JP2017140090A - Fabrication method of bolus and bolus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fabrication method of a bolus in which the bolus fitted to a head shape can be made.SOLUTION: A fabrication method of a bolus 1 has the steps of: generating three-dimensional coordinate data 17 of the bolus 1 of uniform thickness assuming the surface shape of the head top side portion as the shape of the inside surface, based on image data of a three-dimensional tomographic image acquired by CT scanning of a head top side portion; forming a master model 19 of the bolus 1 by a 3D printer based on the coordinate data 17; disposing an uncured mold material 21 around the master model 19; dividing a mold 23 formed by curing the mold material 21 and taking out the master model 19 from the mold 23; disposing an uncured bolus material 27 in the mold 23; and taking out the bolus 1 formed by curing the bolus material 27 from the inside of the mold 23.SELECTED DRAWING: Figure 2

Description

  The present invention relates to 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, and in particular, a method for manufacturing a bolus that fits a patient's head and a bolus. About.

  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 discloses a bolus having a shape that matches the shape of the head in the column of the prior art. Patent Document 1 also discloses that a natural organic polymer water-containing gel is poured into a mold and molded.

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

  Patent Document 1 does not disclose a method for producing a mold for forming a bolus. Therefore, it is difficult to produce a bolus having a shape that fits on the body surface having irregularities such as the head. If the bolus does not fit on the body surface and a gap is formed between the body surface and the bolus, an error occurs in the amount by which the bolus shifts the build-up point with respect to the body surface. As a result, the desired therapeutic effect cannot be increased, and the reproducibility of the treatment is also reduced. On the other hand, in the radiation therapy for the head, since the brain is under the skin, it is preferable that the bolus and the amount of radiation absorbed by the skin are controlled with high accuracy.

  Accordingly, it is desirable to provide a bolus manufacturing method and bolus that can create a bolus that fits the shape of the head.

  A bolus manufacturing method according to an aspect of the present invention is a head bolus manufacturing method that surrounds at least a parietal portion of a head, and performs CT scan of the parietal portion to obtain three-dimensional tomographic image data. Obtaining a three-dimensional coordinate data of a bolus having a uniform thickness in which the surface shape of the parietal portion is the shape of the inner surface based on the three-dimensional tomographic image data; and the coordinates Based on the data, a step of forming a master model of the bolus by a 3D printer, a step of placing an uncured mold material around the master model, and a mold formed by curing the mold material Removing the master model from the mold by dividing, placing uncured bolus material in the mold, and curing the bolus material. The formed the bolus having, retrieving from within the mold.

  Preferably, in the step of generating the coordinate data, the step of generating data obtained by dividing the bolus into frontal and occipital sides, forming the master model, placing the mold material, The step of taking out the master model, the step of placing the bolus material, and the step of taking out the bolus from the mold are performed separately in the frontal portion and the back portion.

  Preferably, a material having transparency to visible light is used as the bolus material.

  Preferably, as the bolus material, a two-component resin whose hardness can be adjusted by the blending ratio of the main agent and the curing agent is used.

  Preferably, a polyurethane resin is used as the bolus material.

  A head bolus according to an aspect of the present invention is made of a polyurethane-based resin, and includes a concave inner surface that surrounds at least the top side portion of the head, and an outer surface that is formed by shifting the shape of the inner surface to the outside. ,have.

  According to the above procedure or configuration, the bolus can be fitted to the head.

1 is an external perspective view showing a bolus according to an embodiment of the present invention. FIG. 2A to FIG. 2G 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)
FIG. 1 is an external perspective view showing a bolus 1 according to an embodiment of the present invention.

  The bolus 1 is configured as a head bolus that covers (at least a part of) a patient's head. 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 neck, including the eyes, nose and mouth. There are cases where the entire upper portion is indicated (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, it is not an essential requirement for the bolus 1 to cover the entire head in a broad sense.

  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 (note that the shape in the state where no external force (including gravity) is applied. Unless otherwise specified, the shape is the same as the shape of the individual patient's head). It is formed as follows. Thus, the bolus 1 fits the individual patient's head. The bolus 1 has a generally uniform thickness. 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 material)
The material of the bolus 1 may be an appropriate material, but 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.

  Examples of the material of the bolus 1 that easily realizes the above characteristics (particularly, the equivalence with the human body of (1)) include synthetic resin (plastic), synthetic rubber, silicon, or gelatin in a narrow sense. In consideration of corrosion resistance, flexibility, adhesion, etc., the bolus 1 is formed by reacting a main agent and a curing agent, and its properties (for example, hardness) are determined by the mixing ratio. Resin is preferred. Examples of the two-component resin include polyurethane resins such as purine gel (trade name).

  As is well known, the polyurethane-based resin is formed, for example, by a reaction between a compound having a hydroxyl group (for example, polyol) and a compound having an isocyanate group (for example, polyisocyanate). The polyurethane-based resin can be softened to the human skin level, and the C hardness of the bolus 1 may be, for example, 5 or less or substantially 0. Moreover, what has the transmittance | permeability with respect to visible light is also known as a polyurethane-type resin.

<Bolus manufacturing method>
(Outline of manufacturing method procedure)
FIG. 2A to FIG. 2G are schematic views for explaining a method for manufacturing the bolus 1. As indicated by arrows between the drawings, the manufacturing method proceeds from FIG. 2A to FIG. 2G in order.

  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. 2 (f), a bolus material 27 is placed in the cavity 25 of the mold 23.

  Then, as shown in FIG. 2G, 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. 2F), and the bolus 1 The removal is performed separately for the front part 3 and the rear part 5. 2B to 2G, 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.

(Bolus material injection (Fig. 2 (f))
As described above, the bolus material 27 is preferably a two-component resin whose hardness varies depending on the mixing ratio of the main agent and the curing agent, such as a polyurethane resin. With such a two-component resin, the hardness of the bolus can be made appropriate depending on the part covered by the bolus. 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.

  It is preferable to defoam the bolus material 27 with a vacuum device before, during and / or after mixing. 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.

  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 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 (g))
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 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, the bolus 1 manufacturing method according to the present embodiment is a head bolus manufacturing method that surrounds at least the parietal portion of the head, and performs a CT scan of the parietal portion to perform a three-dimensional tomographic image. 3D of the bolus 1 having a uniform thickness in which the surface shape of the parietal part is the shape of the inner surface based on the step of obtaining the CT image data 15 (FIG. 2A) and the CT image data 15 Generating the coordinate data 17 (FIG. 2B), forming the master model 19 of the bolus 1 with a 3D printer based on the coordinate data 17 (FIG. 2C), Disposing the uncured mold material 21 around the periphery (FIG. 2D) and dividing the mold 23 formed by curing the mold material 21 and taking out the master model 19 from the mold 23 2 (e)), a step (FIG. 2 (f)) of placing an uncured bolus material 27 in the mold 23, and a bolus 1 formed by curing the bolus material 27 from the mold 23. And a step of taking out (FIG. 2G).

  Therefore, for example, the bolus 1 is formed based on the actual measurement of the head of each individual patient, and the bolus 1 that fits the head of each individual patient is realized. Then, by fitting the bolus 1 to the head, it is possible to reduce the possibility that the build-up point BP is displaced from the affected part 103 due to the gap between the head and the bolus 1. Further, for example, the CT image data 15 that contributes to the manufacture of the bolus 1 can be efficiently obtained because it can be obtained for diagnosis. Also, for example, the body surface coordinates obtained from the CT image data 15 can be used as the coordinates of the inner surface of the bolus 1 (master model 19) as they are, and the coordinates obtained by shifting the coordinates to the outside can be used as the coordinates of the outer surface. Is easy. For example, since a 3D printer is used, it is simple and inexpensive.

  Here, it is conceivable to form the bolus 1 itself with a 3D printer. However, as described above, the material of the bolus 1 needs to satisfy various conditions such as radiation absorption characteristics, softness, and toxicity. On the other hand, at the present time, there is no commercially available 3D printer capable of realizing a three-dimensional shape using a material suitable for such a bolus. Therefore, a master model 19 of the bolus 1 is formed by a 3D printer, a mold 23 is formed by using the master model 19, and the bolus 1 is formed by using the mold 23. Can be selected. From the opposite viewpoint, in the use of a 3D printer, a material suitable for modeling can be used.

  In the present embodiment, in the step of generating the coordinate data 17 for the 3D printer (FIG. 2B), data obtained by dividing the bolus 1 into the frontal and occipital sides is generated. The step of forming the master model 19 (FIG. 2C), the step of arranging the mold material 21 (FIG. 2D), the step of taking out the master model 19 (FIG. 2E), and the bolus material 27 The step of placing (FIG. 2 (f)) and the step of taking out the bolus 1 from the mold 23 (FIG. 2 (g)) include a frontal part (front part 3) and a occipital part (rear part). 5) and separately.

  Therefore, for example, the bolus 1 can be easily attached to and detached from the head as compared with a case where the entire bolus 1 is integrally formed. In particular, when the bolus 1 covers a wide range including the ears and nose, it is easy to avoid the ears and nose from engaging with the bolus 1 during attachment and removal, which is effective. When the bolus 1 is flexible and / or elastic, the bolus 1 can be attached to and detached from the head even if the entire bolus 1 covering a wide area including the ears and nose is integrally formed. . However, in general, the skin of a patient having a tumor on the head is very weak, and it is preferable to avoid applying irritation (pressure) to the skin. And since the bolus 1 is divided | segmented and attachment / detachment is easy, such a irritation | stimulation can be avoided. In the manufacturing process, instead of cutting and dividing the integrally formed bolus 1 (this case is also included in the present invention), the coordinate data 17 is generated in a state of being divided from the beginning, and the manufacturing process is performed. Since the process proceeds, so-called undercut is unlikely to occur in the mold 23.

  In the present embodiment, a material having transparency to visible light is used as the bolus material 27.

  Therefore, for example, the doctor can grasp the range of the body surface to which the radiation should be directly applied, instead of estimating the range of the body surface to which the radiation should be irradiated from the shape of the outer surface of the bolus 1. As a result, for example, the accuracy of treatment is improved. Moreover, for example, the presence or absence of a gap between the body surface and the bolus 1 can be confirmed, and the possibility that the build-up point BP is shifted due to the gap can be reduced. In addition, for example, as described above, it is preferable to avoid applying a stimulus (pressure) to the skin of the head, but it can also be confirmed whether or not a relatively large pressure is applied.

  In the present embodiment, as the bolus material 27, a two-component resin whose hardness can be adjusted by the mixing ratio of the main agent and the curing agent is used.

  Therefore, for example, by appropriately adjusting the mixing ratio of the bolus material 27, the bolus can have a hardness suitable for the site or medical condition to be treated. For example, in this embodiment, the bolus 1 is for the head, but can have a hardness suitable for the head. In addition, for example, as described above, it is preferable to avoid applying irritation to the skin of the head, but by adjusting the mixing ratio, the hardness can be made sufficiently low to avoid irritation to the skin.

  In the present embodiment, a polyurethane resin is used as the bolus material 27.

  If it is a polyurethane-based resin, for example, it is possible to realize characteristics equivalent to those of the human body with respect to radiation, and to realize sufficient softness equivalent to human skin (for example, C hardness of 5 or less, preferably about 0). it can.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  For example, the bolus may not be divided into two and may be integrally formed as a whole. For example, if it is a cap-like thing to cover to the parietal side, even if the whole is formed integrally, it will not interfere with attachment / detachment. Conversely, the bolus may be divided not only into two parts but also into three or more parts. For example, in a bolus that covers the entire head above the neck, the upper part and the lower part are divided into two parts, and each of the upper part and the lower part is divided into two parts in the front and rear, for a total of four parts. May be.

  For example, the material constituting the bolus may not have transparency to visible light, may not be a two-component resin, and may not be a polyurethane-based resin.

DESCRIPTION OF SYMBOLS 1 ... Bolus, 15 ... CT image data, 17 ... Coordinate data, 19 ... Master model, 21 ... Mold material, 23 ... Mold, 25 ... Bolus material

Examples of the material of the bolus 1 that easily realizes the above characteristics (particularly, the equivalence with the human body of (1)) include synthetic resin (plastic), synthetic rubber, silicon, or gelatin in a narrow sense. In consideration of corrosion resistance, flexibility, adhesion, etc., the bolus 1 is formed by reacting a main agent and a curing agent, and its properties (for example, hardness) are determined by the mixing ratio. Resin is preferred. The 2-part resins, poly crystal (trade name), polyurethane-based resins such as Puringeru (trade name).

Claims (6)

A method for manufacturing a bolus for a head that surrounds at least the parietal 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, generating three-dimensional coordinate data of a bolus having a uniform thickness with the surface shape of the parietal portion as the shape of the inner surface;
Forming a master model of the 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 an uncured bolus material in the mold;
Removing the bolus formed by curing the bolus material from the mold;
A method of manufacturing a bolus for a head. In the step of generating the coordinate data, generating data obtained by dividing the bolus into a frontal side and a occipital side,
The steps of forming the master model, placing the mold material, removing the master model, placing the bolus material, and removing the bolus from the mold include a frontal side The method for manufacturing a head bolus according to claim 1, wherein the method is performed separately for the portion and the portion on the back of the head. The method for manufacturing a head bolus according to claim 1, wherein a material having transparency to visible light is used as the bolus material. The method for manufacturing a bolus for a head according to any one of claims 1 to 3, wherein the bolus material is a two-component resin whose hardness can be adjusted by a mixing ratio of a main agent and a curing agent. The method for manufacturing a head bolus according to claim 4, wherein a polyurethane-based resin is used as the bolus material.   A head bolus made of a polyurethane resin and having a concave inner surface surrounding at least the top side portion of the head, and an outer surface formed by shifting the shape of the inner surface outward.

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