JP6512861B2 - Cancer diagnostic equipment - Google Patents

Description

The present invention relates to a cancer diagnostic device .

  Typical cancer tests and diagnostic methods are X-ray imaging, MRI, and PET (Positron Emission Tomography). The reaction probability that X-rays are absorbed by the photoelectric effect is proportional to the fifth power of the atomic number. Although the average atomic number in vivo is 6.5, bone tissue has a high calcium concentration of atomic number 20. If necrosis occurs in the living body to form a blood clot, the iron concentration of atomic number 26 increases. Cancer tissue consumes a large amount of glucose and oxygen because its metabolism is about five times that of normal tissue. If the cancerous tissue is enlarged, nutrients and oxygen will be lacking in the central part and necrosis will occur, so terminal cancer can be diagnosed by radiography. Patent Document 1 describes an X-ray imaging apparatus.

  MRI measures the hydrogen atom concentration using nuclear magnetic resonance of hydrogen atoms, estimates the water concentration from the measured hydrogen atom concentration, and estimates the vascular distribution from the estimated water concentration. Ongoing cancer tissue requires large amounts of glucose and oxygen, and capillary hyperproliferation occurs. Therefore, it is possible to identify a site where a capillary is abnormally proliferating, and to estimate that a cancer is present there. Patent Document 2 describes an MRI apparatus.

PET administers drugs containing proton-rich nuclei that release positrons with β + decay such as ¹⁸ F, ¹¹ C, ¹³ N, ¹⁵ O, and positrons annihilate with electrons in the body and generate in the opposite direction 180 degrees The biodistribution of the PET drug is measured by measuring two 511 keV gamma rays. If glucose is used as a PET drug, in principle, even small primary cancers can be diagnosed. Patent Document 3 describes a positron emission tomography apparatus (PET apparatus).

JP, 2014-223175, A JP, 2014-158623, A JP, 2014-238397, A

  The digestive surface is active in cell division and always in contact with food that may contain carcinogens, resulting in a high carcinogenic rate. However, since the capillaries are originally densely distributed, abnormal distribution and necrosis of the capillaries are unlikely to occur even if cancer progresses, so the X-ray imaging apparatus described in Patent Document 1 and the MRI apparatus described in Patent Document 2 Then, there is a problem that cancer diagnosis of digestive tract is difficult.

  In the PET device described in Patent Document 3, the PET drug is concentrated on cancer tissue in the digestive tract and positron emission occurs, but irregular peristaltic motion causes the PET image to be blurred, and cancer examination and diagnosis There is a problem that it is difficult.

  Although a method of diagnosing digestive tract cancer is performed by visual inspection with an endoscope, there is a problem that it is difficult to detect early digestive cancer by this method.

  Then, in view of the above-mentioned subject, an object of the present invention is to provide the cancer diagnostic device which can diagnose and detect cancer appropriately even if it is an early stage cancer of digestive tract.

  According to one aspect of the present invention, a cancer diagnostic apparatus is inserted into a subject's body, an optical fiber emitting light when positrons are incident, and a light receiving element provided at the tip of the optical fiber for detecting incident light It had it.

  Further, according to another aspect of the present invention, a cancer diagnostic apparatus is disposed around a first linear optical fiber inserted into a subject's body and the first optical fiber and inserted into the subject's body. A second optical fiber spirally arranged clockwise as viewed from the direction, and a third optical fiber spirally arranged counterclockwise as viewed from the direction of insertion into the subject's body. And a light receiving element provided at the tip of each optical fiber.

  Furthermore, it is desirable that the pitch of the second optical fiber and the pitch of the third optical fiber be different.

Furthermore, the trigger threshold of at least one of the first optical fiber, the second optical fiber, and the third optical fiber does not emit light even when electrons generated by Compton scattering of γ-rays are incident, ¹⁸ F, ¹¹ It is desirable to use a trigger threshold that emits light when C, ¹³ N or ¹⁵ O positrons are incident.

  Further, according to another aspect of the present invention, a cancer diagnostic method is provided in an optical fiber inserted into a subject's body and emitting light when positron is incident, and a light receiving element provided at the tip of the optical fiber to detect incident light And a method of using the cancer diagnostic apparatus having

  According to the present invention, it is possible to provide a cancer diagnostic apparatus and a cancer diagnostic method capable of appropriately diagnosing and finding a cancer even in an early stage cancer of digestive system.

FIG. 2 is a view showing the structure of a plastic scintillation fiber of Example 2. FIG. 7 is a view showing the structure of a positron detection unit of Example 2; FIG. 7 is a view showing the intersections of fibers of Example 2; FIG. 7 is a diagram showing the difference in the energy of electrons and positrons of Example 2.

  Hereinafter, examples of the present invention will be described. However, the present invention can be implemented in many different forms, and is not limited to the examples shown below. The cancer diagnostic device in the present specification also includes a cancer inspection device.

  The conventional PET examination method of extracorporeal gamma ray measurement can not eliminate the influence of peristaltic movement of the digestive tract. Therefore, the inventor considered inserting an elongated charged particle measuring instrument such as an endoscope into the digestive organ to directly measure positrons before pair annihilation. By bundling 200 scintillation fibers (a kind of optical fiber) with a diameter of 0.2 mm, electrons and positrons with kinetic energy of 300 keV or more can pass through about 6 layers of fiber. By bonding the light receiving elements to the individual fibers, the incident direction of the positron can be easily measured. The inventor considered that the measurement of the incident position in the longitudinal direction of the fiber was performed by using a wavelength conversion fiber provided with appropriate light shielding at the central portion of the fiber bundle. Although three types of wavelength conversion fibers were used, in the third fiber, the light quantity was 12.5% of the expected value, and the accuracy of measurement of the incident position in the longitudinal direction of the fiber became insufficient. Therefore, an entirely new longitudinal incident position measurement method was considered as described below.

In this example, 1 + 6 + 2 + 18 + 24 + 30 + 36 + 42 = 169 scintillation fibers with a diameter of 0.2 mm and a length of about 2 m are used. No wavelength conversion fiber is used. For diagnosis of the deep part of the small intestine, it may be connected to a transparent fiber which hardly attenuates light. The outermost 42 pieces of fibers, for example, 75mm pitch counterclockwise spiral, 36 pieces of fiber in the second layer from the outside to the right-handed helical 85mm pitch, the remainder are arranged in a straight line. Here, “straight line” does not mean a straight line in a strict sense, and may be bent according to the surrounding shape at the time of use, and includes such a bent state, but a spiral shape Not included. Each of the 108 fibers in the outer three layers is connected to a small light receiving element called PPD (Pixelated Photon Detector) with an effective area of 1 mm × 1 mm, and 61 fibers in the central part are connected to a 64 channel position discrimination type photomultiplier tube Do. In each of the outer three layers, one or more fibers emit light in each layer, and in the central portion, a total of three or more emitted light is recorded. The light emitting fibers of the outer three layers can uniquely determine the incident position of the charged particles in both the angle direction and the length direction.

  The meter is inserted through the mouth, nose or anus during normal whole-body PET examination. Since the effective atomic number of the scintillation fiber is almost the same as that of the living body, this measuring instrument has little effect on whole-body PET examination. The subject does not experience any new exposure from this measurement. The price of this diagnostic device is expected to be as low as 3 million yen or less, and the additional cost is small even if it is diagnosed simultaneously with whole body PET examination. Diagnostic results can be determined in real time.

  At the time of whole-body PET examination, many 511 keV gamma rays are scattered in the body. The ratio of positrons to gamma rays incident on the minute part of this measuring instrument is approximately 1: 200. But if gamma rays only pass, scintillation does not occur. The γ-rays are Compton scattered around the detector to generate electrons, and light is emitted only when the electrons are incident on the present measuring instrument. Therefore, the ratio of luminescence events is approximately 1: 2 for positrons and γ-rays. The maximum kinetic energy of positrons generated from proton-rich nuclei is 341 keV. This energy can only pass the scintillation fiber up to 1 mm. That is, if the fiber requires light emission of 6 or more, most of Compton electrons can be removed and high energy positrons can be measured with high sensitivity.

  According to this embodiment, it is possible to estimate the presence or absence of an early cancer of the digestive system, which has been difficult to detect conventionally, and the position in the case where a cancer is present.

  In this example, a detector using eight layers of scintillation fibers is proposed, which is inserted from the anus and directly detects positrons before pair annihilation.

  FIG. 1 is a view showing the structure of a plastic fiber 1 used in the present embodiment. In this embodiment, a scintillation fiber with a diameter of 0.2 mm is used. The scintillation fiber 1 is coated with an inner coating 12 and an outer coating 13 around the core 11. When the positron 2 enters the core 11, light is generated in the core 11, and the light travels to the end of the fiber while being reflected by the covering materials 12 and 13.

  FIG. 2 is a view showing the structure of a positron detection unit. The total length of the detection unit 3 is about 6 m. The length from the tip of the scintillation fiber is about 1 m, and the length of the clear fiber is about 5 m. The fibers 31 in the first to sixth layers are arranged in a straight line. On the other hand, the seventh layer of fiber 32 is spirally wound at a pitch of 85 mm clockwise as viewed from above in FIG. The eighth layer fiber 33 is spirally wound at a pitch of 75 mm counterclockwise as viewed from above in FIG.

  FIG. 3 is a diagram showing the state of intersection of fibers. In FIG. 3A, two helical fibers are wound at equal pitches. On the contrary, in FIG. 3 (b), two helical fibers are wound at different pitches. In FIG. 3A, a plurality of intersections exist on the same line 41. On the other hand, in FIG. 3 (b), the position of the intersection is shifted little by little with the line 42, the line 43 and the line 44. By adjusting the pitch of the clockwise and counter-clockwise fibers, the three reactive fibers (clockwise, counterclockwise, straight) It is possible to uniquely determine the position of the intersection point of the three fibers that have reacted by the combination. The distance in the z direction (longitudinal direction of the fiber) of the intersection of the two types of helically wound fibers is 80 mm. A reflective film is attached to the end on the human body side of each fiber. Then, an MPPC with an effective area of 1 square mm is connected to the tip on the outer side of each fiber.

  The reason why the pitch of the left-handed fiber is 75 mm and the pitch of the right-handed fiber is 85 mm in this embodiment will be described. With such a pitch, the intersection point of the left-handed fiber and the right-handed fiber at which there is a signal deviates by 22.5 degrees at every 80 mm in the z direction. And it makes a round at 16 intersections. In this embodiment, although the length of the scintillation fiber is about 1 m, the positron incident position is uniquely determined up to 1.28 m. If you want the length of the scintillation fiber to be 2 m, the pitch should be as close as 77 mm and 83 mm. In this example, since the transmission length of the scintillation fiber (the distance at which the intensity of light propagating by total reflection is 1 / e = 36.8%) is approximately 2 m, the measured light quantity is 70% even if the positron strikes the tip of the fiber. The length of the fiber was about 1 m to be a degree.

FIG. 4 is a diagram showing the difference in energy between electrons and positrons. In the present measuring instrument, 511 keV gamma rays can be noise. 511 keV travels 25 cm in the human body. On the other hand, the ¹⁸ F positron travels about 2.4 mm. Since the plastic scintillator has a low average atomic number, it has high sensitivity to positrons. The maximum energy of the electron beam generated by Compton scattering is 341 keV, and the travel distance is 0.9 mm. On the other hand, the maximum energy of ¹⁸ F positrons is 634 keV. Therefore, noise can be reduced by appropriately setting the trigger threshold.

  According to this embodiment, it is possible to estimate the presence or absence of an early cancer of the digestive system, which has been difficult to detect conventionally, and the position in the case where a cancer is present.

  INDUSTRIAL APPLICABILITY The present invention is industrially applicable as a cancer diagnostic apparatus and a cancer diagnostic method.

Reference Signs List 1 scintillation fiber 11 core 12 inner coating material 13 outer coating material 2 positron 3 positron detection unit 31 first to sixth layer fibers 32 seventh layer fiber 33 eighth layer fiber 41, 42, 43, 44 corresponding to intersection point Straight fiber

Claims (2)

A linear first optical fiber inserted into the subject's body,
A second optical fiber, which is disposed around the first optical fiber and spirally disposed clockwise as viewed from the direction of insertion into the body of the subject, and is inserted into the body of the second layer of the subject from the outside ;
A third optical fiber inserted around the first optical fiber and inserted into the body of the outermost subject spirally arranged in a counterclockwise direction as viewed from the insertion direction into the body of the subject ;
And a light receiving element provided at an outer end of each of the optical fibers. The cancer diagnostic apparatus according to claim 1 , wherein a pitch of the second optical fiber and a pitch of the third optical fiber are different.