PET water cooling system temperature stabilizing method, storage medium and equipment

Abstract

The invention relates to a PET water cooling system temperature stabilizing method, a storage medium and equipment. The method comprises the steps that a first curve description formula of a delta T detector and a delta t environment is fitted through the delta T detector and the delta t environment; corresponding detector uniform temperature changes under different water temperatures are obtained by adjusting the outlet water temperature of the water cooling machine; calculating a default difference value delta t water temperature between the current water temperature t water temperature and the default water temperature t water temperature, and a difference value delta T detector between the average temperature of the T detector and the average temperature of the standard detector; fitting a second curve description formula of the delta T detector and the delta t water temperature through the delta T detector and the delta t water temperature; a third description formula of the delta t environment and the delta t water temperature is obtained through the first curve description formula and the second curve description formula; and adjusting the outlet water temperature of the water cooling machine according to the third description formula and the second curve description formula so as to stabilize the temperature of the PET water cooling system. The PET scanning system has the beneficial effects that the average temperature variation amplitude of the detector of the PET system is smaller and more stable, and the overall performance of the PET scanning system is improved.

Description

Technical Field

[0001] The present invention relates to the field of PET technology, and in particular to a temperature stabilization method, storage medium and equipment for a PET water cooling system. Background Art

[0002] As the core component of PET (positron emission tomography) detectors, SiPM (silicon photomultiplier) has the advantage of not being easily disturbed by magnetic fields and exhibiting excellent spatial resolution and high temporal resolution. The former can significantly improve the positioning accuracy of PET equipment for tumors, while the latter greatly enhances the signal-to-noise ratio of reconstructed images. However, SiPM also has its limitations. Fluctuations in ambient temperature will directly affect key parameters such as its breakdown voltage, gain, junction capacitance, dark counts, and photon detection efficiency. In particular, the breakdown voltage will increase at high temperatures, which will in turn affect the gain and photon detection efficiency related to overvoltage. In addition, high temperatures will also increase dark counts due to thermally excited charge carriers, thereby introducing noise.

[0003] In PET equipment, since SiPM is widely used in detectors, the accuracy of temperature compensation is particularly important in the face of large temperature changes. To achieve this goal, a sufficient number of high-precision, high-speed response temperature probes are required to accurately execute the compensation algorithm. Although it is feasible to equip a single detector with a single temperature probe, it is easy to introduce errors because there is a difference in the temperature of the SiPM chip close to and far from the probe. When the number of probes is limited, it can only be assumed that the temperature drift is consistent and fuzzy compensation is performed, which limits the comprehensiveness and accuracy of the compensation. In fact, temperature drift has a significant impact on parameters such as the breakdown voltage, gain, junction capacitance, dark count and photon detection efficiency of SiPM, and the existing temperature drift compensation methods can often only provide limited compensation for gain. Summary of the invention

[0004] Technical issues to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a PET water cooling system temperature stabilization method, storage medium and device, which solves the technical problem of how to make the detector average temperature variation of the PET system smaller and more stable.

[0006] Technical Solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] In a first aspect, the present invention provides a method for stabilizing the temperature of a PET water cooling system, comprising:

[0009] Get the ambient temperature t measured at the same time 环境测 and detector average temperature T 探测器测 ;

[0010] Calculate t 环境测 and the average ambient temperature t 环境均温 The difference Δt 环境 , T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 ;

[0011] By ΔT 探测器 and Δt 环境 Fitting ΔT 探测器 and Δt 环境 The first curve description formula of

[0012] By adjusting the outlet water temperature of the water chiller, the corresponding detector average temperature change under different water temperatures can be obtained;

[0013] Calculate the current water temperature setting t 水温当前设置 and default water temperature t 水温默认 The difference Δt 水温 , T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 ;

[0014] By ΔT 探测器 and Δt 水温 Fitting ΔT 探测器 and Δt 水温 The second curve description formula of

[0015] Δt is obtained by the first curve description formula and the second curve description formula 环境 With Δt 水温 The third description formula of ;

[0016] The outlet water temperature of the water cooler is adjusted according to the third description formula and the second curve description formula to stabilize the temperature of the PET water cooling system.

[0017] Optionally, the first curve description formula is: ΔT 探测器 =a1Δt 环境 +b1, where a1 and b1 are constants obtained by fitting.

[0018] Optionally, the second curve description formula is: ΔT 探测器 =a2Δt 水温 +b2, where a2 and b2 are constants obtained by fitting.

[0019] Optionally, the third description formula is: Δt 水温 =(a1Δt 环境 +b1-b2) / a2.

[0020] Optionally, adjusting the outlet water temperature of the water cooler according to the third description formula and the second curve description formula to stabilize the temperature of the PET water cooling system includes:

[0021] In case of ambient temperature changes, according to Δt 水温 =(a1Δt 环境 +b1-b2) / a2 calculates the temperature difference of the water cooler and adjusts the outlet water temperature of the water cooler to t 水温当前设置 =t 水温默认 +Δt 水温 ;

[0022] When the detector temperature changes, ΔT 探测器 ≥ΔT 上限 or ΔT 探测器 ≤ΔT 下限 When Δt 水温 =(ΔT 探测器 –b2) / a2 calculates the temperature difference of the water cooler and adjusts the outlet water temperature of the water cooler to t 水温当前设置 =t 水温默认 +Δt 水温 .

[0023] Optionally, the method further comprises: determining the temperature sampling frequency according to the time difference of the detector average temperature in response to the ambient temperature change and the temperature change cycle.

[0024] Optionally, the minimum temperature sampling interval is less than or equal to the change response time difference, and the minimum temperature sampling interval is less than or equal to 1 / 5 of the temperature change period.

[0025] In a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed, a method for stabilizing the temperature of a PET water cooling system as described in any one of the first aspects above is implemented.

[0026] In a third aspect, the present invention provides a storage device comprising a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, a method for stabilizing the temperature of a PET water cooling system as described in any one of the first aspects above is implemented.

[0027] Beneficial Effects

[0028] The beneficial effect of the present invention is that a PET water cooling system temperature stabilization method of the present invention monitors the changing trend of the external environment temperature in real time and uses a prediction model to estimate the potential change of the detector average temperature in advance. Based on this prediction, the water outlet temperature of the water cooler can be adjusted proactively and in advance, thereby significantly shortening the response time of the detector average temperature to changes in the external environment and achieving smoother and more stable temperature control. This method not only improves the overall performance of the PET scanning system, but also ensures the continued high standard of image quality, further enhancing the reliability of the system and user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a method for stabilizing the temperature of a PET water cooling system provided by an embodiment of the present invention;

[0030] Figure 2 A relationship diagram of the effect of ambient temperature change on the detector average temperature provided by an embodiment of the present invention;

[0031] Figure 3 A relationship diagram showing the effect of water temperature setting changes on the detector average temperature provided by an embodiment of the present invention;

[0032] Figure 4 A graph showing the relationship between the real-time ambient temperature and the detector average temperature provided by an embodiment of the present invention;

[0033] Figure 5 A diagram showing the change in ambient temperature and detector average temperature after real-time correction provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0035] When deeply analyzing the detector average temperature control of the PET water cooling system, it is not difficult to find that the fluctuation of the external ambient temperature is one of the key influencing factors. When the temperature in the scanning room changes slightly, the average temperature of the detector will change accordingly, but this change will have a certain lag compared to the change in the external ambient temperature, and the direction of change remains consistent. The traditional control mechanism relies on the average temperature fluctuation directly monitored by the detector end. Once the fluctuation exceeds the preset range, it will adjust the outlet water temperature of the water cooler. However, since this adjustment method is based on terminal feedback, that is, from the perception of temperature changes to the actual adjustment of the outlet water temperature of the water cooler, and then to the stabilization of the detector average temperature, the whole process takes a certain amount of time.

[0036] If the first predicted water outlet temperature adjustment is not accurate enough, the traditional method has to wait until the detector average temperature reaches the set threshold critical point again before re-adjusting the temperature. Such a cycle not only prolongs the total time required for temperature stabilization, but may also cause the average temperature fluctuation to exceed the originally set fine-tuning threshold, affecting the stability and accuracy of the system.

[0037] In order to maintain the stable performance and high time resolution of the PET detector, it is necessary to ensure that it works in a stable environment. In addition to using an algorithm to adjust the voltage of the SiPM or the subsequent amplification gain through real-time temperature measurement for compensation, the present invention innovatively introduces external temperature monitoring to predict the impact on the SiPM temperature. The ultra-high precision stabilization of the SiPM temperature on the PET detector is achieved, effectively overcoming the limitations of traditional algorithm compensation.

[0038] In contrast, if SiPM can work in a stable temperature environment, there is no need for complex temperature compensation algorithms, thus avoiding additional measurement errors that may be introduced by the algorithm. Stable low temperature can also effectively suppress the dark counts and dark noise of SiPM, reduce the front signal wandering, and further improve the time resolution of PET equipment, which cannot be achieved by relying solely on temperature compensation mechanisms.

[0039] In addition, the present invention also has excellent site adaptability. In the face of external environmental influences in different sites, differences in the length of the cooling water delivery pipes result in differences in the average temperature at the detector end obtained for the same default water outlet temperature. The present invention can automatically adjust the water outlet temperature to adapt to these differences, ensuring that the average temperature of the detectors on different PET systems can reach the target temperature range and that the temperature fluctuation is controlled within the requirements.

[0040] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0041] PET systems will have a cooling system design. For SiPM detectors as photosensitive elements, water cooling is used to dissipate heat. The temperature stability of the detector itself will be better. In order to cooperate with the water-cooled temperature control monitoring, each detector in the PET system has one or more temperature sensors. The photosensitive element of a detector is generally composed of dozens to hundreds of silicon photomultiplier tube arrays. The average temperature change of all temperature probes on the detector is used to characterize the current working temperature of the detector.

[0042] Adding a temperature sensor to monitor the external environment at the external position of the PET system can identify changes in the external environment temperature. The external environment of PET is generally controlled by air conditioning, and the temperature fluctuates periodically.

[0043] In this embodiment, a high-precision, fast-response temperature probe is set on each detector of the PET system. The temperature probe settings can be reduced or increased according to actual conditions, such as a temperature probe is set on a group of detectors or a ring of detectors. One or more temperature probes for detecting the environment are set at a position close to the PET outside the PET cavity. Multiple environmental temperature probes can be characterized by average temperature, and the water temperature of the water chiller outlet water is used to control and adjust the average temperature of the detector.

[0044] First, combining Figure 1 This embodiment provides a method for stabilizing the temperature of a PET water cooling system, comprising:

[0045] S1, obtain the ambient temperature t measured at the same time 环境测 and detector average temperature T 探测器测 .

[0046] S2, calculate t 环境测 and the average ambient temperature t 环境均温 The difference Δt 环境 、T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 .

[0047] S3, by ΔT 探测器 and Δt 环境 Fitting ΔT 探测器 and Δt 环境 The first curve describes the formula.

[0048] S4, by adjusting the outlet water temperature of the water chiller, the corresponding detector average temperature change under different water temperatures is obtained.

[0049] S5, calculate the current water temperature setting t 水温当前设置 and default water temperature t 水温默认 The difference Δt 水温 、T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 .

[0050] S6, by ΔT 探测器 and Δt 水温 Fitting ΔT 探测器 and Δt 水温 The second curve describes the formula.

[0051] S7, obtaining Δt by using the first curve description formula and the second curve description formula环境 With Δt 水温 The third description formula of .

[0052] S8, adjusting the outlet water temperature of the water cooler according to the third description formula and the second curve description formula to stabilize the temperature of the PET water cooling system.

[0053] First, the relationship between the environment and the detector average temperature needs to be calibrated. The temperature of the external environment of the system is controlled by air conditioning, which will produce a relatively fixed periodic temperature change, while the detector average temperature changes slightly later than the environment, and the period length is the same, such as Figure 4 All test environment temperatures minus the statistical average environment temperature are as follows:

[0054] ΔT 探测器 =T 探测器测 -T 探测器标准 ;

[0055] Δt 环境 =t 环境测 -t 环境均温

[0056] Adjust the detector temperature delay time so that Δt 环境 and ΔT 探测器 The two cycles are consistent, and we can get Figure 2 is the relationship between the real-time ambient temperature change and the detector average temperature change. Through fitting, we can get:

[0057] ΔT 探测器 =a1Δt 环境 +b1;

[0058] a1 and b1 are constants obtained by fitting.

[0059] By transforming the formula we get:

[0060] Δt 环境 =(ΔT 探测器 -b1) / a1;

[0061] The relationship between the water temperature at the outlet of the water chiller and the average temperature change of the detector. By adjusting the water temperature around the default standard water chiller outlet temperature, and waiting for the system temperature to stabilize, the difference between the average temperature of the detector and the standard average temperature under the default water temperature is obtained:

[0062] ΔT 探测器 =T 探测器测 -T 探测器标准 ;

[0063] Δt 水温 =t 水温当前设置 -t 水温默认

[0064] According to the difference between the water temperature change and the detector average temperature change, Figure 3 As shown, through linear fitting:

[0065] ΔT 探测器 =a2Δt 水温 +b2;

[0066] a2 and b2 are constants obtained by fitting.

[0067] By transforming the formula we get:

[0068] Δt 水温 =(ΔT 探测器 –b2) / a2;

[0069] By substituting the formula we get:

[0070] Δt 水温 =(a1Δt 环境 +b1-b2) / a2;

[0071] Relatively high-frequency temperature sampling can more intuitively evaluate whether the stable temperature method is reliable. In actual use, the temperature sampling frequency can be reduced to reduce the system bandwidth occupation. The lower limit of the temperature sampling frequency is confirmed by two indicators. The first is the length of the time difference between the detector average temperature and the ambient temperature change, and the other is the length of the cycle change caused by ambient air conditioning or temperature change. The minimum sampling interval is ≤ the change response time difference and ≤ 1 / 5 of the temperature change cycle.

[0072] The calculation formula obtained during the calibration process is input into the system for judgment and calculation. The water-cooling machine setting temperature is adjusted according to the judgment and calculation results to stabilize the average temperature of the system detector.

[0073] Where T 探测器标准 ΔT 上限 ΔT 下限 t 水温默认 and t 环境均温 Set the value based on system requirements and status.

[0074] The first selection condition is the ambient temperature change value Δt 环境 Make judgment conditions and calculate the judgment conditions for adjusting the water temperature. According to the formula Δt 水温 =(a1Δt 环境 +b1-b2) / a2 calculates the temperature difference of the water cooler and adjusts the water temperature to t 水温当前设置 =t 水温默认 +Δt 水温 However, the water cooler has a minimum adjustment unit. For example, the minimum adjustment unit of the water cooler used in the example is 0.1℃, so the calculated Δt 水温 Approximate by smallest unit.

[0075] The second selection condition is the detector average temperature change value ΔT 探测器 Make judgment conditions and calculate the judgment conditions for adjusting the water temperature.

[0076] ΔT 探测器 =T 探测器测 -T 探测器标准 ;

[0077] When ΔT 探测器 ≥ΔT 上限 or ΔT 探测器 ≤ΔT 下限 When using the second curve scale formula Δt 水温 =(ΔT 探测器 –b2) / a2 calculates the temperature difference of the water cooler and adjusts the water temperature to t 水温当前设置 =t 水温默认 +Δt 水温 . It is also necessary to take an approximate value based on the minimum adjustment unit of the water cooler.

[0078] After using the system temperature stabilization method, the detector temperature is more stable. Figure 4 and Figure 5 By comparison, it can be seen that this method makes the detector average temperature variation of the PET system smaller and more stable.

[0079] This embodiment provides a method for stabilizing the temperature of a PET water cooling system, which predicts temperature changes through an external temperature sensor and adjusts the water temperature in time. The response to temperature changes is a slow-frequency process. Through external changes, it is predicted in advance, and the water temperature is adjusted in advance before the detector senses it, which reduces the response time required and makes the temperature control more ideal and accurate. The temperature stability of the detector is improved, and the accuracy of temperature fluctuation control is improved by an order of magnitude. It ensures that the gain of the PET detector remains stable; compared with the compensation type, fewer temperature sensors are required, and there are no other errors caused by compensation. The time resolution is better, which improves the image quality of the PET system. The differences between equipment in different sites can be adaptively adjusted.

[0080] In a second aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed, a method for stabilizing the temperature of a PET water cooling system as described in any one of the first aspects above is implemented.

[0081] In a third aspect, an embodiment of the present invention provides a storage device, including a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, a method for stabilizing the temperature of a PET water cooling system as described in any one of the first aspects above is implemented.

[0082] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0083] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

[0084] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for stabilizing the temperature of a PET water cooling system, characterized in that: include: Get the ambient temperature t measured at the same time 环境测 and detector average temperature T 探测器测 ; Calculate t 环境测 and the average ambient temperature t 环境均温 The difference Δt 环境 , T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 ; By ΔT 探测器 and Δt 环境 Fitting ΔT 探测器 and Δt 环境 The first curve description formula of By adjusting the outlet water temperature of the water chiller, the corresponding detector average temperature change under different water temperatures can be obtained; Calculate the current water temperature setting t 水温当前设置 and default water temperature t 水温默认 The difference Δt 水温 , T 探测器测 and the standard detector average temperature T 探测器标准 The difference ΔT 探测器 ; By ΔT 探测器 and Δt 水温 Fitting ΔT 探测器 and Δt 水温 The second curve description formula of Δt is obtained by the first curve description formula and the second curve description formula 环境 With Δt 水温 The third description formula of ; The outlet water temperature of the water cooler is adjusted according to the third description formula and the second curve description formula to stabilize the temperature of the PET water cooling system.

2. A PET water cooling system temperature stabilization method according to claim 1, characterized in that: The first curve description formula is: ΔT 探测器 =a1Δt 环境 +b1, where a1 and b1 are constants obtained by fitting.

3. A PET water cooling system temperature stabilization method according to claim 2, characterized in that: The second curve description formula is: ΔT 探测器 =a2Δt 水温 +b2, where a2 and b2 are constants obtained by fitting.

4. A PET water cooling system temperature stabilization method according to claim 3, characterized in that: The third description formula is: Δt 水温 =(a1Δt 环境 +b1-b2) / a2.

5. A PET water cooling system temperature stabilization method according to claim 4, characterized in that: According to the third description formula and the second curve description formula, the water outlet temperature of the water cooler is adjusted to stabilize the temperature of the PET water cooling system, including: In case of ambient temperature changes, according to Δt 水温 =(a1Δt 环境 +b1-b2) / a2 calculates the temperature difference of the water cooler and adjusts the outlet water temperature of the water cooler to t 水温当前设置 =t 水温默认 +Δt 水温 ; When the detector temperature changes, ΔT 探测器 ≥ΔT 上限 or ΔT 探测器 ≤ΔT 下限 When Δt 水温 =(ΔT 探测器 –b2) / a2 calculates the temperature difference of the water cooler and adjusts the outlet water temperature of the water cooler to t 水温当前设置 =t 水温默认 +Δt 水温 .

6. A PET water cooling system temperature stabilization method according to claim 5, characterized in that: The method further comprises: determining the temperature sampling frequency according to the time difference of the detector average temperature in response to the ambient temperature change and the temperature change cycle.

7. A PET water cooling system temperature stabilization method according to claim 6, characterized in that: The minimum temperature sampling interval is less than or equal to the change response time difference, and the minimum temperature sampling interval is less than or equal to 1 / 5 of the temperature change cycle.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a temperature stabilization method for a PET water cooling system as described in any one of claims 1 to 7 is implemented.

9. A storage device comprising a storage medium and a processor, wherein the storage medium stores a computer program, wherein: When the processor executes the computer program, the method for stabilizing the temperature of a PET water cooling system as described in any one of claims 1 to 7 is implemented.

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