Method and system for dose control
The method and system adjust subroom weights based on temporal gradients to optimize dose distribution across varying tissue types, ensuring high image quality and preventing overexposure in AEC systems.
Patent Information
- Application Number
- CN202510047472.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-01-15
- Filing Date
- 2025-01-13
- Publication Date
- 2025-07-15
AI Technical Summary
During medical imaging, existing automatic exposure control systems are difficult to ensure high-quality radiographic images when patients fail to position perfectly during medical imaging, especially in areas of high-attenuation materials such as bones, resulting in premature stopping of radiation resulting in image noise and low quality.
A solid state automatic exposure control system with at least two sub-chambers is used to determine the weight by measuring the cumulative dose change rate (gradient) of each sub-chamber, adjusting the weighted total dose to ensure that sufficient radiation dose is obtained in the region of high absorbent material and stop radiation when the critical dose is reached.
Even if the patient is not fully positioned, high-quality medical images can be ensured, avoiding repeated imaging, saving time and cost while reducing patient radiation dose.
Smart Images
Figure CN120304849A_ABST
Abstract
Description
Technical Field
[0001] The present invention describes methods and systems for dose control using automatic exposure control. Background Art
[0002] In x-ray imaging, it is known in the art to use automatic exposure control (abbreviation: AEC) to measure and control the applied dose.
[0003] During the imaging process, the patient is placed between the radiation source and the detector. The source is configured to emit radiation, in particular x-rays. The detector is configured to detect the radiation passing through the patient. In this way, in particular, a radiographic image of the patient or at least a part of the patient can be obtained.
[0004] Using AEC, the cumulative dose applied to the patient can be measured. For this purpose, the AEC is particularly placed behind the patient and in front of the detector. The measured cumulative dose is compared with a predetermined critical dose. Once the measured cumulative dose reaches the critical dose, the radiation can be stopped to avoid overexposure of the patient.
[0005] There are two types of AEC used in medical imaging processes: ionization AEC and solid-state AEC.
[0006] The solid-state AEC includes a plurality of sub-chambers. Using each of the sub-chambers, the cumulative dose can be measured. Currently, the measured doses of each sub-chamber are summed, and this total cumulative dose is compared with the critical dose.
[0007] It is known that "dense" materials (such as bone) attenuate radiation more than, for example, tissue. Therefore, the dose measured by a sub-chamber placed behind a dense material is lower than the dose measured by a sub-chamber placed behind a material with less attenuation such as tissue or free field. Therefore, the contribution of a sub-chamber placed behind such a dense material to the total cumulative dose is less than that of a sub-chamber measuring the cumulative dose behind, for example, tissue or free field.
[0008] Hereinafter, "high" attenuation and "low" attenuation refer to attenuation relative to surrounding materials and / or other imaging materials.
[0009] In order to obtain high image quality even in the region of dense materials, the patient must be perfectly positioned in front of the AEC. If the structure of interest includes a high-attenuation material such as bone, all the sub-chambers used must be covered by the structure of interest. Especially in orthopedic examinations, the bone is usually the structure of interest.
[0010] Rich experience is required to perfectly position the patient in front of the AEC.
[0011] As a result, the following occurs: The patient positioning is not ideal, and not all sub - chambers contributing to the total cumulative dose are covered by the dense material of interest. Alternatively, the following may occur: The patient is too small, and it may not even be possible for all contributing sub - chambers to be covered by the structure of interest. This is especially the case if the patient is a child.
[0012] Since the dose measured behind tissue or behind the free field increases more rapidly than the dose measured behind, for example, bone, by simply adding up the measured cumulative doses of all sub - chambers, the critical dose may be reached too quickly, thus prematurely stopping the radiation. This results in noisy and grainy radiographic images because the radiation acquired behind, for example, bone is too low for a high - quality radiographic image. Summary of the Invention
[0013] Accordingly, it is an object of the present invention to provide a method that ensures high image quality even if the patient is not perfectly positioned in front of the AEC.
[0014] This object is achieved by a method, an automatic exposure control device, a system, a computer program product, and a computer - readable storage medium according to the present invention. Advantageous features and further developments are listed in the following description.
[0015] Hereinafter, the solution according to the present invention will be described with respect to the claimed system and with respect to the claimed method. Features, advantages, or alternative embodiments herein may be assigned to other claimed objects and vice versa. In other words, the claims of the system may be improved using features described or claimed in the context of the method. In this case, the functional features of the method are implemented by the target units of the system.
[0016] Regardless of the usage of grammatical terms, individuals with male or female identities are included within the term.
[0017] In a first aspect, the present invention relates to a computer-implemented method for dose control using automatic exposure control (abbreviation: AEC). Wherein, the AEC includes at least a first sub-chamber and a second sub-chamber. The method includes the step of receiving a first time course of a first cumulative dose from the first sub-chamber. The method further includes the step of receiving a second time course of a second cumulative dose from the second sub-chamber. The method includes the step of receiving a predetermined critical dose. The method includes the step of determining a first weight based on the first time course. The method further includes the step of determining a second weight based on the second time course. The method includes the step of multiplying the latest value of the first time course by the first weight, wherein a first weighted cumulative dose is determined. The method includes the step of multiplying the latest value of the second time course by the second weight, wherein a second weighted cumulative dose is determined. The method includes the step of adding the first weighted cumulative dose and the second weighted cumulative dose, wherein a weighted total applied dose is determined. The method includes the step of comparing the weighted total applied dose with the predetermined critical dose. The method includes the step of providing the result of the comparison.
[0018] The AEC is in particular a solid-state AEC. In other words, the AEC includes at least two (first and second) sub-chambers that can measure the dose of radiation irradiating the sub-chambers based on semiconductor technology.
[0019] In particular, the AEC can include more than two sub-chambers. In this case, the steps of the method are similarly performed for all sub-chambers.
[0020] In particular, the sub-chambers of the AEC can be grouped. In this case, the sub-chambers of one group must be used together for the described method. In particular, sub-chambers of more than one group can be used together for the described method.
[0021] In the step of receiving the first time course, the first time course of the first cumulative dose is received from the first sub-chamber. In other words, the first time course is measured and provided by the first sub-chamber. The first time course provides information about the increase in the first cumulative dose over time. In particular, the first time course can include values of the first cumulative dose measured every millisecond or every 10 milliseconds or every 100 milliseconds or per second.
[0022] In the step of receiving the second time course, the second time course of the second cumulative dose is received from the second sub-chamber. In other words, the second time course is measured and provided by the second sub-chamber. The second time course provides information about the increase in the second cumulative dose over time. In particular, the second time course can include values of the second cumulative dose measured every millisecond or every 10 milliseconds or every 100 milliseconds or per second.
[0023] In the step of receiving a predetermined critical dose, the predetermined critical dose is received in particular by user input or from a database. The predetermined critical dose describes the value that the cumulative dose applied to a patient should not exceed. The critical dose can be based on official safety requirements. Alternatively, the critical dose can be system-specific. In other words, for a system used in a medical imaging process, the critical dose can be specific. The system particularly includes a source, a detector, and an AEC. In particular, the system-specific critical dose can be based on a value according to official safety requirements, which is adapted to the specific system.
[0024] In the step of determining the first weight, the first weight is determined according to the first time course of the first cumulative dose. In other words, the first weight depends on how the first cumulative dose evolves over time.
[0025] In the step of determining the second weight, the second weight is determined according to the second time course of the second cumulative dose. In other words, the second weight depends on how the second cumulative dose evolves over time.
[0026] In the step of multiplying the latest value of the first time course by the first weight, the first weighted cumulative dose is determined. As described above, the first time course includes a plurality of values describing the time variation of the first cumulative dose measured using the first sub-chamber. In this case, the latest value is the last value in time of the first time course. In other words, the latest value describes the last measured cumulative dose. Therefore, the first weighted cumulative dose describes the last measured value of the cumulative dose in the first sub-chamber weighted by the first weight.
[0027] In particular, all values of the first time course can be multiplied by the first weight. In this case, the first weighted time course is determined, and the first weighted cumulative dose is the latest value of the first weighted time course in this case.
[0028] In the step of multiplying the latest value of the second time course by the second weight, the second weighted cumulative dose is determined. As described above, the second time course includes a plurality of values describing the time variation of the second cumulative dose measured using the second sub-chamber. In this case, the latest value is the last value in time of the second time course. In other words, the latest value describes the last measured cumulative dose. Therefore, the second weighted cumulative dose describes the last measured value of the cumulative dose in the second sub-chamber weighted by the second weight.
[0029] In particular, all values of the second time course can be multiplied by the second weight. In this case, the second weighted time course is determined, and the second weighted cumulative dose is the latest value of the second weighted time course in this case.
[0030] In particular, if the AEC includes more than two sub-chambers, and especially if more than two sub-chambers are used, the above steps are performed for each of the sub-chambers used.
[0031] In the step of adding the first weighted cumulative dose and the second weighted cumulative dose, the weighted total applied dose is determined. The weighted total applied dose does not necessarily describe the dose actually applied to the patient.
[0032] If more than two sub-chambers are used, the corresponding weighted cumulative doses are also added to determine the weighted total applied dose.
[0033] In the step of comparing the weighted total applied dose with a predetermined critical dose, it is checked whether the weighted total applied dose has become equal to or exceeded the critical dose.
[0034] In the step of providing the result of the comparison, in particular, information is provided as to whether the weighted total applied dose is equal to or exceeds the critical dose. In particular, this information can be provided via a user interface such as a monitor and / or a flash lamp. In particular, a warning can be provided as soon as the weighted total applied dose is equal to or exceeds the critical dose. Alternatively or additionally, the result can be provided to a database or a computer system in order to further use this result for further decision-making and / or in order to control an imaging system used in a medical imaging process.
[0035] The inventors have recognized that by taking into account the time course of the cumulative dose in each sub-chamber, it can be ensured that sub-chambers measuring the dose behind a free field or behind a low-absorbing material such as tissue contribute only according to their respective weights to the weighted total applied dose. The inventors have recognized that in this way, the influence of the measured cumulative doses of different sub-chambers on the weighted total applied dose can be controlled. The inventors have recognized that in particular in order to improve the image quality in regions of high-absorbing material, the weights can be determined such that the sub-chamber measuring the cumulative dose behind this high-absorbing material has a higher influence on the weighted total applied dose than the measured cumulative dose of a sub-chamber located, for example, behind a low-absorbing or even non-absorbing material. In this way, the critical dose is reached later. In this way, it can be ensured that a sufficiently high dose is applied to achieve high image quality in the region of interest, even if this region includes high-absorbing material. In this way, repeated imaging of the patient can be avoided, since the required image quality can be achieved by the first acquisition. This saves time and costs on the one hand and is more sustainable, and on the other hand, the dose applied to the patient is reduced, since obtaining a second medical image due to the too low image quality of the first medical image results in an even higher dose, as if the dose of the first medical image were increased somewhat.
[0036] According to another aspect of the invention, the method includes the step of applying radiation to a first sub-chamber and a second sub-chamber.
[0037] The radiation is particularly in the energy range of X-rays, especially in the energy range of X-rays used in medicine. In particular, the radiation is in the energy range of X-rays used for medical imaging.
[0038] The radiation is applied to the first sub-chamber and the second sub-chamber. The radiation can pass through the patient before being applied to the first sub-chamber and the second sub-chamber.
[0039] The first sub-chamber and the second sub-chamber are configured to measure the cumulative dose caused by the applied radiation.
[0040] According to another aspect of the present invention, the method further includes the step of stopping the radiation if, based on a comparison, the weighted total applied dose is equal to and / or exceeds a predetermined critical dose.
[0041] In particular, in the step of providing the result, the result is provided such that the radiation is stopped according to the result. In particular, the result is provided to the source emitting the radiation.
[0042] The inventors recognized that in order to avoid overexposure of the patient, the radiation can be automatically stopped according to the result of the comparison. In this way, if the critical dose is reached, the radiation can be stopped and no further dose is applied to the patient. However, since the contributions of the different sub-chambers to the weighted total applied dose are controlled by weights, high image quality can be ensured even if high-absorbing materials such as bone have to be imaged.
[0043] According to another aspect of the present invention, the first time process is characterized by a first gradient. Wherein, the first weight is determined based on the first gradient. Additionally / alternatively, the second time process is characterized by a second gradient. Wherein, the second weight is determined based on the second gradient.
[0044] The first gradient describes the time increase of the first cumulative dose measured by the first sub-chamber. In other words, the first gradient describes the slope of the first time process of the first cumulative dose.
[0045] The second gradient describes the time increase of the second cumulative dose measured by the second sub-chamber. In other words, the second gradient describes the slope of the second time process of the second cumulative dose.
[0046] The first weight depends on the first gradient. In other words, the value of the first weight is related to the value of the first gradient, that is, there is an association.
[0047] The second weight depends on the second gradient. In other words, the value of the second weight is related to the value of the second gradient, that is, there is an association.
[0048] The inventors recognized that behind highly absorbent, i.e., dense materials such as bone, the increase in cumulative dose over time is slower than behind a free field or behind low-absorbing materials such as tissue. Thus, the inventors recognized that the increase in cumulative dose measured with a sub-chamber over time, i.e., the gradient or slope of the time course, gives an indication of the material in front of the sub-chamber, i.e., the attenuation ability of that material. The inventors recognized that in this way, depending on the medical problem for which a medical image is acquired, the influence of different cumulative doses on the weighted total applied dose can be determined based on the material placed in front of the respective sub-chamber. This is achieved by adjusting the weights as described above.
[0049] According to another aspect of the invention, the first weight is inversely proportional to the first gradient and / or the second weight is inversely proportional to the second gradient.
[0050] In other words, the greater the first gradient, the smaller the first weight. Alternatively or additionally, the greater the second gradient, the smaller the second weight.
[0051] Alternatively, the dependence, i.e., the relationship, does not necessarily have to be continuously inversely proportional.
[0052] For example, within a range of the first gradient, the first weight can be constant. If the first gradient is outside this range, the first weight is adjusted according to the first gradient. If the first gradient is below the range, the first weight increases. If the first gradient is above the range, the first weight decreases.
[0053] Similarly, for example, within a range of the second gradient, the second weight can be constant. If the second gradient is outside this range, the second weight is adjusted according to the second gradient. If the second gradient is below the range, the second weight increases. If the second gradient is above the range, the second weight decreases.
[0054] The inventors recognized that the inverse dependence between the weight and the gradient solves the above problem. In this way, it can be ensured that the influence of the cumulative dose measured behind highly absorbent materials is increased compared to the cumulative dose measured between low-absorbing materials. In this way, it can be ensured that the image quality of highly absorbent materials is good enough for further medical decisions or diagnoses before reaching the critical dose.
[0055] According to another aspect of the present invention, if the first gradient is below a predetermined threshold, the first weight is set to a first value; and if the first gradient is above a predetermined threshold, the first weight is set to a second value. Alternatively or additionally, if the second gradient is below a predetermined threshold, the second weight is set to a first value; and if the second gradient is above a predetermined threshold, the second weight is set to a second value. Wherein, the first value is greater than the second value.
[0056] A predetermined threshold is set such that when determining the weighted total applied dose, the cumulative dose measured behind the region of interest of the patient is weighted stronger compared to other cumulative doses. In particular, the threshold can be set such that the cumulative dose measured behind, for example, bone is weighted more than the cumulative dose measured behind, for example, tissue or measured in a free field.
[0057] The inventors recognize that by using a predetermined threshold and a fixed value to determine the weights, the above advantages can also be achieved. In particular, this provides a simple way to determine the first weight and the second weight. In particular, in this way, less computational resources are used. The threshold can be easily adapted to the material of interest, i.e., the material of the region of interest.
[0058] According to another aspect of the present invention, the steps of the method described above are repeated until the weighted total cumulative dose is equal to and / or exceeds a predetermined critical dose.
[0059] In other words, the steps described above are continuously repeated, where the latest values of the first time course and the second time course change. In particular, the latest values of the first time course and the second time course increase.
[0060] Once the weighted total applied dose reaches and / or exceeds the critical dose, a warning message can be provided. Alternatively or additionally, as described above, in this case, the radiation can be stopped.
[0061] The inventors recognize that by repeating the steps of the method described above, it is ensured that the current cumulative dose value is taken into account to determine the weighted total applied dose. As the cumulative dose value increases over time, by repeating the steps of the method, it can be ensured that the current dose is always taken into account, and overexposure of the patient can be avoided.
[0062] According to a second aspect, the present invention relates to an AEC comprising at least a first sub-chamber and a second sub-chamber. The AEC is configured to perform the method according to the method described above.
[0063] The AEC is in particular a solid-state AEC. The sub-chambers are configured to measure the dose, in particular the cumulative dose, applied by the radiation passing through the sub-chambers of the AEC.
[0064] The AEC can in particular be used for the method as described above.
[0065] According to one aspect of the present invention, the AEC comprises a plurality of sub-chambers which are distributed over a region corresponding to the imaging region of the detector.
[0066] The detector is configured to detect radiation and to acquire a medical image. The detector capable of detecting radiation is characterized by the imaging region.
[0067] The AEC is configured such that the sub - chambers are distributed over an area corresponding to the size of the imaging area.
[0068] The inventors have recognized that in this way, since the entire imaging area is taken into account, a more accurate weighted total applied dose can be determined. The inventors have also recognized that in this way, since individual sub - chambers that measure, for example, free - field dose and fall outside the range have less influence on the weighted total applied dose, just as if the sub - chambers were distributed only over a smaller part of the imaging area. In particular, if the sub - chambers are distributed over the entire imaging area, it is simpler to position the patient perfectly in front of the sub - chambers of the AEC. In this way, it is possible to ensure in a safer manner that the area of interest is in front of at least one sub - chamber.
[0069] According to another aspect of the present invention, a plurality of sub - chambers are evenly distributed over the imaging area.
[0070] The inventors have recognized that in this way, each detector, i.e., the imaging area, can be covered by the sub - chambers. In this way, it is possible to ensure that the cumulative dose takes into account all areas that may be imaged. This makes it easier to position the patient, because as long as the area of interest is in front of the imaging area, the area of interest is always in front of the sub - chambers.
[0071] According to another aspect of the present invention, a plurality of sub - chambers are subdivided into groups. Wherein, the sub - chambers included in one group can only be read out together.
[0072] In other words, the sub - chambers of one group can only be enabled together. Several groups can be used together.
[0073] However, the cumulative dose value of each individual sub - chamber can still be read out.
[0074] In a third aspect, the present invention relates to a system for dose control using an AEC. The AEC includes at least a first sub - chamber and a second sub - chamber. The system includes an interface and a computing unit, wherein the interface and / or the computing unit are configured to perform the following steps:
[0075] - Receive a first time - course of a first cumulative dose from the first sub - chamber,
[0076] - Receive a second time - course of a second cumulative dose from the second sub - chamber,
[0077] - Receive a predetermined critical dose,
[0078] - Determine a first weight based on the first time - course,
[0079] - Determine a second weight based on the second time - course,
[0080] - Multiply the latest value of the first time - course by the first weight to determine a first weighted cumulative dose,
[0081] - Multiply the latest value of the second time process by the second weight to determine the second weighted cumulative dose.
[0082] - Add the first weighted cumulative dose and the second weighted cumulative dose to determine the weighted total applied dose.
[0083] - Compare the weighted total applied dose with a predetermined critical dose.
[0084] - Provide the result of the comparison.
[0085] In particular, the system can be configured to perform the previously described method of dose control using AEC. The system is configured to perform the method and its aspects through an interface and a computing unit configured to perform the corresponding method steps. In particular, the interface may include one or more sub-interfaces. In particular, the computing unit may include one or more computing sub-units.
[0086] In a fourth aspect, the present invention relates to a computer program product having a computer program and a computer-readable medium. The mainly software-based implementation has the following advantages: Even a previously used system can be easily upgraded by software updates to operate in the described manner. In addition to the computer program, such a computer program product may optionally include additional components such as documentation and / or add-ons, as well as hardware components such as a hardware key (dongle, etc.) for using the software.
[0087] In a further aspect, the present invention relates to a computer program product that includes program units that can be directly loaded into the storage unit of a first providing system, and when the program units are executed by the system, cause the system to perform the method according to the claimed method and its aspects.
[0088] In a fifth aspect, the present invention relates to a computer-readable storage medium that includes program units that can be read and executed by a system to perform the claimed method and its aspects when the program units are executed by the system.
[0089] In a further aspect, the present invention relates to a computer-readable storage medium that includes a first trained function as claimed. BRIEF DESCRIPTION OF THE DRAWINGS
[0090] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, it should be understood that the drawings are designed only for the purpose of illustration and not as a definition of the limitations of the present invention.
[0091] Figure 1 A schematic flow chart showing a first embodiment of a method for dose control
[0092] Figure 2 shows a solid-state AEC including sub-chambers, as known in the art,
[0093] Figure 3 shows a solid-state AEC including sub-chambers, some of which are covered by bone,
[0094] Figure 4 shows a flow chart of a second embodiment of a method for dose control,
[0095] Figure 5 shows a first embodiment of an AEC,
[0096] Figure 6 shows a second embodiment of an AEC,
[0097] Figure 7 shows a system. Detailed Description
[0098] Figure 1 shows a schematic flow chart of a first embodiment of a method for dose control.
[0099] In an optional step of applying APP radiation, the radiation is applied to at least a first sub-chamber and a second sub-chamber of an automatic exposure control (abbreviation: AEC) 1. The radiation is emitted by a source. The radiation is particularly in the energy range of x-rays. In particular, the radiation is in the energy range for medical imaging purposes, especially for medical imaging.
[0100] AEC 1 includes at least a first sub-chamber A and a second sub-chamber B. In particular, AEC 1 may include more than two sub-chambers. AEC 1 is particularly placed in front of a detector 3. The detector 3 is configured to detect incident radiation to acquire a medical image.
[0101] Generally, the detector 3 is placed such that the radiation emitted by the source 4 first passes through the region of the patient 2 to be imaged and then reaches the detector 3. AEC 1 is placed between the detector 3 and the patient 2 to detect the dose of radiation applied to the patient 2.
[0102] The patient 2 can be a human or an animal or an object.
[0103] In the step of receiving a first time course TC1 of a first cumulative dose in the first sub-chamber A of REC-1 and a second time course TC2 of a second cumulative dose in the second sub-chamber B of REC-2, the first time course TC1 is provided by the first sub-chamber A and the second time course TC2 is provided by the second sub-chamber B.
[0104] The first time process TC1 describes how the first cumulative dose measured by the first sub-chamber A evolves over time. In particular, the first time process TC1 describes the rate at which the first cumulative dose increases. The first time process TC1 includes at least two data points that describe the first cumulative dose at two different time points measured by the first sub-chamber A. In particular, the first time process TC1 may include more than two data points, i.e., data values. In particular, the first time process TC1 may include data points, i.e., values, measured by the first sub-chamber A every 10 milliseconds, every 100 milliseconds, or every second, for example.
[0105] The second time process TC2 describes how the second cumulative dose measured by the second sub-chamber B evolves over time. In particular, the second time process TC2 describes the rate at which the second cumulative dose increases. The second time process TC2 includes at least two data points that describe the second cumulative dose at two different time points measured by the second sub-chamber B. In particular, the second time process TC2 may include more than two data points, i.e., data values. In particular, the second time process TC2 may include data points, i.e., values, measured by the second sub-chamber B every 10 milliseconds, every 100 milliseconds, or every second, for example.
[0106] In the step of receiving the REC-3 predetermined critical dose COD, the critical dose COD is received, for example, through a user interface and / or from a database. The critical dose COD can be manually predetermined and provided. Alternatively, the critical dose COD can be a standard dose provided by medical regulations. The critical dose COD can depend on the patient to be imaged. In particular, the critical dose COD for a child can be less than the critical dose COD for an adult. In particular, the critical dose COD can depend on the area to be imaged. In particular, the critical dose COD for imaging the knee can be less than the critical dose COD for imaging the chest. The critical dose COD provides the dose value that should be maximally applied to the patient.
[0107] In the step of determining the DET-1 first weight W1, the first weight W1 is determined based on the first time process TC1. In the step of determining the DET-2 second weight W2, the second weight W2 is determined based on the second time process TC2. The first weight W1 and the second weight W2 are determined by a calculation unit.
[0108] In particular, the first weight W1 depends on the temporal change of the first cumulative dose, in particular, on the increase in the first cumulative dose over time.
[0109] In particular, the second weight W2 depends on the temporal change of the second cumulative dose, in particular, on the increase in the second cumulative dose over time.
[0110] According to an embodiment of the present invention, a first time course TC1 is characterized by a first gradient. The first gradient describes the slope of the increase in the first cumulative dose. A first weight W1 is determined based on the first gradient.
[0111] Optionally, the first weight W1 is inversely proportional to the first gradient. This means that the greater the first gradient, the smaller the first weight W1. In particular, this dependency between the first gradient and the first weight W1 can be continuous. Alternatively, this dependency can be stepwise. In other words, within a range of values of the first gradient, the first weight W1 can be constant. If the first gradient is below this range, the first weight W1 can be higher. If the first gradient is above this range, the first weight W1 can be lower.
[0112] Optionally, if the first gradient is below a predetermined threshold, the first weight W1 is set to a first value, and if the first gradient is above the predetermined threshold, the first weight W1 is set to a second value. Wherein, the first value is greater than the second value. In particular, more than one threshold can be predetermined, so as to define a stepwise behavior of the first weight according to the first gradient.
[0113] The predetermined threshold can depend on the patient to be imaged and / or the region of the patient to be imaged. In particular, the predetermined threshold is set such that the material in the region to be imaged, especially the region of interest, is depicted in the medical image with a sufficiently high image quality. The predetermined threshold can be set manually by an experienced user or provided by a database as a standard value.
[0114] According to an embodiment of the present invention, a second time course TC2 is characterized by a second gradient. The second gradient describes the slope of the increase in the second cumulative dose. A second weight W2 is determined based on the second gradient.
[0115] Optionally, the second weight W2 is inversely proportional to the second gradient. This means that the greater the second gradient, the smaller the second weight W2. In particular, this dependency between the second gradient and the second weight W2 can be continuous. Alternatively, this dependency can be stepwise. In other words, within a range of values of the second gradient, the second weight W2 can be constant. If the second gradient is below this range, the second weight W2 can be higher. If the second gradient is above this range, the second weight W2 can be lower.
[0116] Optionally, if the second gradient is below the above-mentioned predetermined threshold, the second weight W2 is set to the first value, and if the second gradient is above the predetermined threshold, the second weight W2 is set to the second value. Wherein, the first value is greater than the second value. In particular, more than one threshold can be predetermined, so as to define a stepwise behavior of the second weight according to the second gradient.
[0117] In the step of multiplying MULT-1 the latest value of the first time process TC1 by the first weight W1, the first weighted cumulative dose is determined. The latest value of the first time process TC1 is the value of the first cumulative dose last measured in the first sub-chamber A. In particular, all values of the first time process TC1 can be multiplied by the first weight W1. In this case, the first weighted time process is determined. The latest value, i.e., the last value, of the first weighted time process corresponds to the first weighted cumulative dose.
[0118] In the step of multiplying MULT-2 the latest value of the second time process TC2 by the second weight W2, the second weighted cumulative dose is determined. The latest value of the second time process TC2 is the value of the second cumulative dose last measured in the second sub-chamber B. In particular, all values of the second time process TC2 can be multiplied by the second weight W2. In this case, the second weighted time process is determined. The latest value, i.e., the last value, of the second weighted time process corresponds to the second weighted cumulative dose.
[0119] In the step of adding ADD the first weighted cumulative dose and the second weighted cumulative dose, the weighted total applied dose WOAD is determined.
[0120] In the step of comparing COMP, the weighted total applied dose WOAD is compared with a predetermined critical dose COD. In particular, it is compared whether the weighted total applied dose WOAD is equal to and / or exceeds the predetermined critical dose COD.
[0121] In the step of providing PROV the result of the comparison, the result of the above comparison is provided.
[0122] In particular, a warning according to the result can be provided. In particular, when the weighted total applied dose WOAD is equal to and / or exceeds the critical dose COD, the user can be notified by a warning. In this case, the warning can be provided, for example, by a flash light and / or by a monitor and / or by an audio output.
[0123] Optionally, the result can be provided to the source emitting radiation and / or the controller of the source. Once, according to the result, the weighted total applied dose WOAD is equal to and / or exceeds the predetermined critical dose COD, the result can be used to stop STOP the radiation.
[0124] Optionally, the steps of the method can be repeated until the weighted total applied dose WOAD is identified as being equal to and / or exceeding the critical dose COD during the step of comparing COMP. In this case, during the step of receiving the first time course TC1 of REC-1 and the step of receiving the second time course TC2 of REC-2, the first time course TC1 and the second time course TC2 are updated. In other words, in these steps, new values of the first cumulative dose and the second cumulative dose are received. In this way, the most recent values of the time courses TC1, TC2 are changed, and the comparison is made with the current values. In this way, the increase in the first cumulative dose and the second cumulative dose can be taken into account, and it can be timely identified whether the weighted total applied dose WOAD is equal to and / or exceeds a predetermined critical dose COD.
[0125] Figure 2 Shown is a solid-state AEC 1 including sub-chambers A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q as known in the art.
[0126] The depicted AEC 1 is the AEC 1 used in the art. The depicted AEC 1 includes 17 sub-chambers A, …, Q.
[0127] The sub-chambers A, …, Q are grouped. In particular, the central sub-chambers A, B, C, D, E form a first group. This group can be enlarged by the other sub-chambers F, G, H, I. The sub-chambers J, K, L, M on the left form a second group, and the sub-chambers N, O, P, Q on the right form a third group.
[0128] The sub-chambers A, …, Q of one group can only be used together, while the sub-chambers A, …, Q of the other groups can be deactivated. In other words, the sub-chambers A, …, Q can only be enabled and disabled in groups. For example, the user can decide to only use, i.e., enable, the first group of sub-chambers A, …, E to perform the above method. In particular, more than one group of sub-chambers A, …, Q can be used together, i.e., enabled.
[0129] The AEC 1 is a solid-state AEC. This means that the radiation is measured by each individual sub-chamber A, …, Q according to the semiconductor principle.
[0130] Figure 3 Shown is a solid-state AEC 1 including sub-chambers A, …, Q, where some of the sub-chambers A, …, Q are covered by the skeleton 2b.
[0131] Figure 3 The AEC 1 shown in Figure 2The AEC 1 shown in. In this embodiment, the first group of sub-chambers A,..., E are selected for use, i.e., enabled. The patient 2 is placed in front of this first group such that the right sub-chambers B, C, E of the first group are covered by the bones of the spine, while the left sub-chambers A, D are not covered or are only covered by surrounding tissues (not depicted).
[0132] This results in a relatively faster increase in the measured cumulative dose in the non-spine-covered sub-chambers A, D, while the measured cumulative dose in the spine-covered sub-chambers B, C, E increases relatively slowly.
[0133] If the critical dose COD is calculated in the conventional manner, the measured cumulative doses of the first group of sub-chambers A,..., E are summed. Since the cumulative doses measured in the non-spine-covered sub-chambers A, D increase much faster than the cumulative doses measured in the other sub-chambers B, C, E, the influence of the non-covered sub-chambers A, D on the final total cumulative dose is much higher than that of the other sub-chambers B, C, E. This results in the critical dose COD being reached too quickly eventually, and the image quality in the spine region is not good enough under the conventional settings.
[0134] Figure 4 A flowchart of a second embodiment of the method for dose control is shown.
[0135] The method is performed in accordance with the description related to Figure 1 related description.
[0136] Schematically, the patient 2 is depicted as being placed between the x-ray emitting source 4 and the detector 3 that detects the x-rays passing through, i.e., penetrating, the patient 2. The AEC 1 is placed in front of the detector 3.
[0137] Exemplarily, three time courses TC1, TC2, TC3 measured by three sub-chambers A, B, C of the AEC 1 are shown. The three time courses TC1, TC2, TC3 show different slopes over time. In other words, the cumulative doses measured with the three sub-chambers increase differently over time, depending on the material of the patient placed in front of the respective sub-chambers A, B, C. Therefore, the three time courses TC1, TC2, TC3 have different gradients. The three time courses TC1, TC2, TC3 are received in the steps of receiving REC-1, REC-2.
[0138] According to the respective gradients of the time courses TC1, TC2, TC3 for each sub-chamber A, B, C, the weights W1, W2, W3 are determined in the steps of determining DET-1, DET-2. The possible dependence relationship between the weights W1, W2, W3 and the time courses TC1, TC2, TC3 is described in the description related to Figure 1 related description.
[0139] In the steps of multiplying MULT-1, MULT-2, each time course TC1, TC2, TC3 is multiplied by the corresponding weights W1, W2, W3. As described above, each time course TC1, TC2, TC3 includes at least two values of the cumulative dose measured by the corresponding sub-chambers A, B, C at two different time points. The at least most recent value of each time course TC1, TC2, TC3 is multiplied by the corresponding weights W1, W2, W3. Thus, three weighted cumulative doses are determined, one for each of the sub-chambers A, B, C. The weighted cumulative dose for a sub-chamber A, B, C corresponds to the multiplication of the most recent value of the corresponding time course TC1, TC2, TC3 by the corresponding weight W1, W2, W3. The most recent value of the time courses TC1, TC2, TC3 is the value last measured by the corresponding sub-chambers A, B, C.
[0140] In the step of adding ADD, the weighted cumulative doses are added. Thus, the weighted total applied dose WOAD is determined.
[0141] In the step of comparing COMP, the weighted total applied dose WOAD is compared with a predetermined critical dose COD that has been received in the step of receiving REC-3.
[0142] If the weighted total applied dose WOAD is less than the critical dose COD, the method steps are repeated. Thus, new current weighted cumulative doses for each of the sub-chambers A, B, C are determined and summed to a new current weighted total applied dose WOAD.
[0143] If the weighted total applied dose WOAD is equal to and / or exceeds the critical dose COD, the comparison result is provided such that the source 4 stops in the step of stopping STOP emitting radiation. For this purpose, the result is provided to the source 4 and / or to the controller of the source 4 in the step of providing PROV.
[0144] Figure 5 A first embodiment of the AEC 1 is shown.
[0145] The AEC 1 includes a plurality of sub-chambers that are distributed over the entire area of the AEC 1.
[0146] Advantageously, the area of the AEC 1 corresponds to the imaging area of the detector 3. In other words, advantageously, the area of the AEC 1 covers the entire imaging area of the detector 3.
[0147] Figure 6 A second embodiment of the AEC 1 is shown.
[0148] The AEC 1 includes a plurality of sub-chambers. As compared with Figure 2Compared with the prior art AEC 1 shown, the embodiment of AEC 1 includes more sub-chambers, and these sub-chambers are more widely distributed over the area of AEC 1.
[0149] Advantageously, the area of AEC 1 corresponds to the imaging area of the detector 3. In other words, advantageously, the area of AEC 1 covers the entire imaging area of the detector 3.
[0150] In particular, a set of sub-chambers of AEC 1 includes more sub-chambers than known in the art. Alternatively or additionally, AEC 1 includes more sets of sub-chambers than known in the art.
[0151] Figure 7 The system SYS is shown. The displayed system SYS is configured to execute a method for dose control according to the present invention. The system SYS includes an interface SYS.IF, a computing unit SYS.CU, and a storage unit SYS.MU.
[0152] The system SYS can in particular be a computer, a microcontroller, or an integrated circuit. Alternatively, the system SYS can be a real network or a virtual network of computers (the technical term for a real network is "cluster", and the technical term for a virtual network is "cloud"). The system SYS can also be designed as a virtual system (technical term "virtualization") executed on a computer, a real network of computers, or a virtual network of computers.
[0153] The interface SYS.IF can be a hardware interface or a software interface (such as a PCI bus, USB, or FireWire). The computing unit SYS.CU can have hardware elements or software elements, such as a microprocessor or a so-called FPGA (abbreviation for "field programmable gate array"). The storage unit SYS.MU can be implemented as a non-permanent working memory (random access memory, abbreviated as RAM) or a permanent mass storage device (hard disk, USB stick, SD card, solid state drive).
[0154] The interface SYS.IF can in particular include a plurality of sub-interfaces that execute different steps of the corresponding method. In other words, the interface SYS.IF can also be understood as a plurality of interfaces SYS.IF. The computing unit SYS.CU can in particular include a plurality of sub-computing units that execute different steps of the corresponding method. In other words, the computing unit SYS.CU can also be understood as a plurality of computing units SYS.CU.
[0155] In the absence of an express description, the respective embodiments or their respective aspects and features may be combined or exchanged with one another without restricting or expanding the scope of the described invention, provided that such combination or exchange makes sense and is within the meaning of the present invention. The advantages described with respect to one embodiment of the present invention are, where applicable, also advantageous for other embodiments of the present invention.
Claims
1. A computer-implemented method for dose control using automatic exposure control (1), Among them, wherein the automatic exposure control (1) includes at least a first sub-chamber (A) and a second sub-chamber (B), the method comprising the steps of: - receiving (REC-1) a first time course (TC1) of a first cumulative dose from the first sub-chamber (A), - receiving (REC-2) a second time course (TC2) of a second cumulative dose from the second sub-chamber (B), - receiving (REC-3) a predetermined critical dose (COD), - determining (DET-1) a first weight (W1) based on the first time course (TC1), - determining (DET-2) a second weight (W2) based on the second time course (TC2), - multiplying (MULT-1) the latest value of the first time course by the first weight (W1) to determine a first weighted cumulative dose, - multiplying (MULT-2) the latest value of the second time course by the second weight (W2) to determine a second weighted cumulative dose, - adding (ADD) the first weighted cumulative dose and the second weighted cumulative dose to determine a weighted total applied dose (WOAD), - comparing (COMP) the weighted total applied dose (WOAD) with the predetermined critical dose (COD), - providing (PROV) the result of the comparison.
2. The method according to claim 1, further comprising the step of: - applying (APP) radiation to the first sub-chamber (A) and the second sub-chamber (B).
3. The method according to claim 2, further comprising the step of: - stopping (STOP) radiation if, based on the comparison, the weighted total applied dose (WOAD) is equal to and / or exceeds the predetermined critical dose (COD).
4. The method according to one of the preceding claims, Among them, wherein the first time course (TC1) is characterized by a first gradient, wherein the first weight (W1) is determined based on the first gradient, and / or wherein the second time course (TC2) is characterized by a second gradient, wherein the second weight (W2) is determined based on the second gradient.
5. The method according to claim 4, Among them, wherein the first weight (W1) is inversely proportional to the first gradient, and / or wherein the second weight (W2) is inversely proportional to the second gradient.
6. The method according to claim 4, Among them, wherein if the first gradient is below a predetermined threshold, the first weight (W1) is set to a first value, and wherein if the first gradient is above a predetermined threshold, the first weight (W1) is set to a second value, and / or wherein if the second gradient is below a predetermined threshold, the second weight (W2) is set to a first value, and wherein if the second gradient is above a predetermined threshold, the second weight (W2) is set to a second value, wherein the first value is greater than the second value.
7. The method according to one of the preceding claims, Among them, Repeat the steps of the method according to one of claims 1 to 6 until the weighted overall accumulated dose (WOAD) is equal to and / or exceeds the predetermined critical dose (COD).
8. An automatic exposure control device (AEC) comprising at least a first sub-chamber (A) and a second sub-chamber (B), Among them, The automatic exposure control device (AEC) is configured to perform the method according to one of claims 1 to 7.
9. The automatic exposure control device (AEC) according to claim 8, Among them, The automatic exposure control device (AEC) includes a plurality of sub-chambers (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q), which are distributed in a region corresponding to the imaging region (IA) of the detector (3).
10. The automatic exposure control device (AEC) according to claim 9, Among them, The plurality of sub-chambers (A, …, Q) are evenly distributed over the imaging region (IA).
11. A system (SYS) for dose control using an automatic exposure control device (AEC) according to one of claims 8 to 10, Among them, The automatic exposure control device (AEC) comprises at least a first sub-chamber (A) and a second sub-chamber (B), wherein the system (SYS) includes an interface (SYS.IF) and a computing unit (SYS.CU), wherein the interface (SYS.IF) and / or the computing unit (SYS.CU) is configured to perform the following steps: - Receive (REC-1) a first time course (TC1) of a first accumulated dose from the first sub-chamber (A), - Receive (REC-2) a second time course (TC2) of a second accumulated dose from the second sub-chamber (B), - Receive (REC-3) a predetermined critical dose (COD), - Determine (DET-1) a first weight (W1) based on the first time course (TC1), - Determine (DET-2) a second weight (W2) based on the second time course (TC2), - Multiply (MULT-1) the latest value of the first time course by the first weight (W1) to determine a first weighted accumulated dose, - Multiply (MULT-2) the latest value of the second time course by the second weight (W2) to determine a second weighted accumulated dose, - Add (ADD) the first weighted accumulated dose and the second weighted accumulated dose to determine a weighted overall applied dose (WOAD), - Compare (COMP) the weighted overall applied dose (WOAD) with the predetermined critical dose (COD), - Provide (PROV) the result of the comparison.
12. A computer program product comprising program units that can be directly loaded into a storage unit of a system (SYS), which, when the program units are executed by the system (SYS), cause the system (SYS) to perform the method according to any one of claims 1 to 7.
13. A computer-readable storage medium, the computer-readable storage medium comprising program units that can be read and executed by a system (SYS) to perform the method according to one of claims 1 to 7 when the program units are executed by the system (SYS).