when a portion (sink) having insufficient thickness is observed in the bolus 1, a necessary amount of uncured bolus material 27 may be applied to the portion and cured.

(Example 2 of manufacturing method)
In Example 1 described above, the master model 17 was created based on the CT image data 15 obtained by the CT scan, and the mold material 21 was placed around the master model 17 to create the mold 23. On the other hand, in the second example of the manufacturing method, the mold 23 is directly created based on the CT image data 15.

  For example, in Example 1, the coordinates of the surface of the master model 17 are obtained based on the CT image data 15, but these coordinates are used as the coordinates of the inner surface of the mold 23, and the coordinates of the outer surface of the mold 23 are appropriately set. That is, the three-dimensional coordinate data of the mold 23 is generated. And based on this three-dimensional coordinate data, you may form the type | mold 23 by using a 3D printer. Example 2 may be the same as Example 1 except that the mold 23 is formed directly.

(Example 3 of manufacturing method)
In Example 1 and Example 2 described above, the mold 23 was created indirectly or directly based on the CT image data 15, and the bolus 1 was created by placing the bolus material 27 on the mold 23. On the other hand, in Example 3, the bolus 1 is created directly based on the CT image data 15. For example, the bolus 1 is created by the 3D printer in the same manner as the master model 17 is created by the 3D printer in Example 1.

<Example of procedure for using bolus>
The procedure for using the bolus 1 as described above is, for example, as follows.

  First, the rear part 5 is placed on the therapeutic bed so that the concave surface is upward. Next, the patient lies on his back on the bed with his head on the rear part 5. Next, the front part 3 is put on the patient's face. Next, an adhesive seal is affixed to the joint between the front part 3 and the rear part 5 to fix both, and as a result, the bolus 1 is fixed to the patient's head. In this state, radiation is applied to the patient's head through the bolus 1 to perform treatment.

  The therapeutic radiation is, for example, X-rays, gamma rays, electron beams, proton beams or heavy particle beams. A wavelength, a dose, etc. may be set suitably. The therapeutic radiation does not have to be the same type of radiation (generally X-rays) used in the CT scan of FIG. When both types are the same, the wavelength, dose, etc. of both need not be the same.

  As described above, in the method for manufacturing the bolus 1 according to the present embodiment, the main material 27a containing polyol and the curing agent 27b containing polyisocyanate and diisononyl phthalate are mixed to produce the bolus material 27 (FIG. 2). (F)).

  From another viewpoint, the bolus 1 according to the present embodiment is mainly composed of a material obtained by blending a polymer compound in which a polyol and a polyisocyanate are urethane-bonded with diisononyl phthalate.

  Therefore, for example, the bolus 1 can be given characteristics equivalent to those of the human body with respect to radiation, and can be given sufficient softness. By having the bolus 1 sufficiently soft, for example, the risk that the patient feels pain can be reduced. Further, for example, the adhesion of the bolus 1 to the body surface can be improved to improve the accuracy of radiotherapy.

  Furthermore, since the bolus 1 is made of polyurethane, it does not contain moisture or has little moisture. As a result, for example, the bolus 1 can maintain characteristics over a relatively long period. As a result, for example, it is expected that the bolus 1 can be used throughout the treatment period of one patient (affected part). As a result, the cost for treatment can be reduced.

  Further, when the polyisocyanate is an HDI system, it does not turn yellow even when exposed to air, so that the transparency of the bolus is easily maintained. The transparency of the bolus facilitates radiation therapy. That is, good characteristics are maintained from the viewpoint of treatment.

<Example>
A bolus sample was made of polyurethane, and its hardness was measured over a predetermined period. Specifically, it is as follows.

(Sample conditions)
The sample material was a two-component polyurethane in which a main agent (polyol) and a curing agent were mixed at a weight ratio of 100: 40 to 100: 60. The curing agent contained HDI polyisocyanate and diisononyl phthalate in a weight ratio of 10:90 to 20:80. In addition, the hardening | curing agent shall contain hexaethylene diisocyanate at 0.15 wt% or less. Four samples were produced by varying the weight ratio of the main agent and the curing agent.

(Measurement method of hardness)
The hardness of the sample was measured with an F-type hardness meter. The hardness 100 of the F-type hardness meter is slightly larger than the hardness 10 of the A-type hardness meter described above.

(Sample environment)
After creating the sample, the sample was exposed to the following environment.
Day 0-20: Exposed to air at about 25 ° C.
Day 21: Radiation (4MV X-ray) irradiation was performed twice (30 Gy, 60 Gy).
Day 22: Radiation (4MV X-ray) irradiation was performed once (60 Gy).
Day 23 to about half a year: exposed to air at about 25 ° C.

(Measurement result)
The results of measurement of hardness with an F-type hardness meter are as follows. The hardness on the 22nd day is a numerical value after radiation irradiation.
Sample 0 days 20 days 22 days About 2 months About half a year 1 61 58 57 57 58
2 65 63 60 60 64
3 72 67 66 66 70
4 75 74 75 74 73

  From the above measurement results, it was confirmed that the hardness of the sample hardly changed even after irradiation with X-rays or about half a year. The hardness maintained over the long term is in the range of 57 or more and 75 or less of the F-type hardness meter, and is included in the range of 0 or more and 10 or less of the hardness of the A-type hardness meter.

  The reason that the measurement period is about half a year later is that the time immediately before the application was about half a year later. Accordingly, the hardness of the bolus is expected to be maintained over a longer period.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects. For example, the mixing ratio of the main agent and the curing agent, the mixing ratio of polyisocyanate and diisononyl phthalate, the content of hexamethylene diisocyanate, and the like are not limited to those exemplified in the embodiment. Other bonds may be formed in addition to the urethane bond.

  Note that the technique for forming a bolus based on image data obtained by CT scan can be applied to materials other than the bolus material described in the embodiment. For example, the bolus material may be a resin other than the resin mentioned in the embodiment, synthetic rubber, silicon, or gelatin. For example, when a bolus is directly formed by a 3D printer, the bolus material may be a material suitable for the 3D printer.

DESCRIPTION OF SYMBOLS 1 ... Bolus, 27a ... Main ingredient, 27b ... Hardener, 27 ... Bolus material.

Claims (9)

Combining a base containing a polyol with a curing agent containing polyisocyanate and diisononyl phthalate to produce a bolus material,
Wherein the weight ratio of the polyisocyanate and the diisononyl phthalate is 10: 90-20: Ri 80 der,
The weight ratio of the main agent to the curing agent is 100: 40 to 100: 60.
A method of manufacturing a bolus for radiation therapy . The method for producing a bolus for radiation therapy according to claim 1 , wherein the polyisocyanate is of a hexamethylene diisocyanate type. The method for producing a bolus for radiotherapy according to claim 1 or 2 , wherein the curing agent contains hexamethylene diisocyanate. The radiotherapeutic bolus is a head for bolus surrounding at least the top portion of the head,
Performing a CT scan of the parietal part to obtain 3D tomographic image data;
Based on the three-dimensional tomographic image data, the coordinates of the shape of the surface of the parietal portion are taken as the coordinates of the shape of the inner surface of the bolus for radiotherapy , and the coordinates obtained by shifting the coordinates outward by a certain distance are the radiotherapy with the coordinates of the outer side surface of the use bolus, and generating the radiation therapy bolus, 3-dimensional coordinate data of uniform thickness,
Forming a master model of the radiation therapy bolus with a 3D printer based on the coordinate data;
Placing uncured mold material around the master model;
Dividing the mold formed by curing the mold material and taking out the master model from the mold ;
Placing the uncured bolus material in the mold;
Removing the radiation therapy bolus formed by curing the bolus material from the mold;
Have
In the step of generating the coordinate data, forehead data and occipital data are generated, and thereafter, the step of forming the master model, the step of arranging the mold material, and the master model are taken out. A step of arranging the bolus material and a step of taking out the radiotherapy bolus from the mold are performed separately on the frontal and occipital sides.
The manufacturing method of the bolus for radiotherapy of any one of Claims 1-3 . The radiotherapeutic bolus is a head for bolus surrounding at least the top portion of the head,
Performing a CT scan of the parietal part to obtain 3D tomographic image data;
Based on the three-dimensional tomographic image data, the coordinates of the shape of the surface of the parietal portion are taken as the coordinates of the shape of the inner surface of the bolus for radiotherapy , and the coordinates obtained by shifting the coordinates outward by a certain distance are the radiotherapy with the coordinates of the outer side surface of the use bolus, and generating a uniform thickness wherein the radiotherapeutic bolus capable of forming mold, three-dimensional coordinate data,
Forming the mold by a 3D printer based on the coordinate data ;
Placing the uncured bolus material in the mold;
Removing the radiation therapy bolus formed by curing the bolus material from the mold;
Have
In the step of generating the coordinate data, forehead data and occipital data are generated, and thereafter, forming the mold, placing the bolus material, and the radiotherapy bolus. The step of removing from the mold is performed separately on the frontal and occipital sides.
The manufacturing method of the bolus for radiotherapy of any one of Claims 1-3 . The radiotherapeutic bolus is a head for bolus surrounding at least the top portion of the head,
Performing a CT scan of the parietal part to obtain 3D tomographic image data;
Based on the three-dimensional tomographic image data, the coordinates of the shape of the surface of the parietal portion are taken as the coordinates of the shape of the inner surface of the bolus for radiotherapy , and the coordinates obtained by shifting the coordinates outward by a certain distance are the radiotherapy with the coordinates of the outer side surface of the use bolus, and generating the radiation therapy bolus, 3-dimensional coordinate data of uniform thickness,
Forming the radiation therapy bolus with a 3D printer based on the coordinate data;
Have
In the step of generating the coordinate data, frontal data and occipital data are generated, and the subsequent step of forming the radiotherapy bolus is performed separately on the frontal and occipital sides. Be called
The manufacturing method of the bolus for radiotherapy of any one of Claims 1-3 . The method for manufacturing a bolus for radiotherapy according to any one of claims 1 to 6 , wherein the bolus material has transparency to visible light. A polymer compound obtained by urethane-bonding a polyol and a polyisocyanate;
Diisononyl phthalate and
The main component is a material that contains
The weight ratio of the polyisocyanate to the diisononyl phthalate is 10:90 to 20:80,
Hardness measured by A-type hardness tester specified in JIS K 6253 is 0-10.
Radiation therapy bolus. The bolus for radiation therapy according to claim 8 , wherein the thickness is 3 mm or more and 20 mm or less.

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