Compensation algorithm for active rise and fall times

Abstract

A method for compensating settings in a pulsed X-ray system is provided. Current, voltage, and expected pulse width settings are selected for the X-ray pulse to be provided. Then, compensation is performed on the selected pulse width settings for the set voltage and tube current, taking into account the ambient temperature of the electronic circuitry of the X-ray vessel, based on one or more standardized values ​​stored at a predetermined temperature. In a calibration step, a standardized value is obtained based on the actual or effective pulse width and its difference from the expected width, and this value is standardized using the temperature of the circuitry supplying the pulse voltage and current to the source.

Description

Technical Field

[0001] This invention relates to the field of radiological diagnostics. More specifically, this invention relates to methods, software products, and systems for generating X-ray pulses, activating, and calibrating X-ray systems, and related calibrated X-ray systems. Background Technology

[0002] Several different X-ray patterns can be generated in an X-ray machine. Depending on the application, the surgeon, the type of surgery, and / or the components used in the X-ray machine, some X-ray patterns are more advantageous than others. One possible X-ray pattern is a pulsed pattern, in which X-rays are generated at a predetermined duty cycle.

[0003] According to international regulations, the applied X-ray parameters should be reported to the user with a specified accuracy. Specifically, for many applications (including medical and surgical applications), for any user-selectable settings, the average tube current is expected to be accurate within 20% of the actual current applied to the tube. For continuous X-ray modes, the average tube current depends only on the amount of tube current. However, for pulsed X-ray modes, the average current is a combination of the peak tube current and the pulse width, as a function of the period (duty cycle) during which that peak tube current is actually applied.

[0004] Due to wiring and circuitry, when a voltage setting (e.g., a square wave) pulse is applied to power the X-ray tube anode, the cable and circuit capacitance causes an increased pulse rise time. On the other hand, when the voltage is removed at the end of the pulse to terminate the X-ray exposure, the discharge of the cable and circuit capacitance current causes the applied kilovolt voltage to decay with a certain delay, rather than dropping instantaneously.

[0005] When the interval is long, such as exceeding 20 milliseconds (ms), the slowed rise time and extended decay time cause an error of one or several percent in the exposure interval. However, for short-duration X-ray exposures, such as less than 20 ms, the rise and decay times represent a significant percentage of the exposure interval.

[0006] US4454606A provides an automatic exposure control for compensating for rise and fall times. However, the compensation cannot account for variations in the X-ray generator, such as those caused by use, and typically requires time-consuming recalibration of the equipment to compensate for such variations.

[0007] Furthermore, such inaccuracies are more difficult to predict and may require compensation for X-ray system settings that are outside the optimal range to achieve improved accuracy. Summary of the Invention

[0008] The purpose of embodiments of the present invention is to provide a method for activating an X-ray system, a method for calibrating an X-ray system, a software implementation method for calibrating and / or activating an X-ray system, and an X-ray system wherein pulses are normalized and compensated for temperature variations in the X-ray source electronic circuitry (e.g., in oil surrounding the X-ray tube).

[0009] In a first aspect, the present invention provides a method for providing or generating X-ray pulses by means of an X-ray system including an X-ray chamber containing an X-ray source or tube, the method comprising:

[0010] - Select the current, voltage, and expected pulse width settings for the X-ray pulse to be provided.

[0011] - Taking into account the internal temperature of the X-ray chamber, the selected pulse width setting is compensated for the set voltage and tube current based on the standardized value at the stored predetermined temperature.

[0012] An X-ray system may include an X-ray generator, and the compensation may be accomplished by introducing a compensated X-ray pulse width into the X-ray generator.

[0013] The advantage of embodiments of the present invention is that pulse width deviations caused by the effects of temperature on the system's electronics, particularly the electronics of the X-ray tube, can be compensated for by using a predictive model that takes temperature into account. Pulse width correction improves the X-ray dose and the accuracy of the average current through the X-ray tube, making it easier to meet international standards and allowing for further reductions in the minimum usable pulse width.

[0014] In other words, for the selected (expected) pulse width, such as the actual pulse width value to be used when generating an X-ray pulse using an X-ray system, it can be derived from one of the corresponding stored normalized values, such as the normalized value determined for the tube voltage and current to match the current settings. Here, "normalized value" should be understood as the deviation, or delta, between the expected X-ray pulse width normalized to a predetermined temperature and the actual X-ray pulse width. Although the normalized value is determined at a predetermined temperature (or reference temperature), the current temperature, specifically the internal temperature of the X-ray vessel, can be taken into account when determining any necessary compensation for the actual X-ray pulse width to be set. For example, as further described herein, a predetermined temperature dependence of the pulse width deviation can be involved.

[0015] In some embodiments of the invention, the method further includes calculating a normalized value by interpolation based on stored normalized values ​​corresponding to a first setting for current and a first setting for voltage, and stored normalized values ​​corresponding to other settings for current and other settings for voltage, at least one of the other settings being different from the first setting value, wherein the selected current and voltage values ​​are between at least one different first setting for current and other settings and / or between the first setting for voltage and other settings.

[0016] An advantage of embodiments of the present invention is that the voltage and / or current settings not used during calibration can still be compensated for by obtaining normalized values ​​through interpolation of values ​​that store the runtime, thus allowing the storage of a small number of values, for example, allowing the use of small LUTs.

[0017] In a second aspect, the present invention provides a method for calibrating an X-ray system including an X-ray chamber, wherein the X-ray chamber includes an X-ray source, the method comprising:

[0018] - The settings for the selected current, selected voltage, and expected pulse width are applied to the X-ray source to generate actual voltage and current signals for the X-ray source, thereby producing at least one X-ray pulse with the actual pulse width.

[0019] - Measure the actual voltage signal applied to the X-ray source and determine the actual pulse width based on the measured actual voltage signal.

[0020] - Obtain the difference between the actual pulse width and the expected pulse width.

[0021] - This difference, obtained at the actual internal temperature of the X-ray chamber, is standardized to a standardized difference for a predetermined internal temperature of the X-ray chamber, which is the ambient temperature for electronic circuitry (e.g., including capacitors). Therefore, taking into account that the internal temperature of the X-ray chamber is, for example, the ambient temperature of a capacitor, a standardized value is obtained from this difference at the predetermined temperature.

[0022] - A function that stores the standardized value from the difference as a setting of the selected current and the selected voltage.

[0023] For example, an X-ray system may include an X-ray generator, and the application settings may include applying the settings in the X-ray generator.

[0024] The stored normalized values ​​can be used in the method of the first aspect of the invention. An advantage of embodiments of the invention is that it provides a predictive model to compensate for temperature-induced deviations in pulse width for all required voltage (kV) and tube current settings of a high-voltage power-supply X-ray system (e.g., an X-ray chamber including an X-ray source). The normalized values ​​are preferably stored in a LUT. The actual pulse width can be determined as the time interval between the moment when the actual voltage signal exceeds a predetermined threshold and the moment when the actual voltage signal falls below the predetermined threshold.

[0025] In some embodiments of the invention, the method further includes measuring the internal temperature of the X-ray chamber (i.e., the ambient temperature of the electronic circuitry of the X-ray chamber) before obtaining a standardized value from the difference.

[0026] The advantage of embodiments of the present invention is that it can use a simple temperature sensor to obtain temperature changes for different settings, and the temperature changes can be standardized to a predetermined temperature through a predetermined relationship between temperature and changes in the electrical characteristics of the circuit in the tank.

[0027] In some embodiments of the invention, the method further includes obtaining the rise and fall time deviations of at least one X-ray pulse based on the difference between the determined actual pulse width and the expected pulse width. Obtaining a normalized value based on the difference at a predetermined temperature further includes obtaining a normalized value for the rise and fall time deviations at the predetermined temperature by using a predetermined relationship between the capacitance change of the X-ray chamber and the internal chamber temperature.

[0028] The advantages of embodiments of the present invention are that, by calculating the changes in electrical characteristics as a function of the internal temperature of the X-ray vessel and its circuitry (e.g., high-voltage converters, wiring, etc.), any reproducible rise and fall time deviations can be compensated for, thereby improving the accuracy of the average current applied to the X-ray source. Another advantage is that international regulatory requirements for current accuracy can be met more easily. Yet another advantage is the ability to use smaller pulse widths with high accuracy.

[0029] In some embodiments of the invention, storing a normalized value from the difference between the actual pulse width and the expected pulse width includes storing a normalized value of the rise and fall time deviations as a function of a selected current and a selected voltage.

[0030] An advantage of embodiments of the present invention is that it can store standardized values ​​of rise and fall deviations without storing pulse widths or their differences.

[0031] In some embodiments of the invention, the method is repeated for at least different selected current and / or voltage settings, thereby storing other normalized values ​​from the difference as functions of the different selected current and selected voltage.

[0032] An advantage of embodiments of the present invention is that it is possible to obtain a list of values ​​for constructing a prediction model.

[0033] In a specific embodiment, the method includes calculating at least one standardized value by interpolation between the selected current and / or voltage setting and different selected current and / or voltage settings.

[0034] An advantage of embodiments of the present invention is that the voltage and / or current settings not used during calibration can still be compensated for by obtaining standardized values ​​through interpolation of values ​​stored during calibration, without providing computational runtime, thereby saving processing time during X-ray system utilization.

[0035] In a third aspect, the present invention provides a software product or program including instructions for controlling an X-ray system, for providing X-ray pulses according to the method of the first aspect of the present invention, and further adapted to receive a desired pulse width setting, and further adapted to receive a standardized value obtained by the method of the second aspect of the present invention.

[0036] Software products or programs may include data storage.

[0037] The advantages of embodiments of the present invention lie in the ability to provide software, for example, in the control unit of the X-ray system and / or in the X-ray generator of the X-ray system, which improves system performance. It enables the use of pulses with smaller widths by improving the accuracy of pulse widths over a wider range of settings than the optimal range for a standalone X-ray system, thus increasing the available range of voltage, current settings, and permissible pulse widths. Another advantage of the X-ray system is the ability to provide X-ray generation at lower power, which in turn increases the lifespan of the X-ray source. Other advantages include the ease with which international regulatory requirements for accuracy can be met.

[0038] In an embodiment of the fourth aspect of the invention, the software product is adapted to calibrate the pulse width of an X-ray pulse provided by an X-ray system, and the software product is adapted to receive a pulse width measurement, and optionally also to receive a temperature measurement. When implemented in an X-ray system, the software product is adapted (e.g., including instructions) to perform the calibration method of the second aspect of the invention.

[0039] An advantage of embodiments of the present invention is that it can provide, for example, software products included in a control unit for an X-ray system, which can establish predictive models for compensating for deviations in pulse width caused by the temperature of the X-ray system (or its X-ray chamber).

[0040] In a fifth aspect, the present invention provides a data storage device for an X-ray system, comprising standardized values ​​obtained by the method of the second aspect of the invention. An advantage of embodiments of the invention is that the data storage device can be used to calibrate different X-ray systems, which include electronic circuitry within an X-ray chamber exhibiting behavior similar to or identical to that of temperature. The data storage device may be included in a control unit or in the software product of the third aspect.

[0041] In a sixth aspect, the present invention provides an X-ray system. The X-ray system includes an X-ray chamber comprising an X-ray tube, and a control unit (e.g., integrated into an X-ray generator unit included in the X-ray system) controllable by a software product of the third aspect of the present invention. Data storage may also be included in the software product of the third or fifth aspect of the present invention.

[0042] In some embodiments of the invention, the X-ray system further includes a temperature sensor for sensing the temperature of at least a portion of the X-ray chamber, such as the internal temperature, the ambient temperature of circuitry within the chamber, or the temperature of fluid surrounding the circuitry.

[0043] In some embodiments of the invention, the X-ray system further includes a data memory of a fifth aspect, which may optionally be a reprogrammable data memory. In this case, for example, the control unit is configured to receive at least one standardized value from the data memory.

[0044] An advantage of embodiments of the present invention is that the X-ray system includes previously obtained standardized values ​​for correcting pulse width, and is optionally able to calibrate itself and update the standardized values ​​to compensate for pulse width when needed.

[0045] Modular devices incorporating the X-ray system of the present invention can be provided, suitable for mobile surgical applications. The advantages of embodiments of the present invention are that an X-ray system with a wide range of usable pulse widths and high accuracy and effective pulses can be obtained even at low pulse energies, and it also allows for a reduction in the peak energy used, thus enabling the device to use a more compact power supply while achieving the same average power, for example, without reducing the average power.

[0046] Specific and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features from the dependent claims may be appropriately combined with features of the independent claims and other dependent claims, and not merely as expressly set forth in the claims.

[0047] These and other aspects of the invention will become apparent and will be illustrated with reference to the embodiments described below. Attached Figure Description

[0048] Figure 1 The diagram shows an X-ray pulse with the desired shape, the actual voltage used to generate the charge beam that forms the X-ray pulse, and the actual shape of the generated X-ray pulse.

[0049] Figure 2 An X-ray system according to some embodiments of the present invention is illustrated schematically;

[0050] Figure 3 A method for generating pulsed X-rays, including compensation for selected settings for X-ray generation, is shown.

[0051] Figure 4 An exemplary graph showing the relationship between the capacitance change of an X-ray system and its ambient temperature is presented.

[0052] Figure 5 A calibration method according to an embodiment of the present invention is shown, including optional steps shown in dashed lines;

[0053] Figure 6 An X-ray system according to some embodiments of the present invention is illustrated schematically.

[0054] The accompanying drawings are illustrative only and are not restrictive. In the drawings, for illustrative purposes, the dimensions of some elements may be exaggerated and not drawn to scale.

[0055] Any reference numerals in the claims should not be construed as limiting the scope.

[0056] In different accompanying drawings, the same reference numerals refer to the same or similar elements. Detailed Implementation

[0057] The invention will be described with reference to specific embodiments and certain accompanying drawings, but is not limited thereto, but only by the claims. Dimensions and relative dimensions do not correspond to an actual simplification of the practice of the invention.

[0058] Furthermore, the terms "first," "second," etc., used in the specification and claims are used to distinguish similar elements and are not necessarily used to describe the order in time, space, hierarchy, or any other way. It should be understood that the terms thus used are interchangeable where appropriate, and the embodiments of the invention described herein can operate in orders other than those described or illustrated herein.

[0059] Furthermore, the terms "above" and "below" in the specification and claims are for descriptive purposes only and are not intended to describe relative positions. It should be understood that such terms are interchangeable where appropriate, and the embodiments of the invention described herein can be operated in orientations other than those described or illustrated herein.

[0060] It should be noted that the term "comprising" as used in the claims should not be construed as limited to the means listed thereafter; it does not exclude other elements or steps. Therefore, it is interpreted as specifying the presence of the mentioned feature, integral, step, or component, but does not exclude the presence or addition of one or more other features, integrals, steps, or components, or combinations thereof. Thus, the term "comprising" covers both the presence of only the stated features and the presence of these features plus one or more other features. Therefore, the scope of the expression "device comprising means A and B" should not be construed as limited to a device consisting solely of components A and B. This means that, for the purposes of this invention, the only relevant components of the device are A and B.

[0061] Throughout this specification, references to "an embodiment" or "an embodiment" mean that a specific feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, specific features, structures, or characteristics may be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure.

[0062] Similarly, it should be understood that in the description of exemplary embodiments of the invention, various features of the invention are sometimes combined in a single embodiment, drawing, or description thereof to simplify the disclosure and aid in understanding one or more different inventive aspects. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the following claims, the inventive aspect lies in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed specification are hereby expressly incorporated into this detailed specification, each claim being an independent embodiment of the invention.

[0063] Furthermore, while some embodiments described herein include features not included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments, as will be understood by those skilled in the art. For example, any claimed embodiment can be used in any combination as described in the claims below.

[0064] Numerous specific details are set forth in the specification provided herein. However, it should be understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0065] X-ray systems, including those for medical applications, typically include an X-ray generator and an X-ray chamber containing an X-ray source. The X-ray source, also referred to in this art as an X-ray tube, typically generates high-energy X-ray photons through the interaction of an electron beam from a cathode with a target anode.

[0066] An electron beam is typically provided by applying a voltage between the cathode and anode. In pulsed mode, the voltage is applied in pulses, with a predetermined voltage applied intermittently. Specifically, a constant voltage is applied for time intervals that constitute the pulse duration, and between pulses, the voltage is insufficient to produce X-ray emission; ideally, no voltage is applied (or zero voltage). The specific pulse parameters with the desired or expected pulse width are selected based on application requirements, such as the type of procedure, the area to be irradiated, the patient's weight, etc.

[0067] The desired pulse could be an ideal pulse wave, such as a square wave, where the voltage reaches a predetermined value instantaneously and drops instantaneously. However, in reality, a perfect pulse wave cannot be obtained simply by applying appropriate settings to the X-ray system or its X-ray generator. The voltage actually applied to the power supply takes time to reach its expected value and reaches its minimum value after the pulse is turned off. Therefore, the effective or actual pulse width may be smaller than the expected pulse width.

[0068] Figure 1 The top curve 10 with the expected X-ray pulse CTRL-X is shown. The expected shape is formed by the expected pulse width T. IW The current, voltage, and width settings are used to determine this. For example, these settings are applied to the system by introducing settings in the X-ray generator.

[0069] Intermediate curve 20 shows the change over time of the actual voltage (kVact) through the source or tube, which generates a beam of charge (typically an electron beam) to produce photons that form an X-ray pulse. The actual voltage kVact includes rising and falling edges 21, 22. These edges arise primarily from circuit electronics, parasitic capacitances, and resistances in the circuitry powering the source. Not all emitted photons are considered effective as the voltage increases or decreases. The actual parameters of the generated X-rays, especially the width, must be calculated taking these edges into account. By definition, an X-ray is considered effective when the voltage is equal to or greater than a predetermined percentage of the set voltage. In other words, the effective width of the actual pulse (or simply the actual pulse width) is measured from the moment the voltage rises above a predetermined threshold (typically 75% of the peak value) until the moment the voltage drops back to the same threshold.

[0070] The actual effective X-ray pulse Xact is shown in Figure 1In the bottom curve 30. Due to the rising edge 21, Xact starts after the control signal for the expected X-ray pulse CTRL-X has been introduced, and only when the actual voltage kVact exceeds 75% of the threshold of the set voltage kVset, in the "rise time (T)" curve. RISE The X-ray is considered valid only after the fall time (T) has elapsed. Similarly, due to the falling edge 22, the pulsed Xact is only considered valid after CTRL-X is turned off, within the fall time (T). FALL After this process, it is specifically considered off only when the actual voltage kVact drops below 75% of the voltage setting threshold kVset. Actual pulse width T EffPW Measurements are taken from the moment Xact begins and ends. Therefore, the actual X-ray pulse, especially its width T... EffPW The rise time of the voltage (T) RISE ) and fall time (T FALL The impact. It should be noted that compensating for the drop time is difficult because the time it will take for the voltage to drop below the threshold is not previously known, and this can change, such as... Figure 1 As shown in the image.

[0071] Furthermore, inaccuracy increases when using very short pulse widths, such as those on the order of milliseconds, because in this case, the relative impact of the rise and fall times of a fixed quantity is greatest compared to the actual X-ray pulse under the intended settings. Inaccuracy also increases for very low voltage (kV) and current (mA) conditions. This is believed to be due to the reduced speed of the high-voltage power supply and its circuitry. Specifically, it is due to the exponential discharge curve of the capacitor. At higher voltages, the initial portion of the capacitor's discharge phase is faster than at lower voltages. For example, at 100kV, the discharge rate from 100% to 75% is 100kV to 75kV, while at 40kV it is 40kV to 30kV, thus the discharge rate is different.

[0072] Furthermore, temperature fluctuations in the X-ray chamber have been observed to increase inaccuracies. Without being bound by theory, this increase is thought to be due to changes in impedance (e.g., capacitance) parameters caused by temperature variations in the circuitry supplying pulsed voltage and current to the power source (typically present within the chamber).

[0073] This invention provides a predictive model that allows for rise and fall time compensation even for very short pulses, low voltages and currents, and in some embodiments, for different temperature variations. Specifically, the invention allows for the temperature of the electronic circuitry to be taken into account, for example, for temperature variations, even before generating the X-ray pulse, correcting the settings of the X-ray generator for the pulse width as a function of voltage and current. In some embodiments, the predictive model is capable of predicting the rise and fall time performance obtained from the electrical characteristics of the circuitry in the X-ray generator as a function of temperature.

[0074] In a first aspect, the present invention provides a method for generating or providing X-ray pulses using a pre-calibrated X-ray system. Figure 2 This schematically illustrates an X-ray system 200 according to some embodiments of the present invention, which includes an X-ray chamber 201 and an X-ray generator 202. Chamber 201 includes an X-ray source 203 surrounded by a fluid 206 (e.g., a cooling fluid) and circuits 204, 205 (including transformers, capacitors, etc.). At least one normalized value for correcting the pulse width is stored in a data storage device 207 such as memory, a software database, a lookup table (LUT), a matrix formula, etc.

[0075] A normalized value is the deviation between the expected pulse width and the effective or actual pulse width at a predetermined or reference temperature for setting specific tube current and voltage (kV). In the context of this application, these deviation values ​​are referred to as being "normalized" relative to the predetermined or reference temperature. The temperature can be controlled or measured when determining the normalized value.

[0076] By compensating the actual pulse width based on a normalized value, the expected variation of electrical characteristics with temperature, or a correction factor, can be taken into account. Electrical characteristics can include the circuit's impedance (e.g., capacitance), which has a desired or known variation depending on temperature. During calibration, a normalized value can be calculated from a measurement of the difference between the actual and expected pulse widths and then stored. Alternatively or additionally, a normalized value can be interpolated based on previously stored normalized values, for example, when no matching stored normalized value is available for a specific combination of tube current and voltage.

[0077] exist Figure 3 The document illustrates the process flow for generating X-rays using an X-ray system, including maintenance procedures. First, the voltage, current, and pulse width settings are selected. For example, selecting a pulse width T... IWThe expected pulse (CTRL-X) is generated and introduced into the X-ray generator 202. These settings, along with the voltage and current settings for the X-ray source, can be defined in a database for examination setup. These settings typically depend on the type of examination, patient thickness or the body part being studied, structures in the image area, etc., and are usually predefined in the database. For example, the user can select the type of application (veterinary, human, body part to be irradiated, bone or vascular setup, etc.) and / or radiation dose, etc. The actual pulse settings for voltage, current, and pulse width are applied internally by the system based on the user's selection.

[0078] The method includes accessing a stored value (referred to as the "normalized value") that is at least related to the pulse width and normalized to a predetermined temperature.

[0079] Normalized values ​​have been obtained during calibration using the selected voltage, current, and pulse width settings, and these values ​​are linked to the voltage and current settings. These normalized values ​​can be obtained during a prior calibration procedure performed by the manufacturer (e.g., as part of system manufacturing), by a service engineer, or by the end user once the system is provided to the user. The obtained normalized values ​​are stored in data memory 207 for reference and access during the X-ray generation method. The calibration is explained in more detail with reference to an embodiment of the second aspect of the invention.

[0080] It is possible to obtain a normalized value for correcting the pulse width for one or more current and / or voltage settings. When the current and voltage settings selected for generating X-rays are consistent with the current and voltage settings that have already stored a normalized value in the data memory 207, the normalized value is selected.

[0081] In some embodiments, when the current and voltage settings selected for generating X-rays are inconsistent with the values ​​of current and voltage settings already stored in the data memory, a normalized value of 106 is inserted. Therefore, the normalized value for the selected settings is calculated by inserting normalized values ​​for the nearest higher and nearest lower settings. For example, the selected voltage and current settings may not correspond to any values ​​used to obtain the normalized value. In this case, two normalized values ​​are selected, namely the voltage setting that decreases from the selected voltage setting and the value of the nearest current setting. The normalized value for the selected current and voltage settings is calculated by inserting the normalized values ​​of the two selected voltage settings. If it is necessary to insert normalized values ​​based on the nearest higher and lower current settings or a combination of voltage and current settings, a similar procedure is applied. In some embodiments, a voltage / current curve is selected, and the inserted value is calculated based on the selected voltage (and its associated current).

[0082] In some embodiments, linear interpolation can be used. However, other types of interpolation can be used in embodiments of the invention, for example, when using several voltage settings for a specific voltage / current curve. It should be noted that if interpolation is performed during X-ray applications, a small amount of normalized values ​​needs to be stored, thereby reducing the size of data memory 207. However, interpolation can also be performed during calibration, thereby reducing runtime computation at the cost of a larger data memory 207.

[0083] Before providing the pulse to the X-ray source, the pulse width (e.g., the width of a CRTL-X pulse) can be corrected or compensated using at least one normalized value. Therefore, during application, the X-ray settings (e.g., pulse width) can be updated before providing the voltage pulse using the stored normalized value for a predetermined temperature by applying the compensated settings (e.g., pulse width correction at a temperature for the selected voltage and current settings) to the source (e.g., to practically achieve the desired pulse width). The update can be performed using a programmed control unit 208, for example, inside or outside the X-ray generator. Unit 208 may include a data memory 207; however, the update can also be performed using an algorithm, for example, in an X-ray generator including the data memory 207, that includes instructions to control and adjust parameters.

[0084] To properly account for the effects of temperature on the electronic characteristics of the capacitor, specifically the effects of temperature on the electrical characteristics of high-voltage capacitors and / or smoothing capacitors, the following information can be used:

[0085] - The expected change of one or more electrical characteristics of the circuitry in the tank with temperature, and

[0086] - The temperature of electronic circuits.

[0087] This temperature can be controlled by the heating and / or cooling subsystem 210 (in... Figure 2 The temperature of its control circuits 204 and 205 (e.g., the temperature of their environment, or the temperature of a fluid such as transformer oil 206 in contact with the circuit) is controlled by the control circuits (as shown in the diagram). Therefore, the actual temperature is a predetermined temperature at which a value related to the pulse width is normalized. In this case, this value can be used as a normalized value to directly correct or compensate for the pulse setting (e.g., width) before the pulse is applied. The normalized value can be, for example, the difference between the actual pulse width obtained through calibration and the measured pulse width, normalized to a predetermined temperature, and thus can be directly applied to the pulse width setting when the X-ray chamber is set at the predetermined temperature without the need for calculation to obtain the normalized value.

[0088] Alternatively or additionally, it is possible to measure the temperature of the 105 circuit. For example, temperature sensor 209 (in Figure 2(As shown in the diagram) The temperature of the 105 X-ray tank can be measured before the pulse is applied, so that electrical characteristics can be taken into account when compensating for the 104 setup. The temperature of the 105 tank can be measured by measuring the ambient temperature around the high-voltage converter 204 and / or the high-voltage (HV) and smoothing capacitor 205 in the tank, such as measuring the temperature of the surrounding fluid 206 (e.g., transformer oil).

[0089] In the embodiment of temperature measurement, the expected changes in electrical characteristics (considering capacitors, cables, etc. of the power supply) and temperature are known, so correction factors for electrical characteristics (e.g., impedance, capacitance) can be used to account for rise and fall times caused by the circuit, while taking into account the different behavior of the circuit when the temperature changes.

[0090] It is important to emphasize that the relationship between electrical characteristics and temperature can be used for standardization during calibration (as will be seen in the second aspect) and during applications of temperature measurement, to effectively convert pulse width correction from standardization to actual temperature.

[0091] Figure 4 A graph showing an exemplary relationship 400 between the capacitance change of X-rays, measured as a percentage change (and therefore the capacitance correction factor), and ambient temperature in degrees Celsius is presented. This relationship can be provided theoretically or empirically. In other words, the correlation between electrical characteristics and temperature can be known from the circuit component manufacturer's specifications, from the type of capacitors and components in the X-ray generator, from datasheets, etc.; or it can be measured; or both, for fine-tuning. During application, obtaining the capacitance change in relation to the temperature of the circuit (e.g., the tank), and "de-normalizing" the value related to the pulse width, allows for compensation of 103 pulse widths.

[0092] Finally, the compensated settings can be applied to the source to obtain an X-ray pulse with a corrected pulse width (e.g., a series of X-ray pulses, thus providing pulsed X-ray generation), which is closer to the expected width than the effective pulse width obtained by simply using the settings. For example, the corrected pulse width can match the expected width.

[0093] Furthermore, the fall time can be updated by measuring the temperature run time and updating the normalized value, which can change over time due to degradation of the X-ray source and / or X-ray chamber. This reduces the need for recalibration and the demands on service engineers. The method is similar to the one described, but does not introduce defined voltage and current settings.

[0094] In a second aspect, the present invention provides a calibration method based on a prediction model for compensating for pulse rising and falling edges 21, 22 (in Figure 1The rise and fall times (shown in the diagram) are measured. The method includes providing at least one pulse (e.g., a series of pulses) with predetermined current and voltage settings to obtain a pulse with a desired width, measuring the actual pulse width, obtaining the difference between the desired pulse width and the actual pulse width, and standardizing the value at a predetermined temperature. Standardization can be accomplished by setting the temperature of the circuit to a known value (e.g., a predetermined standardized value), or by measuring the temperature (e.g., using a sensor) and then standardizing the value at the predetermined temperature. From the difference between temperature and width, the effect of temperature on the rise and fall times caused by the circuit can be taken into account. The standardized values ​​obtained from the measurements are stored in data memory 207, for example, in a LUT. This can be repeated for multiple values ​​of voltage, current, or a combination of voltage and current to obtain standardized values ​​corresponding to different settings of current and voltage. In principle, these settings are effective for a wide range of pulse widths.

[0095] Figure 5 An example of this calibration procedure is shown. First, setting 501 is selected and introduced in the X-ray system (e.g., via a user interface or database, such as in X-ray generator 202) to provide a pulse with a predefined shape CTRL-X, specifically with a predetermined desired pulse width T. IW The pulse. These settings may include voltage, current, and expected pulse width.

[0096] The application 502 is set to source 203, which is activated and provides at least one pulse. The actual voltage signal applied by 503 to the X-ray source is then measured. The measurement can be performed using a subsystem for measuring voltage, such as electronic circuitry in control unit 208, or, for example, in X-ray generator 202, etc.

[0097] Based on this measurement, the actual pulse width 504 is determined. The actual pulse width 504 can be determined as the time interval between the moment when the actual voltage signal exceeds a predetermined threshold and the moment when the actual voltage signal drops below the predetermined threshold.

[0098] In other words, it can measure the rise time T of the voltage signal. RISE and descent time T FALL Therefore, the effective width of the actual X-ray pulse (“actual pulse width”) is determined by taking into account the time interval between when the voltage exceeds a predetermined threshold (conventionally, 75% of the voltage fixed in the setup) and when the voltage drops below that predetermined threshold.

[0099] Then obtain the expected pulse width (T) of 505. IW ) and actual pulse width (T) effPW The difference between them.

[0100] In addition, consider the temperature of the 506 circuit. This can be done by obtaining the temperature of the circuit, which may include setting the temperature to a predetermined value before applying the setting to the source with 502, or by measuring the temperature of the circuit while applying the setting to the source with 502 and generating a pulse.

[0101] Setting the temperature can include heating or cooling the circuit using a heater or cooler, such as the temperature of the fluid surrounding the electronics (e.g., oil in a can), as explained above. Measuring the temperature can include (as also explained above) measuring the ambient temperature of the electronics, such as the ambient temperature of the converter, or the temperature of the HV and smoothing capacitor, for example, by sensing the temperature of the fluid in the can, or by using a temperature sensor 209 including a sensing probe.

[0102] Then, the difference between the actual width and the expected width can be standardized to a predetermined temperature, such as the temperature of the circuit set by the user, or the temperature typically found in a transformer, such as room temperature (e.g., between 20°C and 40°C, such as 25°C).

[0103] It can compensate not only for rise and fall times, but also for the effects of temperature variations in electrical characteristics at the rise and fall edges. Specifically, rise and fall times depend on the electrical characteristics (e.g., impedance, such as capacitance) of the specific circuitry of the X-ray chamber (including transformers, capacitors, cables), which in turn depend on temperature. Therefore, as previously explained, variations in electrical characteristics such as impedance can be obtained 508 by measurement or from the circuit manufacturer's instructions. Then, taking into account the temperature of the X-ray chamber and the variations in the previously obtained 508 electrical characteristics, a normalized value 509 can be obtained from measurements of the actual pulse width and the expected pulse width.

[0104] For example, the capacitance of HV and smoothing capacitors can be obtained as 508 or known as a function of temperature, such as... Figure 4 As shown in the figure. The rise and fall times of 509 with temperature change are obtained from the percentage change of capacitance with temperature. The measured temperature shows the change of nominal capacitance in curve 400. The normalized value is obtained by calculating this change for a predetermined temperature.

[0105] The obtained standardized value, together with the current and voltage settings at which the standardized value is obtained, is stored in, for example, a data memory 207.

[0106] The loop can be repeated for multiple settings. In general, the current and voltage settings can be selected differently for different settings (such as high current and low current).

[0107] For example, it is possible to provide standardized values ​​for a small number of voltage settings, linking them to predetermined values ​​for current settings, and to repeat the same loop for the same small number of voltage settings, linking them to predetermined but different current settings. This means that calibration can only be provided for a small number of voltage and current settings, so values ​​for voltage or current settings not selected for calibration are not assigned to their standardized values.

[0108] In some embodiments of the invention, it is still possible to insert 511 normalized values ​​corresponding to voltage or current settings not selected for calibration from the normalized values ​​of the selected settings, in a manner similar to the insertion performed with reference to the embodiments of the first aspect, for example, inserting normalized values ​​from values ​​obtained using voltage values ​​higher or lower than the unselected settings, but closest to the unselected settings. When such insertion is performed during calibration, a larger data storage 207 is required, but processing time is saved during the use of the X-ray system.

[0109] In any case, the insertion can be completed during calibration, and if necessary, the insertion can also be completed during operation if the selected settings are not among those used to obtain normalized values ​​or normalized values ​​inserted during calibration.

[0110] The following sections provide exemplary procedural steps for calibration and subsequent application processes:

[0111] Exemplary steps for calibration:

[0112] Obtain voltage, current, and expected pulse width settings.

[0113] transmit pulse

[0114] The actual (effective) width of the measurement pulse

[0115] Measuring the ambient temperature of the internal circuitry of the measuring tank

[0116] The deviation between the effective pulse width and the expected pulse width is compared using the following method:

[0117] The expected change in capacitor capacitance in the high-voltage converter is calculated from the measured temperature, and the rise and fall time deviations of the pulses are obtained using the actual capacitance (normalized) over the defined temperature.

[0118] The rise time and fall time deviations and temperature are stored in the LUT for the selected voltage and current settings.

[0119] Exemplary steps for the application process:

[0120] Considering standardized compensation, voltage and current settings, as well as the expected pulse width, are introduced.

[0121] Measuring temperature

[0122] The expected change in capacitance compared to the capacitance at a predetermined temperature is obtained based on temperature.

[0123] The compensation required for the anticipated rise and fall times is obtained based on the voltage and current settings and the expected changes in the capacitance.

[0124] Apply voltage and current settings, as well as the pulse width (including non-normalized compensation), to transmit the corrected pulse.

[0125] Table I below shows the exemplary values ​​set and the standardized values ​​obtained for multiple calibration settings in a specific calibration method for measuring the temperature of the tank. The voltage, current, and expected pulse width, as well as the predetermined temperature Tp, are user-set values, while the effective pulse width and temperature are measured. The difference between the pulse width (Delta) and the standardized value NV is then calculated.

[0126]

[0127] Table I. Calibration Documents.

[0128] For Table I, two curves (A and B) with different current settings are used. For each curve, the expected pulse width is 10 ms, but the actual effective pulse width (obtained from the measured actual voltage) is different for each setting. The difference (Delta) is derived from the difference between the expected pulse width and the effective pulse width:

[0129] Delta D = T IW -T EFFPW

[0130] Measure the temperature for each setting, and use... Figure 4 The relationship is obtained by standardizing delta to Tp = 25℃ to obtain the standardized value of Delta:

[0131] The standardized value NV = D(1 + (0.005(T - Tp))

[0132] In this case, the relationship is linear, but in other cases, NV can be calculated using different factors depending on the circuit components.

[0133] Table II below shows an exemplary correction for the pulse width in the "CTRL-X Programmed APW" column, using the normalized values ​​from Table I, for each of curves A and B. It should be noted that each voltage setting is linked to a different current setting value in curve A and curve B. In the case of Table II, the number of selected voltage settings is greater than the voltage settings used for calibration; therefore, interpolation is used to obtain intermediate values ​​(interpolated NV).

[0134] In this case, linear interpolation is used. Temperature (Tm) is also measured, with the normalized value of the predetermined temperature Tp being the same as in calibration. Linear interpolation is performed based on the voltage setting value, but a different linear interpolation is performed for each current setting (for each curve A, B). The difference in the linear interpolation between curves depends on the difference in current (or curve shape). The measured temperature Tm causes a percentage change. Different expected pulse widths are selected for each setting of curve A and each setting of curve B.

[0135]

[0136] Table II Correction based on stored standardized values

[0137] The selected voltage V range is between 41 and 50. Therefore, for each curve (each different mA setting), the normalized values ​​are inserted from the normalized values ​​obtained for the 40kV and 80kV settings, respectively -5.4 and -2.2 for curve A, and -1 and 0 for curve B (see Table I).

[0138] In each case, linear interpolation is:

[0139] For curve A, the interpolation NVIntNV = -5.4 + (V – 40kV)(-2.2 - (-5.4)) / (80kV - 40kV),

[0140] For curve B, the interpolation NV is IntNV=-1.0+(V–40kV) / (80kV-40kV),

[0141] In the case of curve A, the actual temperature of the circuit (e.g., the tank) is constant, equal to 40°C. In the case of curve B, the measured value of the circuit temperature varies. The predetermined temperature Tp for standardization (25°C in this case) is again used to obtain the actual Delta correction Dc, which should be applied as follows:

[0142] Dc = IntNV(1 - (0.005(Tm - Tp))

[0143] Finally, delta correction is used to obtain the actual pulse width (APW) that the user needs to program for the expected pulse width TIW:

[0144] CTRL-X is programmed with APW=T IW +Dc

[0145] Therefore, it is clear that the calibration method of the second aspect can be used to provide standardized values ​​used in the method of providing X-ray pulses in the first aspect of the invention.

[0146] In a third aspect, the invention provides a software product, such as a computer program product, or a data carrier including such a program, such that when linked to an X-ray system, the software product allows the provision of X-ray pulses according to the method of the first aspect of the invention.

[0147] The software product can be adapted to receive the required pulse width settings, and is also adapted to receive standardized values ​​obtained by the calibration method of the second aspect of the present invention.

[0148] X-ray systems incorporating such software products (e.g., in control unit 208 or in X-ray generator 202) can improve system performance, enabling the use of narrower pulse widths and thus increasing the available range. The control unit also allows X-rays to be generated at lower power, which in turn increases the lifespan of the X-ray source. Furthermore, by reducing the difference between the expected and obtained pulses for the same voltage and current settings, it is easier to meet international regulatory requirements for accuracy. This also helps to increase the available range of pulse widths in a lower range, such as accurately providing small widths (very short pulses).

[0149] In a fourth aspect of the invention, a software product for calibrating an X-ray system is provided. The software product may be adapted to receive pulse width measurements, may optionally be adapted to receive temperature measurements, and may include instructions, when implemented in an X-ray system, for performing the calibration method of an embodiment of the second aspect of the invention. This software product is capable of establishing a predictive model for compensating for deviations in pulse width, including variations in tank temperature, thereby providing an X-ray system with compensated pulse width when the software is implemented in the X-ray system.

[0150] The software product according to embodiments of the present invention may include the third and fourth aspects of the invention, thereby allowing the calibration of an X-ray system and providing pulsed X-rays with the corrected pulse width obtained during calibration.

[0151] In a fifth aspect, the present invention provides a data storage device comprising standardized values ​​obtained by the method of a second aspect of the invention. This data storage device may be linked to a control unit, such as a unit comprising a software product according to embodiments of a third and / or fourth aspect of the invention. In some embodiments, the data storage device is implemented in software. For example, it may be implemented as part of a software product according to a third and / or fourth aspect of the invention.

[0152] Such a data storage device may be reprogrammable and capable of including updated standardized values, for example by interpolation or by a calibration method according to an embodiment of the second aspect of the invention.

[0153] In a sixth aspect, the present invention provides an X-ray system adapted to generate pulses with effective widths, different values ​​set for voltage or current and compensated independently of temperature, according to embodiments of the first aspect, and / or for performing calibrations described with reference to embodiments of the second aspect. For example, the X-ray system may include software or program products according to embodiments of the third and / or fourth aspects of the present invention.

[0154] The voltage range provided by an X-ray system can be between 35 kV and 150 kV, for example, between 40 kV and 120 kV. Conventional X-ray systems have an optimal setting that closely matches the effective pulse, typically between 70 kV and 80 kV. For higher and lower kV settings, the deviation between the expected and effective pulse width increases. This invention provides effective correction for pulse widths for a wider range of voltage and current settings, even for very low current and / or voltage values, allowing for optimized dose and reduced wasted power. Due to the more accurate pulse width, it is possible to obtain an average current with higher accuracy that conforms to current and voltage accuracy specifications, and in turn, smaller pulse widths can be achieved.

[0155] Back Figure 2 The figure illustrates a schematic embodiment of such an X-ray system 200, which includes an X-ray generator 202 and an X-ray source 203 contained in a tank 201. In a specific example of this figure, the X-ray system 200 includes a high-voltage converter 204 and an HV and smoothing capacitor 205 surrounded by fluid 206. For example, at least the converter 204 and the smoothing capacitor 205 may be surrounded by oil (e.g., transformer oil) in, for example, a tank 201, which may also include the source 203. A control unit 208 is included, which may include software programs according to embodiments of the third aspect of the invention. The control unit 208 may be external as shown, or internal, for example, as part of the X-ray generator 202. A data memory 207 may include normalized values ​​for adjusting the pulse width according to embodiments of the first aspect. The data memory 207 may optionally be part of the control unit 208. The data memory may be reprogrammable to provide additional normalized values ​​by measuring it from actual pulses or by interpolating it from known values.

[0156] X-ray systems can be adapted to take into account the temperature of circuitry used to provide pulses (e.g., high-voltage converters, and / or HV and smoothing capacitors) or portions thereof. In some embodiments, the temperature can be measured by a temperature sensor 209, which includes any sensor that measures parameters as a function of temperature. For example, the temperature sensor may include elements that measure changes in conductor resistance due to temperature variations. In some embodiments of the invention, the ambient temperature of the circuitry within the vessel is measured. For example, the temperature of the HV and smoothing capacitor 205 can be measured. For example, the temperature of the environment surrounding the circuitry of the high-voltage converter 204, or the circuitry of both the converter 204 and the smoothing capacitor 205, can be measured, optionally including wiring, etc. In some embodiments, the environment surrounding at least a portion of the circuitry is a fluid 206, such as oil (e.g., transformer oil, commonly used for cooling, but the invention is not limited to cooling functions). The temperature of the fluid is an important indicator of the ambient temperature, especially where the fluid 206 surrounds the HV and smoothing capacitor 205, as these capacitors play a major role in the shape of the voltage pulse and its edges 21, 22. Therefore, in embodiments of the present invention, one or more NTC thermistors, thermocouples, etc. are used to measure the fluid temperature, for example, in the immediate vicinity of a smoothing capacitor.

[0157] In some embodiments, the fluid can be circulated to provide a uniform temperature distribution within the tank. For example, an oil pump may be included. Cooling may be implemented, such as passive cooling.

[0158] In an alternative embodiment, to take into account the temperature of the circuit, system 200 includes a heating and / or cooling temperature subsystem 210, such as a heater and / or absorber, for setting the temperature 206 of the fluid. In this case, the temperature sensor 209 may still be optionally present. The subsystem 210 may be actuated by the X-ray system, for example by its control unit 208, for example during calibration and / or during use of the X-ray system.

[0159] The X-ray system may include a subsystem 211 for measuring the effective width of the actual pulse provided during calibration. For example, subsystem 211 may include electronic circuitry in control unit 208 and / or the X-ray generator. It is capable of measuring the actual voltage level in the X-ray chamber and processing the measured values ​​(e.g., in the system controller, control unit, etc.) to determine the signal level.

[0160] The X-ray system 200 may be included in a single unit, at least the tank 201, and optionally the X-ray generator 202 may also be integrated into a single block, which may be part of, for example, a CR unit for mobile surgical applications, a mammography unit, or a mobile X-ray imaging device, and the invention is not limited to these applications.

[0161] Figure 6 A component 600 is shown, which may be fixed or movable, including, for example, an X-ray chamber 201 containing a source 203 in a rotatable tomography setup and a detector 601 arranged away from the source 203. An X-ray generator 202 is included, for example, comprising data storage and executable instructions for performing the methods of the first and second aspects of the present invention.

Claims

1. A method for providing an X-ray pulse via an X-ray system including an X-ray chamber, the X-ray chamber including an X-ray source, the method comprising: For the X-ray pulse selection (101) to be provided, the current, voltage and expected pulse width settings are configured. Taking into account the predetermined internal temperature of the X-ray chamber, the pulse width setting selected for the selected voltage and current compensation (103) is based on the normalized value stored at the predetermined internal temperature of the X-ray chamber, wherein the normalized value is determined based on the deviation between (i) the expected pulse width for a specific current and voltage setting and (ii) the actual pulse width for the specific current and voltage setting at the predetermined internal temperature of the X-ray chamber.

2. The method according to the preceding claim further comprises calculating (106) a standardized value by interpolation based on stored standardized values ​​corresponding to a first setting for current and a first setting for voltage, and stored other standardized values ​​corresponding to other settings for current and other settings for voltage, wherein at least one of the other settings differs from the value of the first setting, wherein, The selected current and voltage values ​​are between the first and other settings of the at least one different current and / or the first and other settings of the voltage.

3. A method for calibrating an X-ray system including an X-ray chamber, wherein, The X-ray chamber includes an X-ray source, and the method includes: The X-ray source is applied (502) with settings for the selected current, selected voltage, and expected pulse width, thereby generating actual voltage and current signals for the X-ray source to produce at least one X-ray pulse, thus producing at least one X-ray pulse with an actual pulse width. The measurement (503) is applied to the actual voltage signal of the X-ray source. The actual pulse width (504) is determined based on the measured actual voltage signal. Obtain the difference between the actual pulse width and the expected pulse width (505). Considering the internal temperature of the X-ray chamber (506), a standardized value (507) is obtained based on the difference at a predetermined temperature, where the internal temperature is the ambient temperature for the electronic circuitry of the X-ray chamber, and The standardized value from the difference is stored (510) as a function of the settings of the selected current and the selected voltage.

4. The method of claim 3, further comprising measuring the internal temperature of the X-ray chamber before obtaining a standardized value based on the difference, the internal temperature of the X-ray chamber being the ambient temperature for the electronic circuitry of the X-ray chamber.

5. The method according to claim 3 or 4, further comprising obtaining (509) the rise and fall time deviations of the at least one X-ray pulse based on the difference between the determined actual pulse width and the expected pulse width, wherein, Obtaining a standardized value based on the difference at a predetermined temperature also includes obtaining (508) a standardized value of the rise and fall time deviation at the predetermined temperature by using a predetermined relationship between the capacitance change of the X-ray container and the internal container temperature, the internal container temperature being the ambient temperature for the electronic circuit.

6. The method according to claim 5, wherein, The standardized value for storing the difference between the actual pulse width and the expected pulse width includes: The standardized value of the rise and fall time deviation is stored (510) as a function of the selected current and the selected voltage.

7. The method of claim 3 or 4, further comprising repeating the method for at least one different selected current and / or voltage setting, thereby storing (510) other normalized values ​​from the difference as a function of the different selected current and selected voltage.

8. The method of claim 7, further comprising calculating (511) at least one standardized value of current and / or voltage between the selected current and / or voltage setting and different selected current and / or voltage settings by interpolation.

9. A computer program product comprising instructions that, when executed by a computer, cause the computer to control an X-ray system to provide X-ray pulses according to the method of claim 1 or 2.

10. A computer program product comprising instructions that, when executed by a computer, cause the computer to control the calibration of an X-ray system according to any one of claims 3 to 8.

11. A data storage device (207) for an X-ray system, comprising standardized values ​​obtained by the method according to any one of claims 3 to 8.

12. An X-ray system (200) including an X-ray container (201) including an X-ray source (203), the X-ray system (200) further including a control unit (208) controllable by a computer program product according to claim 9 or 10.

13. The X-ray system of claim 12, further comprising a temperature sensor (209) for sensing the temperature of at least a portion of the X-ray chamber.

14. The X-ray system according to any one of claims 12 or 13, further comprising the data storage (207) according to claim 11, wherein, The control unit (208) is configured to receive at least one of the standardized values.

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