Proton range verification method, apparatus and computer-readable storage medium

Abstract

This application provides a proton range verification method, apparatus, and computer-readable storage medium, comprising: calculating a time integration factor corresponding to a positron-emitting nuclide; calculating the activity distribution after removing the positron-emitting nuclide using the time integration factor; calculating the gradient sequence difference before and after removing the positron-emitting nuclide using the original activity distribution and the activity distribution after removing the positron-emitting nuclide; and determining the proton range of action using the gradient sequence difference. According to the example embodiments of this application, it is at least possible to directly remove the contribution of a specific positron-emitting nuclide from the mixed signal of the activities of multiple positron-emitting nuclides, providing a more accurate proton depth range of action.

Description

Technical Field

[0001] This application relates to the field of data processing, and more specifically, to a proton range verification method, apparatus, and computer-readable storage medium. Background Technology

[0002] During proton therapy, when a proton enters the body, it forms a sharp dose peak at the end of its range, called the Bragg peak. By modulating the energy broadening, the Bragg peak can be made to cover the tumor, thus achieving the therapeutic goal. During this process, the proton rays simultaneously induce the production of a series of particles, such as positron-emitting nuclides (e.g., radioactive isotopes of oxygen, carbon, and nitrogen). The decay of these positron-emitting nuclides then produces positrons. Clinically, PET (Position Emission Tomography) can image the signals emitted by the positron-induced positron-emitting nuclides, thereby obtaining the proton-induced activity distribution and achieving the purpose of monitoring proton therapy. Because the proton-induced positron-emitting nuclide activity distribution is related to the proton dose deposition range, the difference is approximately 2–13 mm. Since proton induction is dominated by two different physical processes, the correlation and underlying mechanism between the positron-emitting nuclide activity distribution and the proton dose deposition range have not yet been fully understood.

[0003] Previously, indirect range validation processes were commonly used, mainly including the following two methods: The first method involved obtaining an ideal activity distribution through Monte Carlo simulation of the treatment plan or convolution of the planned dose distribution with a filter function, and then verifying the ideal activity distribution against the measured activity distribution. The second method involved obtaining an estimated dose distribution through deconvolution of the measured activity distribution with a filter function or iterative optimization of the measured activity distribution, and then verifying the estimated dose distribution against the planned dose distribution.

[0004] The two indirect range validation processes described above have several drawbacks. While both processes involve comparing intermediate distributions with known distributions for verification, the process of solving for these intermediate distributions introduces new uncertainties due to various factors, including a lack of accurate nuclear reaction cross-section databases, a lack of in-depth understanding of the biophysical mechanisms of biological scour effects, high variable complexity in clinical treatment scenarios, approximate constraint assumptions in solving inverse problems, and the introduction of multiple stretching adjustment factors. Furthermore, indirect range validation processes often involve multiple steps, complex simulations and calculations, and significant time consumption, thus limiting the clinical feasibility of online range validation.

[0005] Protons undergo inelastic nuclear reactions with atomic nuclei, and positron-emitting nuclides produced via the (p, n) pathway have a high reaction threshold. However, channels such as (p, α) and (p, γ) also exist, with reaction thresholds much lower than the former. A lower reaction threshold means closer proximity to the Bragg peak. If the effective range of positron-emitting nuclides with low reaction thresholds can be extracted, it could potentially provide reliable absolute depth information for online monitoring of proton therapy. Based on this principle, a method for proton range verification using early and late PET scans has been proposed. Studies have found that the difference between the depth range extracted by this method and the proton range is 4-5 mm, a difference that holds promise for direct range verification. The specific operational steps include:

[0006] The first step is to collect signals. Two sets of data are collected after the proton beam irradiation ends. The first set is collected for 3 minutes 1 minute after the irradiation ends; the second set is collected for 10 minutes 21 minutes after the irradiation ends.

[0007] The second step is to extract the activity distribution and reconstruct the one-dimensional activity distribution of the two sets of data respectively.

[0008] The third step is to calculate the depth range by calculating the gradient distribution of the two activity distributions, finding the difference between the gradient distributions, and defining the peak position of the gradient difference along the region where the activity decreases as the target depth range.

[0009] Since the proton range verification method essentially utilizes the differences in signal composition resulting from the natural decay of positron-emitting nuclides after proton beam irradiation, an indoor PET monitoring mode is adopted to wait for the natural compositional differences to occur. On the one hand, this severely impacts the acquisition time pattern of the clinical workflow, which is unacceptable for clinical applications; on the other hand, issues such as patient repositioning and biological flushing effects also affect the localization accuracy of this method. Summary of the Invention

[0010] This application provides a proton range verification method, apparatus, and computer-readable storage medium to solve at least one of the above-mentioned problems.

[0011] According to one aspect of this application, a proton range verification method is proposed, the proton range verification method comprising: calculating a time integration factor corresponding to a positron-emitting nuclide; calculating an activity distribution after removing the positron-emitting nuclide using the time integration factor; calculating a gradient sequence difference before and after removing the positron-emitting nuclide using the original activity distribution and the activity distribution after removing the positron-emitting nuclide; and determining the proton action range using the gradient sequence difference.

[0012] According to some embodiments, before calculating the time integration factor corresponding to the positron-emitting nuclide, positron-emitting nuclide signals for two time periods are acquired, and signal processing and image reconstruction are performed to obtain PET images.

[0013] According to some embodiments, the calculation of the time integration factor corresponding to the positron-emitting nuclide includes: calculating the time integration factor of the positron-emitting nuclide in the first time period and the time integration factor of the positron-emitting nuclide in the second time period.

[0014] According to some embodiments, the time integration factor of the positron-emitting nuclide in the first time period and the positron-emitting nuclide time integration factor in the second time period are calculated using formula (1):

[0015]

[0016] Among them, I iΔt t is the time integration factor for the i-th positron-emitting nuclide in the first time period or the second time period. start t represents the start time of either the first or second time period. end τ represents the end time of the first time period or the end time of the second time period. i t is the decay constant of a positron-emitting nuclide. irr t represents the proton beam irradiation time.

[0017] According to some embodiments, the activity distribution after removing the positron-emitting nuclide is calculated using formula (2):

[0018]

[0019] Among them, A w / oi (j) represents the activity distribution after removing the positron-emitting nuclide, A Δt1 (j) represents the measured activity value of the j-th voxel in the depth direction during the first time period, A Δt2 (j) represents the measured activity value of the j-th voxel in the depth direction during the second time period, I iΔt1 I is the time integration factor of the positron-emitting nuclide in the first time period. iΔt2 This is the time integration factor for the positron-emitting nuclide in the second time period.

[0020] According to some embodiments, the original activity distribution includes: the activity distribution of positron-emitting nuclides in a first time period and the activity distribution of positron-emitting nuclides in a second time period.

[0021] According to some embodiments, the gradient sequence difference before and after the removal of the positron-emitting nuclide is calculated using formula (14):

[0022] ΔG(j)=G(j)-G w / oi (j) Formula (14)

[0023] Where ΔG(j) is the gradient sequence difference before and after the removal of the positron-emitting nuclide, G(j) is the gradient sequence of the original activity, and G w / oi (j) is the gradient sequence of the activity distribution after removing the positron-emitting nuclide.

[0024] According to some embodiments, before calculating the gradient sequence difference before and after removing the positron-emitting nuclide, the original activity distribution and the activity distribution after removing the positron-emitting nuclide are normalized respectively, and the gradient sequence difference is calculated using the normalized activity distribution.

[0025] According to some embodiments, the original activity distribution and the activity distribution after removing the positron-emitting nuclide are normalized using formula (3), respectively.

[0026]

[0027] Where A′(j) is the normalized activity distribution of the j-th voxel, and A(j) is the activity distribution of the j-th voxel. When the activity distribution is normalized after removing the main nuclide, A(j) = A w / oi min(A(j)) and max(A(j)) are the minimum and maximum values ​​of the activity value of the j-th individual, respectively.

[0028] According to some embodiments, the gradient sequence of two sets of normalized activity distributions is calculated using formula (13):

[0029] G(j)=A′(j)-A′(j-1) Formula (13).

[0030] According to some embodiments, before calculating the gradient sequence difference before and after the removal of the positron-emitting nuclide, the gradient sequences before and after the removal of the positron-emitting nuclide are normalized respectively, and the gradient sequence difference is calculated using the normalized gradient sequence value.

[0031] According to some embodiments, the gradient sequence before and after the removal of the positron-emitting nuclide is normalized using formula (B) or formula (C):

[0032]

[0033] Where G′(j) is the normalized value of the gradient sequence of the original activity distribution, G(j) is the gradient sequence of the original activity distribution or the normalized original activity distribution, and min(G(j)) and max(G(j)) are the minimum and maximum values ​​of G(j), respectively.

[0034]

[0035] Among them, G′ w / oi (j) is the normalized value of the gradient sequence of the activity distribution of positron-free nuclides, G w / oi (j) represents the activity distribution of positron-removed nuclides or the gradient sequence of the normalized activity distribution of positron-removed nuclides, min(Gw / oi (j)) and max(G w / oi (j) respectively calculate G w / oi The minimum and maximum value functions of (j).

[0036] According to some embodiments, the normalization includes normalizing the original activity distribution and the activity distribution after removing the positron-emitting nuclide for the first time period or the second time period, respectively.

[0037] According to some embodiments, calculating the gradient sequence difference before and after removing the positron-emitting nuclide includes: calculating the gradient sequence difference using the gradient sequence of the activity distribution of the positron-emitting nuclide in the first time period or the second time period after normalization, and the gradient sequence of the original activity distribution after normalization.

[0038] According to some embodiments, calculating the gradient sequence difference before and after positron-removed nuclide includes: calculating the gradient sequences of the original activity distribution and the activity distribution after positron-removed nuclide, respectively, to obtain the original gradient sequence and the positron-removed nuclide gradient sequence; and calculating the gradient sequence difference between the original gradient sequence and the positron-removed nuclide gradient sequence.

[0039] According to some embodiments, at least one of the positron-emitting nuclides induced by proton beams is selected as the main nuclide, and the time integration factor corresponding to the main nuclide is calculated.

[0040] According to some embodiments, determining the proton action range using gradient sequence difference includes: determining the proton action range based on the maximum point of the gradient sequence difference.

[0041] According to some embodiments, when there is a local maximum point with an Euclidean distance in the vicinity of the intersection depth of the two sets of activity decline edges before and after the removal of the positron-emitting nuclide, the proton's range of action is the depth of the local maximum point; when there are two local maximum points with equal Euclidean distance in the vicinity of the intersection depth of the two sets of activity decline edges before and after the removal of the positron-emitting nuclide, the proton's range of action is the depth at the midpoint of the two local maximum points.

[0042] According to some embodiments, before calculating the time integration factor corresponding to the positron nuclide, the proton range verification method further includes: simultaneously acquiring at least one segment of positron nuclide signal data during the process of proton beam irradiation of the target.

[0043] According to some embodiments, after obtaining the activity distribution of the positron-removed nuclide, the proton range verification method further includes: using wavelet denoising to suppress high-frequency noise in the activity distribution after the positron-removed nuclide.

[0044] According to some embodiments, when the high-frequency noise of the activity distribution after removing positron-emitting nuclides is removed using wavelet denoising method, the determination of the proton's effective range based on the gradient sequence difference differs from the above determination method. The proton's effective range is the depth at the peak of the gradient sequence difference within the region of the activity decrease before and after the removal of positron-emitting nuclides.

[0045] According to one aspect of this application, a proton range verification method is proposed, the proton range verification method comprising: synchronously acquiring positron nuclide signal data during proton beam irradiation of a target; reconstructing the positron nuclide signal data and extracting a one-dimensional activity distribution; calculating the difference between gradient sequences of two sets of one-dimensional activity distributions; and determining the activity depth range of proton irradiation using the gradient sequence difference.

[0046] According to one aspect of this application, a proton range verification device is proposed, the proton range verification device comprising: a time integration factor calculation unit for calculating the time integration factor corresponding to a positron-emitting nuclide; a nuclide removal unit for calculating the activity distribution after removing the positron-emitting nuclide using the time integration factor; a gradient sequence calculation unit for calculating the gradient sequence difference before and after removing the positron-emitting nuclide using the original activity distribution and the activity distribution after removing the positron-emitting nuclide; and a proton action range calculation unit for determining the proton action range using the gradient sequence difference.

[0047] According to some embodiments, the proton range verification device further includes a data acquisition unit for synchronously acquiring positron nuclide signal data during the process of proton beam irradiation of the target.

[0048] According to one aspect of this application, a proton range verification device is proposed, the proton range verification device comprising: a data acquisition unit for synchronously acquiring positron nuclide signal data during proton beam irradiation of a target; an activity distribution extraction unit for reconstructing the positron nuclide signal data and extracting a one-dimensional activity distribution; a gradient sequence calculation unit for calculating a gradient sequence difference using gradient sequences of two sets of the one-dimensional activity distribution; and a proton action range calculation unit for determining the proton action range based on the gradient sequence difference.

[0049] According to one aspect of this application, a proton range verification apparatus is provided, comprising: one or more processors; a storage device for storing a computer program; and, when the computer program is executed by the one or more processors, causing the one or more processors to implement the proton range verification method as described above.

[0050] According to one aspect of this application, a computer-readable storage medium is provided having program instructions stored thereon, which, when executed, implement the proton range verification method as described above.

[0051] According to an example embodiment of this application, by decomposing the activity distribution of proton-induced positron-emitting nuclides into time-dependent integral factors, the contribution of a specific positron-emitting nuclide can be directly removed from the mixed signal of multiple positron-emitting nuclide activities, providing a more accurate proton depth-of-effect range. Simultaneously extracting the range of low-reaction-threshold main nuclides online during proton beam irradiation for proton therapy range verification breaks through the existing technology's requirement for long acquisition time and avoids positioning inaccuracies caused by patient repositioning and biological flushing. This helps doctors optimize treatment plans, improve treatment efficacy, and maximize the treatment of cancerous tissue while avoiding damage to normal tissue. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0053] Figure 1 A flowchart of a proton range verification method according to an example embodiment of this application is shown;

[0054] Figure 2 A flowchart of a proton range verification method according to another example embodiment of this application is shown;

[0055] Figure 3 A flowchart of a proton range verification method according to yet another example embodiment of this application is shown;

[0056] Figure 4 A block diagram of a proton range verification apparatus according to an example embodiment of this application is shown;

[0057] Figure 5 A block diagram of a proton range verification apparatus according to another example embodiment of this application is shown;

[0058] Figure 6 A block diagram of a proton range verification apparatus according to yet another example embodiment of this application is shown;

[0059] Figure 7 A proton action range localization diagram obtained according to an example embodiment of this application is shown;

[0060] Figure 8 A block diagram of another proton range verification apparatus according to an embodiment of this application is shown. Detailed Implementation

[0061] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0062] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, apparatus, or operations may be employed. In these cases, well-known structures, methods, apparatuses, implementations, materials, or operations will not be shown or described in detail.

[0063] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0064] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0065] The specific embodiments according to this application will now be described in detail with reference to the accompanying drawings.

[0066] Figure 1 A flowchart of a proton range verification method according to an example embodiment of this application is shown. Refer below... Figure 1 This application provides a detailed description of a proton range verification method according to an example embodiment.

[0067] In step S101, the positron-emitting nuclide time integration factor corresponding to the positron-emitting nuclide is calculated.

[0068] According to some embodiments, before performing step S101, it is necessary to use a PET system to acquire the positron-induced positron nuclide signal, and perform signal processing and image reconstruction to obtain a PET activity image. It should be noted that there are no limitations on the PET system used for acquisition, as long as it can acquire the positron activity distribution induced by the proton beam and reconstruct the activity change curve over time, it can be applied to the example embodiments of this application.

[0069] The aforementioned positron-emitting nuclides include a variety of types, such as oxygen ( 15 O), carbon ( 11 C) and nitrogen ( 13 These positron-emitting nuclides (N) produce a large number of positrons during decay. These positrons combine with electrons in the surrounding environment to produce annihilation events. Each annihilation event corresponds to a pair of gamma photons traveling in opposite directions with the same energy. The positron-emitting nuclide signal acquired by the PET system is the signal corresponding to the gamma photons. Typically, the PET system uses a scintillation crystal to convert the gamma photons into visible light signals, and a photoelectric conversion device coupled to the scintillation crystal to convert the visible light signals into electrical signals. The electrical signals are then sampled to obtain digital signals for signal processing.

[0070] According to some example embodiments of this application, before performing step S101, positron-emitting nuclide signals for two time periods are acquired, and signal processing and image reconstruction are performed to obtain PET images. These two time periods are preferably located before the end of proton beam irradiation. For example, if the decay of positron-emitting nuclides takes one hour after the end of proton beam irradiation, it is preferable to acquire positron-emitting nuclide signals for two time periods in the first half hour after the end of proton beam irradiation, such as minutes 1-3 and minutes 3-5 after the end of proton beam irradiation.

[0071] According to some example embodiments of this application, in step S101, after obtaining the positron-emitting nuclide signals of two time periods, the time integration factor of the positron-emitting nuclide in the first time period and the time integration factor of the positron-emitting nuclide in the second time period are calculated respectively.

[0072] According to some embodiments, in step S101, the time integration factor of the positron nuclide in the first time period and the time integration factor of the positron nuclide in the second time period are calculated by formula (1).

[0073]

[0074] Among them, I iΔt t is the time integral factor for the i-th positron-emitting nuclide in the first or second time period. start t represents the start time of either the first or second time period. end τ represents the end time of the first time period or the end time of the second time period.i Let t be the decay constant of the i-th positron-emitting nuclide. irr The duration of proton beam irradiation is t, where t is time.

[0075] It should be noted that the time points for distinguishing between the two time periods are not fixed, as long as the amount of data in both time periods can be sufficient to obtain high-quality reconstructed PET activity images.

[0076] According to some exemplary embodiments of this application, in step S101, it is preferable to calculate the main nuclide time integration factor corresponding to the main nuclide. The main nuclide can be any of the positron-emitting nuclides induced by proton beams, for example, oxygen, which is usually mainly distributed in the human body, is selected. 15 O is chosen as the main nuclide because the oxygen production is relatively high and the reaction threshold is relatively low, which masks the activity peaks of the (p, α) and (p, γ) low reaction threshold channels of interest.

[0077] In step S103, the activity distribution after removing the positron-emitting nuclide is obtained based on the result of step S101.

[0078] According to some example embodiments of this application, the activity distribution after removing positron-emitting nuclides is calculated by formula (2).

[0079]

[0080] Among them, A w / oi (j) represents the activity distribution after removing the positron-emitting nuclide, A Δt1 (j) represents the measured activity value of the j-th voxel in the depth direction during the first time period, A Δt2 (j) represents the measured activity value of the j-th voxel in the depth direction during the second time period, I iΔt1 I is the time integration factor of the positron-emitting nuclide in the first time period. iΔt2 This is the time integration factor for the positron-emitting nuclide in the second time period.

[0081] According to some embodiments, after obtaining the activity distribution of the positron-free nuclide, the method further includes: removing high-frequency noise from the activity distribution after removing the positron-free nuclide using a denoising method.

[0082] For example, wavelet denoising can be used to remove high-frequency noise from the activity distribution of positron-emitting nuclides. Wavelet denoising can be performed using formula (A):

[0083]

[0084] Among them, T l Let D be the denoising threshold for the l-th layer, and median denote the median function. lLet be the detail coefficients of the l-th layer decomposition, N be the length of the activity distribution data after removing positron-emitting nuclides, and l be the wavelet decomposition scale. Those skilled in the art can select the number of wavelet denoising layers, wavelet basis, detail coefficients, and wavelet decomposition scale according to actual needs.

[0085] In step S105, the gradient sequence difference before and after removing the positron-emitting nuclide is calculated using the original activity distribution and the activity distribution after removing the positron-emitting nuclide.

[0086] According to some example embodiments of this application, the original activity distribution includes a positron-emitting nuclide activity distribution over a first time period and a positron-emitting nuclide activity distribution over a second time period.

[0087] It should be noted that the size and location of the cross-sectional region when extracting the original activity distribution are not fixed; it only needs to be extracted within the irradiated area of ​​the target. It is important to note that the more pixel lines included, the less noise caused by statistical fluctuations, and the smoother the extracted activity distribution will be along the beam transport path.

[0088] According to some example embodiments of this application, the gradient sequence difference before and after the removal of the positron-emitting nuclide is calculated using formula (14):

[0089] ΔG(j)=G(j)-G w / oi (j) Formula (14)

[0090] Where ΔG(j) is the gradient sequence difference before and after the removal of the positron-emitting nuclide, G(j) is the gradient sequence of the original activity distribution, and G w / oi (j) is the gradient sequence of the activity distribution after removing the positron-emitting nuclide.

[0091] According to some example embodiments of this application, in step S105, the original activity distribution and the activity distribution after removing the main nuclide are normalized respectively, and the gradient sequence difference is calculated using the normalized activity distribution.

[0092] According to the example embodiments of this application, the original activity distribution and the activity distribution after removing the main nuclide are normalized by formula (3).

[0093]

[0094] Where A(j) is the activity distribution of the j-th voxel. When the activity distribution is normalized after removing the main nuclide, A(j) takes the value of A in formula (2). w / oi A′(j) is the normalized activity distribution of the j-th voxel, and min(A(j)) and max(A(j)) are the minimum and maximum value functions for calculating the activity value of the j-th voxel, respectively.

[0095] According to some example embodiments of this application, the gradient sequences of the two sets of normalized activity distributions are calculated using formula (13):

[0096] G(j)=A′(j)-A′(j-1) Formula (13)

[0097] Here, G(j) is the gradient sequence of the original activity distribution after normalization.

[0098] According to some example embodiments of this application, the gradient sequence difference between two sets of normalized activity distributions is calculated using formula (14):

[0099] ΔG(j)=G(j)-G w / oi (j) Formula (14)

[0100] In this embodiment, G(j) is the gradient sequence of the normalized original activity distribution. w / oi (j) is the gradient sequence of the activity distribution of positron-free nuclides after normalization.

[0101] According to some example embodiments of this application, before calculating the gradient sequence difference before and after removing the positron-emitting nuclide, the gradient sequence before and after removing the positron-emitting nuclide can be normalized again using formulas (B) and (C):

[0102]

[0103] Where G′(j) is the normalized value of the gradient sequence of the original activity distribution, G(j) is the gradient sequence of the original activity distribution or the normalized original activity distribution, and min(G(j)) and max(G(j)) are the minimum and maximum values ​​of G(j), respectively.

[0104]

[0105] Among them, G′ w / oi (j) represents the normalized gradient sequence value of the activity distribution after removing the positron-emitting nuclide, G w / oi (j) represents the activity distribution of positron-removed nuclides or the gradient sequence of the normalized activity distribution of positron-removed nuclides, min(G w / oi (j)) and max(G w / oi (j) respectively calculate G w / oi The minimum and maximum value functions of (j).

[0106] It is worth noting that normalizing the gradient sequence is similar to normalizing the activity distribution. However, by normalizing the gradient sequences before and after removing the positron-emitting nuclide, the characteristic peaks of the final determined gradient sequence difference can be made more significant, thereby more accurately determining the range of proton interaction depth.

[0107] In step S107, the activity depth range of proton irradiation is determined based on the gradient sequence difference obtained in step S105.

[0108] According to some example embodiments of this application, the proton activity depth range is obtained by calculating the local maximum point of the gradient sequence difference at the falling edge.

[0109] It should be noted that in step S107, when determining the proton action range based on the maxima of the gradient sequence difference, there are usually multiple maxima in the descent region. There are no restrictions on the method of selecting the maxima, but maxima with high stability of the localization result should be selected.

[0110] It is also worth noting that when the high-frequency noise of the activity distribution after removing the positron-emitting nuclide is removed using a denoising method, the determination of the proton's effective range based on the gradient sequence difference differs from the above method. The proton's effective range should be the depth at the peak of the gradient sequence difference within the region along the activity decrease before and after the removal of the positron-emitting nuclide.

[0111] according to Figure 1 The illustrated example embodiment, by decomposing the activity distribution of proton-induced positron-emitting nuclides into time-dependent integral factors, can directly remove the contribution of a specific positron-emitting nuclide from the mixed signal of multiple positron-emitting nuclide activities, providing a more accurate proton depth-of-effect range. This helps doctors optimize treatment plans, improve treatment outcomes, and maximize the treatment of cancerous tissue while avoiding damage to normal tissue.

[0112] The following is combined Figure 1 The embodiments shown provide a detailed explanation of the principles upon which they rely.

[0113] Positron-emitting nuclides produced by proton beam irradiation of a target undergo both "production" and "decay" processes simultaneously when the beam is turned on. The yield of positron-emitting nuclides in the target initially shows a gradual increase followed by a tendency to saturate. After irradiation for a period of time t... irr Afterwards, the proton beam is turned off, and no new radioactive nuclides will be produced, leaving only the "decay" process.

[0114] Since the branching ratio of the main radionuclides produced by the inelastic nuclear reaction between the proton beam and the human body is close to 1, the activity a of the positron-emitting nuclide i produced by a certain nuclear reaction channel at time t can be determined by neglecting the β+ decay branching ratio. i (t), for the cyclotron scenario, satisfies formula (4).

[0115]

[0116] For the synchrotron scenario, formula (5) is satisfied.

[0117]

[0118] Where Φ is the intensity of the proton beam, measured in protons·cm. -2 ·s -1 N represents the total number of target atoms within the target body; σ represents the reaction cross-section of the corresponding nuclear reaction channel, in units of 10. -24 cm 2 ;y i Let y be the pure production rate of positron-emitting nuclide i during irradiation, neglecting decay processes, which remains constant throughout the same irradiation. i =ΦNσ;τ i This represents the decay constant of positron-emitting nuclide i; the unit is s. -1 ;t irr t is the duration of proton beam irradiation. s t is the time for one beam extraction from the synchrotron. p This refers to the time of one beam gap in a synchrotron.

[0119] Over any given time interval Δt, the total activity A contributed by positron-emitting nuclide i i This is the integral of formula (4) or formula (5) with respect to time t. The total activity can be decomposed into a time-invariant yield factor Y. i and the time-dependent positron-emitting nuclide time integral factor I iΔt The product of is shown in formulas (6) to (8). As shown in formula (7), the time-invariant yield factor Y i The expression varies depending on the type of accelerator.

[0120]

[0121]

[0122]

[0123] The linear superposition of multiple positron-emitting nuclides induced by the proton beam together constitutes the total induced activity distribution, as shown in formula (9).

[0124] A Δt =∑ i A iΔt =∑ i Y i I iΔt Formula (9)

[0125] Time-invariant factor Y iIt is difficult to calculate quickly and accurately, especially in complex clinical scenarios, due to the influence of factors such as beam flux, target tissue composition, and nuclear reaction cross-section. Therefore, the elimination method shown in formula (10) is used to remove Y. i .

[0126] Collect the total activity distribution A in the two time periods of formula (8). Δt1 and A Δt2 By transforming using formula (10), the activity distribution A of any positron-removed nuclide i can be obtained. w / oi .

[0127]

[0128] Among them, A w / oi To determine the activity distribution after removing the main nuclide, A Δt1 The activity distribution of positron-emitting nuclides in the first time period, A Δt2 For the positron-emitting nuclide activity distribution in the second time period, I iΔt1 I is the integral factor of the positron-emitting nuclide in the first time period. iΔt2 This is the integral factor for positron-emitting nuclides in the second time period.

[0129] In formula (10), dividing the total activity distribution by the time integral factor of positron-emitting nuclide i is equivalent to normalizing the activity contribution of positron-emitting nuclide i to the time-invariant factor Y. i Therefore, subtracting the two terms removes the contribution of positron-emitting nuclide i to the activity.

[0130] Formula (9) is the total activity based on the time domain, but in practical applications, the total activity value obtained in the depth direction is obtained in PET image-based measurements. Therefore, formulas (9), (11), and (12) show the total activity based on the spatial domain.

[0131] make,

[0132] A Δt (j)=∑ i w i,j Y i I iΔt Formula (11)

[0133]

[0134] Among them, A Δt (j) represents the measured activity value of voxel j in the depth direction; w i,j is the activity weighting factor of the total activity of positron-emitting nuclide i at the j-th voxel position, reflecting the unit spatial distribution of positron-emitting nuclide i induced by protons.

[0135] Since each proton irradiates the target independently, the total activity of the positron-emitting nuclide increases with the accumulation of the number of protons. After irradiation, the activity of the positron-emitting nuclide in each voxel decays independently over time, showing a decrease. However, the activity weighting factor reflecting the unit spatial distribution of a certain positron-emitting nuclide remains constant.

[0136] Because of Y i and w i,j Both are time-invariant, and formula (10) can be directly extended to formula (2) in the spatial domain. The activity distribution after removing positron-emitting nuclide i can be obtained through formula (2). Then, the activity before and after the removal of the nuclide can be normalized using formula (3). Alternatively, a smooth activity distribution after removing positron-emitting nuclide i can be obtained by wavelet denoising.

[0137] Define the depth of the intersection point of the normalized activities of the two groups before and after the removal of the nuclide as R1, and use formula (13) to calculate the gradient sequence of the normalized activities of the two groups respectively.

[0138] G(j)=A′(j)-A′(j-1) Formula (13)

[0139] The gradient sequence difference between the two sets of normalized activities is calculated using formula (14).

[0140] ΔG(j)=G(j)-G w / oi (j) Formula (14)

[0141] The local maximum point of the gradient sequence difference at the falling edge is calculated using formula (14), which is the range of proton action.

[0142] According to some embodiments, if there is a local maximum point with the closest Euclidean distance near R1, then the depth of that point is the target depth to be extracted. If there are two local maximum points with equal Euclidean distance, then the midpoint between the two points, i.e., R1, is the target depth to be extracted.

[0143] Based on the above Figure 1 As can be seen from the detailed description of the principles upon which the illustrated embodiments rely, the exemplary embodiments of this application decompose the activity distribution of proton-induced positron-emitting nuclides into a time-invariant yield factor and a time-varying integral factor, making it possible to remove the contribution of the activity of a specific positron-emitting nuclide to the total activity.

[0144] Figure 2 A flowchart of a proton range verification method according to another example embodiment of this application is shown. (Refer to below) Figure 2 The proton range verification method according to the example embodiments of this application will be described in detail.

[0145] In step S201, positron nuclide signal data are collected simultaneously during the process of proton beam irradiation of the target.

[0146] According to an example embodiment of this application, a PET system combined with a proton therapy system is used to acquire positron-induced positron-emitting nuclide signals, and signal processing and image reconstruction are performed to obtain PET activity images. It should be noted that the combination of the PET system used for acquisition and the proton therapy system is preferably in the form of PET embedded in the proton therapy system, because the operation of the proton therapy system does not affect the operation of the PET system, and the information acquisition between the two is independent of each other.

[0147] According to some example embodiments of this application, during step S201, positron-emitting nuclide signals from two time periods are simultaneously acquired during the proton beam irradiation of the target, and signal processing and image reconstruction are performed respectively to obtain PET images. Both time periods are within the proton beam irradiation process. For example, if the total proton beam irradiation time is 120 seconds, the PET system can be activated to continuously acquire data for 120 seconds throughout the irradiation process. The data from the first 80 seconds of irradiation is used as the first set of positron-emitting nuclide signal data, and the data from the last 40 seconds is used as the second set of positron-emitting nuclide signal data.

[0148] According to some example embodiments of this application, during step S201, at least one time period of positron-emitting nuclide signal is simultaneously acquired during the proton beam irradiation of the target, and another time period of positron-emitting nuclide signal is acquired after irradiation. Signal processing and image reconstruction are then performed respectively to obtain a PET image. For example, if the total proton beam irradiation time is 120 seconds, the PET system can be continuously acquiring data for 80 seconds during the entire irradiation process. This 80-second data is used as the first set of positron-emitting nuclide signal data, and then 1 minute of data is acquired after irradiation as the second set of positron-emitting nuclide signal data.

[0149] All technical means not mentioned in step S201 above can be combined with Figure 1 The same applies to the embodiments, and will not be repeated here.

[0150] In step S203, positron-emitting nuclide signal data is reconstructed based on the data obtained in step S201, and a one-dimensional activity distribution is extracted.

[0151] In step S205, the difference between the gradient sequences of the two sets of one-dimensional activity distributions is calculated.

[0152] In step S207, the activity depth range of proton irradiation is determined using gradient sequence difference.

[0153] In steps S203-S207 above, other unmentioned technical means can be the same as those in the prior art, and will not be described in detail here.

[0154] according to Figure 2 The illustrated example embodiment can simultaneously acquire positron-emitting nuclide signal data during proton beam irradiation without waiting for the natural decay of each component positron-emitting nuclide. This allows for "online" provision of the proton interaction depth range, saving acquisition time in clinical procedures and overcoming the limitations of existing technologies regarding acquisition duration. It also avoids inaccuracies caused by patient repositioning and biological flushing. Furthermore, the earlier acquisition timeframe means more accurate signals, helping doctors optimize treatment plans and improve treatment outcomes.

[0155] Figure 3 A flowchart of a proton range verification method according to yet another example embodiment of this application is shown. Referring below... Figure 3 The proton range verification method according to the example embodiments of this application will be described in detail.

[0156] In step S301, positron-emitting nuclide signal data are simultaneously acquired during the proton beam irradiation of the target. This step can be combined with... Figure 2 The steps in step S201 are the same and will not be repeated here.

[0157] In step S303, the positron-emitting nuclide time integration factor corresponding to the positron-emitting nuclide is calculated.

[0158] According to some example embodiments of this application, after obtaining the positron nuclide signals of two time periods in step S303, the time integration factor of the main nuclide in the first time period and the time integration factor of the main nuclide in the second time period can be calculated by formula (1).

[0159] In step S305, the activity distribution after removing the positron-emitting nuclide is obtained based on the result of step S303.

[0160] According to some example embodiments of this application, in step S303, the activity distribution after removing the positron-emitting nuclide can be calculated by formula (2).

[0161] In step S307, the gradient sequence difference before and after removing the positron-emitting nuclide is calculated using the original activity distribution and the activity distribution after removing the positron-emitting nuclide.

[0162] According to some example embodiments of this application, the gradient sequence difference before and after the removal of the positron-emitting nuclide can be calculated using formula (14).

[0163] According to some example embodiments of this application, in step S307, the original activity distribution and the activity distribution after removing the main nuclide can be normalized by formula (3) before calculating the gradient sequence difference, and the gradient sequence difference can be calculated using the normalized activity distribution.

[0164] According to some example embodiments of this application, the gradient sequences of two sets of normalized activity distributions are calculated using formula (13).

[0165] According to some example embodiments of this application, the gradient sequence difference between two sets of normalized activities is calculated using formula (14).

[0166] In step S309, the activity depth range of proton irradiation is determined based on the gradient sequence difference obtained in step S307.

[0167] According to some example embodiments of this application, the proton activity depth range is obtained by calculating the local maximum point of the gradient sequence difference at the falling edge.

[0168] It should be noted that the parts not detailed in steps S303-S309 can be referred to Figure 1 The embodiments described herein will not be repeated here.

[0169] according to Figure 3 The illustrated embodiment not only allows for the simultaneous acquisition of positron-emitting nuclide signal data during proton beam irradiation, eliminating the need to wait for the natural decay of individual positron-emitting nuclides and thus providing the proton depth range "online," saving acquisition time in clinical procedures, but also, by decomposing the activity distribution of proton-induced positron-emitting nuclides into time-dependent integral factors, it can directly remove the contribution of a specific positron-emitting nuclide from the mixed signal of multiple acquired positron-emitting nuclide activities, providing a more accurate proton depth range. This helps physicians optimize treatment plans, improve treatment outcomes, and maximize the treatment of cancerous tissue while avoiding damage to normal tissue.

[0170] Figure 4 A block diagram of a proton range verification apparatus according to an example embodiment of this application is shown. Referring below... Figure 4 This application provides a detailed description of a proton range verification apparatus according to an example embodiment.

[0171] like Figure 4The proton range verification device shown includes a time integration factor calculation unit 401, a nuclide removal unit 403, a gradient sequence calculation unit 405, and a proton action range calculation unit 407. The time integration factor calculation unit 401 calculates the positron-emitting nuclide time integration factor corresponding to the positron-emitting nuclide. The nuclide removal unit 403 calculates the activity distribution after positron-emitting nuclide removal based on the positron-emitting nuclide time integration factor. The gradient sequence calculation unit 405 calculates the gradient sequence difference before and after positron-emitting nuclide removal using the original activity distribution and the activity distribution after positron-emitting nuclide removal. The proton action range calculation unit 407 determines the proton action range based on the gradient sequence difference.

[0172] Figure 5 A block diagram of a proton range verification apparatus according to another example embodiment of this application is shown. Referring below... Figure 5 This application provides a detailed description of a proton range verification apparatus according to an example embodiment.

[0173] like Figure 5 The proton range verification device shown includes a data acquisition unit 501, an activity distribution extraction unit 503, a gradient sequence calculation unit 505, and a proton action range calculation unit 507. The data acquisition unit 501 is used to simultaneously acquire positron-emitting nuclide signal data during proton beam irradiation of the target. The activity distribution extraction unit 503 is used to reconstruct the positron-emitting nuclide signal data and extract a one-dimensional activity distribution based on the acquired data. The gradient sequence calculation unit 505 is used to calculate the gradient sequence difference using the gradient sequences of two sets of one-dimensional activity distributions. The proton action range calculation unit 507 is used to determine the proton action range based on the gradient sequence difference.

[0174] Figure 6 A block diagram of a proton range verification apparatus according to yet another example embodiment of this application is shown. Referring below... Figure 6 This application provides a detailed description of a proton range verification apparatus according to an example embodiment.

[0175] like Figure 6The proton range verification device shown includes a data acquisition unit 601, a time integration factor calculation unit 603, a nuclide removal unit 605, a gradient sequence calculation unit 607, and a proton action range calculation unit 609. The data acquisition unit 601 is used to simultaneously acquire positron-emitting nuclide signal data during proton beam irradiation of the target. The time integration factor calculation unit 603 is used to calculate the positron-emitting nuclide time integration factor corresponding to the positron-emitting nuclide. The nuclide removal unit 605 is used to calculate the activity distribution after positron-emitting nuclide removal based on the positron-emitting nuclide time integration factor. The gradient sequence calculation unit 607 is used to calculate the gradient sequence difference before and after positron-emitting nuclide removal using the original activity distribution and the activity distribution after positron-emitting nuclide removal. The proton action range calculation unit 609 is used to determine the proton action range based on the gradient sequence difference.

[0176] Figure 7 A depth localization map obtained according to an example embodiment of this application is shown. For example... Figure 7 As shown, A_t1 represents the activity depth distribution in the first time period, and A_w / o 15 O indicates that it has been removed. 15 The activity depth distribution after O, with arrow 1 indicating a forward shift between the falling edges of G_t1 and G_w / o. 15 O represents the gradient distributions of the two activities. The solid line pointed to by arrow 2 represents the difference between the two gradient distributions. The depth of the local maximum pointed to by arrow 3 is the extracted activity depth.

[0177] Figure 8 A block diagram of another proton range verification apparatus according to an embodiment of this application is shown. Figure 8 The proton range verification device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0178] like Figure 8 As shown, the proton range verification device is presented in the form of a general-purpose computing device. The components of this proton range verification device may include, but are not limited to: at least one processor 810, at least one memory 820, a bus 830 connecting different system components (including the memory 820 and the processor 810), a display unit 840, etc. The memory 820 stores program code, which can be executed by the processor 810, causing the processor 810 to perform the methods described in this specification according to the various exemplary embodiments of this application. For example, the processor 810 can perform, as... Figure 1 The method shown.

[0179] The memory 820 may include a readable medium in the form of volatile memory cells, such as random access memory (RAM) 8201 and / or cache memory 8202, and may further include read-only memory (ROM) 8203.

[0180] The memory 820 may also include a program / utility 8204 having a set (at least one) of program modules 8205, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0181] Bus 830 can represent one or more of several types of bus structures, including a memory cell bus or memory cell controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus using any of the various bus structures.

[0182] The proton range verification device can also communicate with one or more external devices 800 (e.g., keyboard, pointing device, Bluetooth device, etc.), one or more devices that enable a user to interact with the proton range verification device, and / or any device that enables the proton range verification device to communicate with one or more other computing devices (e.g., router, modem, etc.). This communication can be performed via input / output (I / O) interface 850. Furthermore, the proton range verification device can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 860. Network adapter 860 can communicate with other modules of the proton range verification device via bus 830. It should be understood that, although not shown in the figures, other hardware and / or software modules can be used in conjunction with the proton range determination device, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0183] From the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. The technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a computer-readable storage medium (such as a CD-ROM, USB flash drive, or external hard drive) or on a network, including several computer program instructions to cause a computing device (such as a personal computer, server, or network device, etc.) to execute the methods described above according to the embodiments of this application.

[0184] Software products may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections with one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0185] Computer-readable storage media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable storage medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0186] Program code for performing the operations of this application can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0187] The aforementioned computer-readable medium carries one or more program instructions that, when executed by a device, cause the computer-readable medium to perform the aforementioned functions.

[0188] Those skilled in the art will understand that the above modules can be distributed in the device as described in the embodiments, or they can be modified accordingly to be uniquely different from one or more devices in this embodiment. The multiple modules of the above embodiments can be combined into one module, or a single module can be further divided into multiple sub-modules.

[0189] From the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. The technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a computer-readable storage medium (such as a CD-ROM, USB flash drive, or external hard drive) or on a network, including several computer program instructions to cause a computing device (such as a personal computer, server, or network device, etc.) to execute the methods described above according to the embodiments of this application.

[0190] Software products may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections with one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0191] Computer-readable storage media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable storage medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0192] Program code for performing the operations of this application can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0193] The aforementioned computer-readable medium carries one or more program instructions that, when executed by a device, cause the computer-readable medium to perform the aforementioned functions.

[0194] Those skilled in the art will understand that the above modules can be distributed in the device as described in the embodiments, or they can be modified accordingly to be uniquely different from one or more devices in this embodiment. The multiple modules of the above embodiments can be combined into one module, or a single module can be further divided into multiple sub-modules.

[0195] According to some example embodiments of this application, it is not necessary to wait for the natural decay of the main component positron-emitting nuclide. The contribution of a specific nuclide can be directly removed from the mixed signal of the activities of multiple nuclides. Therefore, the depth of action range can be provided online, thereby helping doctors optimize treatment plans, improve treatment effects, and maximize the treatment of cancerous tissue while avoiding damage to normal tissue.

[0196] While this application provides the operational steps of the methods described in the above embodiments or flowcharts, the methods may include more or fewer operational steps based on conventional or non-inventive methods. For steps where there is no logically necessary causal relationship, the execution order of these steps is not limited to the execution order provided in the embodiments of this application.

[0197] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0198] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for verifying the range of protons, characterized in that, include: The time integration factors corresponding to the positron-emitting nuclides in the first and second time periods are calculated using formula (1). Official (1) in, The time integral factor for the i-th positron-emitting nuclide in the first or second time period. This refers to the start time of either the first or second time period. This refers to either the end time of the first time period or the end time of the second time period. t is the decay constant of a positron-emitting nuclide. irr t represents the proton beam irradiation time. The activity distribution after removing positron-emitting nuclides is calculated using formula (2). Official (2) in, The activity distribution after removing positron-emitting nuclides. The measured activity value of the j-th voxel in the depth direction during the first time period is denoted as . Let j be the measured activity value of the j-th voxel in the depth direction during the second time period. The time integration factor for the positron-emitting nuclide in the first time period is [value]. The time integration factor for the positron-emitting nuclide in the second time period; The gradient sequence difference before and after positron-removal is calculated using the original activity distribution and the activity distribution after positron-removal. The range of proton action is determined by using gradient sequence differences.

2. The proton range verification method according to claim 1, characterized in that, Before calculating the time integration factor corresponding to the positron-emitting nuclide, positron-emitting nuclide signals for two time periods are acquired, and signal processing and image reconstruction are performed to obtain PET images.

3. The proton range verification method according to claim 2, characterized in that, The calculation of the time integration factor corresponding to the positron-emitting nuclide includes: Calculate the time integration factor of positron-emitting nuclides in the first time period and the time integration factor of positron-emitting nuclides in the second time period.

4. The proton range verification method according to claim 1, characterized in that, The original activity distribution includes: Activity distribution of positron-emitting nuclides in the first time period and activity distribution of positron-emitting nuclides in the second time period.

5. The proton range verification method according to claim 1, characterized in that, The gradient sequence difference before and after removing the positron-emitting nuclide is calculated using formula (14): Official (14) in, To remove the gradient sequence difference before and after the positron-emitting nuclide, The gradient sequence of the original activity. This is a gradient sequence of the activity distribution after removing positron-emitting nuclides.

6. The proton range verification method according to claim 1, characterized in that, Before calculating the gradient sequence difference before and after removing the positron-emitting nuclide, the original activity distribution and the activity distribution after removing the positron-emitting nuclide are normalized respectively, and the gradient sequence difference is calculated using the normalized activity distribution.

7. The proton range verification method according to claim 6, characterized in that, The normalization includes normalizing the original activity distribution and the activity distribution after removing the positron-emitting nuclide for the first time period or the second time period, respectively.

8. The proton range verification method according to claim 7, characterized in that, The original activity distribution and the activity distribution after removing the positron-emitting nuclide are normalized using formula (3), respectively. Official (3) in, The activity distribution of the j-th voxel after normalization. Let be the activity distribution of the j-th voxel. When the activity distribution is normalized after removing the main nuclide, = ,min( ) and max( ) are functions for calculating the minimum and maximum values ​​of the activity value of the j-th individual, respectively.

9. The proton range verification method according to claim 8, characterized in that, The gradient sequences of the two sets of normalized activity distributions are calculated using formula (13): Official (13).

10. The proton range verification method according to claim 1 or 9, characterized in that, Before calculating the gradient sequence difference before and after removing the positron-emitting nuclide, the gradient sequences before and after removing the positron-emitting nuclide are normalized respectively, and the gradient sequence difference is calculated using the normalized gradient sequence value.

11. The proton range verification method according to claim 10, characterized in that, The gradient sequences before and after the removal of the positron-emitting nuclide are normalized using formula (B) or formula (C): Formula (B) in, This is the normalized value of the gradient sequence of the original activity distribution. The gradient sequence of the original activity distribution or the normalized original activity distribution, min( ) and max( ) are respectively calculated The minimum and maximum values ​​of the function; Formula (C) in, To remove the gradient sequence normalization values ​​of the activity distribution of positron-emitting nuclides, To represent the activity distribution of positron-removed nuclides or the gradient sequence of the activity distribution of positron-removed nuclides after normalization, min( ) and max( ) are respectively calculated The minimum and maximum values ​​of the function.

12. The proton range verification method according to claim 7, characterized in that, The calculation of the gradient sequence difference before and after the removal of the positron-emitting nuclide includes: The gradient sequence difference is calculated using the gradient sequence of the activity distribution of positron-emitting nuclides in the first or second time period after normalization and the gradient sequence of the original activity distribution after normalization.

13. The proton range verification method according to claim 1, characterized in that, The calculation of the gradient sequence difference before and after the removal of the positron-emitting nuclide includes: The gradient sequences of the original activity distribution and the activity distribution after removing the positron-emitting nuclide are calculated respectively to obtain the original gradient sequence and the gradient sequence after removing the positron-emitting nuclide; Calculate the gradient sequence difference between the original gradient sequence and the gradient sequence of the positron-removed nuclide.

14. The proton range verification method according to claim 1, characterized in that, At least one of the positron-emitting nuclides induced by proton beams is selected as the main nuclide, and the time integration factor corresponding to the main nuclide is calculated.

15. The proton range verification method according to claim 1, characterized in that, The method of determining the proton action range using gradient sequence differences includes: The range of action of the proton is determined based on the maximum point of the gradient sequence difference.

16. The proton range verification method according to claim 15, characterized in that, When there is a local maximum point with an Euclidean distance within the depth range of the intersection of the two sets of activity decline edges before and after the removal of the positron-emitting nuclide, the range of action of the proton is the depth of the local maximum point; when there are two local maximum points with equal Euclidean distance within the depth range of the intersection of the two sets of activity decline edges before and after the removal of the positron-emitting nuclide, the range of action of the proton is the depth at the midpoint of the two local maximum points.

17. The proton range verification method according to claim 1, characterized in that, Before calculating the time integration factor corresponding to the positron-emitting nuclide, the proton range verification method further includes: At least one segment of positron nuclide signal data is collected simultaneously during the process of proton beam irradiation of the target.

18. The proton range verification method according to claim 1, characterized in that, After obtaining the activity distribution of the positron-removed nuclide, the proton range verification method further includes: Wavelet denoising is used to suppress high-frequency noise in the activity distribution after positron-emitting nuclides are removed.

19. The proton range verification method according to claim 18, characterized in that, The range of proton action is the depth at the peak of the gradient sequence difference within the region where the activity decreases before and after the removal of the positron-emitting nuclide.

20. A proton range verification device, characterized in that, include: The time integration factor calculation unit is used to calculate the time integration factors corresponding to the positron-emitting nuclides in the first and second time periods respectively using formula (1). Official (1) in, The time integral factor for the i-th positron-emitting nuclide in the first or second time period. This refers to the start time of either the first or second time period. This refers to either the end time of the first time period or the end time of the second time period. t is the decay constant of a positron-emitting nuclide. irr t represents the proton beam irradiation time. The nuclide removal unit is used to calculate the activity distribution after removing the positron-emitting nuclide using formula (2). Official (2) in, The activity distribution after removing positron-emitting nuclides. Let be the measured activity value of the j-th voxel in the depth direction during the first time period. Let j be the measured activity value of the j-th voxel in the depth direction during the second time period. The time integration factor for the positron-emitting nuclide in the first time period is [value]. The time integration factor for the positron-emitting nuclide in the second time period; The gradient sequence calculation unit is used to calculate the gradient sequence difference before and after positron-removed nuclides using the original activity distribution and the activity distribution after positron-removed nuclides. The proton action range calculation unit is used to determine the proton action range using the gradient sequence difference.

21. The proton range verification device according to claim 20, characterized in that, The proton range verification device further includes: The data acquisition unit is used to simultaneously acquire positron-emitting nuclide signal data during the process of proton beam irradiation of the target.

22. A proton range verification device, characterized in that, include: One or more processors; Storage device for storing computer programs; When the computer program is executed by the one or more processors, the one or more processors implement the proton range verification method as described in any one of claims 1-19.

23. A computer-readable storage medium, characterized in that, It stores program instructions that, when executed, implement the proton range verification method as described in any one of claims 1-19.

Images