Method for detecting activity and position of residual radionuclide in human body

Abstract

The invention discloses a method for detecting the activity and position of residual radionuclides in a human body, and the method comprises the steps: obtaining a radioactive detector, calibrating the radioactive detector in the air, and obtaining the detection efficiency and cps value of the radioactive detector; determining the ray energy and type of a radioactive source in the human body to be detected, and calculating to obtain a human body attenuation factor of the human tissue; and the residual radionuclide activity is calculated according to a corresponding formula. The human body residual radioactive activity and the position of the human body can be accurately measured, it is guaranteed that the residual activity of a patient meets the national standard when the patient is discharged from a hospital, and radiation safety of the public around the patient is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of radioactive detection technology, and in particular to a method for detecting the activity and position of residual radioactive nuclides in a human body. Background Art

[0002] During radiation therapy, patients receiving medical radioisotopes, such as radioiodine ( 131 I) Patients who are being treated for thyroid disease do need to be assessed for dose rates before they are discharged to determine if they have reached a safe level in order to protect the public from unnecessary radiation exposure. This process is often referred to as "discharge criteria" or "discharge permission" and is set in accordance with national and international radiation protection guidelines. Dose rate meters are generally used to measure the dose rate on the surface of the patient's body, but this method does not accurately measure the residual radioactivity in the human body, and may result in discharge in excess of national standards. Therefore, how to develop a more accurate method to measure the residual radioactivity in the patient's body requires further consideration. Summary of the invention

[0003] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: how to provide a method for detecting the activity and position of residual radionuclides in the human body that can accurately measure the residual radioactive activity in the human body and ensure the radiation safety of the public around the patient.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for detecting the activity and position of residual radioactive nuclides in a human body comprises the following steps: obtaining a radioactive detector, calibrating the radioactive detector in air, obtaining the detection efficiency ε and the cps value of the radioactive detector; determining the radiation energy and type of the radioactive source in the human body to be detected, and calculating the human attenuation factor ζ of the human tissue; and then calculating the residual radioactive nuclide activity according to the formula = radioactive detector cps / (ε×ζ).

[0005] The gamma rays emitted by radionuclides in the human body are detected by detectors, and the activity in the human body is calculated by counting the detectors. First, the detector is calibrated in air to obtain the detection efficiency of the detector; then, considering the attenuation of the human body, a more accurate radioactive activity in the human body can be obtained.

[0006] As an optimization, the BMI index of people with standard physique is set, and the BMI index of the person to be tested is obtained, and the BMI factor of the person to be tested η = BMI index of people with standard physique / BMI index of people to be tested is obtained, and then the residual radionuclide activity of people with different physiques is calculated according to the formula = radioactive detector cps / (ε×ζ×η).

[0007] People of different heights, weights, and physiques will affect the accuracy of detection, so the BMI index of people with standard physique is set as a measurement standard to further improve the accuracy of residual radioactive activity detection.

[0008] As an optimization, when calibrating the radioactive detector, the radioactive source is placed at a fixed position in front of the radioactive detector, and the cps value of the radioactive detector is measured. The detection efficiency ε of the radioactive detector = detector cps value / number of decays of the radioactive source per second.

[0009] As an optimization, the radioactive detector includes a GM counter tube and its signal readout circuit I and a scintillation counter and its signal readout circuit II. The use of the scintillation counter and the GM counter tube can respectively measure low and high end activities.

[0010] As an optimization, a radioactive source with a power less than 20 mCi is used to calibrate the scintillation counter, and a radioactive source with a power greater than 50 mCi is used to calibrate the GM counter tube.

[0011] As an optimization, the radioactive detector also includes a box body made of radiation source shielding material, and a plurality of collimators are arranged in a horizontal linear array on the front side of the box body to connect the inside and outside of the box body, and SiPM type scintillator detection units are installed in the box body and at the rear end of each collimator. The collimator can limit the position where radioactive rays enter, so a plurality of SiPM type scintillator detection units form a detector array to scan the patient's whole body, and the position of residual radionuclides can be accurately obtained through the radioactivity of each SiPM type scintillator detection unit.

[0012] As an optimization, when calculating the human body attenuation factor ζ of human tissue, the entire human body is segmented, and the Monte Carlo method is used to simulate the attenuation percentage of the human body to the radiation source at different segmented positions. The human body attenuation factor ζ = 1-the attenuation percentage of the human body segmented position. For different positions of human body detection, the corresponding human body attenuation factor ζ is used. The density and thickness of the human tissue that the radiation passes through are different, and the attenuation degree of the radiation intensity is also different. Therefore, segmenting the human body can obtain more accurate detection results. The final human body activity is equal to the sum of the activities of all segmented scanning positions.

[0013] Compared with the prior art, the present invention has the following beneficial effects: the present invention can more accurately measure the residual radioactive activity of the human body and its location in the human body, ensure that the residual activity meets the national standards when the patient is discharged from the hospital, and protect the radiation safety of the public around the patient. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the appearance structure of the radioactive detector in the present invention. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0016] like Figure 1 As shown, the method for detecting the activity and position of residual radioactive nuclides in the human body in this specific embodiment is to obtain a radioactive detector, calibrate the radioactive detector in the air, obtain the detection efficiency ε and cps value of the radioactive detector; determine the radiation energy and type of the radiation source in the human body to be detected, and calculate the human attenuation factor ζ of the human tissue; and then calculate the residual radioactive nuclide activity according to the formula = radioactive detector cps / (ε×ζ).

[0017] In this specific implementation, the BMI index of a person with a standard physique is set, the BMI index of the person to be tested is obtained, and the BMI factor of the person to be tested η = BMI index of a person with a standard physique / BMI index of the person to be tested is obtained, and then the residual radionuclide activity of people with different physiques is calculated according to the formula = radioactive detector cps / (ε×ζ×η).

[0018] In this specific implementation, when calibrating the radioactive detector, the radioactive source is placed at a fixed position in front of the radioactive detector, and the cps value of the radioactive detector is measured. The detection efficiency ε of the radioactive detector = detector cps value / number of decays of the radioactive source per second.

[0019] In this specific implementation, the radioactive detector includes a GM counter tube and its signal readout circuit I and a scintillation counter and its signal readout circuit II, wherein the GM counter tube and its signal readout circuit I are installed in a box body I1, and the scintillation counter and its signal readout circuit II are installed in a box body II2; a radioactive source less than 20mCi is used to calibrate the scintillation counter, and a radioactive source greater than 50mCi is used to calibrate the GM counter tube. In this specific implementation, the scintillation counter uses a plastic scintillator, and 1mCi of 131I was placed 40cm in front of the radioactive detector, and the cps value of the plastic scintillator was measured. The radiation source and the radioactive detector were moved up and down while keeping the distance constant. The detection efficiency was measured at different heights to determine whether the detection efficiency of the radioactive detector was consistent. In addition, the same method was used to use a 100mCi 131 I Calibrate the GM counter tube.

[0020] In this specific embodiment, the radioactive detector also includes a box body III3 made of radiation source shielding material, box body I1 and box body II2 are fixedly connected to box body III3, and a plurality of collimators 4 are arranged in a horizontal linear array on the front side of box body III3 to connect the inside and outside of box body III3, and SiPM type scintillator detection units are respectively installed in the box body III3 and at the rear end of each collimator 4.

[0021] In this specific implementation, when calculating the human body attenuation factor ζ of human tissue, the entire human body is segmented, and the Monte Carlo method is used to simulate the attenuation percentage of the human body to the radiation source at different segmented positions. The human body attenuation factor ζ = 1-the attenuation percentage of the human body segmented position. For different positions of the human body detection, the corresponding human body attenuation factor ζ is used.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for detecting the activity and location of residual radionuclides in the human body, characterized in that: Obtain a radioactive detector, calibrate the radioactive detector in the air, and obtain the detection efficiency ε and cps value of the radioactive detector; Determine the radiation energy and type of the radiation source in the human body to be detected, calculate the human attenuation factor ζ of the human tissue; then calculate the residual radionuclide activity according to the formula = radioactive detector cps / (ε×ζ).

2. The method for detecting the activity and location of residual radionuclides in the human body according to claim 1, characterized in that: Set the BMI index of a person with a standard physique, obtain the BMI index of the person to be tested, and obtain the BMI factor of the person to be tested η = BMI index of a person with a standard physique / BMI index of the person to be tested, and then calculate the residual radionuclide activity of people with different physiques according to the formula = radioactive detector cps / (ε×ζ×η).

3. The method for detecting the activity and location of residual radionuclides in the human body according to claim 1, characterized in that: When calibrating the radioactive detector, a radioactive source is placed at a fixed position in front of the radioactive detector, and the cps value of the radioactive detector is measured. The detection efficiency ε of the radioactive detector is equal to the cps value of the detector / the number of decays of the radioactive source per second.

4. The method for detecting the activity and location of residual radionuclides in the human body according to claim 3, characterized in that: The radioactive detector comprises a GM counter tube and its signal readout circuit I and a scintillation counter and its signal readout circuit II.

5. The method for detecting the activity and location of residual radionuclides in the human body according to claim 4, characterized in that: The scintillation counter is calibrated by using a radioactive source of less than 20 mCi, and the GM counter tube is calibrated by using a radioactive source of more than 50 mCi.

6. The method for detecting the activity and location of residual radionuclides in the human body according to claim 3, characterized in that: The radioactive detector also includes a box body made of radiation source shielding material, and a plurality of collimators are arranged in a horizontal linear array on the front side of the box body to connect the inside and outside of the box body, and SiPM type scintillator detection units are installed in the box body and at the rear end of each collimator.

7. The method for detecting the activity and location of residual radionuclides in the human body according to claim 1, characterized in that: When calculating the human attenuation factor ζ of human tissue, the entire human body is segmented, and the Monte Carlo method is used to simulate the attenuation percentage of the human body to the radiation source at different segment positions. The human body attenuation factor ζ = 1-the attenuation percentage of the human body segment position. For different positions of human body detection, the corresponding human body attenuation factor ζ is used.

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