CN107411768B - Equipment calibration method and device - Google Patents
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Abstract
The present disclosure provides a device calibration method and apparatus, wherein the method comprises: acquiring scanning data of background radiation of a detection crystal; determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data; adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor; and correcting the image reconstruction data acquired by the detection crystal according to the application data correction factor. The method and the device can calibrate the equipment according to the scanning data of the background radiation, an external source is not needed, and the cost is saved.
Description
Technical Field
The present disclosure relates to medical imaging technologies, and in particular, to a device calibration method and apparatus.
Background
By scanning a subject (e.g., a patient) with a medical scanning system, a lesion may be located and a more targeted treatment may be taken. For example, PET (Positron Emission Tomography) is one of the most advanced medical diagnostic imaging apparatuses today, and is capable of providing functional information on organs and lesions thereof at a molecular level by using living body metabolism, and has excellent performance in diagnosing diseases such as tumors, cardiovascular diseases, and nervous systems.
Due to the complexity of PET systems and their susceptibility to environmental factors, equipment aging, etc., it is generally necessary to detect their daily status and perform calibration periodically. Daily status detection generally only checks the status of the device and does not adjust the parameters of the device. If a problem is found in the state, a service engineer can be contacted for calibration; some necessary adjustments to the device parameters may be made during the periodic calibration. Currently, the mainstream method in the industry is to use an external source for calibrating the equipment, for example, some equipment uses a Ge68 barrel source, and the equipment is placed on a scanning bed or rotates at a constant speed in a detector so as to perform daily or periodic quality control on the PET equipment. In addition, there are also related techniques that use background radiation from the crystal itself for quality control, but when problems with the device state are detected, it is still necessary to use an external source for device calibration.
Disclosure of Invention
In view of this, the present disclosure provides a device calibration method and apparatus, so that the device calibration of a PET device can be implemented without using an external source, and the use cost of the PET device is reduced.
Specifically, the present disclosure is realized by the following technical solutions:
in a first aspect, a device calibration method is provided, the method comprising:
acquiring scanning data of background radiation of a detection crystal;
determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation;
and correcting the image reconstruction data acquired by the detection crystal according to the application data correction factor.
In a second aspect, there is provided a PET system, the system comprising: the system comprises a PET detector, a detection processing circuit, a controller and a memory; the memory includes: reference data and computer instructions executable on the controller;
the PET detector includes a detection crystal having background radiation;
the detection processing circuit is used for acquiring scanning data of background radiation of the detection crystal;
the controller, when executing the computer instructions in the memory, performs the steps of:
comparing the scanning data according to the reference data to determine that the equipment state is to be adjusted;
obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation;
and correcting the image reconstruction data of the equipment according to the application data correction factor.
In a third aspect, there is provided a computer-readable storage medium having instructions stored thereon, which when executed by one or more processors, cause the one or more processors to perform a method of data processing, the method comprising:
acquiring scanning data of background radiation of a detection crystal;
determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation;
and correcting the image reconstruction data acquired by the detection crystal according to the application data correction factor.
According to the device calibration method and device, the data correction factor is obtained according to the scanning data of the background radiation, the factor is adjusted through the energy factor conversion coefficient, and the application data correction factor is finally obtained, so that the device calibration can be carried out according to the scanning data of the background radiation, an external source is not needed, and the cost is saved.
Drawings
FIG. 1 is a schematic diagram illustrating background radiation of a crystal according to an exemplary embodiment of the present disclosure;
FIG. 2 is a system architecture diagram of a PET system, shown in an exemplary embodiment of the present disclosure;
FIG. 3 is a flow chart illustrating a method of device calibration according to an exemplary embodiment of the present disclosure;
FIG. 4 is a flow chart illustrating another method of device calibration according to an exemplary embodiment of the present disclosure;
FIG. 5 illustrates the principle of event consistent data acquisition according to an exemplary embodiment of the present disclosure;
FIG. 6 is a crystal efficiency gain schematic shown in an exemplary embodiment of the present disclosure.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.
The detection crystal in the PET detector, which includes radioactive material, may be a lutetium-based scintillation crystal, for example. The radiation emitted by the radioactive material contained in the crystal itself may be referred to as background radiation, which is the beta-gamma decay. For example, the lutetium element, when decayed, may release four particles, one of which is a beta particle of 589KeV and the other three of which are gamma photons, with energies of 307KeV, 202KeV and 88KeV, respectively, unlike a typical gamma decay which releases two gamma photons of 511 KeV. Wherein the beta particles have a weak penetration ability and are difficult to penetrate the crystals where they are located, for example, if the lutetium element in crystal a decays, the released beta particles remain in crystal a, and the other three gamma particles can penetrate the crystals and be received by other crystals of the PET detector.
Referring to the schematic of fig. 1, assuming that crystal a undergoes lutetium decay and beta particles remain on crystal a, the release of beta particles can be considered a start signal (start signal), while one of the gamma particles released by the lutetium decay can be emitted through crystal a and can be detected, for example, by crystal B, and the detection of the gamma particle can be considered an end signal (stop signal). Crystal a and crystal B this crystal is a coincidence event for the detected start signal and end signal. That is, in the background radiation of the crystal, the radioactive substance of the same crystal decays to release beta particles and gamma particles, which can form beta-gamma coincidence events. For example, a single event that detects beta particles and a single event that detects 307KeV gamma particles may form one coincident event, 589KeV beta particles and 202KeV gamma particles may form another coincident event, and 88KeV gamma particles are generally not detected because the energy is too low.
According to the equipment calibration method provided by the disclosure, the state detection of the PET equipment and the automatic calibration when the state needs to be adjusted can be automatically realized by utilizing the crystal background radiation, so that external sources such as Ge68 are not used any more, and the cost of using the PET equipment by a user is reduced.
FIG. 2 illustrates a system architecture diagram of a PET system, which, as shown in FIG. 2, may include: a PET gantry 21, which gantry 21 may include PET detectors and detection processing circuitry therein. Where the PET detector includes a detection crystal having background radiation, in one example, the detection crystal may be a lutetium-based scintillation crystal. The lutetium element in the crystal can decay to release beta particles and gamma particles, and the detection processing circuit can detect single events of the beta particles and the gamma particles through the energy window.
The PET system may also include a controller 22 and a memory 23. Among them, the memory 23 may include: the reference data, as well as computer instructions executable on the controller, may also include energy factor conversion coefficients in one example in memory 23. In the subsequent processing flow, the controller 22 may obtain the reference data and the energy factor conversion coefficient from the memory 23, and apply the reference data and the energy factor conversion coefficient to the state detection and the calibration of the device, which will be described in detail later. Also, the controller 22 may be used to execute computer instructions in the memory 23 to implement the device calibration method of the present disclosure. In one example, the controller 22 and memory 23 may be located in an image reconstruction computer. In other examples, computer instructions in memory 23 may also be stored in a computer-readable storage medium, which when executed by a processor, may implement the methods of the present disclosure.
The present disclosure provides a device calibration method that may be performed by a controller in a PET system. The calibration method may be performed with scan data of crystal background radiation, as in the example of fig. 3, including:
in step 301, scan data is acquired that detects background radiation of the crystal.
For example, the controller may acquire scan data of background radiation transmitted by the detection processing circuitry, which may include detected single events and coincidence events.
In step 302, the device status is determined to be adjusted according to the scan data, and a data correction factor is obtained according to the scan data.
For example, the controller may calculate consistency data from the obtained scan data and determine whether the device state needs to be adjusted by comparing the consistency data with reference data. In this example, the controller may also calculate a data correction factor based on the scan data when the device state needs to be adjusted.
In step 303, the data correction factor is adjusted by an energy factor conversion coefficient to obtain an application data correction factor, where the energy factor conversion coefficient is used to represent the correlation between the particle energy of the background radiation and the data correction factor at the particle energy of the annihilation radiation.
In this example, the data correction factor obtained in step 302 cannot be directly applied to data correction of image reconstruction data, and the controller may adjust the data correction factor according to the energy factor conversion coefficient to obtain an application data correction factor that can be actually used. In one example, the energy factor conversion coefficients may be stored in a memory of the PET system, and the controller may be retrieved from the memory.
In step 304, image reconstruction data acquired by the detection crystal is corrected in accordance with the application data correction factor.
According to the device calibration method, the data correction factor is obtained according to the scanning data of the background radiation, the factor is adjusted through the energy factor conversion coefficient, and the application data correction factor is finally obtained, so that the device calibration can be carried out according to the scanning data of the background radiation, an external source is not needed, and the cost is saved.
In another example, the PET system may also perform a source-consistency calibration on each crystal before performing the calibration using scan data of background radiation. Fig. 4 illustrates a flow of a device calibration method in another example of the present disclosure, in which a process of state detection and device calibration of a PET device from scan data of background radiation will be described.
The PET system may have a global PET system work plan file, and in one example, the example may set a timer, periodically query the global work plan, and determine whether the device is in an idle state for several hours in the future. If it is determined that the device is idle for several hours in the future, the flow shown in FIG. 4 may begin, performing detection and calibration of the device's state.
In step 401, scan data is acquired that detects background radiation of the crystal.
In this example, the detection processing circuit can detect single events of beta particles and gamma particles released by the crystal background radiation through the time window and the energy window. Wherein the time window can be suitably increased to ensure that the coincidence line whose distance is the diameter of the detector can fall within the coincidence window. The energy window may also be suitably opened to ensure that particles of the three energies 202KeV, 307KeV and 589KeV fall within the energy window.
In one example, the detection processing circuit may detect a high energy single event and a low energy single event resulting in background radiation through a plurality of energy windows for filtering different energy particles, respectively. For example, the detection processing circuitry may open two energy windows, with the lower energy window ensuring that particles of 202KeV and 307KeV are detectable and the higher energy window ensuring that particles of 589KeV are detectable.
In this example, the energy identification and the receiving crystal identification may also be marked for detected single events. Wherein the energy identification represents the particle energy corresponding to a single event, and the received crystal identification represents the crystal which detects the single event. For example, assuming that crystal B receives 202KeV gamma particles with lower energy, the single event may be labeled "crystal B, window D", where crystal B is the receiving crystal identification, the crystal receiving the event is crystal B, window D may be the energy identification, and the energy window detecting the event is window D (e.g., window D is a low energy window for detecting 202KeV and 307KeV gamma particles, and window G is a high energy window for detecting 589KeV beta particles). The energy signature and the received crystal signature for a single event in this step can be used in subsequent steps to obtain the radioactivity intensity of the crystal therefrom and for source consistency calibration, as described in detail in the subsequent steps.
The detection processing circuit may transmit the detected single event to the controller. The controller may obtain a coincidence event according to the single event pair satisfying the time coincidence condition, for example, the single event pair satisfying the time window setting in the scanning process may be referred to as a coincidence event. In addition, the controller can also strip out non-high-low coincidences through a set software energy window. For example, coincidence of 202KeV and 307KeV gamma particles is discarded, and normally retained coincidence events may be beta-gamma coincidence events of high and low energy.
In this step, the controller acquires scan data of background radiation of the detection crystal, including the single event and coincidence event described above.
In step 402, consistency data and time data are obtained from the scan data.
In this step, the consistency data of the whole PET system, which may include single event consistency data and coincidence event consistency data, may be calculated according to the scan data obtained by scanning the background radiation.
The calculation of the single-event consistency data may be to calculate a relative error inside each Block and a relative error between blocks in a Block unit. Wherein Block is a module composed of a plurality of crystals, for example, one Block may include 121 crystals. In this example, the relative error within each Block can be expressed by dividing the standard deviation by the mean, based on the count of single events detected by each crystal in the scan data. The count of single events detected by each crystal may include a count of all high and low energy single events.
The coincident event consistency data may include: whether stripes exist in the data or not and the average value of the number of coincidence events of each Block and the just opposite blocks. Referring to the schematic diagram of fig. 5, taking Block a as an example, the blocks directly opposite to Block a include B0 to B4, and the calculation method of the total number of tokens on each Block can be calculated according to the following formula (1):
wherein, in the formula (1), N represents the number of blocks opposite to A and ABiDenotes Block A and Block BiNumber of coincidence events therebetween.
The time data calculated in this step may be the deviation of the actual time difference and the theoretical time difference detected by two single events of the coincidence event. In the crystal background radiation, a detection crystal generating the background radiation is a radioactive source, and two corresponding crystal positions can be easily obtained through two crystal numbers according with an event, so that the physical distance L between the two crystals can be determined. For example, referring to the illustration of fig. 1, crystal a and crystal B are two crystals that detect coincident events, crystal a detects a single event of β particles, crystal B detects a single event of γ particles, and the distance L between crystal a and crystal B is the distance between the two events. Furthermore, by energy identification, it is possible to determine which of the two crystals the beta particle is in, i.e. where the decay occurs, where the beta particle occurs first in time and the gamma particle is detected to occur later, and the exact time difference, i.e. the theoretical time difference, may be "L/C", where C is the speed of light. And actually detecting that the recording time difference of the two single events of the beta particles and the gamma particles is the actual time difference, and recording the deviation between the theoretical time difference and the actual time difference to obtain the time data.
After the controller calculates the obtained consistency data and time data, it may temporarily store the data in the memory 23 in fig. 2, and proceed to step 403.
In step 403, it is determined whether reference data exists.
In this example, the reference data is data for comparing with the consistency data and the time data obtained this time to determine whether the device state is normal. If the PET system does not have the reference data currently, after the practitioner confirms that the current system status is normal, the practitioner performs step 404 to use the current consistency data and time data as the reference data of the system. If reference data is present, step 405 is performed.
In step 405, the current consistency data and the time data are compared with the reference data to determine whether the state meets the requirement.
In this step, the consistency data and the time data obtained in step 402 may be compared with the reference data, and the reference data may also include the consistency data and the time data, and a threshold may be preset to determine whether the comparison is passed according to the threshold. For example, the coincidence event consistency data may be compared with coincidence event consistency data in the reference data, and whether a difference between the coincidence event consistency data and the coincidence event consistency data exceeds a corresponding coincidence event consistency threshold may be determined, and if the difference exceeds a predetermined threshold range, the device state may be determined to be adjusted.
If the determined result is that the state meets the requirement, for example, the single event consistency data, the coincidence event consistency data and the time data are respectively compared with the corresponding reference data, and the comparison difference is within the threshold range, it can be determined that the state of the PET device is qualified, the adjustment and calibration are not required, and steps 406 to 409 can be continuously performed. If the determination result is that the status is to be adjusted, the steps 410 to 414 are continued.
In step 406, the baseline data is updated.
In this example, the setting of the comparison threshold may be to consider that the device has a slow aging process, and if the current data is very close to the reference data, which may be considered as a natural result of slow aging and belongs to an allowable range, the reference data may be covered with the current data. For example, the consistency data and time data obtained in step 402 may be used as new reference data for comparison with data for the next state detection.
In addition, since the normalization correction of the apparatus requires the amount of data several tens or even hundreds times as much as the daily calibration, it is necessary to accumulate data that is qualified at ordinary times, and after the amount of data that can satisfy the normalization requirement is accumulated, it is used for the calculation of the normalization factor. Therefore, if the equipment state detection is qualified, the acquired scanning data of the crystal background radiation can be stored for later use. The scan data may be stored to a data set, which may be a first-in-first-out queue.
In step 407, a determination is made as to whether the current data set is full.
If the result of the determination is that the data set is not full, step 409 may be directly performed to store the current scan data to the data set, including data of single events and coincident events.
If the data set is full, step 408 may be performed to exclude the oldest data in the data set and continue to place the current scan data in the data set in step 409.
In step 410, it is determined whether the current data set is full.
In this example, when it is determined that the current device needs to be adjusted, the current scan data may be stored in the data set of accumulated scan data. And, still judge whether the data set is full at present, the same reason, after accumulating enough data in the data set, just carry out subsequent correction.
If not, the method can return to step 402 to continue to acquire the scanning data of the crystal background radiation and continue to store the scanning data to the data set. If so, step 411 may continue.
In step 411, background uniformity calibration is performed based on the scan data of the background radiation.
If the device status detection fails, then crystal uniformity may be adjusted. Because the detection crystals are influenced by the processing technology and the like, the self radioactivity of each crystal has certain difference, therefore, before the consistency adjustment of the crystals, the background uniformity calibration of each crystal can be carried out firstly, so that each crystal becomes an emission source with consistent radiation intensity and isotropic emission, namely a uniform emission source is formed.
For example, as described above, the related information of a single event includes the energy identifier and the received crystal identifier of the single event, and a statistical count of the single event corresponding to 589KeV β particles received by the same crystal cumulatively can be obtained from the accumulated data set of the scan data according to the energy identifier and the received crystal identifier, and the statistical count of the β particles is taken as the self-radioactivity intensity of each crystal. The reciprocal of the statistical count can also be used as a source consistency correction factor of the crystal, and the source consistency correction factor is used for carrying out consistency correction on the scanning data corresponding to the crystal.
In one example, for crystal i, assume its source-uniformity correction factor is aiIndicates that the single event count s on the crystal iiCan be adjusted to ai*si. And the count of coincidence events on the coincidence line composed of crystal i and crystal j is pijThen the coincidence event count is pijCan be adjusted to ai*aj*pij。
In step 412, a data correction factor is derived from the scan data for the background radiation.
In this example, the data correction factor calculated from the scan data of the background radiation may include, for example: any one of the following: a crystal intrinsic efficiency, a crystal interference factor, a Block efficiency factor, or a geometric efficiency factor. The calculation of these factors can be done in a conventional way, except that in the conventional calculation, coincidence data in annihilation radiation is used, which means that a positron is released when a radionuclide injected into the subject decays, and annihilates with a negative electron around the positron, releasing two gamma photons of 511KeV energy traveling back to back; the data correction factor of this example is calculated using coincidence data derived from background radiation, i.e., the aforementioned beta-gamma coincidence data.
Taking the crystal intrinsic efficiency calculation as an example, y in FIG. 6 after background uniformity calibration in step 4110～yn-1All of the crystals in (a) can be considered as emission sources with uniform radiation intensity and isotropic emission. Then crystal x0Efficiency of (2)bkgIt can be calculated in the following way:
in the above formula (2), wherein yiIs a crystal x0A plurality of crystals facing each other, n being crystal yiS is a global scaling factor, ensuring an efficiency average of 1.
In step 413, the data correction factor is adjusted by the pre-stored energy factor conversion coefficient, so as to obtain the application data correction factor.
In this example, the crystal on which the 589KeV β particles are located is considered as an emission source, and its efficiency is 1; gamma particles of 202KeV and 307KeV are incident on another crystal and detected, and the efficiency of this part is not equal to 1 and needs to be calculated. In practice, however, in the clinical application scenario of a PET device, the received gamma photon energy is 511 KeV. Energy inconsistencies can cause deviations in the calculated data correction factors. The partial deviation is caused by double output inconsistency of the crystal in photoelectric absorption of particles with different energies, and is caused by corresponding inconsistency of the back-end electronic circuit in different input currents/voltages. For example, the efficiency of a crystal may vary for different energetic particles.
In order to reduce the calculation difference of the data correction factors caused by different particle energies, the data correction factor obtained in step 412 can be adjusted through the pre-stored energy factor conversion coefficient, so that a factor which can be used in clinical application, namely the data correction factor in clinical application of annihilation radiation, which is called as application data correction factor, can be obtained.
The energy factor conversion coefficient is used to represent the correlation between the particle energy of the background radiation and the data correction factor at the particle energy of the annihilation radiation, and can be obtained as follows: before the PET equipment leaves the factory, the calculation of the energy factor conversion coefficient is carried out, taking the crystal efficiency calculation as an example, as follows:
scanning background radiation data of the PET device, performing source consistency correction on the background radiation data, performing the method in step 412, and calculating crystal efficiency of each crystal at background energybkg. Scanning a phantom that ensures that each crystal receives a uniform 511KeV photon, such as a cylindrical source injected with F18 or Ge68, a rod source rotating around the inner wall of the field of view, etc., and calculating the efficiency of each crystal at 511KeV energy using the method of step 412511. Then, the energy factor conversion coefficient C of each crystal is calculated511/bkg。
Finally, the energy factor conversion coefficient of each crystal is saved in the memory of the PET device, and when the device status calibration is performed subsequently by performing the process shown in fig. 4 on the user site, the energy factor conversion coefficient is multiplied by the intrinsic efficiency of the crystal calculated by using the background radiation data in step 413, so as to obtain the intrinsic efficiency of the crystal applied to the clinical scene. For example, by multiplying the energy factor conversion coefficient and the crystal efficiency at the background energy, the crystal efficiency at 511KeV can be obtained:511＝bkgc. For any two crystals a and b in the apparatus, the crystal efficiencies at 511KeV were used respectivelyaAndbshowing the crystal efficiency corresponding to the response line formed by the pair of crystalsab＝a·b. ThereinaAndbis the crystal efficiency of the crystal at 511 KeV. The factorabCan be directly used for crystal efficiency correction of clinical data, and is an application data correction factor.
In step 414, the image reconstruction data acquired by the detection crystal is corrected based on the application data correction factor. For example, the crystal efficiency calculated in substep 413 of this example may be usedabFor clinical dataAccording to the crystal efficiency correction.
According to the device calibration method, the data correction factor is calculated by using background radiation data, and the application data correction factor capable of being clinically applied can be obtained by adjusting the energy factor conversion coefficient, so that not only can the daily state be detected by using the background, but also automatic adjustment in certain aspects can be performed on the device, such as crystal efficiency, the device is ensured to be in a better state, and the working efficiency is improved; moreover, PET users do not need to consider the cost of purchasing external sources, the trouble caused by replacing external sources and disposing waste external sources, automatic calibration of the equipment can be achieved according to background radiation data, and the use cost of the equipment is reduced.
The functionality of the device calibration method of the present disclosure, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present disclosure may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a control and processing device to execute all or part of the steps of the method according to the embodiments of the present disclosure. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
As mentioned above, a PET system is provided in examples of the present disclosure and, in conjunction with the illustration of FIG. 2, may include a PET detector, detection processing circuitry, a controller, and a memory. Wherein the PET detectors and the detection processing circuitry may be located in the gantry 21 of fig. 2, the gantry 21 is connected to a controller 22, and the controller 22 may retrieve data stored in a memory 23.
The PET system may acquire scan data for background radiation of a crystal, which may be a detection crystal in the PET detector, via the detection processing circuitry, and may determine from the scan data whether the current state of the PET device needs to be adjusted via the controller 22. The controller 22 may further obtain a data correction factor according to the scanning data of the background radiation when the PET device needs to be adjusted, adjust the factor through the energy factor conversion coefficient, obtain an application data correction factor, and correct the image reconstruction data of the PET device by using the application data correction factor.
For the above processing procedure of the PET system, reference may be made to the method embodiment, which is not described herein again. For example, the detection processing circuitry may mark the energy and receive the crystal identification for a single event acquired as scan data is acquired. The controller may perform a source uniformity correction on the probe crystal based on the energy signature and the received crystal signature. And after source consistency correction is completed, a data correction factor can be obtained from the scan data.
The PET system of this example can be enabled by the detection processing circuitry to mark an energy signature and receive a crystal signature for detecting a single event, so that source consistency correction can be performed on the crystal, laying the basis for the calculation of the data correction factor; moreover, the controller in the system can also adjust the data correction factor through the energy factor conversion coefficient to obtain the application data correction factor finally used for correcting the image reconstruction data. The system can adjust the equipment state by using the scanning data of the crystal background radiation, and does not need to use an external source, thereby saving the use cost of the PET equipment.
Examples of the present disclosure also provide a computer-readable storage medium having instructions stored thereon, which when executed by one or more processors, cause the one or more processors to perform a data processing method, the method comprising: acquiring scanning data of background radiation of a detection crystal;
determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation;
and correcting the image reconstruction data acquired by the detection crystal according to the application data correction factor.
The above description is only exemplary of the present disclosure and should not be taken as limiting the disclosure, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (10)
1. A method of device calibration, the method comprising:
acquiring scanning data of background radiation of a detection crystal;
determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation; the energy factor conversion coefficient is stored in advance;
correcting image reconstruction data acquired by the detection crystal according to the application data correction factor;
after the determining, according to the scan data, that the device state is to be adjusted, the method further includes:
storing the scan data to a data set of accumulated scan data;
determining whether the data set is full;
if not, continuously acquiring the scanning data of the background radiation and continuously storing the scanning data to the data set; and if the scanning data is full, executing the step of obtaining a data correction factor according to the scanning data.
2. The method of claim 1, wherein the scan data comprises single events and coincident events;
the single event comprises an energy identifier and a receiving crystal identifier, the energy identifier represents the particle energy corresponding to the single event, and the receiving crystal identifier represents the crystal of the single event detected;
the coincident events comprise single event pairs meeting time coincidence conditions.
3. The method of claim 2, wherein prior to deriving the data correction factor from the scan data, further comprising:
acquiring the statistical count of the single event corresponding to 589KeV particles received by the same crystal accumulatively according to the energy identifier and the received crystal identifier in the data set of the accumulated scanning data;
taking the reciprocal of the statistical count as a source identity correction factor for the crystal;
and utilizing the source consistency correction factor to carry out consistency correction on the scanning data corresponding to the crystal.
4. The method of claim 1, wherein determining the device status as to be adjusted based on the scan data comprises:
obtaining consistency data and time data according to the scanning data;
and comparing the consistency data and the time data with reference data, and if the consistency data and the time data exceed a preset threshold range, determining that the equipment state is to be adjusted.
5. The method of claim 1, wherein the data correction factor comprises at least one of: a crystal intrinsic efficiency, a crystal interference factor, a Block efficiency factor, or a geometric efficiency factor.
6. A PET system, characterized in that the system comprises: the system comprises a PET detector, a detection processing circuit, a controller and a memory; the memory includes: reference data and computer instructions executable on the controller;
the PET detector includes a detection crystal having background radiation;
the detection processing circuit is used for acquiring scanning data of background radiation of the detection crystal;
the controller, when executing the computer instructions in the memory, performs the steps of:
comparing the scanning data according to the reference data to determine that the equipment state is to be adjusted;
obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation; the energy factor conversion coefficient is stored in advance;
correcting image reconstruction data of the device according to the application data correction factor;
after the device state is determined to be adjusted according to the scanning data, the method further comprises the following steps:
storing the scan data to a data set of accumulated scan data;
determining whether the data set is full;
if not, continuously acquiring the scanning data of the background radiation and continuously storing the scanning data to the data set; and if the scanning data is full, executing the step of obtaining a data correction factor according to the scanning data.
7. The system of claim 6,
the detection processing circuit, when configured to acquire the scan data, includes: detecting a high-energy single event and a low-energy single event of background radiation through a plurality of energy windows for filtering different energy particles respectively, and marking an energy identifier and a received crystal identifier for the detected single event, wherein the energy identifier represents the particle energy corresponding to the single event, and the received crystal identifier represents the crystal of the detected single event; and obtaining the coincident events according to the single event pairs meeting the time coincidence conditions.
8. The system of claim 7, wherein the controller, when executing the computer instructions in the memory, is further configured to:
acquiring the statistical count of the single event corresponding to 589KeV particles received by the same crystal accumulatively according to the energy identifier and the received crystal identifier in the data set of the accumulated scanning data;
taking the reciprocal of the statistical count as a source identity correction factor for the crystal;
and utilizing the source consistency correction factor to carry out consistency correction on the scanning data corresponding to the crystal.
9. The system of claim 6, wherein the data correction factor comprises at least one of: a crystal intrinsic efficiency, a crystal interference factor, a module efficiency factor, or a geometric efficiency factor.
10. A computer-readable storage medium having instructions stored thereon, which when executed by one or more processors, cause the one or more processors to perform a method of data processing, the method comprising:
acquiring scanning data of background radiation of a detection crystal;
determining the equipment state to be adjusted according to the scanning data, and obtaining a data correction factor according to the scanning data;
adjusting the data correction factor through an energy factor conversion coefficient to obtain an application data correction factor, wherein the energy factor conversion coefficient is used for representing the correlation between the particle energy of background radiation and the data correction factor under the particle energy of annihilation radiation; the energy factor conversion coefficient is stored in advance;
correcting image reconstruction data acquired by the detection crystal according to the application data correction factor;
after the determining, according to the scan data, that the device state is to be adjusted, the method further includes:
storing the scan data to a data set of accumulated scan data;
determining whether the data set is full;
if not, continuously acquiring the scanning data of the background radiation and continuously storing the scanning data to the data set; and if the scanning data is full, executing the step of obtaining a data correction factor according to the scanning data.
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| CN112014870A (en) * | 2019-05-31 | 2020-12-01 | 佳能医疗系统株式会社 | Radiation detection device, energy correction method, and program |
| CN110301926B (en) * | 2019-07-04 | 2023-05-30 | 沈阳智核医疗科技有限公司 | Method, apparatus, storage medium and medical device for determining inherent efficiency of crystal |
| CN110687585B (en) * | 2019-09-23 | 2021-05-11 | 上海联影医疗科技股份有限公司 | Method, device, computer equipment and storage medium for obtaining crystal efficiency |
| CN111568453A (en) * | 2020-05-25 | 2020-08-25 | 上海联影医疗科技有限公司 | Energy correction state detection method, energy correction state detection device, computer equipment and storage medium |
| CN111568452A (en) * | 2020-05-25 | 2020-08-25 | 上海联影医疗科技有限公司 | PET system state detection method, PET system state detection device, computer equipment and storage medium |
| JP7512440B2 (en) | 2020-05-25 | 2024-07-08 | 上海聯影医療科技股▲ふん▼有限公司 | Method and system for detecting the state of an image forming apparatus |
| CN111887875B (en) * | 2020-08-21 | 2024-04-23 | 上海联影医疗科技股份有限公司 | PET device correction method, PET device correction device, computer device and storage medium |
| CN117202852A (en) * | 2021-06-08 | 2023-12-08 | 中加健康工程研究院(合肥)有限公司 | Method, apparatus, system, medium and program for detecting crystal efficiency of PET device |
| CN113712584B (en) * | 2021-09-30 | 2024-06-18 | 上海联影医疗科技股份有限公司 | PET scanning method, device, electronic device and storage medium |
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