CN217365892U - Thyroid I-131 activity measuring system based on double-layer detector - Google Patents
Thyroid I-131 activity measuring system based on double-layer detector Download PDFInfo
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- CN217365892U CN217365892U CN202123165151.7U CN202123165151U CN217365892U CN 217365892 U CN217365892 U CN 217365892U CN 202123165151 U CN202123165151 U CN 202123165151U CN 217365892 U CN217365892 U CN 217365892U
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Abstract
The utility model provides a thyroid gland I-131 activity measurement system based on double-deck detector for I-131 activity in to human thyroid gland is measured, include: the double-layer detector is used for receiving gamma rays emitted to the outside of a body by the I-131 and converting the gamma rays into optical signals and is provided with a front-end CsI (TI) crystal and a rear-end CsI (TI) crystal which are attached to each other front and back; the nuclear electronic equipment is matched with the double-layer detector for use and is used for converting the optical signal into an electric signal; the annular bridle is fixedly attached to the neck of a human body, and a double-layer detector and nuclear electronics equipment are arranged in the annular bridle; the spectrum analysis module is used for analyzing according to the electric signal to obtain an energy spectrum of the gamma ray; the detection efficiency calibration module is used for calibrating the detection efficiency of the double-layer detector and comprises an OTT calibration unit and a detection efficiency calibration unit; and the energy spectrum analysis module is used for analyzing the energy spectrum of the gamma rays received by the graduated double-layer detector to obtain the activity of I-131.
Description
Technical Field
The utility model belongs to the field of radiation is diagnose, concretely relates to thyroid gland I-131 activity measurement system based on double-deck detector.
Background
The development of clinical nuclear medicine in China is very rapid, the radioactive isotope plays an indispensable important role in medical diagnosis and treatment, and the use frequency and the use amount of nuclide are continuously increased. The risk of exposure to internal radiation for nuclear medicine patients and staff is not negligible compared to other radiation-related medical applications. In addition, in recent years, the concept of precise medicine is widely accepted and popularized all over the world, the importance of modern personalized radiological diagnosis and treatment technology is increasingly prominent, and the precise and personalized requirements are provided for the benefit-oriented and hazard-avoiding radiation protection.
In addition, China is in a strategic transformation period from a nuclear power kingdom to a nuclear power strong country, and radiation emergency management and disposal under the nuclear accident situation relate to national safety and have strategic significance of nourishing arms for thousands of days and using arms for one time. In great contrast to the pressing strategic demands, however, I-131 is relatively lacking in its measurement and dose evaluation related studies as one of the most commonly used medical radionuclides in nuclear medicine, as well as the major nuclides in the gaseous effluents of nuclear accidents. In particular, the accuracy of thyroid I-131 activity measurement, the individuation of internal irradiation dose evaluation and the field adaptability of a detection means are important technical problems to be solved urgently.
Since the last 80 s, researchers have conducted research work related to the measurement of I-131 activity in the thyroid and evaluation of internal radiation dose. The currently used I-131 activity measuring methods comprise three major types, namely in-vitro direct measurement, biological sample analysis and air sampling analysis. Wherein, the biological sample analysis utilizes the urine, the excrement and other excretion waste sampling analysis of the testee to trace the activity of the nuclide and the internal irradiation dose in the body. And the air sampling analysis method evaluates the internal irradiation dose based on the environment source item and the biodynamics model. In practice, in view of the convenience of operation and the measurement accuracy, the monitoring of the activity of I-131 in thyroid gland is a preferred in vitro direct measurement method and is the most popular monitoring means.
The in vitro quantitative measurement of I-131 activity is classified into the following categories:
and (I) large scanning equipment such as an ECT (emission computed tomography), a gamma camera, a whole body counter and the like is adopted, and measurement is carried out by combining a calibration source and related efficiency correction. The method has the following disadvantages that 1. the measurement precision is higher, but the precious equipment time and the precious equipment time are occupied, the culture period of operators is long, and the starting and the instrument cost are high; 2. for large-scale measuring equipment represented by a whole-body counter, a high atomic number shielding layer and a low background measuring environment enable the large-scale measuring equipment to have higher sensitivity and nuclide resolution capability, however, the strong shielding capability also means that the high measuring load can enable the system to face the risk of radioactive pollution; 3. due to high cost and small quantity of instruments, the method is not suitable for large-batch population screening work and is only suitable for scientific research of individual cases.
And (II) directly measuring gamma rays emitted from I-131 to the outside of the body by adopting a portable gamma spectrometer, which is the most common technical scheme used in the current practice, and a thyroid I-131 measuring instrument based on NaI (Tl) scintillator, the portable gamma spectrometer and the like belong to the measuring methods. Such methods have limited measurement accuracy.
And (III) the research is carried out by adopting films and an Image Plate (IP) system, and most of the work is experimental attempts. The disadvantages of such methods are as follows: 1. based on one-time complete measurement of an IP system, four steps of erasing, exposing, transporting and reading are needed, the measurement process is complex, and the consumed time is long; and 2, reading of the IP system needs to be carried out in a professional laboratory, and field reading of data cannot be realized. In the transportation process of the data, the image plate can read redundant background noise information under the influence of factors such as fading effect, temperature, background noise and the like. In a longer data reading time, the local crystal can emit part of radiation in advance, so that radioactive information is lost; 3. the rear-end analysis instrument is expensive; 4, the IP system is difficult to carry out simulation calculation by a Monte Carlo simulation mode, is limited by the type of a phantom used for experiments, and is deficient in related research; 5. the film is not sensitive to the small-dose irradiation effect, and the application scene is limited.
In general, the three methods are influenced by the equivalence of a die body and a human body in the quantity value tracing, and different short measurement plates with poor adaptability to human body structure difference exist, so that the three methods can only be used as a qualitative or semi-quantitative measurement means in practice. The concrete aspects are as follows:
common error-influencing factors are: the measurement accuracy of any activity evaluation tool is influenced by factors such as environmental background radiation, nuclear electronics noise, measurement condition variation, gamma spectrum analysis algorithm and the like, and the anti-interference energy is inconsistent due to the working characteristics of the measurement tool.
(II) the measurement can not be personalized: the thyroid gland is caused by the anatomical difference between individuals, the distortion of scale model bodies, the geometric deviation of a measuring system and the like 131 I major factor in activity measurement error. These factors are caused by anatomical differences including thyroid to ventral Thickness of the Neck Tissue (OTT), thyroid volume, shape of the thyroid, etc., and systematic geometric differences including Neck Detector Distance (NDD), Detector angular offset, Detector position offset, etc., and the original parameters of these efficiency scales are often difficult to reproduce completely in actual measurements.
SUMMERY OF THE UTILITY MODEL
The utility model relates to a solve above-mentioned problem and go on, aim at provides a thyroid gland I-131 activity measurement system based on double-deck detector.
The utility model provides a thyroid gland I-131 activity measurement system based on double-deck detector for I-131 activity in to human thyroid gland is measured, has such characteristic, include: the double-layer detector is used for receiving gamma rays emitted to the outside of a body by I-131 and converting the gamma rays into optical signals and is provided with a front-end CsI (TI) crystal and a rear-end CsI (TI) crystal which are attached to each other in a front-back mode; the nuclear electronics equipment is matched with the double-layer detector for use and is used for converting the optical signal into an electric signal; the annular bridle is fixedly attached to the neck of a human body, and a double-layer detector and nuclear electronics equipment are arranged in the annular bridle; the spectrum analysis module is used for analyzing according to the electric signal to obtain an energy spectrum of the gamma ray; the detection efficiency calibration module is used for calibrating the detection efficiency of the double-layer detector and reducing the measurement error caused by the difference of the thickness of the covering tissue from the thyroid to the ventral side of the neck, and comprises an OTT calibration unit for calculating the thickness of the covering tissue and a detection efficiency calibration unit for calculating the detection efficiency; and the energy spectrum analysis module is used for analyzing the energy spectrum of the gamma rays received by the graduated double-layer detector to obtain the activity of I-131.
The utility model provides an among the thyroid gland I-131 activity measurement system based on double-deck detector, can also have such characteristic: wherein, the thickness of the front CsI (TI) crystal is 6 mm-10 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm, the thickness of the back CsI (TI) crystal is 15 mm-25 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm, and the surface area ratio distribution of the front CsI (TI) crystal and the back CsI (TI) crystal is 0.5-2.
The utility model provides an among the thyroid gland I-131 activity measurement system based on double-deck detector, can also have such characteristic: the double-layer detector is a detection structure formed by front and back bonding of a front-end CsI (TI) crystal and a rear-end CsI (TI) crystal, and the front and back bonding distance is 1-5 mm.
The utility model provides an among the thyroid gland I-131 activity measurement system based on double-deck detector, can also have such characteristic: wherein, the girth of cyclic annular band can carry out adaptability according to human neck circumference and adjust.
Action and effect of the utility model
According to the thyroid I-131 activity measuring system based on the double-layer detector, on the premise of fully ensuring the detection efficiency, the square double-layer detector with the volume close to that of a 2-inch conventional detector is used, and is not required to be matched with calibration and fixing equipment such as a jack and the like for use, so that the thyroid I-131 activity measuring system is light and portable; and the close-contact type measuring structure realized by the annular bridle can eliminate the error influence caused by the distance between the neck and the surface of the detector. Therefore, the utility model discloses a thyroid gland I-131 activity measurement system based on double-deck detector has adopted the measurement structure of pressing close to the formula and has the double-deck csi (ti) crystal structure of higher quantum efficiency, so detection efficiency is higher, and measuring time is shorter, can satisfy the demand of carrying out quick screening, batch measurement in the short time to lower detection lower limit has.
Drawings
Fig. 1 is a system block diagram of a thyroid I-131 activity measuring system based on a double-layer detector according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a thyroid I-131 activity measuring system based on a double-layer detector according to an embodiment of the present invention;
fig. 3 is a schematic workflow diagram of a thyroid I-131 activity measuring system based on a double-layer detector in an embodiment of the present invention.
Detailed Description
In order to make the technical means and functions of the present invention easy to understand, the present invention will be described in detail with reference to the following embodiments and accompanying drawings.
< example >
Fig. 1 is a system block diagram of a thyroid I-131 activity measuring system based on a double-layer detector according to an embodiment of the present invention.
As shown in fig. 1, a thyroid I-131 activity measuring system 100 based on a double-layer detector according to the present embodiment is used for measuring I-131 activity in a human thyroid, and includes a double-layer detector 10, a nuclear electronics device 20, an annular band 30, a spectrum analysis module 40, a detection efficiency calibration module 50, and an energy spectrum analysis module 60.
Fig. 2 is a schematic structural diagram of a thyroid I-131 activity measuring system based on a double-layer detector in an embodiment of the present invention.
As shown in fig. 2, the double-layer detector 10 is used for receiving gamma rays emitted from the I-131 to the outside of the body and converting the gamma rays into optical signals, and has a front csi (ti) crystal 11 and a rear csi (ti) crystal 12 which are attached to each other in front and rear.
The double-layer detector is a detection structure formed by front and back bonding of a front-end CsI (TI) crystal 11 and a back-end CsI (TI) crystal 12, and the front-back bonding distance is 1 mm-5 mm.
The front CsI (TI) crystal 11 is closer to the surface of the human neck, the back Cs (TI) crystal 12 is farther from the surface of the human neck,
the thickness of the front CsI (TI) crystal 11 is 6 mm-10 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm,
the thickness of the rear CsI (TI) crystal 12 is 15 mm-25 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm,
the surface area ratio distribution of the front Cs (TI) crystal 11 and the rear Cs (TI) crystal 12 is 0.5-2.
In this embodiment, the size of the front csi (ti) crystals 11 is 37mm × 8mm × 37mm, and the size of the rear csi (ti) crystals 12 is 37mm × 20mm × 36 mm.
In this embodiment, the material used for the double-layer detector 10 may also be nai (ti) crystal.
The nuclear electronics device 20 is used in conjunction with the double layer detector 10 for converting optical signals into electrical signals.
The annular belt 30 is used for being fixedly attached to the neck of a human body, and the double-layer detector 10 and the nuclear electronics device 20 are arranged inside the annular belt.
The circumference of the ring-shaped belt 30 can be adjusted adaptively according to the neck circumference of the human body.
The spectrum analysis module 40 is used for analyzing according to the electrical signal to obtain an energy spectrum of the gamma ray.
In this embodiment, the spectrum analysis module 40 is gamma aant.
The detection efficiency calibration module 50 is used for calibrating the detection efficiency of the double-layer detector 10, and reducing the measurement error caused by the difference of the thickness of the covering tissue from the thyroid to the ventral surface of the neck, and comprises an OTT calibration unit for calculating the thickness of the covering tissue and a detection efficiency calibration unit for calculating the detection efficiency.
And the OTT scale unit establishes a relation function between the correction factor and the thickness of the covering tissue by changing the thickness of the covering tissue of the thyroid-neck phantom according to the energy spectrum.
The correction factor is based on the double-layer crystal structure of the double-layer detector 10 and is obtained by the counting ratio of the front-end CsI (TI) crystal 11 and the rear-end CsI (TI) crystal 12 at the full energy peak of 365 keV.
The detection efficiency calibration unit establishes a relation function between the thickness of the covering tissue and the detection efficiency by changing the thickness of the covering tissue of the thyroid-neck mold body according to the energy spectrum,
the detection efficiency calibration module 50 obtains a correction factor through measurement of the double-layer detector 10, the correction factor is used for being brought into the OTT calibration unit to obtain a relation function between the correction factor and the thickness of the covering tissue, a numerical value of the thickness of the covering tissue is obtained through calculation, the numerical value of the thickness of the covering tissue is brought into the relation function between the thickness of the covering tissue and the detection efficiency obtained by the detection efficiency calibration unit to obtain the detection efficiency, the energy spectrum analysis module 60 analyzes an energy spectrum of gamma rays received by the double-layer detector 10 after being calibrated through the detection efficiency, and an accurate measurement value of the activity of the thyroid gland I-131 is obtained through calculation.
Fig. 3 is a schematic workflow diagram of a thyroid I-131 activity measuring system based on a double-layer detector in an embodiment of the present invention.
As shown in fig. 3, the workflow of the thyroid I-131 activity measuring system 100 based on the double-layer detector of the present embodiment includes the following steps:
step 1, a double-layer detector 10 and nuclear electronics equipment 20 are fixedly attached to the neck of a tester through an annular belt 30, the double-layer detector 10 receives gamma rays emitted to the outside of a body from an I-131 and converts the gamma rays into optical signals, the optical signals are converted into electric signals through the nuclear electronics equipment 20, and a spectrum analysis module 40 analyzes the electric signals to obtain an energy spectrum of the gamma rays;
step 2, the OTT calibration unit changes the thickness of the covering tissue of the thyroid-neck phantom according to the energy spectrum, establishes a relation function between a correction factor (the count ratio of a front-end CsI (TI) crystal 11 and a rear-end CsI (TI) crystal 12 at a full energy peak of 365 keV) and the thickness of the covering tissue, and the detection efficiency calibration unit establishes a relation function between the thickness of the covering tissue and the detection efficiency by changing the thickness of the covering tissue of the thyroid-neck phantom according to the energy spectrum and calculates to obtain the detection efficiency;
and step 3, after the detection efficiency calibration of the double-layer detector 10 is completed, measuring, and analyzing by the energy spectrum analysis module 60 according to the energy spectrum of the gamma ray received by the double-layer detector 10 to obtain the activity of I-131.
Effects and effects of the embodiments
According to the thyroid I-131 activity measuring system based on the double-layer detector, on the premise that the detection efficiency is fully guaranteed, the square double-layer detector with the volume close to that of a 2-inch conventional detector is used, and the system is not required to be matched with calibration and fixing equipment such as a jack and the like, so that the system is light and portable; the close-contact type measuring structure realized by the annular bridle can eliminate the error influence caused by the distance between the neck and the surface of the detector; in addition, in the embodiment, the functional relationship between the ratio of the front and rear CsI (TI) crystals at the 365keV photoelectric peak and the thickness of the covering tissue and the functional relationship between the thickness of the covering tissue and the detection efficiency are obtained, so that the thickness of the covering tissue of the measured person is estimated in a personalized manner, the efficiency is corrected, and the accurate measurement is realized; in addition, the double-layer detector algorithm used in the embodiment reduces the requirement of the instrument on radiation shielding of the environmental background due to the use of the characteristic peak convenient for identifying and analyzing 365keV, so that the low-activity I-131 can be evaluated. Therefore, the thyroid I-131 activity measuring system based on the double-layer detector of the embodiment adopts the proximate measurement structure and the double-layer csi (ti) crystal structure with higher quantum efficiency, so that the detection efficiency is higher, the measurement time is shorter, the requirements of rapid screening and batch measurement in a short time can be met, and the detection lower limit is lower.
The above embodiments are preferred embodiments of the present invention, and are not intended to limit the scope of the present invention.
Claims (4)
1. A thyroid I-131 activity measuring system based on a double-layer detector is used for measuring I-131 activity in a human thyroid, and is characterized by comprising:
the double-layer detector is used for receiving gamma rays emitted to the outside of a body by I-131 and converting the gamma rays into optical signals and is provided with a front-end CsI (TI) crystal and a rear-end CsI (TI) crystal which are attached to each other in a front-back mode;
the nuclear electronics equipment is matched with the double-layer detector for use and is used for converting the optical signal into an electric signal;
the annular bridle is fixedly attached to the neck of a human body, and the double-layer detector and the nuclear electronics equipment are arranged in the annular bridle;
the spectrum analysis module is used for analyzing according to the electric signal to obtain an energy spectrum of the gamma ray;
the detection efficiency calibration module is used for calibrating the detection efficiency of the double-layer detector and reducing the measurement error caused by the thickness difference of the covering tissue from the thyroid gland to the ventral side of the neck, and comprises an OTT calibration unit used for calculating the thickness of the covering tissue and a detection efficiency calibration unit used for calculating the detection efficiency;
and the energy spectrum analysis module is used for analyzing the energy spectrum of the gamma rays received by the double-layer detector after calibration to obtain the activity of the I-131.
2. The dual-layer probe-based thyroid I-131 activity measuring system according to claim 1, wherein:
wherein the thickness of the front CsI (TI) crystal is 6 mm-10 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm,
the thickness of the rear CsI (TI) crystal is 15 mm-25 mm, the length is 30 mm-45 mm, the height is 30 mm-45 mm,
the surface area ratio distribution of the front-end CsI (TI) crystal and the rear-end CsI (TI) crystal is 0.5-2.
3. The dual-layer probe-based thyroid I-131 activity measuring system according to claim 1, wherein:
the double-layer detector is a detection structure formed by front and back bonding of the front-end CsI (TI) crystal and the rear-end CsI (TI) crystal, and the front and back bonding distance is 1 mm-5 mm.
4. The dual-layer probe-based thyroid I-131 activity measuring system according to claim 1, wherein:
wherein, the girth of cyclic annular band can carry out the adaptability according to human neck circumference and adjust.
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