A multi-treatment head heavy ion radiotherapy quality assurance verification method and system
By establishing a reference treatment head and a unified evaluation process in heavy ion radiotherapy systems, the problem of inconsistent quality assurance results in multi-treatment head systems was solved, unified verification of different treatment heads was achieved, and the comparability and stability of verification results were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG CANCER HOSPITAL
- Filing Date
- 2026-07-06
- Publication Date
- 2026-08-04
AI Technical Summary
In multi-treatment-head heavy ion radiotherapy systems, existing validation methods struggle to uniformly address the differences between various treatment heads, resulting in a lack of consistency and comparability in quality assurance results. This is particularly true in scan-beam heavy ion programs, where the scan point weights and energy layer combinations have insufficient impact on dose distribution.
By establishing a reference treatment head, determining the internal sensitivity correction coefficient, treatment head calibration factor, and absolute dose conversion coefficient, and combining the fixed measurement geometry of the multi-channel ionization chamber array, a normalization factor is calculated to unify the measurement results under different treatment heads to the same reference scale, and synchronous sampling and joint evaluation are performed.
This improves the comparability, stability, and traceability of patient quality assurance verification results under multi-treatment-head conditions, establishes a unified clinical verification standard, and reduces the impact of inherent output differences in treatment heads.
Smart Images
Figure CN122499441A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of quality assurance technology for heavy ion radiotherapy, specifically to a method and system for quality assurance verification in multi-treatment-head heavy ion radiotherapy. Background Technology
[0002] Heavy ion radiotherapy, characterized by concentrated dose distribution and highly controllable range, is now used in tumor radiotherapy. With advancements in equipment configuration, multiple treatment heads are often integrated into a single heavy ion therapy system, each capable of handling clinical irradiation tasks in different treatment rooms and under different incident directions. Before treatment, patients typically require quality assurance verification of their treatment plan to confirm the consistency between the planned dose distribution and the actual delivery.
[0003] Current patient quality assurance validation primarily focuses on single-treatment-head scenarios. For multi-treatment-head systems, clinical practice typically involves directly performing measurements on the planned treatment head and comparing the measured results with the planned results. However, due to potential differences in beam path, energy layer output characteristics, scan control timing, mechanical mounting conditions, and measurement geometry among different treatment heads, even with identical treatment plans, validation results obtained from different treatment heads may exhibit systematic biases. Consequently, patient quality assurance results are easily affected by treatment head variations, lacking a unified reference point and increasing the difficulty of comparing and interpreting results under multi-treatment-head conditions.
[0004] On the other hand, existing validation methods often lack a unified processing mechanism for measurement devices, phantom arrangement, and planning data interfaces. If different measurement conditions are used for different treatment heads, or if comparisons are made solely based on single planning results, it is difficult to distinguish inherent differences in treatment heads, channel response differences, and differences in planning energy layer composition. Especially for heavy ion scanning beams, the scan point weights and energy layer combinations directly affect the final dose distribution; existing methods do not adequately consider these factors, easily affecting the consistency and comparability of validation results. Summary of the Invention
[0005] This application provides a method and system for quality assurance verification of multi-treatment head heavy ion radiotherapy, which at least solves some of the technical problems existing in the related technologies described above.
[0006] According to a first aspect of the embodiments of this application, a method for quality assurance verification of multi-treatment head heavy ion radiotherapy is provided, comprising: Obtain scan point information, energy layer information, scan point weight information, and planned dose distribution information for the treatment plan to be validated; Based on the multi-channel ionization chamber array arranged in the preset phantom, the coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information is established; A reference treatment head is determined, and the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient are obtained based on the standard field measurement results. Based on the energy layer information, scan point weight information, and pre-established channel-energy layer response ratio data, the normalization factor for each channel corresponding to the treatment plan to be validated is calculated. Quality assurance irradiation was performed under the treatment head corresponding to the treatment plan to be verified. Measurement signals from each channel of the multi-channel ionization chamber array were collected. The equivalent measured dose at the reference treatment head scale was obtained by combining the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor in sequence. According to the coordinate correspondence, the predicted dose for each channel is extracted from the planned dose distribution information, and the verification result is output based on the equivalent measured dose and the predicted dose.
[0007] As an optional solution, the multi-channel ionization chamber array is a finger-shaped ionization chamber array, in which the relative positions of each channel in the array remain fixed throughout the quality assurance verification process, and the coordinate correspondence is determined by the phantom positioning information, the array installation position, and the center position of the treatment system.
[0008] As an optional approach, the internal sensitivity correction coefficient is determined by statistical results of the response of each channel of the reference treatment head under a standard uniform irradiation field; the treatment head calibration factor is determined by the ratio of the array average response of each treatment head under the same preset standard field and the same measurement geometry to the array average response of the reference treatment head; the absolute dose conversion coefficient is determined by the correspondence between the array average response of the reference treatment head under the standard field and the independent absolute dose measurement results.
[0009] As an optional approach, the scan point weight information is aggregated by energy layer to obtain the energy layer weight of each energy layer in the treatment plan to be validated. The normalization factor is determined based on the weighted result of each energy layer weight and the corresponding channel-energy layer response ratio. The channel-energy layer response ratio data is established by the channel response measurement results of each treatment head under the same geometric conditions and the standard layered beam irradiation corresponding to each energy layer.
[0010] As an optional approach, during quality assurance irradiation, data acquisition and beam control are synchronized at each scan point. The charge signal of each channel is acquired for each irradiation time window corresponding to each scan point, and the charge signal of each channel corresponding to each scan point is accumulated and processed to obtain the measurement signal of each channel.
[0011] As an optional approach, the acquisition of the equivalent measured dose includes: performing internal sensitivity correction on the measurement signals of each channel to obtain the corrected signal; performing dose conversion on the corrected signal in combination with the treatment head calibration factor and the absolute dose conversion coefficient to obtain the baseline absolute dose; and performing channel-level transformation on the baseline absolute dose in combination with the normalization factor to obtain the equivalent measured dose at the reference treatment head scale.
[0012] As an optional approach, the predicted dose for each channel is extracted from the planned dose distribution information, including: The position of each channel is matched in the dose field corresponding to the planned dose distribution information based on the spatial coordinates of each channel. When the spatial coordinates of each channel do not coincide with the sampling point of the dose field, the neighboring dose data is interpolated to obtain the predicted dose corresponding to each channel.
[0013] As an optional approach, the verification results are obtained by at least one of the following: the relative deviation between the equivalent measured dose and the predicted dose for each channel, the average value of the relative deviation for each channel, the dispersion of the relative deviation for each channel, and the extreme value of the relative deviation for each channel.
[0014] As an optional approach, the verification results also include distance-dose joint evaluation results; the distance-dose joint evaluation results are calculated based on the equivalent measured dose of each channel, the spatial coordinates of each channel, and the dose values at the corresponding positions and / or within the allowable range of the corresponding positions in the planned dose distribution information.
[0015] According to a second aspect of the embodiments of this application, a quality assurance verification system for multi-treatment head heavy ion radiotherapy is also provided, comprising: The plan data acquisition module is configured to acquire scan point information, energy layer information, scan point weight information, and planned dose distribution information of the treatment plan to be validated. The geometric mapping module is configured to establish a coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information based on a multi-channel ionization chamber array arranged in a preset phantom. The calibration processing module is configured to determine the reference treatment head and obtain the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient based on the standard field measurement results. The normalization calculation module is configured to calculate the normalization factor for each channel corresponding to the treatment plan to be validated based on the energy layer information, scan point weight information and pre-established channel-energy layer response ratio data. The measurement processing module is configured to perform quality assurance irradiation under the treatment head corresponding to the treatment plan to be verified, acquire the measurement signals of each channel of the multi-channel ionization chamber array, and combine them in sequence with the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor to obtain the equivalent measured dose at the reference treatment head scale. The verification output module is configured to extract the predicted dose corresponding to each channel from the planned dose distribution information according to the coordinate correspondence, and output the verification result based on the equivalent measured dose and the predicted dose.
[0016] According to a third aspect of the embodiments of this application, an electronic device is provided, including: a processor; a memory for storing a computer program executable by the processor; wherein the processor is configured to execute the computer program in the memory to implement the method described in the first aspect.
[0017] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided, which, when an executable computer program in the storage medium is executed by a processor, enables the implementation of the method described in the first aspect.
[0018] This invention addresses the challenge of unifying and comparing patient quality assurance verification results in multi-treatment-head heavy ion radiotherapy scenarios. By establishing a reference treatment head under fixed measurement geometry, implementing internal sensitivity correction, treatment head calibration, plan-related normalization, and a unified evaluation process, measurement results obtained from different treatment heads are converted to the same reference scale and then compared with the planned dose distribution. This ensures that verification results have a consistent data source and a clear processing path. After generating a normalization factor based on scan point weights and energy layer information, the energy layer composition of the treatment plan itself can be incorporated into the verification process, reducing the impact of inherent output differences between different treatment heads on result determination. Combined with synchronous sampling, position matching, and joint evaluation processing of a multi-channel ionization chamber array, this invention improves the comparability, stability, and traceability of patient quality assurance verification results under multi-treatment-head conditions, facilitating the formation of a unified clinical verification standard.
[0019] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Furthermore, no embodiment in this disclosure is required to achieve all the effects described above. Attached Figure Description
[0020] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.
[0021] Figure 1 This is a schematic diagram of a quality assurance verification method for multi-treatment head heavy ion radiotherapy provided in an embodiment of this disclosure.
[0022] Figure 2 This is a schematic diagram of the calibration benchmark establishment and channel correction process provided in the embodiments of this disclosure.
[0023] Figure 3 This is a schematic diagram of the normalization factor calculation process provided in an embodiment of this disclosure.
[0024] Figure 4 This is a schematic diagram of a quality assurance verification system for multi-treatment head heavy ion radiotherapy provided in an embodiment of this disclosure.
[0025] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this disclosure. Detailed Implementation
[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0027] It should be noted that the information collected in this application (including but not limited to user device information, user personal information, collected data, used data, generated data, processed data, etc.) and the data (including but not limited to data used for analysis, stored data, displayed data, collected information, used information, generated information, processed information, etc.) are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, storage, use, processing, transmission, provision, disclosure, and application of the relevant data all comply with the relevant laws, regulations, and standards of the relevant countries and regions, have taken necessary confidentiality measures, do not violate public order and good morals, and provide corresponding operation access points for users to choose to authorize or refuse.
[0028] This implementation method is applicable to heavy ion radiotherapy systems with two or more treatment heads, and is particularly suitable for patient quality assurance verification scenarios where horizontal treatment heads, vertical treatment heads, oblique incidence treatment heads, or subsequent extended treatment heads exist in different treatment chambers. In actual implementation, the treatment planning system outputs scan point information, energy layer information, scan point weight information, and planned dose distribution information; the measurement side is configured with a preset phantom, a multi-channel finger-shaped ionization chamber array, a data acquisition device, and a data processing device. Differences are permissible between treatment heads in terms of beam path, energy layer switching method, scan control timing, and mechanical mounting position; therefore, a unified reference benchmark must be established first, and then the measurement results obtained from different treatment heads must be converted to the same comparison scale. The entire process is based on fixed measurement geometry, unified data sources, and unified evaluation criteria, making it suitable for pre-treatment verification of clinical patients.
[0029] First, some nouns or terms that appear in the description of the embodiments of this application shall be interpreted as follows: In this embodiment, the multi-channel ionization chamber array adopts a finger-shaped ionization chamber structure. A finger-shaped ionization chamber array refers to an ionization chamber assembly in which multiple elongated sensitive elements are arranged along a predetermined direction to form discrete sampling channels. This structure facilitates the simultaneous acquisition of dose responses at multiple locations on a fixed depth plane. The reference treatment head scale refers to the dose expression scale consistent with the reference treatment head, after using a pre-selected treatment head as a benchmark and converting the measurement results under other treatment heads into a scale consistent with the benchmark treatment head through calibration and normalization. The channel-energy layer response ratio refers to the ratio of the response of the reference treatment head to the same energy layer beam at the same channel location under the same geometric conditions to the response of the treatment head to be evaluated to the same energy layer beam. Indicates the channel index. Indicates the treatment head index, Indicates the energy layer index. Indicates the scan point index; Indicates a reference treatment head; This indicates the planned forecast amount.
[0030] The phantom can be a water phantom or an equivalent water phantom. If a water phantom is used, the finger-shaped ionization chamber array is fixed inside the phantom using a dedicated bracket. If an equivalent water phantom is used, the array is placed within a predetermined thickness layer, and the geometric relationship between the measurement plane of the array and the isocenter of the treatment system is set before verification. According to the embodiments of this disclosure, the relative positions of each channel in the array remain fixed throughout the verification process. The channel arrangement order is not changed during a single planned verification, nor is the channel spacing altered. The measurement results of any channel can stably correspond to the same spatial position in the planned dose field.
[0031] The implementation process of the method described in this application will be described in detail below with reference to specific embodiments. It should be noted that this embodiment is only used to explain this application and is not intended to limit the scope of protection of this application. Conventional adjustments or substitutions of each step by those skilled in the art without departing from the concept of this application should be included in the scope of protection of this application.
[0032] Please see Figure 1 , Figure 1 This is a flowchart of a quality assurance verification method for multi-treatment head heavy ion radiotherapy according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes steps S1-S6: In step S1, the scan point information, energy layer information, scan point weight information, and planned dose distribution information of the treatment plan to be verified are obtained.
[0033] In practice, the operator exports the treatment plan to be validated to the data processing device. The exported content includes at least the scan point sequence, the energy layer where the scan point is located, the scan point weight, and the dose distribution results. The scan point weight refers to the dose contribution share of a single scan point in the entire plan delivery. This share can be represented by a monitoring unit value, a control weight value, or a control parameter equivalent to the dose contribution.
[0034] According to embodiments of this disclosure, the data processing device includes a planned data reading unit, a geometric mapping unit, a treatment head calibration unit, a normalization calculation unit, a measurement signal processing unit, and an evaluation output unit. The planned data reading unit reads conventional data files exported from the treatment planning system; the geometric mapping unit establishes the coordinate correspondence between channel coordinates and planned dose distribution information; the treatment head calibration unit manages internal sensitivity correction coefficients, treatment head calibration factors, and absolute dose conversion coefficients; the normalization calculation unit calculates the normalization factor based on energy layer information, scan point weight information, and channel-energy layer response ratio; the measurement signal processing unit receives sampling results from each channel and generates equivalent measured doses; and the evaluation output unit combines the predicted dose to complete deviation analysis and joint evaluation. These units can be executed by the same processor or by multiple processors working in parallel, as long as the input-output relationship remains consistent.
[0035] In step S2, based on the multi-channel ionization chamber array arranged in the preset phantom, a coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information is established.
[0036] After the phantom is in place, the operator positions it according to the isocenter of the treatment system and the phantom's positioning marks, and then installs the finger-shaped ionization chamber array. After array installation, the system records the position of each channel in the array coordinate system and, combined with the phantom positioning information, the array installation position, and the isocenter position of the treatment system, establishes a spatial mapping relationship. If the first... The spatial coordinates of each channel are represented as follows: ,but It includes three components: lateral position, longitudinal position, and depth position, all of which are derived from the actual geometric arrangement.
[0037] In step S3, a reference treatment head is determined, and the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient are obtained based on the standard field measurement results.
[0038] According to an embodiment of this disclosure, the standard field is a pre-set uniform irradiation field, and the standard field has at least the following fixed conditions: field size, measurement depth, phantom type, array installation position, center position of the treatment system, and reference energy layer or a combination of reference energy layers.
[0039] To ensure the comparability of measurement results across multiple treatment heads, a reference treatment head is first selected. The reference treatment head can be chosen based on commonly used clinical treatment heads, treatment heads with high routine stability, or pre-defined standard treatment heads. After the reference treatment head is determined, standard field irradiation is performed on both the reference and other treatment heads. The standard field should ideally be a test field with well-defined geometry, uniform irradiation area, and ease of statistical channel response analysis.
[0040] Please see Figure 2 , Figure 2 A schematic diagram illustrating the calibration reference establishment and channel correction process provided in this embodiment of the present disclosure is shown. Figure 2 As shown, in step S201, the internal sensitivity correction coefficient is determined.
[0041] Because slight differences may exist between different ionization chamber channels in terms of manufacturing consistency, cable connections, front-end readout, and long-term usage, the internal response of the array is first calibrated. For the response of each channel acquired by the reference treatment head under a standard uniform irradiation field, let be denoted as . The original response of each channel is Using the statistical value of the full array response as a benchmark, the first... Internal sensitivity correction coefficient for each channel The corrected response can be expressed as:
[0042] in, Indicates the first The correction ratio of each channel relative to the array reference response is derived from the statistical results of standard field measurements and typically varies around 1. If array replacement, readout channel maintenance, or periodic checks reveal a persistent shift in the response of a particular channel, the corresponding value is remeasured and updated. The outputs from each channel are used to first eliminate individual differences between devices before proceeding to the subsequent inter-head comparison process.
[0043] In step S202, the treatment head calibration factor of each treatment head relative to the reference treatment head is determined. After completing the intra-channel calibration, the array average response of each treatment head under the same standard field is calculated. Let the treatment head... The average array response after channel correction under standard field conditions is: The average response of the reference treatment head array is Then treat the head Treatment head labeling factor It can be determined by the following formula:
[0044] in, and All are statistical responses obtained under the same geometric conditions and the same standard field conditions. Indicates treating the head The overall output scale is transformed to the reference treatment head scale, and the reference treatment head corresponds to... Set to 1. This factor is only used at the treatment head level and does not replace channel-level corrections or subsequent planned normalization factors. If the output characteristics change after treatment head maintenance, standard field measurements can be re-executed and updated. .
[0045] In step S203, the absolute dose conversion coefficient is determined based on the absolute dose measurement under the standard field. After completing the relative calibration between treatment heads, the measurement signal also needs to be converted into a dose value. Under the standard field of the reference treatment head, the absolute dose value is obtained using an independent absolute dose measurement device, denoted as . Then, by correlating this with the array-averaged response of the reference treatment head, the absolute dose conversion coefficient is obtained. :
[0046] coefficient It represents the correspondence between absolute dose measurement and array average response under standard field conditions. This coefficient can be used continuously if the standard field conditions and absolute dose measurement chain remain unchanged. If the standard field definition changes, the absolute dosimeter is recalibrated, or the measurement chain is adjusted, this coefficient should be reacquired.
[0047] In step S4, based on the energy layer information, scan point weight information, and pre-established channel-energy layer response ratio data, the normalization factor for each channel corresponding to the treatment plan to be validated is calculated.
[0048] Treatment head calibration factors alone are insufficient to handle differences between patient plans because different plans involve different energy layer compositions and varying scan point weight distributions. Even if two treatment heads perform similarly in a standard field, differences between treatment heads may still be amplified if one plan relies more heavily on a specific energy layer. Therefore, this implementation continues with normalization calculations corresponding to the current plan after treatment head calibration.
[0049] Please see Figure 3 , Figure 3 A schematic diagram of the normalization factor calculation process provided in an embodiment of this disclosure is shown. For example... Figure 3 As shown, in step S301, the planning data is parsed and energy layer weights are generated.
[0050] After reading the scan point information of the treatment plan to be verified, the data processing device aggregates the energy layers to which each scan point belongs. (Design plan in progress) The weight of each scan point is Its energy level is The weights of all scan points within the same energy layer are summed, and then compared with the total weights of all scan points in the entire plan to obtain the energy layer weight in the current plan. The weights are represented as Then it can be expressed by the formula:
[0051] Indicates energy layer The relative contribution to the entire plan, with a value between 0 and 1, and the sum of all energy layer weights is 1. This weight comes from the scan point weight information derived from the current plan, so it is recalculated every time a plan is changed. If the same plan remains unchanged, this value does not need to be updated.
[0052] In step S302, channel-to-energy layer response ratio data is established. Before clinical planning validation, a treatment head-level response database is first established. Specifically, under the same geometric conditions, multiple sets of standard layered beam irradiation are performed on each treatment head. Standard layered beam refers to the test beam output layer by layer according to a predetermined energy layer, with each layer measured under the same phantom arrangement and array position. For any treatment head, any channel, and any energy layer, the response value of that channel under that energy layer can be obtained. Then, the response of the reference treatment head under the same channel and energy layer is divided by the response of the corresponding treatment head under the same channel and energy layer to form the channel-to-energy layer response ratio data.
[0053] If the treatment head In the passage Energy layer The response conversion ratio relative to the reference treatment head is denoted as It describes the response of a treatment head relative to a reference treatment head at a certain energy level and channel location. This quantity also includes channel index and energy level index, which can reflect the impact of different plans on different treatment heads in more detail.
[0054] In step S303, the normalization factor for each channel corresponding to the treatment plan to be validated is calculated for the current plan. After obtaining the energy layer weights and channel-energy layer response ratios, the normalization factor for each channel can be calculated for the current plan. Let the treatment head... Next The normalization factor for each channel in the current plan is: Then it can be determined by the weighted result of each energy layer weight and the corresponding response ratio:
[0055] In this formula, Determined by the current plan, This is provided by a pre-established response ratio database. Multiplying the two and then summing them over all energy levels yields a comprehensive normalization factor for the current plan, current treatment head, and current channel. This results in... It is a calculation result associated with the current treatment plan, and the normalization factor is determined by the energy layer weights of the current plan and pre-established response ratio data.
[0056] In actual implementation, The value range is determined by the response ratio database and the energy layer weights. Generally, its value is positive; if a certain energy layer does not appear in the current plan, the corresponding value is negative. A value of zero has no impact on the results. If the plan update changes the energy layer composition, then all channels will be recalculated. .
[0057] In step S5, quality assurance irradiation is performed under the treatment head corresponding to the treatment plan to be verified. The measurement signals of each channel of the multi-channel ionization chamber array are collected and combined with the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor in sequence to obtain the equivalent measured dose at the reference treatment head scale.
[0058] After the baseline establishment and normalization calculation are completed, the quality assurance irradiation under the corresponding treatment head is performed. The irradiation here maintains the same control logic as clinical delivery, including the scan point sequence, energy layer switching sequence and scan point weight allocation. The difference is that the irradiation target changes from the patient to the finger-shaped ionization chamber array in the preset phantom.
[0059] To ensure a one-to-one correspondence between measured values and the planned delivery process, the data acquisition device and beam control are synchronized in time according to the scanning points. Sampling is initiated and terminated separately for the irradiation time window corresponding to each scanning point, and the charge signal of each channel is recorded. If the first... The first channel in the The charge signal within the irradiation time window of each scanning point is denoted as This quantity is obtained by integrating the current within that time window. It is directly derived from real-time sampling and corresponds one-to-one with the scanning point information and energy layer information.
[0060] After sampling, the system accumulates the channel charge signal corresponding to each scan point. Let the first scan point be... The cumulative measurement signal of each channel is ,but Through the above formula, the measurement values of a single scan point are aggregated into a channel-level planned measurement signal, while retaining the distinction between the planned weights and their contributions to different scan points.
[0061] The equivalent measurement dose is generated in a preset order: first, internal channel calibration is performed; then, the treatment head dose conversion is performed; and finally, plan-related normalization is performed. Let the... The cumulative measurement signal of each channel is The corresponding internal sensitivity correction coefficient is The corrected signal is:
[0062] Combined with therapeutic head labeling factors and absolute dose conversion factor The corrected signal is converted into a basic absolute dose, denoted as . :
[0063] Then, combine this with the normalization factor corresponding to the current plan. The equivalent measured dose at the reference treatment head scale was obtained. :
[0064] Internal sensitivity correction is performed first because channel-specific differences must be eliminated before cross-treatment head comparisons; treatment head calibration and dose conversion are then performed to convert the current treatment head data to a uniform dose scale; finally, a normalization factor is applied to reflect the current plan's dependence on different energy levels in the channel-level results.
[0065] In step S6, the predicted dose corresponding to each channel is extracted from the planned dose distribution information according to the coordinate correspondence, and the verification result is output based on the equivalent measured dose and the predicted dose.
[0066] After obtaining the equivalent measured dose, the predicted dose corresponding to each channel is extracted from the planned dose distribution information. Since the spatial coordinates of each channel have already been established in the previous steps, position matching is performed directly based on the coordinate correspondence. The planned dose distribution information can be either two-dimensional dose plane data or a three-dimensional dose matrix.
[0067] Specifically, the geometric mapping unit reads the first... Spatial coordinates of each channel The corresponding location is located within the planned dose field. If this location happens to fall on a sampling point within the planned dose field, the dose value at that sampling point is directly read as the first... The predicted dose for each channel is denoted as... Since the location of the ionization chamber channel is determined by the actual device, while the sampling grid of the planned dose distribution is determined by the computational grid, the two do not necessarily coincide completely. If the channel coordinates do not coincide with the sampling points of the planned dose field, interpolation calculations are performed on the neighboring dose data.
[0068] In one example, if the planned dose distribution is a three-dimensional regular grid, then interpolation is performed using the dose values of the voxel containing the channel and its adjacent voxels to obtain... If the planned dose distribution is a two-dimensional grid on a certain depth plane, the depth plane corresponding to the channel is first identified, and then interpolation is performed on the neighboring grid points within the plane. This predicted dose is obtained based on the established spatial coordinates and planned dose distribution information, thus forming a one-to-one correspondence with the measured dose.
[0069] After obtaining the equivalent measurement dose and predicted dose Then, the evaluation output unit compares the two. The basic comparison method is based on relative deviation, specifically, assuming the first... The relative deviation of each channel is , can be represented as:
[0070] in, This indicates the degree of deviation of the equivalent measured dose from the predicted dose, expressed by all channels. Further statistical analysis can be performed on the mean, dispersion, and extreme values. The mean reflects the overall level of deviation, dispersion reflects the degree of difference between channels, and extreme values reflect the deviation at the most inconsistent local locations. Regarding dispersion, statistical measures such as the standard deviation can be used in practice.
[0071] In addition, optionally, in some embodiments, a distance-dose joint evaluation result can also be generated. The joint evaluation further incorporates spatial deviation considerations between the channel location, equivalent measured dose, and planned dose field. During actual calculation, the location within the allowable range in the planned dose field is searched using the channel's spatial coordinates as the center, and the dose difference and spatial distance are comprehensively compared to obtain the joint evaluation value. Dose difference limits and distance limits can be provided by equipment quality control specifications, institutional daily verification standards, or preset evaluation parameters. The resulting joint evaluation result can be output simultaneously with the basic relative deviation result. Regarding the evaluation parameters, the dose difference limit can be preset by the institution, and the distance limit is jointly determined by positioning accuracy and planned verification requirements.
[0072] In some embodiments, certain channels in the planned dose distribution may fall in locations where local dose changes rapidly, such as near the end of the range or near the lateral edge. For these locations, even small geometric deviations can cause significant dose differences, therefore they should be recorded separately in the output results. Specifically, the system determines the local dose gradient at each channel location based on the planned dose distribution information. If the local dose gradient meets preset conditions, the channel is marked as a high-gradient channel. The preset conditions refer to gradient discrimination thresholds pre-defined by the system, derived from historical validation experience, equipment positioning accuracy, or in-hospital quality control rules. During the output phase, the evaluation results of high-gradient channels and unmarked channels are recorded separately. This ensures consistency between data sources and calculation processes and facilitates the operator's identification of differences that may be related to the geometric sensitivity of high-gradient regions.
[0073] As a concrete example, the operator first imports the plan to be verified into the data processing device; the system reads the scan point information, energy layer information, scan point weight information, and planned dose distribution information, and automatically generates the energy layer weight; then the operator completes the phantom placement and finger-shaped ionization chamber array installation, and the system establishes the correspondence between spatial coordinates and the planned dose field; next, the system calls the reference treatment head, internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient, and channel-energy layer response ratio data to complete the normalization factor calculation corresponding to the current plan; then, quality assurance irradiation is performed, synchronous sampling is performed according to the scan points, the measured charge of the channel corresponding to each scan point is accumulated to form the measurement signal of each channel, and the equivalent measured dose is obtained in a predetermined order; finally, the predicted dose of each channel is extracted from the planned dose field, and relative deviation, statistical results, joint evaluation results, and high gradient channel recording results are generated.
[0074] In summary, this invention divides the patient quality assurance verification process in multi-treatment-head heavy ion radiotherapy into several stages: plan data reading, fixed geometry establishment, reference benchmark calibration, plan correlation normalization, synchronous irradiation sampling, equivalent measurement dose generation, predicted dose extraction, and result output. Through this process, measurement data from different treatment heads can be uniformly converted to the same reference scale, and the verification process is completed under fixed geometric conditions, thus helping to maintain consistent results.
[0075] Please see Figure 4 , Figure 4 This is a schematic diagram of a quality assurance verification system for multi-treatment head heavy ion radiotherapy provided in an embodiment of this application. Figure 4 As shown, the system includes: The plan data acquisition module 401 is configured to acquire scan point information, energy layer information, scan point weight information and plan dose distribution information of the treatment plan to be verified; The geometric mapping module 402 is configured to establish a coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information based on the multi-channel ionization chamber array arranged in the preset phantom. The calibration processing module 403 is configured to determine a reference treatment head and obtain the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient based on the standard field measurement results. The normalization calculation module 404 is configured to calculate the normalization factor of each channel corresponding to the treatment plan to be verified based on the energy layer information, scan point weight information and pre-established channel-energy layer response ratio data. The measurement processing module 405 is configured to perform quality assurance irradiation under the treatment head corresponding to the treatment plan to be verified, collect the measurement signals of each channel of the multi-channel ionization chamber array, and combine them in sequence with the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor to obtain the equivalent measured dose at the reference treatment head scale. The verification output module 406 is configured to extract the predicted dose corresponding to each channel from the planned dose distribution information according to the coordinate correspondence, and output the verification result based on the equivalent measured dose and the predicted dose.
[0076] Each processing unit and / or module in the embodiments of this application can be implemented by an analog circuit that implements the functions described in the embodiments of this application, or by software that executes the functions described in the embodiments of this application.
[0077] Please see Figure 5 It shows a schematic diagram of the structure of an electronic device according to an embodiment of this application, which can be used to implement... Figure 1The method in the illustrated embodiment. (As shown) Figure 5 As shown, the electronic device may include: The system includes at least one processor 501, at least one network interface 504, a user interface 503, a memory 505, and at least one communication bus 502. The communication bus 502 is used to enable connection and communication between the components. The user interface 503 may include buttons, and optionally include a standard wired or wireless interface. The network interface 504 may include, but is not limited to, a Bluetooth module, an NFC module, a Wi-Fi module, etc.
[0078] The processor 501 may include one or more processing cores and connect to various parts within the electronic device through various interfaces and lines. It implements various functions and data processing of the electronic device by running or executing instructions, programs, code sets, or instruction sets stored in the memory 505, and by accessing data in the memory 505. Optionally, the processor 501 may be implemented using at least one hardware form of DSP, FPGA, or PLA. The processor 501 may also integrate one or more combinations of CPU, GPU, and modem.
[0079] Memory 505 may include random access memory (RAM) or read-only memory (ROM). Optionally, memory 505 includes a non-transitory computer-readable medium for storing instructions, programs, code, code sets, or instruction sets. Memory 505 may be divided into a program storage area and a data storage area, wherein the program storage area can be used to store instructions for implementing an operating system and instructions for implementing the foregoing method embodiments; the data storage area can be used to store data related to the relevant method embodiments. Memory 505 may also be at least one storage device located remotely from processor 501. Figure 5 As shown, the memory 505, which serves as a computer storage medium, may contain an operating system, a network communication module, a user interface module, and program instructions.
[0080] In particular, the methods and / or embodiments in this application can be implemented as computer software programs. For example, the embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowchart. When the computer program is executed by processor 501, it performs the functions defined in the methods of this application.
[0081] Another embodiment of this application provides a storage medium storing computer program instructions thereon, which can be executed by a processor to implement the methods and / or technical solutions of any one or more embodiments of this application.
[0082] In the above embodiments, the descriptions of each embodiment have different focuses. Parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. The above descriptions are merely preferred embodiments of this application and explanations of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by specific combinations of the above technical features, but should also cover other technical solutions formed by arbitrary combinations of the above technical features or their equivalent features without departing from the inventive concept.
Claims
1. A method for quality assurance verification in multi-treatment-head heavy ion radiotherapy, characterized in that, include: Obtain scan point information, energy layer information, scan point weight information, and planned dose distribution information for the treatment plan to be validated; Based on the multi-channel ionization chamber array arranged in the preset phantom, the coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information is established; A reference treatment head is determined, and the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient are obtained based on the standard field measurement results. Based on the energy layer information, scan point weight information, and pre-established channel-energy layer response ratio data, the normalization factor for each channel corresponding to the treatment plan to be validated is calculated. Quality assurance irradiation was performed under the treatment head corresponding to the treatment plan to be verified. Measurement signals from each channel of the multi-channel ionization chamber array were collected. The equivalent measured dose at the reference treatment head scale was obtained by combining the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor in sequence. According to the coordinate correspondence, the predicted dose for each channel is extracted from the planned dose distribution information, and the verification result is output based on the equivalent measured dose and the predicted dose.
2. The method according to claim 1, characterized in that, The multi-channel ionization chamber array is a finger-shaped ionization chamber array. Each channel in the array maintains a fixed relative position throughout the entire quality assurance verification process. The coordinate correspondence is determined by the phantom positioning information, the array installation position, and the center position of the treatment system.
3. The method according to claim 1, characterized in that, The internal sensitivity correction coefficient is determined by statistical results of the response of each channel of the reference treatment head under a standard uniform irradiation field; the treatment head calibration factor is determined by the ratio of the array average response of each treatment head under the same preset standard field and the same measurement geometry to the array average response of the reference treatment head; the absolute dose conversion coefficient is determined by the correspondence between the array average response of the reference treatment head under the standard field and the independent absolute dose measurement results.
4. The method according to claim 1, characterized in that, The scan point weight information is aggregated by energy layer to obtain the energy layer weight of each energy layer in the treatment plan to be verified. The normalization factor is determined based on the weighted result of each energy layer weight and the corresponding channel-energy layer response ratio. The channel-energy layer response ratio data is established by the channel response measurement results of each treatment head under the same geometric conditions and the standard layered beam irradiation corresponding to each energy layer.
5. The method according to claim 1, characterized in that, During quality assurance irradiation, data acquisition and beam control are synchronized with each scanning point. The charge signal of each channel is acquired for each irradiation time window corresponding to each scanning point, and the charge signal of each channel corresponding to each scanning point is accumulated and processed to obtain the measurement signal of each channel.
6. The method according to claim 5, characterized in that, The acquisition of the equivalent measured dose includes: performing internal sensitivity correction on the measurement signals of each channel to obtain the corrected signal; performing dose conversion on the corrected signal in combination with the treatment head calibration factor and the absolute dose conversion coefficient to obtain the baseline absolute dose; and performing channel-level transformation on the baseline absolute dose in combination with the normalization factor to obtain the equivalent measured dose at the reference treatment head scale.
7. The method according to claim 1, characterized in that, Extract the predicted dose for each channel from the planned dose distribution information, including: The position of each channel is matched in the dose field corresponding to the planned dose distribution information based on the spatial coordinates of each channel. When the spatial coordinates of each channel do not coincide with the sampling point of the dose field, the neighboring dose data is interpolated to obtain the predicted dose corresponding to each channel.
8. The method according to claim 1, characterized in that, The verification results are obtained through at least one of the following: the relative deviation between the equivalent measured dose and the predicted dose for each channel, the average value of the relative deviation for each channel, the dispersion of the relative deviation for each channel, and the extreme value of the relative deviation for each channel.
9. The method according to claim 8, characterized in that, The verification results also include distance-dose joint evaluation results; the distance-dose joint evaluation results are calculated based on the equivalent measured dose of each channel, the spatial coordinates of each channel, and the dose values at the corresponding positions and / or within the allowable range of the corresponding positions in the planned dose distribution information.
10. A quality assurance verification system for multi-treatment head heavy ion radiotherapy, characterized in that, include: The plan data acquisition module is configured to acquire scan point information, energy layer information, scan point weight information, and planned dose distribution information of the treatment plan to be validated. The geometric mapping module is configured to establish a coordinate correspondence between the spatial coordinates of each channel and the planned dose distribution information based on a multi-channel ionization chamber array arranged in a preset phantom. The calibration processing module is configured to determine the reference treatment head and obtain the internal sensitivity correction coefficient of each channel, the treatment head calibration factor of each treatment head relative to the reference treatment head, and the absolute dose conversion coefficient based on the standard field measurement results. The normalization calculation module is configured to calculate the normalization factor for each channel corresponding to the treatment plan to be validated based on the energy layer information, scan point weight information and pre-established channel-energy layer response ratio data. The measurement processing module is configured to perform quality assurance irradiation under the treatment head corresponding to the treatment plan to be verified, acquire the measurement signals of each channel of the multi-channel ionization chamber array, and combine them in sequence with the internal sensitivity correction coefficient, treatment head calibration factor, absolute dose conversion coefficient and normalization factor to obtain the equivalent measured dose at the reference treatment head scale. The verification output module is configured to extract the predicted dose corresponding to each channel from the planned dose distribution information according to the coordinate correspondence, and output the verification result based on the equivalent measured dose and the predicted dose.