F-18 radiation monitor based on standard f-18 film source

Abstract

The present application relates to a kind of F-18 radiation monitor verification method based on standard F-18 film source, comprising: using medical F-18 deoxyglucose solution to prepare standard F-18 film source;With standard F-18 film source, F-18 radiation monitor is carried out overload detection, if the average value deviation of the coincidence multichannel F-18 region of interest count of F-18 radiation monitor before and after overload is greater than overload threshold, then F-18 radiation monitor verification ends, otherwise, using standard F-18 film source, F-18 radiation monitor is carried out coefficient of variation detection;If the coefficient of variation is greater than variation threshold, then F-18 radiation monitor verification ends, otherwise, using standard F-18 film source, F-18 radiation monitor is carried out relative inherent error detection;If the relative inherent error is greater than relative inherent error threshold, then F-18 radiation monitor verification ends, otherwise, using standard F-18 film sources, F-18 radiation monitor is carried out repeatability detection.The method fills the F-18 radiation monitor verification technology blank, and F-18 radiation monitor can be effectively verified whether measurement is accurate or qualified.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation measurement technology, and in particular to a calibration method for an F-18 radiation monitor based on a standard F-18 thin-film source. Background Technology

[0002] Leaks in the reactor coolant pressure boundary (RCPB) of a pressurized water reactor nuclear power plant can threaten the safe operation of the plant. RCPB leak monitoring involves measuring F-18 aerosol in the atmosphere within the containment vessel; the measurement results reflect the integrity of the RCPB and the magnitude of the coolant leakage rate.

[0003] In existing technology, F-18 aerosol measurements within the containment atmosphere are performed using an F-18 radiation monitor. The F-18 radiation monitor consists of an F-18 detector, a 4π lead shield, a local radiation processing unit (LRP), sampling tubing, a sampling pump, an electrical control box, and an integrated support frame. The F-18 detector is located inside the 4π lead shield. The F-18 detector mainly comprises a main detector, a coincidence detector, signal processing circuitry, a full-spectrum multichannel, a coincidence multichannel, a paper feed mechanism, and filter paper. The circuit connections of the F-18 detector, signal processing circuitry, and local radiation processing unit are as follows: Figure 1 As shown. The positional relationship between the main detector, symbol detector, and filter paper of the F-18 detector is as follows. Figure 2 As shown, filter paper is used to collect F-18 aerosol in the sampled gas. Two opposing NaI(Tl) detectors are used to measure and identify gamma photons released during the decay of the F-18 nuclide.

[0004] When in operation, the F-18 radiation monitoring system uses a main detector to detect upward-directed 511 keV gamma rays generated by F-18 aerosols, and a coincidence detector to detect 511 keV gamma rays generated in the opposite direction. The main detector signal is amplified and then sent to a coincidence digital multichannel for acquisition. The coincidence detector signal undergoes discrimination, shaping, and delay processes before being sent to the coincidence digital multichannel as a coincidence gate signal. Under the control of the gate signal, the coincidence digital multichannel records and analyzes the 511 keV annihilation gamma ray signal generated by F-18 aerosols in the sample. Finally, through transport modeling and analysis, the specific radioactivity concentration of F-18 within the containment is calculated, thus determining whether a leak has occurred at the reactor's primary circuit pressure boundary.

[0005] The F-18 radiation monitor is a highly suitable metrological device for determining the leakage rate of an RCPB (Recovery Room Power Plant). The accuracy of the metrological device is crucial; substandard equipment will result in inaccurate measurement results. Therefore, effective methods are needed to calibrate the F-18 radiation monitor to ensure it is a qualified product before use. However, current technology lacks methods for calibrating the F-18 radiation monitor. Summary of the Invention

[0006] Therefore, it is necessary to provide a calibration method for F-18 radiation monitors based on a standard F-18 thin-film source to address the aforementioned technical problems. This method fills the technical gap in F-18 radiation monitor calibration and can effectively verify whether the F-18 radiation monitor is accurate or qualified.

[0007] This invention provides a method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source, comprising:

[0008] A standard F-18 thin-film source was prepared using a medical-grade F-18 deoxyglucose solution;

[0009] The F-18 radiation monitor is overloaded using the standard F-18 thin film source. If the deviation of the average value of the multichannel F-18 region of interest counts of the F-18 radiation monitor after overload from the value before overload is greater than the overload threshold, the calibration of the F-18 radiation monitor is completed. Otherwise, the F-18 radiation monitor is tested for coefficient of variation using the standard F-18 thin film source.

[0010] If the coefficient of variation is greater than the variation threshold, the calibration of the F-18 radiation monitor is completed; otherwise, the F-18 radiation monitor is subjected to relative inherent error detection using the standard F-18 thin film source.

[0011] If the relative inherent error is greater than the relative inherent error threshold, the calibration of the F-18 radiation monitor is completed; otherwise, the F-18 radiation monitor is subjected to repeatability testing using the standard F-18 thin-film source.

[0012] In one embodiment, the preparation of a standard F-18 thin-film source using a medical F-18 deoxyglucose solution includes:

[0013] The medical F-18 deoxyglucose solution was placed in a high-precision activity meter;

[0014] When the reading of the high-precision activity meter is less than 10 6 At Bq, take 1 ml to 4 ml of the F-18 deoxyglucose solution from the high-precision activity meter and drop it onto the center of GF / D filter paper;

[0015] A GF / D filter paper containing an F-18 deoxyglucose solution was encapsulated to obtain a standard F-18 film source. The standard F-18 film source was then placed into a high-precision activity meter for static measurement. The displayed activity of the high-precision activity meter and the time when the standard F-18 film source was placed into the high-precision activity meter were recorded.

[0016] In one embodiment, overload detection of the F-18 radiation monitor using the standard F-18 thin-film source includes:

[0017] Obtain the coincident multichannel F-18 region of interest counts from 10 to 30 F-18 radiation monitors without radioactive sources;

[0018] Calculate the average value X of the F-18 radiation monitors that match the multichannel F-18 region of interest counts under all non-radioactive conditions;

[0019] Obtain the same number of coincident multichannel F-18 region of interest counts as the F-18 radiation monitor without a radioactive source, using a standard F-18 thin-film source as the radiation source;

[0020] Calculate the average value Y of all regions of interest that conform to the multichannel F-18 radiation source using the standard F-18 thin-film source;

[0021] Calculate the deviation between the average value X and the average value Y.

[0022] In one embodiment, using the standard F-18 thin-film source to perform coefficient of variation detection on an F-18 radiation monitor includes:

[0023] Wait for the standard F-18 thin-film source to decay, until the reading of the F-18 radiation monitor is on the order of 10. 3 ~10 5 During CPS, acquire 10-30 region of interest counts that match the multichannel F-18 region of interest count;

[0024] Calculate the average value Z of 10–30 regions of interest that conform to the multichannel F-18 region of interest count;

[0025] Calculate the coefficient of variation V of the F-18 radiation monitor;

[0026]

[0027] In the formula, n is the total number of regions of interest that conform to the multichannel F-18 count; N i Let i be the i-th region of interest that matches the multichannel F-18 count; Z represents the average value.

[0028] In one embodiment, the relative inherent error detection of the F-18 radiation monitor using the standard F-18 thin-film source includes:

[0029] The readings on the F-18 radiation monitor were on the order of 10. 5 cps, 10 4 cps or 10 3 In CPS, one test point is selected for each order of magnitude, and for each test point, 5 to 15 regions of interest that conform to the multichannel F-18 region of interest are selected as a set of data.

[0030] Calculate the average of the multichannel F-18 region of interest counts for each group of readings;

[0031] Calculate the relative error I of the indicated value at each test point;

[0032]

[0033] In the formula, A is the conventional true value of the activity of the standard F-18 thin film source at the current measurement moment, in Bq. t The activity concentration of the standard F-18 thin film source at time t is expressed in Bq.

[0034] Calculate the relative inherent error E of the F-18 radiation monitor;

[0035]

[0036] In the formula, I MAX This represents the maximum value of the relative error I in the F-18 radiation monitor's indication; I MIN This is the minimum value of the relative error I in the indicated value of the F-18 radiation monitor.

[0037] In one embodiment, repeatability testing of the F-18 radiation monitor using the standard F-18 thin-film source includes:

[0038] Obtain 5 to 15 regions of interest that match the multichannel F-18 region of interest count;

[0039] Repeat the process of turning off the F-18 radiation monitor for 8 to 12 minutes and then turning it back on, acquiring 5 to 15 regions of interest (ROIs) that match the multichannel F-18 region of interest count three to five times.

[0040] The repeatability M of the F-18 radiation monitor is calculated based on all acquired regions of interest (ROIs) that conform to the multichannel F-18 count.

[0041]

[0042] In the formula, p represents the number of repetitions; Q pThe average value of the multichannel F-18 region of interest count measurement for the qth repetition; It is the average of all measurements that conform to the multichannel F-18 region of interest count.

[0043] In one embodiment, the method further includes: if the deviation of the average value of the multichannel F-18 region of interest counts of the F-18 radiation monitor after overload and before overload is less than or equal to the overload threshold, then the F-18 radiation monitor is tested for detection efficiency using the standard F-18 thin film source, and after the detection efficiency test is completed, the F-18 radiation monitor is tested for coefficient of variation using the standard F-18 thin film source.

[0044] In one embodiment, detecting the detection efficiency of an F-18 radiation monitor using the standard F-18 thin-film source includes:

[0045] When the F-18 radiation monitor readings dropped to the order of 10 5 During CPS, obtain the counts of all regions of interest that match the multichannel F-18 region of interest within 30h to 40h;

[0046] The sensitivity of the F-18 radiation monitor at different levels is calculated based on the count of all regions of interest that match the multichannel F-18 within the 30h to 40h period. The sensitivity of the F-18 radiation monitor at different levels is then fitted to obtain the final sensitivity of the F-18 radiation monitor.

[0047] Calculate the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment;

[0048] A = A0 × e -λΔt (5)

[0049] Δt=t0-t (6)

[0050] In the formula, λ is the decay constant of F-18; A0 is the displayed activity of the high-precision activity meter recorded after the preparation of the standard F-18 thin film source, in Bq; Δt is the decay correction time of the standard F-18 thin film source at the current measurement time, in min; t0 is the moment when the standard F-18 thin film source is placed into the high-precision activity meter during the preparation of the standard F-18 thin film source, and t is the moment of the current measurement, down to the second;

[0051] Calculate the detection efficiency X of the F-18 radiation monitor at time t, where the activity-defined true value is A. t ;

[0052] X t =(N tance -B0) / A×100% (7)

[0053] In the formula, N tanceB0 is the count rate of the containment atmospheric F-18 radiation monitor conforming to the multichannel F-18 region of interest, in cps; B0 is the background count rate of the containment atmospheric F-18 radiation monitor, in s. -1 .

[0054] In one embodiment, the overload threshold is 10%, the variation threshold is 10%, and the relative inherent error threshold is 20%.

[0055] The above-mentioned verification method for an F-18 radiation monitor based on a standard F-18 thin-film source includes: preparing a standard F-18 thin-film source using a medical F-18 deoxyglucose solution; performing an overload test on the F-18 radiation monitor using the standard F-18 thin-film source; if the deviation of the average value of the multichannel F-18 region of interest counts of the F-18 radiation monitor after overload from the value before overload is greater than an overload threshold, the verification of the F-18 radiation monitor ends; otherwise, performing a coefficient of variation test on the F-18 radiation monitor using the standard F-18 thin-film source; if the coefficient of variation is greater than a variation threshold, the verification of the F-18 radiation monitor ends; otherwise, performing a relative inherent error test on the F-18 radiation monitor using the standard F-18 thin-film source; if the relative inherent error is greater than a relative inherent error threshold, the verification of the F-18 radiation monitor ends; otherwise, performing a repeatability test on the F-18 radiation monitor using the standard F-18 thin-film source. The availability of medical F-18 deoxyglucose solution is unrestricted. This method uses medical F-18 deoxyglucose solution to prepare a standard F-18 thin-film source, which can reduce the difficulty of preparing F-18 radiation sources. Furthermore, this method fills the gap in F-18 radiation monitoring instrument calibration technology and can effectively verify whether the F-18 radiation monitoring instrument is accurate or qualified. Attached Figure Description

[0056] Figure 1 This is a schematic diagram showing the circuit connection relationship between the F-18 detector, signal processing circuit, and on-site radiation processing unit in the prior art.

[0057] Figure 2 This is a schematic diagram showing the positional relationship between the main detector, symbol detector, and filter paper in the existing technology of the F-18 detector.

[0058] Figure 3 This is a flowchart illustrating the verification method for an F-18 radiation monitor based on a standard F-18 thin-film source according to the present invention.

[0059] Figure 4 This is one of the flowcharts for the fabrication of the standard F-18 thin film source of this invention. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0061] Pressurized water reactor (PWR) nuclear power plants produce F-18 nuclides at high concentrations during high-power operation. Fast neutrons in the PWR undergo elastic scattering with hydrogen nuclei in the primary coolant loop, generating high-energy protons that react with oxygen nuclei in the water to produce radioactive F-18 nuclides. The physical process is as follows:

[0062]

[0063] After being generated, F-18 nuclides diffuse into the atmosphere of the nuclear power plant containment vessel along with the coolant leaking from the primary loop, forming F-18 aerosols. Because F-18 nuclides have a moderate half-life (109.8 minutes), they do not decay and weaken quickly after being generated, nor do they persist for a long time to cause a large accumulation, making them suitable for determining the leakage rate of the RCPB.

[0064] In the design of third-generation passive nuclear power plants, a method was proposed to measure the radioactivity concentration of F-18 aerosols inside the containment vessel to reflect the leakage rate of the RCPB.

[0065] However, due to the inability to store and transport F-18 radioactive sources stably for extended periods, and the difficulty in obtaining the raw materials for their preparation, there are currently no stable F-18 standard radioactive sources with known radioactivity levels available domestically or internationally. Therefore, those skilled in the art need to prepare their own standard F-18 thin-film sources. A standard radioactive source is any radioactive source with consistent radioactivity and shape / structure used by those skilled in the art to determine the leakage rate of an RCPB using an F-18 radioactive source. However, due to technological differences, the standard F-18 thin-film sources prepared by those skilled in the art are different.

[0066] To measure the radioactivity concentration of F-18 aerosols within containment facilities, existing technology provides a novel F-18 radiation detector capable of effectively measuring the radioactivity concentration of F-18 aerosols within containment facilities. However, there are no existing methods or corresponding standards or national metrological verification procedures for calibrating this novel F-18 radiation detector.

[0067] Please refer to Figure 3 , Figure 3 This is a flowchart illustrating the F-18 radiation monitor calibration method based on a standard F-18 thin-film source according to the present invention. The present invention discloses a calibration method for an F-18 radiation monitor based on a standard F-18 thin-film source, comprising the following steps:

[0068] A standard F-18 thin-film source was prepared using a medical-grade F-18 deoxyglucose solution. The F-18 radiation monitor was then subjected to overload testing using this standard F-18 thin-film source. If the deviation between the average count of the multichannel F-18 region of interest counts after and before the overload exceeded the overload threshold, the F-18 radiation monitor calibration was completed. Otherwise, the F-18 radiation monitor underwent coefficient of variation testing using the standard F-18 thin-film source. If the coefficient of variation exceeded the variation threshold, the F-18 radiation monitor calibration was completed. Otherwise, the F-18 radiation monitor underwent relative inherent error testing using the standard F-18 thin-film source. If the relative inherent error exceeded the relative inherent error threshold, the F-18 radiation monitor calibration was completed. Otherwise, the F-18 radiation monitor underwent repeatability testing using the standard F-18 thin-film source.

[0069] This invention discloses a method for calibrating F-18 radiation monitors based on a standard F-18 thin-film source. The standard F-18 thin-film source is prepared using a medical-grade F-18 deoxyglucose solution, which is readily available, reducing the difficulty of preparing the F-18 radioactive source. Furthermore, this method can calibrate F-18 radiation monitors, filling a gap in the industry where calibrating F-18 radiation monitors was previously impossible. In addition, this method, considering the decay characteristics of F-18 nuclides, provides a testing sequence for F-18 radiation monitors using a standard F-18 thin-film source: overload, coefficient of variation, relative inherent error, and repeatability. This sequence requires only one preparation of the standard F-18 thin-film source to complete the calibration of the F-18 radiation monitor, reducing the number of preparations of the standard F-18 thin-film source and the calibration time of the F-18 radiation monitor, effectively reducing material and time costs, and also reducing the time and risk of radiation exposure for calibration personnel.

[0070] Specifically, overload testing assesses the self-protection capabilities of the F-18 radiation monitor; coefficient of variation testing detects the dispersion of the F-18's measurements, thus assessing its operational stability; relative inherent error primarily stems from inherent defects in the F-18, such as errors caused by its structure, installation, and measurement standard transmission; and repeatability testing determines whether the F-18 meets operational requirements and provides accurate results upon re-operation. These tests collectively evaluate the accuracy of the F-18's measurements and the quality of its manufacturing.

[0071] It should be noted that if the average deviation of the F-18 radiation monitor's counts of multiple channels of F-18 region of interest after overload is greater than the overload threshold, and if the coefficient of variation is greater than the variation threshold, then the F-18 radiation monitor calibration is completed. If the relative inherent error is greater than the relative inherent error threshold, then the F-18 radiation monitor calibration is completed. All these calibration results indicate that the F-18 radiation monitor is unqualified.

[0072] like Figure 4 As shown, Figure 4 One embodiment of the standard F-18 thin film source fabrication process is shown in the flowchart below. In one embodiment, the standard F-18 thin film source is prepared using a medical F-18 deoxyglucose solution, including:

[0073] Place the medical F-18 deoxyglucose solution in a high-precision activity meter; when the high-precision activity meter reading is less than 10... 6 At Bq, 1 ml to 4 ml of F-18 deoxyglucose solution was taken from the high-precision activity meter and dropped onto the center of GF / D filter paper; the GF / D filter paper containing the F-18 deoxyglucose solution was filled to obtain a standard F-18 film source, and the standard F-18 film source was placed into the high-precision activity meter for static measurement. The displayed activity of the high-precision activity meter and the time when the standard F-18 film source was placed into the high-precision activity meter were recorded.

[0074] Specifically, the high-precision activity meter reading is less than 10. 6 Bq, then the radiation level of the standard F-18 thin-film source prepared by the above method is in the range of 10. 6 Above cps. Furthermore, the above method provides a unified standard, allowing those skilled in the art to prepare standard F-18 thin-film sources with the same radiation levels.

[0075] In addition, the preparation of standard F-18 thin film sources using medical F-18 deoxyglucose solution is simple, quick, and low-cost. After verification, the source will not generate radioactive waste or cause radioactive pollution.

[0076] Preferably, the error of the high-precision activity meter is less than 5%.

[0077] In an optional embodiment, overload detection of the F-18 radiation monitor using a standard F-18 thin-film source includes: acquiring the coincident multichannel F-18 region of interest (ROI) counts of 10 to 30 F-18 radiation monitors without a radiation source; calculating the average value X of all coincident multichannel F-18 ROI counts of the F-18 radiation monitors without a radiation source; acquiring the same number of coincident multichannel F-18 ROI counts of the F-18 radiation monitors without a radiation source, using the standard F-18 thin-film source as the radiation source; calculating the average value Y of all coincident multichannel F-18 ROI counts using the standard F-18 thin-film source as the radiation source; and calculating the deviation between the average value X and the average value Y. The deviation between the average value X and the average value Y indicates whether the F-18 radiation monitor can recover to normal after an overload.

[0078] In an optional embodiment, detecting the coefficient of variation of an F-18 radiation monitor using a standard F-18 thin-film source includes: waiting for the standard F-18 thin-film source to decay, until the reading of the F-18 radiation monitor is on the order of 10. 3 ~10 5 During CPS, obtain 10–30 counts of multichannel F-18 regions of interest; calculate the average value Z of the 10–30 counts of multichannel F-18 regions of interest; calculate the coefficient of variation V of the F-18 radiation monitor.

[0079]

[0080] In the formula, n is the total number of regions of interest that conform to the multichannel F-18 count; N i Let i be the i-th region of interest that matches the multichannel F-18 count; Z represents the average value.

[0081] After a standard F-18 thin-film source is placed in an F-18 radiation monitor, its radiation level gradually and steadily decreases. Therefore, the count values ​​of the multichannel F-18 region of interest (ROI) of the F-18 radiation monitor should also gradually and steadily decrease, meaning that the count values ​​of the multichannel F-18 ROI have a certain degree of convergence. The coefficient of variation reflects the dispersion of the multichannel F-18 ROI counts of the F-18 radiation monitor, providing a standard for the calibration of the F-18 radiation monitor.

[0082] Specifically, the value that matches the multichannel F-18 region of interest count is the detection value of the F-18 radiation monitor.

[0083] To eliminate inherent defects in the F-18 radiation monitor, a standard F-18 thin-film source is used to detect the relative inherent error of the F-18 radiation monitor. In an optional embodiment, detecting the relative inherent error of the F-18 radiation monitor using a standard F-18 thin-film source includes: when the F-18 radiation monitor readings are on the order of 10... 5 cps, 10 4 cps or 10 3 In CPS, one test point is selected for each order of magnitude. For each test point, 5 to 15 counts of multichannel F-18 regions of interest are selected as a set of data. The average value of the counts of multichannel F-18 regions of interest in each set of readings is calculated. The relative error I of the indication value of each test point is calculated.

[0084]

[0085] In the formula, A is the conventional true value of the activity of the standard F-18 thin film source at the current measurement moment, in Bq. t The activity concentration of the standard F-18 thin film source at time t is expressed in Bq.

[0086] Calculate the relative inherent error E of the F-18 radiation monitor.

[0087]

[0088] In the formula, I MAX This represents the maximum value of the relative error I in the F-18 radiation monitor's indication; I MIN This is the minimum value of the relative error I in the indicated value of the F-18 radiation monitor.

[0089] In an optional embodiment, repeatability testing of the F-18 radiation monitor using a standard F-18 thin-film source includes: acquiring 5 to 15 counts of multichannel F-18 regions of interest; repeatedly turning off the F-18 radiation monitor for 8 to 12 minutes and then turning it back on, acquiring 5 to 15 counts of multichannel F-18 regions of interest three to five times; and calculating the repeatability M of the F-18 radiation monitor based on all acquired counts of multichannel F-18 regions of interest.

[0090]

[0091] In the formula, p represents the number of repetitions; Q p The average value of the multichannel F-18 region of interest count measurement for the qth repetition; It is the average of all measurements that conform to the multichannel F-18 region of interest count.

[0092] Preferably, in this embodiment, if the repeatability M is less than 10%, the F-18 radiation monitor is considered qualified; otherwise, the F-18 radiation monitor is considered unqualified.

[0093] To further verify the accuracy and qualification of the F-18 radiation monitor, in an optional embodiment, the verification method of the F-18 radiation monitor based on the standard F-18 thin-film source further includes: if the average deviation of the multichannel F-18 region of interest count of the F-18 radiation monitor after overload and before overload is less than or equal to the overload threshold, then the detection efficiency of the F-18 radiation monitor is tested using the standard F-18 thin-film source, and after the detection efficiency test is completed, the coefficient of variation of the F-18 radiation monitor is tested using the standard F-18 thin-film source.

[0094] Preferably, the detection efficiency test of the F-18 radiation monitor using a standard F-18 thin-film source includes: when the readings of the F-18 radiation monitor drop to the order of 10... 5 During CPS, the counts of all regions of interest (ROIs) conforming to the multichannel F-18 are obtained within 30-40 hours. Based on the counts of all ROIs conforming to the multichannel F-18 within 30-40 hours, the sensitivity of the F-18 radiation monitor at different magnitudes is calculated. The sensitivity of the F-18 radiation monitor at different magnitudes is then fitted to obtain the final sensitivity of the F-18 radiation monitor.

[0095] It should be noted that sensitivity is a measure of a physical instrument. In this embodiment, the sensitivity reflects the measurement sensitivity of the F-18 radiation monitor to the radiation source, namely the standard F-18 thin-film source.

[0096] Calculate the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment.

[0097] A = A0 × e -λΔt (5)

[0098] Δt=t0-t (6)

[0099] In the formula, λ is the decay constant of F-18; A0 is the displayed activity of the high-precision activity meter recorded after the preparation of the standard F-18 thin film source, in Bq; Δt is the decay correction time of the standard F-18 thin film source at the current measurement time, in min; t0 is the moment when the standard F-18 thin film source is placed into the high-precision activity meter during the preparation of the standard F-18 thin film source, and t is the moment of the current measurement down to the second.

[0100] It should be noted that the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment can also be measured by a high-precision activity meter. However, in order to avoid the impact of taking the standard F-18 thin film source out of the F-18 radiation monitor on the identification process, to save the measurement time, and to reduce the radiation damage to the verification personnel during the measurement, the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment is obtained by calculation in this embodiment.

[0101] Calculate the detection efficiency X of the F-18 radiation monitor at time t, where the activity conventional true value is A. t ;

[0102] X t =(N tance -B0) / A×100% (7)

[0103] In the formula, N tance B0 is the count rate of the containment atmospheric F-18 radiation monitor conforming to the multichannel F-18 region of interest, in cps; B0 is the background count rate of the containment atmospheric F-18 radiation monitor, in s. -1 .

[0104] Specifically, the count rate of the containment atmospheric F-18 radiation monitor background can be obtained using publicly available measurements prior to verification, or background testing can be performed before overload testing of the equipment.

[0105] More specifically, the background test in this embodiment includes: placing filter paper free of radioactive nuclide contamination at the central test position within the 4π lead shield, and after 8 to 12 hours, exporting the counts of the coincident multichannel F-18 region of interest from all F-18 radiation monitors; then calculating the gamma background of the environment in which the F-18 radiation monitors are located, i.e., the count rate B0 of the containment atmospheric F-18 radiation monitor background, based on the counts of the coincident multichannel F-18 region of interest from all F-18 radiation monitors after 8 to 12 hours.

[0106]

[0107] In the formula, B l To conform to the multichannel F-18 region of interest count, the unit is cps; n is the number of regions of interest that conform to the multichannel F-18 radiation monitor output.

[0108] For nuclear radiation measuring instruments, under the same external conditions, the detection efficiency depends on the nuclear radiation detector itself. In this embodiment, when the F-18 radiation monitor is being calibrated, all other external conditions are the same. The detection efficiency of the F-18 radiation monitor depends on the F-18 radiation monitor itself. Therefore, the detection efficiency X of the F-18 radiation monitor at time t, where the activity conventional true value is A, is calibrated.t This is a verification of the F-18 radiation monitor itself. The quality of the F-18 radiation monitor can be determined by its detection efficiency.

[0109] Preferably, the overload threshold is 10%, the variation threshold is 10%, and the relative inherent error threshold is 20%.

[0110] Specifically, equipment verification can also include testing the equipment's appearance and basic functions.

[0111] More specifically, the external inspection of the F-18 radiation monitor includes checking the integrity of each component and verifying its specifications, serial number, and manufacturer. The basic functional checks of the F-18 radiation monitor include powering it on and allowing it to warm up. Then, check if the monitor issues any fault warnings. If no warnings are issued, the monitor's basic functions are considered malfunctioning; otherwise, they are considered functioning correctly.

[0112] The above-described verification method for F-18 radiation monitors based on a standard F-18 thin-film source can be used to test the background, overload, detection efficiency, coefficient of variation, relative inherent error, and repeatability of F-18 radiation monitors using a single standard F-18 thin-film source. It can be used as a metrological verification procedure for F-18 radiation monitors.

[0113] In one specific embodiment, assuming that the calibration of the F-18 radiation monitor cannot be completed until repeatability testing is finished, the calibration method for the F-18 radiation monitor based on the standard F-18 thin-film source includes the following steps:

[0114] S1: Connect the data output port of the on-site radiation processing unit of the F-18 radiation monitor to at least one computer. The computer is used to perform calculations on the monitoring data from the F-18 radiation monitor.

[0115] S2: Inspect the appearance of the F-18 radiation monitor. If the appearance is incomplete or there is damage that affects the function of the F-18 radiation monitor, the F-18 radiation monitor is deemed unqualified. Otherwise, proceed to step S3.

[0116] S3: Check the basic functions of the F-18 radiation monitor. If the basic functions are not normal, the F-18 radiation monitor is deemed unqualified; otherwise, proceed to step S4.

[0117] S4: Calculate the gamma background of the environment in which the F-18 radiation monitor is located.

[0118] S41: Turn on the F-18 radiation monitor and warm it up for 30 minutes.

[0119] S42: Place the filter paper free of radioactive nuclide contamination into the center test position inside the 4π lead shield. After 10 hours, export the count of the multichannel F-18 region of interest from the F-18 radiation monitor to the computer.

[0120] S42: Calculate the gamma background of the environment in which the F-18 radiation monitor is located based on the 10-hour coincident multichannel F-18 region of interest count.

[0121] The formula for calculating the gamma background of the environment in which the F-18 radiation monitor is located is:

[0122]

[0123] In the formula, B l To conform to the multichannel F-18 region of interest count, the unit is cps; n is the number of times the F-18 radiation monitor outputs a conforming multichannel F-18 region of interest count.

[0124] Specifically, as shown in Table 1, this embodiment presents the background count rate (cps) for 10 hours from 10 PM to 8 AM the following day on a certain date in Xi'an under natural conditions with a temperature of 20.5℃ and a humidity of 45.7%.

[0125] Table 1. Background count rate within 10 hours

[0126] 1h <![CDATA[2.96×10 -3 ]]> 2h <![CDATA[2.80×10 -3 ]]> 3h <![CDATA[2.40×10 -3 ]]> 4h <![CDATA[1.76×10 -3 ]]> 5h <![CDATA[2.72×10 -3 ]]> 6h <![CDATA[4.72×10 -3 ]]> 7h <![CDATA[4.80×10 -3 ]]> 8h <![CDATA[3.36×10 -3 ]]> 9h <![CDATA[3.60×10 -3 ]]> 10h <![CDATA[3.12×10 -3 ]]> Average background count rate (cps) <![CDATA[3.22×10 -3 ]]>

[0127] Substituting the data from Table 1 into equation (8), we obtain the gamma background of the environment in which the F-18 radiation monitor is located as 3.22 × 10⁻⁶. - 3 The cps meets the requirements for device background in this field.

[0128] S5: Prepare a standard F-18 thin film source;

[0129] Specifically, the preparation process of the standard F-18 thin film source is as follows:

[0130] S51: Source preparation: Prepare a high-precision activity meter (calibrated with a measurement error within 5%), GF / D filter paper, syringe, medical mask and gloves, sealing device, lead shield, and stopwatch.

[0131] S52: Obtain medical F-18 deoxyglucose solution. Locate the F-18 deoxyglucose solution production unit or hospital near the testing location. At the start of the test, go to the unit or hospital to obtain the medical F-18 deoxyglucose solution and transport it to the testing location as soon as possible. During the transportation process, to ensure the safety of personnel and the environment, place the radioactive solution in a lead shield.

[0132] S53: Power on the high-precision activity meter and start it up for preheating.

[0133] S54: Place the F-18 deoxyglucose solution into a calibrated high-precision activity meter for measurement and allow it to stand until its specific activity decreases to a reasonable range (<106 Bq) before source preparation. The standing time depends on the specific activity of the F-18 deoxyglucose solution. If the F-18 solution has strong initial radioactivity, add a lead shield around the activity meter.

[0134] S55: Use a syringe to draw about 3 ml of F-18 deoxyglucose solution, take a piece of GF / D filter paper, and drop a small amount of F-18 deoxyglucose solution onto the center of the filter paper.

[0135] S56: Thin-film source encapsulation, which involves sealing GF / D filter paper with F-18 deoxyglucose solution in a transparent plastic bag to prevent leakage of radioactive liquid.

[0136] S57: Place the encapsulated thin film source into the activity meter, measure the agreed true value of the source activity, and record the source activity and the time of measurement, accurate to the second.

[0137] S58: The preparation of the standard F-18 thin film source is completed. At the same time, the standard F-18 thin film source is quickly transferred to the measurement position of the F-18 radiation monitor for measurement.

[0138] S6: Perform an overload test on the F-18 radiation monitor using a standard F-18 thin-film source. If the average reading of the F-18 radiation monitor after the overload test deviates by more than 10% from the average reading before the overload test, the F-18 radiation monitor is deemed unqualified. Otherwise, proceed to step S7.

[0139] Specifically, overload testing of the F-18 radiation monitor using a standard F-18 thin-film source includes:

[0140] S61: After completing step S4, turn off the F-18 radiation monitor and allow the equipment to cool down, then remove the filter paper.

[0141] S62: Turn on the F-18 radiation monitor and allow it to warm up for 30 minutes. The equipment needs to be secured before warming up.

[0142] S63: Read the counts of conforming to the multichannel F-18 region of interest (ROI) under no-radiation source conditions, once every 5 seconds, for a total of 20 ROI counts before overload tests. Calculate the average of the ROI counts before the 20 overload tests as the average reading of the ROI counts before the overload tests. In this embodiment, the counts of conforming to the ROI in channels 400-600 are recorded.

[0143] Specifically, as shown in Table 2, this embodiment presents the multichannel F-18 region of interest counts before 20 overload tests in Xi'an under natural conditions of 24.5℃ and 60.0% humidity.

[0144] Table 2 shows the number of F-18 radiation monitors conforming to multichannel F-18 regions of interest counts before overload testing.

[0145]

[0146] S64: Place the standard F-18 thin film source at the center test position inside the 4π lead shield, and read the multichannel F-18 region of interest count within 5 minutes. Read the count every 5 seconds for a total of at least 20 multichannel F-18 region of interest counts during overload testing.

[0147] Specifically, as shown in Table 3, this embodiment presents the multichannel F-18 region of interest counts during 20 overload tests in Xi'an under natural conditions of 24.5℃ and 60.0% humidity.

[0148] Table 3 shows the F-18 radiation monitor's compliance with multichannel F-18 region of interest counts during overload testing.

[0149]

[0150]

[0151] S65: Remove the standard F-18 thin-film source and allow the F-18 radiation monitor to operate for 5 minutes without a radiation source. Then, take the counts of the multichannel F-18 region of interest after the overload test without a radiation source, taking a reading every 5 seconds for a total of 20 counts. Calculate the average of the 20 counts of the multichannel F-18 region of interest after the overload test as the average reading of the multichannel F-18 region of interest after the overload test.

[0152] Specifically, as shown in Table 4, this embodiment presents the results of 20 overload tests conducted in Xi'an under natural conditions of 24.5℃ and 60.0% humidity, which meet the requirements for multichannel F-18 region of interest counts.

[0153] Table 4 shows the F-18 radiation monitor's conformance to multichannel F-18 region of interest counts after overload testing.

[0154]

[0155]

[0156] According to Tables 2 to 4, after the overload was removed for 5 minutes, the deviation between the reading of the F-18 radiation monitor (7.31) and the reading of 7.21 before the overload source was removed was 1.30%, which is less than 10% and meets the requirements. Moreover, after the equipment was overloaded, the counting returned to normal and the equipment was working normally.

[0157] S7: The detection efficiency of the F-18 radiation monitor was tested using a standard F-18 thin-film source.

[0158] Specifically, the detection efficiency test of the F-18 radiation monitor using a standard F-18 thin-film source includes:

[0159] S71: After step S6 is completed, wait for the standard F-18 thin film source to continue decaying.

[0160] S72: Wait until the coincident multichannel F-18 region of interest count reading of the F-18 radiation monitor drops to 10. 5 After cps, the count of the F-18 region of interest (ROI) within 36 hours of the F-18 radiation monitor begins to be recorded.

[0161] S73: Calculate the sensitivity of the F-18 radiation monitor at different levels based on the number of regions of interest (ROIs) for multichannel F-18 radiation within 36 hours. These levels include 10... 5 cps, 10 4 cps and 10 3 cps.

[0162] S74: Fit the sensitivity of the F-18 radiation monitor at different levels to obtain the final sensitivity of the F-18 radiation monitor.

[0163] S75: Calculate the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment.

[0164] A = A0 × e -λΔt (5)

[0165] Δt=t0-t (6)

[0166] In the formula, λ is the decay constant of F-18; A0 is the displayed activity of the high-precision activity meter recorded after the preparation of the standard F-18 thin film source, in Bq; Δt is the decay correction time of the standard F-18 thin film source at the current measurement time, in min; t0 is the moment when the standard F-18 thin film source is placed into the high-precision activity meter during the preparation of the standard F-18 thin film source, and t is the moment of the current measurement down to the second.

[0167] S76: Calculate the detection efficiency X of the F-18 radiation monitor at time t with the activity conventional true value A. t .

[0168] X t =(N tance -B0) / A×100% (7)

[0169] In the formula, N tance The count rate for the containment atmospheric F-18 radiation monitor conforming to the multichannel F-18 region of interest is expressed in cps.

[0170] It should be noted that those skilled in the art can continue to obtain the counts of the multichannel F-18 region of interest within 36 hours after the overload detection is completed to perform detection efficiency testing. In this embodiment, the data required for detection efficiency testing and the calculation process will not be described in detail.

[0171] S8: Calculate the coefficient of variation of the F-18 radiation monitor using a standard F-18 thin-film source. If the coefficient of variation is greater than 10%, the F-18 radiation monitor fails the test; otherwise, proceed to step S9.

[0172] Specifically, the coefficient of variation for calculating the F-18 radiation monitor using a standard F-18 thin-film source includes:

[0173] S81: After step S7 is completed, wait for the standard F-18 thin film source to continue decaying;

[0174] S82: When the reading of the F-18 radiation monitor is on the order of 10 3 ~10 5 Furthermore, when the readings are stable, the counts of the F-18 regions of interest (ROIs) are taken every 5 seconds, for a total of 20 ROIs. Stable readings mean that the F-18 radiation monitor readings do not change significantly over a short period of time.

[0175] S83: Calculate the average count of 20 regions of interest that match the multichannel F-18 region of interest count.

[0176] S84: Calculate the coefficient of variation V of the F-18 radiation monitor;

[0177]

[0178] In the formula, n is the total number of reads that match the multichannel F-18 region of interest count; N i Let be the count of the region of interest conforming to the multichannel F-18 algorithm during the i-th read; This is the arithmetic mean of the number of regions of interest (ROIs) for n reads that conform to the multichannel F-18 region of interest count.

[0179] Specifically, as shown in Table 5, this embodiment presents the readings of the F-18 radiation monitor in Xi'an under natural conditions of 24.5℃ and 60.0% humidity, with readings on the order of 10.3 ~10 5 Furthermore, the 20 coincident multichannel F-18 regions of interest counts when the readings are stable are given. The coefficient of variation values ​​are provided in Table 5.

[0180] Table 5. Counts of regions of interest corresponding to the F-18 radiation monitor's coefficient of variation.

[0181]

[0182] As shown in Table 5, the coefficient of variation of the F-18 radiation monitor is 1.19%, which is less than the variation threshold of 10% and meets the requirements.

[0183] S9: Calculate the relative inherent error of the F-18 radiation monitor using a standard F-18 thin-film source. If the relative inherent error is greater than 20%, the F-18 radiation monitor fails the test; otherwise, proceed to step S10.

[0184] Specifically, the relative inherent error of the F-18 radiation monitor calculated using a standard F-18 thin-film source includes:

[0185] S91: Waiting for the standard F-18 thin-film source to decay to the order of 10. 5 cps, 10 4 cps or 10 3 cps.

[0186] S92: Select one test point in each order of magnitude.

[0187] S93: For each test point, after the reading of the F-18 radiation monitor stabilizes, record a count of the multichannel F-18 region of interest every 10 seconds. Record 10 counts of the multichannel F-18 region of interest for each order of magnitude as a group, and calculate the average value of each group of data.

[0188] S94: Calculate the relative error I of the indicated value for each test point.

[0189]

[0190] In the formula, A t The activity concentration of the standard F-18 thin film source at time t is expressed in Bq.

[0191] S95: Calculate the relative inherent error E of the F-18 radiation monitor.

[0192]

[0193] In the formula, I MAX This represents the maximum relative error of the F-18 radiation monitor reading; I MINThis is the minimum relative error of the indicated value of the F-18 radiation monitor.

[0194] It should be noted that those skilled in the art can continue to obtain the data required for relative inherent error detection after the coefficient of variation detection is completed. In this embodiment, the data required for detection efficiency detection and the calculation process will not be described in detail.

[0195] S10: Calculate the repeatability of the F-18 radiation monitor using a standard F-18 thin-film source. If the repeatability is greater than 10%, the F-18 radiation monitor is deemed unqualified; otherwise, the F-18 radiation monitor is deemed qualified.

[0196] Specifically, calculating the equipment repeatability of the F-18 radiation monitor using a standard F-18 thin-film source includes:

[0197] S101: Read the F-18 radiation monitor reading every 10 seconds, and read a total of 10 F-18 region of interest count data that conform to the multichannel F-18.

[0198] S102: Turn off the F-18 radiation monitor for 10 minutes, then turn it back on. After the F-18 radiation monitor stabilizes, read the F-18 radiation monitor reading every 10 seconds, and read a total of 10 F-18 region of interest count data that conform to the multichannel F-18 region of interest count.

[0199] S103: Repeat step S102 five times.

[0200] S104: Calculate the repeatability M of the F-18 radiation monitor based on the 50 multichannel F-18 region of interest count data obtained in steps S102 and S103;

[0201]

[0202] In the formula, p represents the number of repetitions; Q p The average value of the multichannel F-18 region of interest count measurement for the qth repetition; It is the average of all measurements that conform to the multichannel F-18 region of interest count.

[0203] More specifically, as shown in Table 6, this embodiment presents the detection data of the F-18 radiation monitor when performing repeatability tests in Xi'an under natural conditions of 24.5℃ and 60.0% humidity. The repeatability values ​​are given in Table 6.

[0204] Table 6 shows the test data during the repeatability test of the F-18 radiation monitor.

[0205]

[0206] As shown in the table above, the repeatability of the F-18 radiation monitor, which was tested five times, was 0.68%, less than 10%, and met the requirements.

[0207] In summary, by conducting a series of tests on the F-18 radiation monitor based on the radiation characteristics of the standard F-18 thin film source, the F-18 radiation monitor can be verified to be accurate and qualified. Moreover, only one standard F-18 thin film source needs to be prepared to complete the series of tests on the F-18 radiation monitor, which can effectively reduce costs and verification time.

[0208] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0209] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source, characterized in that, include: A standard F-18 thin-film source was prepared using a medical-grade F-18 deoxyglucose solution; The F-18 radiation monitor is overloaded using the standard F-18 thin film source. If the deviation of the average value of the multichannel F-18 region of interest counts of the F-18 radiation monitor after overload from the value before overload is greater than the overload threshold, the calibration of the F-18 radiation monitor is completed. Otherwise, the F-18 radiation monitor is tested for coefficient of variation using the standard F-18 thin film source. If the coefficient of variation is greater than the variation threshold, the calibration of the F-18 radiation monitor is completed; otherwise, the F-18 radiation monitor is subjected to relative inherent error detection using the standard F-18 thin film source. If the relative inherent error is greater than the relative inherent error threshold, the calibration of the F-18 radiation monitor is completed; otherwise, the F-18 radiation monitor is subjected to repeatability testing using the standard F-18 thin-film source. The standard F-18 thin film source prepared using medical F-18 deoxyglucose solution includes: The medical F-18 deoxyglucose solution was placed in a high-precision activity meter; When the reading of the high-precision activity meter is less than 10 6 At Bq, take 1 ml to 4 ml of the F-18 deoxyglucose solution from the high-precision activity meter and drop it onto the center of GF / D filter paper; A GF / D filter paper containing an F-18 deoxyglucose solution was encapsulated to obtain a standard F-18 film source. The standard F-18 film source was then placed into a high-precision activity meter for static measurement. The displayed activity of the high-precision activity meter and the time when the standard F-18 film source was placed into the high-precision activity meter were recorded.

2. The calibration method for an F-18 radiation monitor based on a standard F-18 thin-film source according to claim 1, characterized in that, Overload detection of the F-18 radiation monitor using the standard F-18 thin-film source includes: Obtain the coincident multichannel F-18 region of interest counts from 10 to 30 F-18 radiation monitors without radioactive sources; Calculate the average value X of the multichannel F-18 region of interest counts from all F-18 radiation monitors under no-radiation-source conditions; Obtain the same number of coincident multichannel F-18 region of interest counts as the F-18 radiation monitor without a radioactive source, using a standard F-18 thin-film source as the radiation source; Calculate the average value Y of all regions of interest (ROIs) that conform to the multichannel F-18 radiation source using a standard F-18 thin-film source; Calculate the deviation between the average value X and the average value Y.

3. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to claim 2, characterized in that, The coefficient of variation detection of the F-18 radiation monitor using the standard F-18 thin-film source includes: Wait for the standard F-18 thin-film source to decay, until the reading of the F-18 radiation monitor is on the order of 10. 3 ~10 5 During CPS, acquire 10-30 region of interest counts that match the multichannel F-18 region of interest count; Calculate the average value Z of 10-30 regions of interest that conform to the multichannel F-18 region of interest count; Calculate the coefficient of variation V of the F-18 radiation monitor; （1） In the formula, The total number of regions of interest for multichannel F-18s; Let i be the i-th region of interest that conforms to the multichannel F-18; Z represents the average value.

4. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to claim 3, characterized in that, Detecting the relative inherent error of the F-18 radiation monitor using the standard F-18 thin-film source includes: The readings on the F-18 radiation monitor were on the order of 10. 5 cps, 10 4 cps or 10 3 In CPS, one test point is selected for each order of magnitude, and 5 to 15 regions of interest that conform to the multichannel F-18 are selected for each test point to form a set of data. Calculate the average of the multichannel F-18 region of interest counts for each group of readings; Calculate the relative error I of the indicated value at each test point; （2） In the formula, A is the conventional true value of the activity of the standard F-18 thin film source at the current measurement moment, in Bq. For the standard F-18 thin film source in Activity concentration at time t, in Bq; Calculate the relative inherent error E of the F-18 radiation monitor; （3） In the formula, This represents the maximum value in the relative error I of the F-18 radiation monitor's indication value; This is the minimum value of the relative error I in the indicated value of the F-18 radiation monitor.

5. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to claim 4, characterized in that, Repeatability testing of the F-18 radiation monitor using the standard F-18 thin-film source includes: Obtain 5-15 regions of interest that match the multichannel F-18; Repeat the process of turning off the F-18 radiation monitor for 8 to 12 minutes and then turning it back on, acquiring 5 to 15 regions of interest (ROIs) matching the multichannel F-18 three to five times; The repeatability M of the F-18 radiation monitor is calculated based on all acquired regions of interest (ROIs) that conform to the multichannel F-18 count. （4） In the formula, Q represents the number of repetitions. p For the first The average value of multiple repetitions of the F-18 region of interest count measurement; It is the average of all measurements that conform to the multichannel F-18 region of interest count.

6. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to any one of claims 2 to 5, characterized in that, The method further includes: if the deviation of the average value of the multichannel F-18 region of interest count of the F-18 radiation monitor after overload and before overload is less than or equal to the overload threshold, then the F-18 radiation monitor is tested for detection efficiency using the standard F-18 thin film source, and after the detection efficiency test is completed, the F-18 radiation monitor is tested for coefficient of variation using the standard F-18 thin film source.

7. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to claim 6, characterized in that, The detection efficiency test of the F-18 radiation monitor using the standard F-18 thin-film source includes: When the F-18 radiation monitor readings dropped to the order of 10 5 During CPS, obtain the counts of all regions of interest that conform to the multichannel F-18 within 30h~40h; The sensitivity of the F-18 radiation monitor at different levels is calculated based on the count of all regions of interest that conform to the multichannel F-18 within the 30h~40h period, and the sensitivity of the F-18 radiation monitor at different levels is fitted to obtain the final sensitivity of the F-18 radiation monitor. Calculate the conventional true value A of the activity of the standard F-18 thin film source at the current measurement moment; （5） （6） In the formula, The decay constant of F-18; The displayed activity of the high-precision activity meter, recorded after the preparation of the standard F-18 thin film source, is given in Bq. t0 represents the decay correction time of the standard F-18 thin film source at the current measurement moment, in minutes; t0 represents the moment when the standard F-18 thin film source was placed into the high-precision activity meter during its preparation. This refers to the current measurement time, specified to the second. Calculate the F-18 radiation monitor in The truth value of the time-liveness convention is Detection efficiency ; （7） In the formula, The count rate of the containment atmospheric F-18 radiation monitor conforming to the multichannel F-18 region of interest is expressed in cps. The count rate is the background of the containment atmospheric F-18 radiation monitor, expressed in seconds. -1 .

8. The method for calibrating an F-18 radiation monitor based on a standard F-18 thin-film source according to any one of claims 2 to 5, characterized in that, The overload threshold is 10%, the variation threshold is 10%, and the relative inherent error threshold is 20%.

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