Experimental teaching materials, sequence generation method, and method of using the experimental teaching materials

Abstract

To provide an experiment teaching material which allows a user to learn principles of image reconstruction of a computer tomographic apparatus in a safer and easy-to-understand manner.SOLUTION: In an experiment teaching material 1, a block matrix body 4 is formed such that the same number of blocks formed of a raw material that transmits a light beam having a larger wavelength than a radiation are arranged in a plurality of X, Y axial directions orthogonal to each other, and makes the light beams incident in the X, Y axial directions travel in a straight line in the X, Y axial directions. A light source 11 makes an infrared ray IL on the block matrix body 4 along the X, Y axial directions. A detection unit 12 detects the intensity of the infrared ray IL passing through the block matrix body 4. A lid shields the blocks 10 constituting the block matrix body 4 so as not to be visually recognized. A first block 10a and a second block 10b having mutually-different attenuation degrees of the transmitted infrared ray IL are included as the blocks 10. The block matrix body 4 includes the first block 10a and the second block 10b so as to be freely arranged.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an experiment teaching material, a sequence generation method, and a method for using the experiment teaching material. [Background technology]

[0002] A computed tomography (CT) scanning device places an X-ray source and a detector facing each other across the subject, and detects the intensity of X-rays that pass through the subject. The transmitted intensity of X-rays represents the amount of absorption, which is the integrated information of the subject through which the X-rays have passed. For this reason, it is not possible to obtain an image of the subject from the transmitted intensity of X-rays by measuring from a single direction. Therefore, a CT scanning device measures the transmitted intensity of X-rays while changing the direction of the X-ray source and detector relative to the subject, and then performs image reconstruction based on the transmitted intensity of X-rays from different directions to generate an image of the subject's inside the body. This is the principle of image reconstruction in a CT scanning device.

[0003] The principle of image reconstruction in the above-mentioned CT scanning device is difficult to understand for students, especially for those who have not studied physics. Therefore, in order to understand the principle of image reconstruction, student experiments are being conducted using a radiation source and a GM tube (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Hideo Nitta, Physics Education 52-4 (2004) 311-314 [Non-patent document 2] Tokyo Shoseki "Revised Physics", 2020 edition, reviewed in 2017, pp. 458-459 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the experiments disclosed in the above-mentioned Non-Patent Documents 1 and 2 use sealed radiation sources, which are not suitable for students to use easily. There is a need for experimental teaching materials that enable students to learn the principles of image reconstruction in a safer and easier-to-understand manner.

[0006] The present invention has been made in light of the above-mentioned circumstances, and aims to provide an experimental teaching material, an array generation method, and a method for using the experimental teaching material that enable students to learn the principles of image reconstruction in a computed tomography apparatus in a safer and easier-to-understand manner. [Means for solving the problem]

[0007] In order to achieve the above object, the experimental teaching material according to the first aspect of the present invention comprises: An experimental teaching material for learning the principles of image reconstruction using a computed tomography apparatus, a block matrix configured by arranging an equal number of blocks formed of a material that transmits light rays having wavelengths longer than the radiation in a plurality of axial directions perpendicular to each other, and causing the light rays incident in the axial directions to travel straight in the axial directions; a light source that directs the light beam into the block matrix along the axis; a detection unit that detects the intensity of the light beam that has passed through the block matrix; a cover that shields the blocks that constitute the block matrix so that they cannot be seen from the outside, The blocks include a first block and a second block having different attenuation levels of the transmitted light beam, The block matrix allows the first blocks and the second blocks to be freely arranged.

[0008] A filter that attenuates the transmitted light is inserted into the second block. This may also be the case.

[0009] The second block is filled with a liquid that attenuates the light beam passing through it. This may also be the case.

[0010] The light is any one of infrared light, visible light, and ultraviolet light. This may also be the case.

[0011] The block matrix is ​​capable of adjusting the number of blocks in the axial direction. This may also be the case.

[0012] A sequence generation method according to a second aspect of the present invention comprises: 1. An array generation method for generating, by an information processing device, array information of first blocks and second blocks in a two-dimensional square matrix formed by an array of first blocks and second blocks, each having a different transmission intensity for a light beam having a wavelength larger than that of a radiation beam, the method comprising: Information indicating N, which is the number of rows and columns of the two-dimensional square matrix, and M, which is the number of second blocks in the two-dimensional square matrix (M≦N 2 an input step of inputting information indicating the a matrix generation step of generating the two-dimensional square matrix by packing the second blocks into any one of four corner regions of the two-dimensional square matrix based on the information input in the input step; a matrix transformation step of moving an entire block of any row in the two-dimensional square matrix generated in the matrix generation step to a different row, or exchanging it with an entire block of any other row, or moving an entire block of any column in the two-dimensional square matrix to a different column, or exchanging it with an entire block of any other column; Includes.

[0013] A method of using the experiment teaching material according to the third aspect of the present invention comprises: a block matrix configured by arranging an equal number of blocks formed of a material that transmits light rays having wavelengths larger than that of radiation in a plurality of axial directions perpendicular to each other, the block matrix causing the light rays incident in the axial directions to travel straight in the axial directions; a light source that makes the light rays incident on the block matrix along the axial directions; a detection unit that detects the intensity of the light rays that have transmitted through the block matrix; and a cover that shields the blocks that constitute the block matrix so that they cannot be seen from the outside, the blocks including first blocks and second blocks that have different attenuation rates of the transmitted light rays, the block matrix being capable of being freely arranged, a reference information generating step of detecting, with the detection unit, the intensity of the light beam when the light beam is incident on the block matrix from the light source while increasing the number of the second blocks in each of the axial directions of the block matrix, and generating reference information indicating a relationship between the number of the second blocks and the intensity of the light beam detected by the detection unit; an arranging step of rearranging the arrangement of the first blocks and the second blocks in the block matrix and shielding them with the cover; a measuring step of measuring the intensity of the light beams transmitted through the block matrix in the axial direction at least once by detecting the intensity of the light beams when the light beams are incident from the light source in each of the axial directions of the block matrix with the block matrix shielded by the cover, with the detecting unit; Includes. [Effects of the Invention]

[0014] According to the present invention, by using light rays having a wavelength larger than that of radiation instead of X-rays, it is possible to show students in an easy-to-understand manner the configuration of the X-ray tube and detector in a computed tomography apparatus, and the relationship between the detection results and the image, thereby enabling them to learn the principles of image reconstruction in a computed tomography apparatus in a safer and easier-to-understand manner. [Brief explanation of the drawings]

[0015] [Figure 1]1 is a perspective view of an experiment teaching material according to an embodiment of the present invention; [Figure 2] FIG. 2 is a top view showing the configuration of the optical system of the experimental teaching material in FIG. [Figure 3] (A) is a perspective view of the first block, and (B) is a perspective view of the second block. [Figure 4] FIG. 2 is a schematic diagram showing an example of the arrangement of first and second blocks. [Figure 5] (A) is a semi-logarithmic graph showing the relationship between the number of substances passing through and the intensity of transmitted light. (B) is a flowchart showing how to use the experimental teaching material in Figure 1. [Figure 6] FIG. 10 is a schematic diagram for determining block placement conditions. [Figure 7] (A) to (D) are schematic diagrams showing the simplest block arrangement. [Figure 8] 10(A) to 10(C) are schematic diagrams showing basic patterns of block arrangement. [Figure 9] 10(A) to 10(F) are schematic diagrams showing an example of the operation procedure for placement. [Figure 10] 10 is a flowchart of an array generation process executed by the information processing device. [Figure 11] 1. (A) and (B) are top views showing modified examples of the experimental teaching material of FIG. [Figure 12] FIG. 10 is a perspective view of another example of a block structure constituting the experimental teaching material according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals.

[0017] [Overall configuration] 1 is an experimental device used to learn the principles of image reconstruction in a computed tomography apparatus. The experimental device 1 includes a rectangular parallelepiped housing 2 and a lid 3 as covers, a block matrix body 4 housed in the housing 2 and the lid 3, and an optical probe 5 for inputting and outputting light rays.

[0018] As shown in Fig. 1, the experimental teaching material 1 is used by placing it on a table (not shown) with the lid 3 facing up. In this embodiment, the up-down direction is defined as the Z-axis direction, and the normal directions to the side surface of the housing 2 are defined as the X-axis direction and the Y-axis direction, and the explanation will be given with reference to these three-axis Cartesian coordinate system. The shape of the housing 2 and the lid 3 is square when viewed from above.

[0019] A gap is provided between the housing 2 and the lid 3, and a part of the side surface of the block matrix 4 is exposed to the outside through the gap. The optical probe 5 is disposed so as to straddle the lid 3, and both ends of the optical probe 5 extend to the exposed portion of the block matrix 4.

[0020] [Optical probe] The optical probe 5 emits a light beam from one end into the block matrix 4. The incident light beam travels straight through the block matrix 4, passes through it, and is received at the other end of the optical probe 5. Here, the light beam refers to an electromagnetic wave whose wavelength is in the range from the far ultraviolet region to the far infrared region. The wavelength of the light beam is longer than that of radiation such as X-rays, so there is no risk of radiation exposure. In this embodiment, the light beam is infrared.

[0021] The optical probe 5 can slide on the lid 3 in the Y-axis direction relative to the housing 2, the lid 3, and the block matrix 4. The optical probe 5 can also be installed on the lid 3 so as to straddle the Y-axis direction. In this case, the optical probe 5 can slide on the lid 3 in the X-axis direction. This makes it possible for the optical probe 5 to transmit infrared light in the Y-axis direction at any X position on the block matrix 4, and to transmit infrared light in the X-axis direction at any Y position.

[0022] The optical system of the experimental teaching material 1 has a configuration as shown in Fig. 2. This optical system is configured with a block matrix body 4 at its center.

[0023] [Block matrix field] The block matrix 4 is composed of a two-dimensional square matrix of blocks 10 made of a material that transmits infrared light IL. That is, the block matrix 4 is composed of an equal number of blocks 10 arranged in the X-axis and Y-axis directions that are orthogonal to each other. In this embodiment, the block matrix 4 has 5 rows and 5 columns.

[0024] The shape of the block 10 is a rectangular parallelepiped, as shown in Figures 3(A) and 3(B). The block 10 is made entirely of a material that transmits infrared light IL, for example, plastic such as acrylic, or glass. For example, a plastic cell for a spectrophotometer can be used as the block 10.

[0025] Returning to FIG. 2, the block matrix body 4 has a frame member 4a into which the blocks 10 are inserted. The frame member 4a can be manufactured using a 3D printer or the like. The frame member 4a has insertion portions into which the blocks 10 are inserted formed in a two-dimensional square matrix. The blocks 10 are inserted into the insertion portions of the frame member 4a to form the block matrix body 4. The frame member 4a is made of the same material as the blocks 10. This allows the block matrix body 4 to direct infrared rays IL incident in the X-axis and Y-axis directions (row direction and column direction) of the two-dimensional matrix of the blocks 10 in a straight line.

[0026] [block] In this embodiment, as shown in FIGS. 3A and 3B, the block 10 includes a first block 10a and a second block 10b. The side surfaces of the first block 10a shown in FIG. 3A do not have infrared cut filters attached to them that attenuate the infrared rays IL that pass through them. On the other hand, the second block 10b shown in FIG. 3B has filters attached to it that absorb the infrared rays IL. Specifically, filters are attached to the +x-side and -y-side sides of the second block 10b. This results in different degrees of attenuation of the infrared rays IL that pass through the side surfaces of the first block 10a and the second block 10b.

[0027] The first block 10a indicates that there is no substance that absorbs the transmitted light, and the second block 10b indicates that there is a substance that absorbs the transmitted light. Therefore, hereinafter, the first block 10a is also referred to as an empty cell, and the second block 10b is also referred to as an absorbing cell.

[0028] Returning to FIG. 2, the first blocks 10a and the second blocks 10b can be freely arranged in the block matrix body 4. In the experiment conducted in this experimental teaching material 1, the question setter first decides the arrangement of the first blocks 10a and the second blocks 10b in the block matrix body 4. Then, the student conducting the experiment measures the intensity of infrared light IL transmitted through each row and each column of the block matrix body 4, and estimates the arrangement of the first blocks 10a and the second blocks 10b in the block matrix body 4 based on the measurement results. This is the main content of the experiment.

[0029] [light source] A light source 11 is provided at one end of the optical probe 5. The light source 11 emits infrared rays IL into the block matrix 4 along the X-axis direction and the Y-axis direction. In this embodiment, the light source 11 includes a light-emitting diode that emits infrared rays IL. The infrared rays IL emitted from this light-emitting diode are incident on the block matrix 4. External power is supplied to the light source 11 via an AC adapter and a coaxial cable, and the light-emitting diode emits light using that power.

[0030] The electrical circuit within light source 11 is configured such that a voltage stepped down by a variable three-terminal regulator is used to pass a current adjusted to a constant level by a constant current diode through the light-emitting diode, thereby generating infrared light IL of a constant intensity. Light source 11 may be equipped with several constant current diodes to make the current flowing through the light-emitting diode adjustable. Light source 11 is also provided with a heat sink for dissipating heat generated by the light-emitting diode to the outside, thereby enabling the internal temperature to be maintained constant. In light source 11, light emitted from the photodiode is emitted only in the +X direction through a through hole so that it travels in the +X direction. The through hole serves to narrow the infrared light IL.

[0031] [Detection section] The detection unit 12 detects the intensity of the infrared rays IL that have passed through the block matrix 4. The detection unit 12 includes a photodiode that outputs a signal according to the intensity of the received infrared rays IL, and a signal amplifier circuit connected to the photodiode. The infrared rays IL that have passed through the block matrix 4 are received by the photodiode through the through-hole. The through-hole is provided so that the photodiode receives only the infrared rays IL that have traveled straight through the block matrix 4. It is also desirable to use a photodiode that blocks visible light so that it is not affected by visible light.

[0032] The signal detected by the photodiode is amplified by a signal amplifier circuit including an operational amplifier and output from the detection unit 12. The signal amplifier circuit has an amplification factor that can be varied using a variable resistor. The detection unit 12 is connected to a tester via a coaxial cable, and the tester displays the detection results of the transmitted light intensity of the detected infrared light IL. In the experiment, the arrangement of the first block 10a and the second block 10b is estimated based on the detection results of the tester. The light source 11 and the detection unit 12 may be stored in a drawer for easy viewing by students, and their circuit configuration may be confirmed by pulling out the drawer.

[0033] [Connection part] In the optical probe 5, the light source 11 and the detection unit 12 are connected by a connection unit 13. This fixes the relative positional relationship between the light source 11 and the detection unit 12.

[0034] [Housing and lid] As shown in FIG. 1, the housing 2 and the lid 3 shield the arrangement of the blocks 10 that make up the block matrix 4 so that it cannot be seen from the outside.

[0035] [Principles of image reconstruction] A computed tomography apparatus places an X-ray source and a detector facing an object, detects the intensity of transmitted X-rays from multiple directions, and performs computer processing based on the transmitted X-ray intensities in multiple directions to reconstruct an image showing the spatial distribution of the object. In contrast, in the experimental teaching material 1 according to this embodiment, a block matrix 4 is used as the detection target, and measurements are taken one baseline at a time from only two directions, "vertical" and "horizontal" (X-axis direction and Y-axis direction), with the aim of having students think about the internal structure of the object without using a computer. Naturally, there are cases where the information required for reconstruction from only two directions is insufficient, making it impossible to determine the internal structure of the object. However, in the experimental teaching material 1 according to this embodiment, the infrared IL is irradiated in two directions, prioritizing an easy understanding of the principles of image reconstruction.

[0036] The transmitted light intensity of X-rays passing through a uniform medium decreases exponentially with the thickness x of the medium, according to the following equation (1) which represents Lambert's law. I=I0e -μx ···(1) Here, I0 is the incident light intensity, I is the transmitted light intensity, and μ is the absorption coefficient. I is the transmitted light intensity of the infrared IL measured by the tester. This Lambert's law also applies to infrared IL. If infrared IL passes through two materials, each with a thickness of d, the transmitted light intensity is as follows: I=I0e -2μd

[0037] In Figure 4, the first block 10a is shown as a white square, and the second block 10b is shown as a hatched square. The width of each square on the X and Y axes is d. As mentioned above, the first block 10a does not have a filter that attenuates infrared IL, while the second block 10b has a filter that attenuates infrared IL. Therefore, here, the first block 10a is considered to have no material, while the second block 10b has material. Students performing the experiment are assumed to be unaware of this internal structure. The numbers to the right and below the block matrix 4 in Figure 4 represent the total number of materials (total thickness) arranged in the corresponding row and column.

[0038] When infrared light IL passes through the block matrix 4 from left to right in the +X direction, if the width of each square is d, then absorption of a thickness of 3d occurs in the first row, and absorption of a thickness of 1d occurs in the fifth row. Since the absorption coefficient μ of materials is the same, simply by measuring the transmitted light intensity I for a material whose thickness is known in advance, the number of materials on the path of the infrared light IL (total thickness) can be determined based on the above equation (1).

[0039] Once the number of substances on the path is known, we next consider the internal structure of the specimen (block matrix body 4). In the arrangement shown in Figure 4, the number of substances in the second row and fourth column is 0, so it is immediately clear that the transmitted light intensity is equal to the incident light intensity and that no substances exist there. Next, considering the second column, the number of substances is 4, but since we know that there is nothing in the second row, we can see that there is substance everywhere else in the second column. Next, looking at the fifth row, we see that there is only one substance in the fifth row, but since we know that it is in the second column, we can see that there is no substance in the rest of the rows. By considering in this way, we can estimate which positions in the five rows and five columns the substances exist.

[0040] [Experimental Procedure] The specific experimental procedures used by students using experimental teaching material 1 will be explained. 1) In one row or one column, the transmitted light intensity of the infrared IL is measured while increasing the number of second blocks 10b, that is, the number of absorption cells 10b, from 0 to 5. 2) Plot the relationship between I / I0 and the number n of absorption cells 10b on a semi-logarithmic graph, where the axis of transmitted light intensity I / I0 is logarithmic (see FIG. 5(A)). 3) A block matrix 4 having an array of empty cells 10a and absorbing cells 10b to be estimated is generated. 4) The lid 3 is placed over the sample, which is a 5x5 sample to be estimated and whose arrangement is unknown. The transmitted light intensity of infrared light IL is measured 10 times for each of the 5 rows in the row direction (X-axis direction) and the 5 columns in the column direction (Y-axis direction) of the sample, and the number of absorption cells 10b in each row and column is estimated based on the results of step 1). 5) The arrangement of the empty cells 10a and the absorbing cells 10b in the block matrix 4 is estimated. 6) After making the estimate, remove lid 3 and have the students check the contents.

[0041] Some older digital cameras do not have infrared blocking capabilities. If you use the display of such a digital camera, you can visually confirm that infrared light IL is being emitted from light source 11.

[0042] In step 1), a block matrix of 2 rows and 5 columns to 6 rows and 5 columns may be prepared separately. By inserting the absorption cells 10b and empty cells 10a into this block matrix and shifting the optical probe 5, it is possible to simultaneously obtain multiple patterns of transmitted light intensity of infrared light IL. For example, by using a block matrix of 6 rows and 5 columns, it is possible to obtain the transmitted light intensity of infrared light IL for 0 to 5 absorption cells at a time.

[0043] In conducting this experiment, the relationship between the number of material fibers n and the normalized transmitted light intensity I / I0 must be linear, as shown by the solid line in the semi-logarithmic graph in Figure 5(A). If the sensitivity of the normalized transmitted light intensity I / I0 to changes in the number of material fibers n is low, as shown by the dotted line, or if the normalized transmitted light intensity I / I0 changes nonlinearly with changes in the number of material fibers n, as shown by the dash-dot line, it is necessary to adjust the intensity of the infrared light IL emitted from the filter of the second block 10b or the light source 11 so that the normalized transmitted light intensity I / I0 changes along the solid line with changes in the number of material fibers n.

[0044] The method of using the experimental teaching material 1 exemplified by the experimental procedure described above can be generalized as shown in the flowchart of FIG. 5(B), for example.

[0045] First, in one row or one column of the block matrix 4, while increasing the number of second blocks 10b, the detection unit 12 detects the transmitted light intensity of the infrared rays IL when the infrared rays IL are incident on the block matrix 4 from the light source 11, and generates reference information indicating the relationship between the number of second blocks 10b and the transmitted light intensity of the infrared rays IL detected by the detection unit 12 (step S1; reference information generation step). This step corresponds to the above-mentioned experimental procedures 1) and 2).

[0046] Next, the arrangement of the first blocks 10a and second blocks 10b in the block matrix 4 is rearranged and shielded with the housing 2 and the lid 3 (step S2; arrangement step). This step corresponds to the above-mentioned experimental procedure 3).

[0047] Next, in a state shielded by the housing 2 and the lid 3, the intensity of the infrared rays IL incident on each row and each column of the block matrix 4 from the light source 11 is detected by the detection unit 12, thereby measuring the intensity of the infrared rays IL passing through each row and each column of the block matrix 4 at least once (step S3; measurement step). This step corresponds to the above-mentioned experimental procedure 4). In experimental procedure 4), the number of measurements is set to 10 for each row and each column, but this number is not limited.

[0048] Then, using the reference information generated in step S1 and the measurement results in step S3, the students estimate the arrangement of the first blocks 10a and the second blocks 10b in the block matrix body 4, and then remove the lid 3 to confirm the arrangement. This corresponds to experimental procedure 5).

[0049] [Arrangement of empty cells and absorption cells] The arrangement conditions of the first block 10a (empty cells) and the second block 10b (absorbing cells) will be described below. Here, the matrix of the block 10 in the block matrix field 4 is generalized to have n rows and n columns (n ​​is a natural number).

[0050] Generally, when a block 10 having an arbitrary absorption coefficient is inserted into a block matrix 4 having n rows and n columns, and infrared light IL is irradiated onto each row and each column to perform measurement, n data I corresponding to the transmitted light intensity of each row are obtained. m (m=1~n) and n data I corresponding to the transmitted light intensity of each column k (k=1 to n) and 2n pieces of data are obtained. Data I m corresponds to the number of second blocks 10b in each row, and data I n corresponds to the number of second blocks 10b in each column.

[0051] In the experiment, these 2n data I m ,I k As shown in Figure 6, element a ij is the first block 10a, it is set to 0, and the element a ij If the case where the second block 10b is set to 1, each of the obtained data I m ,I k By solving the simultaneous equations based on ij It is possible to estimate whether element a is 0 or 1. ij Since is either 0 or 1, the element a of each row or column ij The sum of is between 0 and n.

[0052] For example, for some m, Im If =0, then a mi About a m1 ,a m2 ,a m3 ,…a mn are all 0. Also, for some m, I m If =n, then a mi About a m1 ,a m2 ,a m3 ,…a mn are all 1's.

[0053] However, even if all elements are 0 or 1 and the number of measurable rows and columns is the same as the number of unknowns, a solution may not be found if it contains equations that are not independent. For example, even when n=2, i.e., two rows and two columns, it is not possible to distinguish between the cases of Figure 7(A) and Figure 7(B) when measuring from two directions. This is because the measurement results for both Figure 7(A) and Figure 7(B) show that the total amount of infrared IL absorbed by the rows and columns is equal to one beam.

[0054] On the other hand, even if the number of absorption cells 10b and empty cells 10a is the same as in Figure 7(A), if their arrangement is as shown in Figure 7(C) or Figure 7(D), the arrangement of the empty cells 10a and absorption cells 10b can be uniquely determined. For example, in the arrangement shown in Figure 7(C), the following four equations are a 11 +a 12 =2 a 21 +a 22 =0 a 11 +a 21 =1 a 12 +a 22 =1 and a 11 =1,a 12 =1,a 21 =0,a 22= 0 can be obtained. In an actual CT scanning device, X-rays are transmitted from oblique directions and their intensity is measured, so even if the arrangement is as shown in Figures 7(A) and 7(B), the arrangement of the absorption cell 10b and empty cell 10a can be determined. However, in an experiment from two directions, care must be taken to avoid the arrangement shown in Figure 7(A) or 7(B).

[0055] Technically, whether the internal structure can be uniquely determined from the arrangement of the blocks 10 in the n-by-n block matrix field 4 can be determined by exchanging rows or columns to see if the entire row or column with the largest number of columns can be swapped and moved to the top left, resulting in top-left justification, bottom-left justification, top-right justification, or bottom-right justification. That is, for the two-dimensional square matrix of the block 10 in the block matrix field 4, where empty cells 10a are set to 0 and absorbing cells 10b are set to 1, an operation is performed to convert the matrix to a standard form by a left (or right) elementary transformation, and whether a submatrix such as that shown in Figure 7(A) or 7(B) is contained within the matrix can be confirmed. This confirmation is related to the operation of arranging 2n linear equations, creating a coefficient matrix, and performing elementary transformations.

[0056] [Placement Recipe] Basically, by following the steps below, you can create an arrangement that will give you one answer. 1. As a basic type, first arrange the absorption cells 10b starting from the top left. As shown in Figures 8(A) to 8(C), if the number of absorption cells 10b decreases in the +X direction (right) and the -Y direction (left), the solution can be found by removing rows and columns that are all 0s or all 1s from the side. 2. The basic type cannot be solved by exchanging the entire column or row. Taking advantage of this, examples of various derivations of the basic type are shown in Figure 9.

[0057] The operation is as follows: Figure 9(A) to Figure 9(B): Swapping lines 3 and 5 Figure 9(B) to Figure 9(C): Swapping rows 2 and 5 Figure 9(C) to Figure 9(D): Move the fourth line to the top Figure 9(D) to Figure 9(E); Move the fourth column to the left Figure 9(E) to Figure 9(F): Insert the fourth row after the first row

[0058] The internal structure can be uniquely determined for any of the arrangements shown in Figures 9(A) to 9(F). Of course, the entire arrangement may be rotated 90 degrees or inverted. Individual empty cells 10a and absorption cells 10b cannot be exchanged. Here, an example of 5 rows and 5 columns is given, but this also applies to other numbers of rows and columns. In this way, by exchanging or moving entire blocks in each column or entire blocks in each row with other rows, various internal structure arrangement examples can be created, and a block matrix field 4 can be generated that allows students to guess the interior from measurements.

[0059] Generally, the smaller the matrix, the easier it is to derive the answer in one's head, and the easier it is to solve if the layout is fixed. If there are columns or rows that contain only empty cells 10a, or columns or rows that are all absorbing cells 10b, the matrix can be made smaller immediately, making it easier for students to consider the layout.

[0060] Furthermore, if the properties of the machine or film make it difficult to distinguish between five and four absorption cells 10b, the maximum number of absorption cells 10b in one row or column may be limited to four, and blank rows or columns may be used to fill in the blanks. Conversely, if the amount of infrared light IL overflows and it is difficult to distinguish between 0 and 1, the number of absorption cells 10b may be increased.

[0061] The arrangement of the empty cells 10a and the absorption cells 10b can be generated by an information processing device, which generates the arrangement of the empty cells 10a and the absorption cells 10b to be estimated by a computer executing a software program.

[0062] The information processing device includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a display. The CPU is, for example, a microprocessor, and is a central processing unit that executes various processes and calculations. The information processing device reads out a program stored in the ROM and executes the program on the CPU while using the RAM as a work memory, thereby performing a process of generating an array pattern (array information) of the empty cells 10a and absorption cells 10b to be estimated, i.e., an array generation process.

[0063] As shown in FIG. 10, in the array generation process, first, the information processing device obtains N (N is a natural number) which is information indicating the number of rows and columns of the two-dimensional square matrix, and M (M≦N 2 ) is input (Step S11; input step).

[0064] Next, the information processing device calculates N (N is a natural number) which is information indicating the number of rows and columns of the two-dimensional square matrix input in step S11, and M (M≦N 2 ), a two-dimensional square matrix is ​​generated in which the second blocks 10b are packed and arranged in one of the four corner regions of the two-dimensional square matrix (step S12; matrix generation step). Here, for example, an arrangement of the first blocks 10a and the second blocks 10b as shown in FIG. 8(A) is generated as a basic pattern. There are multiple basic patterns to be generated, and the information processing device selects one from the multiple basic patterns using a random number. In these arrangements, the second blocks 10b are packed and arranged in the upper left. Alternatively, the second blocks 10b may be packed and arranged in the upper right, lower left, or lower right.

[0065] Next, the information processing device moves all of the blocks 10 in any row in the two-dimensional square matrix generated in step S11 to a different row, or exchanges them with all of the blocks 10 in another row, or moves all of the blocks 10 in any column in the two-dimensional square matrix to a different column, or exchanges them with all of the blocks 10 in another column (step S13; matrix conversion step). For example, all of the blocks 10 in a row or all of the blocks 10 in a column are moved or exchanged according to the flow shown in Figures 9(A) to 9(F). Which rows and which columns are moved or exchanged can be determined by random numbers. As a result, arrangement information of the empty cells 10a and the absorbing cells 10b is generated.

[0066] After completing step S12, the information processing device outputs and displays on the display the arrangement information of the empty cells 10a and the absorption cells 10b (step S14; arrangement information output step). According to the displayed arrangement information, the empty cells 10a and the absorption cells 10b are arranged to generate a block matrix field 4. Using this block matrix field 4, a student conducts an experiment to estimate the arrangement from the transmitted light intensity of infrared light IL.

[0067] After step S14 is completed, the information processing device ends the array generation process.

[0068] As explained in detail above, according to the experimental teaching material 1 of the above embodiment, it is possible to show students in an easy-to-understand manner the configuration of the X-ray tube and detector in a computed tomography apparatus, and the relationship between the detection results and the image, by using light (infrared rays IL) having a wavelength longer than that of radiation instead of X-rays. As a result, it is possible to learn the principles of image reconstruction in a computed tomography apparatus in a safer and easier-to-understand manner.

[0069] The experiments using the experimental teaching material 1 according to the above embodiment are interesting cases with puzzle elements, which can motivate students to participate. In addition, since it does not require complex mathematical formulas, the operation is simple, and it is visually easy to understand, even students without mathematical knowledge can conduct experiments that incorporate a physical perspective. Another advantage is that the structure is simplified, so the experiment can be completed in a relatively short time.

[0070] In the experimental teaching material 1 according to the above embodiment, infrared light IL is used as the light beam. However, the present invention is not limited to this. Visible light or ultraviolet light may be used as the light beam. Furthermore, ultraviolet light does not expose or affect the human body as much as radiation such as X-rays, but it is considered to be light that causes chemical changes in the human body, so it is desirable to use visible light or infrared light IL.

[0071] The light beam may also include different wavelengths, for example, red and green light in the visible range, allowing for modification to study differences in absorption due to different colors.

[0072] In the experimental teaching material 1 according to the above embodiment, the second block 10b may be filled with a liquid that attenuates the intensity of the light beam. In this way, the second block 10b that attenuates the intensity of the light beam can also be realized.

[0073] In the experimental teaching material 1 according to the above embodiment, the block matrix 4 is configured by inserting the blocks 10 into the frame member 4a. However, the present invention is not limited to this. The block matrix 4 may be configured so that the side surfaces of the blocks 10 are in direct contact with each other.

[0074] The number of blocks 10 in the row direction and the number of blocks 10 in the column direction of the block matrix 4 may be adjustable. As shown in Figures 11(A) and 11(B), the number of blocks 10 in the row direction and the column direction may be arbitrary, and the length of the connecting portion 13 connecting the light source 11 and the detecting portion 12 may be adjustable so that it can be adjusted according to the number of rows and columns of the blocks 10. In this case, different housings 2 and lids 3 may be provided according to the number of rows and columns, or the housings 2 and lids 3 may be adjustable in size.

[0075] Furthermore, the light absorption rate of the blocks 10 may be set to three or more levels instead of two levels. For example, if a third block with a different absorption rate is added to the arrangement relative to the second block 10b, it becomes possible to estimate the block arrangement in more complex situations. Such blocks with different absorption rates can be generated by attaching films to four surfaces or by attaching multiple films on top of each other. Furthermore, when the light is visible light, they can be generated by attaching films that absorb different colors.

[0076] Furthermore, as shown in FIG. 12, the block matrix body 4 formed by cubes may be a matrix body of three-dimensional matrices, and light may be made incident on the block matrix body 4 from the X-axis, Y-axis, and Z-axis directions instead of the two axial directions of the X-axis and Y-axis, thereby further approaching the structure of a computed tomography apparatus.

[0077] This invention allows various embodiments and modifications without departing from the broad spirit and scope of this invention. Furthermore, the above-described embodiments are intended to explain this invention and do not limit the scope of this invention. That is, the scope of this invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of this invention. [Industrial Applicability]

[0078] It can be used as an experimental teaching material for understanding the principles of image reconstruction in a computed tomography device. [Explanation of symbols]

[0079] 1 Experimental teaching material, 2 Housing, 3 Lid, 4 Block matrix, 4a Frame member, 5 Optical probe, 10 Block, 10a First block (empty cell), 10b Second block (absorption cell), 11 Light source, 12 Detection unit, 13 Connection unit, IL Infrared

Claims

1. An experimental teaching material for learning the principles of image reconstruction using a computed tomography apparatus, a block matrix configured by arranging an equal number of blocks formed of a material that transmits light rays having wavelengths longer than the radiation in a plurality of axial directions perpendicular to each other, and causing the light rays incident in the axial directions to travel straight in the axial directions; a light source that directs the light beam into the block matrix along the axis; a detection unit that detects the intensity of the light beam that has passed through the block matrix; a cover that shields the blocks that constitute the block matrix so that they cannot be seen from the outside, The blocks include a first block and a second block having different attenuation degrees of the transmitted light beam, The block matrix allows the first blocks and the second blocks to be freely arranged. Experimental teaching materials.

2. a filter for attenuating the transmitted light beam is inserted into the second block; The experiment teaching material according to claim 1.

3. The second block is filled with a liquid that attenuates the light beam passing through it. The experiment teaching material according to claim 1.

4. The light is any one of infrared light, visible light, and ultraviolet light. The experiment teaching material according to any one of claims 1 to 3.

5. The block matrix is ​​capable of adjusting the number of blocks in the axial direction. The experiment teaching material according to any one of claims 1 to 4.

6. 1. An array generation method for generating, by an information processing device, array information of first blocks and second blocks in a two-dimensional square matrix formed by an array of first blocks and second blocks, each having a different transmission intensity for a light beam having a wavelength larger than a radiation beam, the method comprising: Information indicating N, which is the number of rows and columns of the two-dimensional square matrix, and M, which is the number of second blocks in the two-dimensional square matrix (M≦N ２ an input step of inputting information indicating the a matrix generation step of generating the two-dimensional square matrix by packing the second blocks into one of four corner areas of the two-dimensional square matrix based on the information input in the input step; a matrix transformation step of moving an entire block of any row in the two-dimensional square matrix generated in the matrix generation step to a different row, or exchanging it with an entire block of any other row, or moving an entire block of any column in the two-dimensional square matrix to a different column, or exchanging it with an entire block of any other column; Array generation methods including:

7. a block matrix configured by arranging an equal number of blocks formed of a material that transmits light rays having wavelengths larger than that of radiation in a plurality of axial directions perpendicular to each other, the block matrix causing the light rays incident in the axial directions to travel straight in the axial directions; a light source that makes the light rays incident on the block matrix along the axial directions; a detection unit that detects the intensity of the light rays that have transmitted through the block matrix; and a cover that shields the blocks that constitute the block matrix so that they cannot be seen from the outside, the blocks including first blocks and second blocks that have different attenuation rates of the transmitted light rays, the block matrix being capable of being freely arranged, a reference information generating step of detecting, with the detecting unit, the intensity of the light beam when the light beam is incident on the block matrix from the light source while increasing the number of the second blocks in each of the axial directions of the block matrix, and generating reference information indicating a relationship between the number of the second blocks and the intensity of the light beam detected by the detecting unit; an arranging step of rearranging the arrangement of the first blocks and the second blocks in the block matrix and shielding them with the cover; a measuring step of measuring, at least once, the intensity of the light beams transmitted through the block matrix in the axial direction by detecting, with the detecting unit, the intensity of the light beams when the light beams are incident from the light source in each of the axial directions of the block matrix in a state where the block matrix is ​​shielded by the cover; How to use the experimental materials, including:

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