Wide angle automatic exposure control in tomosynthesis

Abstract

A system and method for calculating a dose for automatic exposure control (AEC) calibration for tomosynthesis sweep is disclosed. For example, a reference image may be acquired and corresponding reference detector count maps may be generated and stored for a plurality of projection angles using a tomosynthesis imaging system. The tomosynthesis imaging system may then acquire a scout image using the scout dose, identify a densest region within the scout image, and calculate an average detector count value associated with the densest region. A dose of the AEC calibration can be calculated based on a ratio of an average reference detector count value corresponding to a detector count value of pixels having a corresponding densest region of the reference image to the calculated average detector count value.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application was filed as a PCT international patent application on June 30, 2023, and claims priority and benefits to U.S. Provisional Application No. 63 / 358,350 filed on July 5, 2022, which is incorporated herein by reference in its entirety. Background Art

[0003] Breast cancer and other breast lesions remain a significant threat to women's health. X-ray mammography and tomosynthesis are the most widely used early detection, screening and diagnostic tools. Tomosynthesis is a technology that allows doctors to view multiple images of the breast instead of the single image available in conventional mammograms.

[0004] For example, conventional mammography provides doctors with a single two-dimensional (2D) image to evaluate the breast. However, this can be limited by overlapping tissue layers, which can produce ambiguous results, false positives, or cause doctors to miss cancerous changes. In contrast, tomosynthesis generates multiple x-ray images of the breast because the x-ray source moves relative to the breast. The x-ray images are then processed into a stack of 2D images that represent the entire volume of the breast, which allows doctors to better evaluate a patient's breast. Summary of the invention

[0005] Examples of the present disclosure are directed to automatic exposure control methods and systems for wide-angle tomosynthesis.

[0006] In a first example, a method of performing an automatic exposure control (AEC) operation using a tomosynthesis system is disclosed. The method includes acquiring a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dose toward the patient's breast with a tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel in the plurality of pixels is associated with a detector count value in a plurality of detector count values; identifying a first region on the scout image as corresponding to a densest portion of the patient's breast; calculating an average detector count value by averaging one or more detector count values ​​corresponding to one or more pixels within the first region; identifying a second region on a first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image; obtaining one or more reference detector count values ​​associated with one or more reference pixels within the second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and setting a radiation dose for a tomosynthesis sweep over the patient's breast at the plurality of projection angles to the AEC-calibrated dose.

[0007] In a second example, a tomosynthesis system for performing an automatic exposure control (AEC) operation is disclosed. The system includes: a processor; a memory including instructions that, when executed by the processor, cause the processor to: acquire a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dose toward the patient's breast with a tomosynthesis system, the scout image including a plurality of pixels, wherein each pixel in the plurality of pixels is associated with a detector count value in a plurality of detector count values; identify a first region on the scout image as corresponding to a densest portion of the patient's breast; calculate an average detector count value by averaging one or more detector count values ​​corresponding to the one or more pixels within the first region; identify a second region on a first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image; obtain one or more reference detector count values ​​associated with one or more reference pixels within the second region of the first reference image; calculate an average reference detector count value by averaging the one or more reference detector count values; calculate an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and set a radiation dose for a tomosynthesis sweep over the patient's breast at the plurality of projection angles to the AEC-calibrated dose.

[0008] In a third example, a method for performing a calibration operation associated with an automatic exposure control (AEC) operation using a tomosynthesis system is disclosed. The method includes: acquiring multiple reference images of a phantom at multiple projection angles, wherein each of the multiple reference images includes multiple reference image pixels; generating multiple reference image detector count maps corresponding to each of the multiple reference images by compiling multiple reference image pixels and corresponding reference image detector count values ​​associated with each of the multiple reference images; storing the multiple reference image detector count maps; acquiring a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dose toward the patient's breast with the tomosynthesis system, the scout image including multiple pixels, wherein each of the multiple pixels is associated with a detector count value in a plurality of detector count values; identifying a first region on the scout image as corresponding to the densest portion of the patient's breast; and identifying a first region on the scout image as corresponding to the densest portion of the patient's breast by aligning one or more of the first region with the densest portion of the patient's breast. The invention relates to a method for performing a tomosynthesis scan of a patient's breast using a first reference image and a second reference image scanning apparatus. The method comprises: averaging one or more detector count values ​​corresponding to one or more pixels of the first reference image to calculate an average detector count value; identifying a second area on the first reference image associated with a first projection angle, wherein the second area corresponds to a position on the first reference image that matches the position of the first area on the scout image, and the first projection angle is one of the plurality of projection angles, and the first reference image is one of the plurality of reference images; obtaining one or more reference detector count values ​​associated with one or more reference pixels within the second area of ​​the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and setting a radiation dose for a tomosynthesis sweep at the plurality of projection angles on the patient's breast to the AEC-calibrated dose. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following drawings are used to illustrate specific examples of the present disclosure and therefore do not limit the scope of the present disclosure. The drawings are not drawn to scale and are intended to be used in conjunction with the explanations in the following detailed description. Examples of the present disclosure will be described below in conjunction with the accompanying drawings, wherein the same reference numerals represent the same elements.

[0010] Figure 1A is a schematic diagram of an exemplary imaging system.

[0011] Figure 1B yes Figure 1A A perspective view of the imaging system.

[0012] Figure 2 Pictured Figure 1A An example configuration of the Automatic Exposure Control (AEC) engine for a system.

[0013] Figure 3 An example schematic diagram of an imaging system during generation of a reference image is illustrated.

[0014] Figure 4 An example schematic diagram of a reference image and a corresponding reference detector count map generated by a reference detector count map generation module of an imaging system is illustrated.

[0015] Figure 5 An example schematic diagram of a curve fitting operation to estimate reference detector count values ​​at intermediate projection angles is illustrated.

[0016] Figure 6 An example method of generating a reference detector count map at each of a plurality of projection angles using a reference detector count map generation module of an imaging system is illustrated.

[0017] Figure 7 An example method for calculating an AEC x-ray dose required to perform x-ray imaging including a wide-angle tomosynthesis sweep of a patient's breast using an imaging system is illustrated.

[0018] Figure 8 One example of a suitable operating environment in which one or more of the present examples may be implemented is illustrated.

[0019] Fig. 9 is an example of a network in which the various systems and methods disclosed herein may operate. DETAILED DESCRIPTION

[0020] Various examples will be described in detail with reference to the accompanying drawings, wherein the same reference numerals represent the same parts and components in several views. Reference to various examples does not limit the scope of the appended claims. In addition, any examples set forth in this specification are not intended to be limiting, but only to set forth some of the many possible examples of the appended claims.

[0021] Digital tomosynthesis is a process that acquires several two-dimensional projection views from different projection angles. The total angular range over which x-ray images are acquired is typically about + / - 7.5 degrees. Each image is acquired using a lower x-ray dose than conventional mammography. The acquired two-dimensional projection views are reconstructed into tomosynthesis slice views that can be along any desired plane in the breast and can represent any thickness of breast tissue. Thus, the combined set of reconstructed tomosynthesis images represents the entire volume of the breast in a stack of two-dimensional images. For tomosynthesis, the breast is immobilized or compressed to the same or lesser extent than in conventional mammography.

[0022] Typically, tomosynthesis systems can use automatic exposure control (AEC) systems and methods to automatically control the amount of radiation delivered to a patient's breast. The AEC system can automatically terminate the exposure when the desired amount of radiation has been delivered. The desired amount of radiation is based on balancing the need to minimize the patient's radiation exposure with the need to generate an adequately exposed image.

[0023] The AEC system can be operated by controlling one or more technical factors in order to obtain a desired amount of radiation, including kilovolt peak (kVp), which is the potential difference applied across the x-ray cathode and x-ray anode tubes, and milliampere-seconds (mAs), which is a measure of the current from the x-ray cathode to the x-ray anode applied via the x-ray tube for a set amount of time. The combination of kVp and mAs values ​​directly affects the radiation dose delivered to the patient's breast and the image quality of the mammogram. In some examples, the operator of the tomosynthesis system can select the kVp value based on the thickness of the patient's breast, and the mAs value can be changed by the AEC system to achieve the desired radiation level. In other examples, the AEC system can also select both kVp and mAs values.

[0024] Generally speaking, an AEC system can initially deliver short, low-dose x-ray pulses or emissions to the patient's breast. The resulting scout image of the image receptor is read by a computer process to determine the breast area with the greatest radiodensity. Based on the detector values ​​at the breast area with the greatest radiodensity within the scout image, the AEC system can calculate the correct final AEC dose, including kVp and mAs values, to produce a sufficiently exposed final image.

[0025] However, AECs for wide-angle tomosynthesis face several challenges that are not present in narrow-angle tomosynthesis. Here, "wide-angle tomosynthesis" can be defined as a range greater than about + / -15 degrees. In a typical tomosynthesis system, the scout exposure and image are acquired at a zero-degree angle to the breast. In wide-angle tomosynthesis, the scout exposure can occur at a large incident angle to the breast that is away from the zero-degree normal direction to the breast. For example, the scout exposure angle can vary between + / -30 degrees or even + / -60 degrees. The scout exposure can typically be acquired at any angle within the range of angles that the x-ray source and the tomosynthesis equipment were at after the last use of the equipment. In other words, the tomosynthesis equipment does not need to be reset or realigned to a certain angle (such as 0 degrees) in order to perform the scout exposure. This allows the tomosynthesis equipment to be used without wasting time resetting the equipment to a 0-degree angle between uses. More specifically, the disclosed systems and methods describe accurately acquiring images by fully considering the incident angle when the incident angle of the scout exposure is anywhere within the range of angles. At large incident angles, the x-ray path length through the breast is much longer than the compressed thickness of the breast. Therefore, to accurately calculate the AEC dose, the AEC system needs to consider parameters such as the emission angle and the "heel effect." The heel effect is caused by the decrease in x-ray intensity along the direction from the chest wall to the nipple.

[0026] For example, the angle and heel effects affect the accuracy of the calculated AEC dose because the detector count value at the center of the detector from the scout exposure decreases as the AEC tube angle increases. In other words, the larger the projection angle, the smaller the detector count from the scout exposure for the same x-ray dose. In addition, the counts of detector pixels on the side of the detector away from the chest wall tend to be lower than the counts of pixels on the chest wall side of the detector. In addition, as the projection angle changes, the center position of the breast projected on the detector shifts. Since the densest part of the breast is usually selected from the center position of the breast for dose calculation, the shift in the center position must be taken into account to accurately calculate the AEC dose.

[0027] In order to accurately calculate the radiation dose that produces a sufficiently exposed image that meets the image quality threshold from the wide-angle tomosynthesis process, the present disclosure generates a reference detector count map at each projection angle. For example, one or more wide-angle tomosynthesis scans with high x-ray doses can be performed on a uniform phantom at one or more projection angles to generate a reference detector count map for each of one or more discrete angles. A lookup table with a scaling factor can also be used to generate reference detector count maps for breasts of different thicknesses. Curve fitting can be applied to the reference detector count map to derive detector count values ​​at intermediate projection angles. The reference detector count map associated with each of the multiple projection angles can be stored and used to calculate the AEC x-ray dose required to acquire x-ray images during the tomosynthesis scan.

[0028] The process of calculating an x-ray dose begins by acquiring a scout image of a patient's breast at a first projection angle using the scout dose. Once the scout image is acquired, the densest portion of the patient's breast is identified within the scout image and an average detector count value associated with the identified densest portion of the patient's breast is calculated. A reference image associated with the first projection angle and a corresponding reference detector count map are then retrieved. A second region corresponding to the location of the first region on the scout image is then identified within the reference image. The reference detector count map is used to determine a reference detector count value associated with the second region on the reference image, and an average reference detector count value associated with the second region is calculated. The reference x-ray dose value and a ratio of the average reference detector count value to the average detector count value can be used to calculate the x-ray dose required for a tomosynthesis scan.

[0029] Figure 1A is a schematic diagram of an exemplary imaging system 100 and Figure 1B is a perspective view of imaging system 100. Figure 1A and 1B, not every element described below is depicted in both figures. The imaging system 100 locks the patient's breast 102 for x-ray imaging (one or both of mammography, tomosynthesis or other imaging modalities) via a breast compression locker unit 104 including a static breast support platform 106 and a movable paddle 108. Different paddles, each with different uses, are known in the art. For context, some example paddles are also described herein. The breast support platform 106 and the paddle 108 each have compression surfaces 110 and 112, respectively, which move toward each other to compress, lock, stabilize or otherwise hold and fix the breast 102 during the imaging process. In known systems, the compression surfaces 110, 112 are exposed so as to be in direct contact with the breast 102. One or both of these compression surfaces 110, 112 can be rigid plastic, flexible plastic, elastic foam, mesh or screen, etc. The platform 106 also houses an image receptor 116 and optionally a tilt mechanism 118, and optionally an anti-scatter grid (not depicted, but disposed above the image receptor 116). The latch unit 104 is in the path of an imaging beam 120 emitted from an x-ray source 122 so that the beam 120 impinges on the image receptor 116.

[0030] The locker unit 104 is supported on the first support arm 124 via a compression arm 134, which is configured to be raised and lowered along the support arm 124. The x-ray source 122 is supported on a second support arm, also referred to as a tube head 126. For mammography, the support arms 124 and 126 can rotate as a unit about an axis 128 between different imaging orientations such as CC and MLO, so that the system 100 can capture mammographic projection images in each orientation. In operation, the image receptor 116 remains in position relative to the platform 106 while the images are captured. The locker unit 104 releases the breast 102 to allow the arms 124, 126 to move to different imaging orientations. For tomosynthesis, the support arm 124 remains in position, with the breast 102 locked and held in position, while at least the second support arm 126 rotates the x-ray source 122 about the axis 128 relative to the locker unit 104 and the compressed breast 102. The system 100 acquires a plurality of tomosynthesis projection images of the breast 102 at various projection angles of the light beam 120 relative to the breast 102 .

[0031] At the same time and optionally, the image receptor 116 can be tilted relative to the breast support platform 106 and synchronously with the rotation of the second support arm 126. The tilt can be by the same angle as the rotation of the x-ray source 122, but can also be by a different angle, which is selected so that the image beam 120 remains substantially in the same position on the image receptor 116 for each of the multiple images. The tilt can be about an axis 130, which can but is not necessarily in the image plane of the image receptor 116. A tilt mechanism 118 coupled to the image receptor 116 can drive the image receptor 116 in a tilting motion. For tomosynthesis imaging and / or CT imaging, the breast support platform 106 can be horizontal and can be at an angle to the horizontal, for example, in an orientation similar to that used for conventional MLO imaging in mammography. The system 100 can be entirely a mammography system, a CT system, or entirely a tomosynthesis system, other modalities such as ultrasound, or a "combination" system that can perform multiple forms of imaging. The assignee of the present invention provides an example of a system under the trade name Selenia Dimensions.

[0032] When the system is operated, image receptor 116 generates imaging information in response to illumination by imaging beam 120 and provides it to image processor 132 for processing and generation of a breast x-ray image.

[0033] The system control and workstation unit 138, including software, controls the operation of the system and interacts with an operator to receive commands and deliver information including processed radiographic images. The system control and workstation unit 138 may include an automatic exposure control (AEC) engine that may be configured to calculate the AEC x-ray dose required to perform x-ray imaging (such as a tomosynthesis sweep) of a patient's breast. Figure 2 Describes the configuration of the AEC engine in more detail.

[0034] The imaging system 100 includes a floor stand or base 140 for supporting the imaging system 100 on a floor. A gantry 142 extends upward from the floor stand 140 and rotatably supports a tube head 126 and a support arm 124. The tube head 126 and the support arm 124 are configured to rotate independently of each other and can also be raised and lowered along a surface 144 of the gantry 142 to accommodate patients of different heights. The x-ray source 122 is disposed within the tube head 126. The tube head 126 and the support arm 124 may be collectively referred to as a C-arm 144.

[0035] A number of interfaces and displays are disposed on the imaging system 100. These include a foot display 146, a gantry interface 148, a support arm interface 150, and a compression arm interface 152. In general, the various interfaces 148, 150, and 152 may include one or more tactile buttons, knobs, switches, and one or more displays, including a capacitive touch screen with a graphical user interface (GUI), to enable a user to interact with and control the imaging system 100. In general, the foot display 146 is primarily a display screen, but a capacitive touch screen may also be used if needed or desired.

[0036] Figure 2 Pictured Figure 1A An example configuration 200 of an automatic exposure control (AEC) engine 202 of a system of FIG. The AEC engine 202 may be configured within the workstation 138 of the imaging system 100. Thus, Figure 2 Description reference Figure 1A and Figure 1B Components depicted in and numbered accordingly.

[0037] The AEC engine 202 may include a reference detector count map generation module 204 and an AEC dose calibration module 206. Other types of modules are also possible. The AEC engine is configured to calculate an AEC x-ray dose to be used during x-ray imaging of a patient's breast, including during the entire tomosynthesis sweep process. The AEC x-ray dose may include an x-ray dose calculated to balance the need to reduce the amount of radiation to which the patient is exposed with the need to obtain images clear enough to detect potential abnormal areas within the patient's breast.

[0038] The reference detector count map generation module 204 can be configured to generate a reference detector count map for each of a plurality of projection angles at which the imaging system 100 can be configured to operate. For example, for a wide angle tomosynthesis sweep, the range of projection angles at which the imaging system 100 can operate is typically +30 to -30 degrees, and in some cases can even be between + / -60 degrees. The reference detector count map generation module 204 can acquire a reference detector count map at each of the discrete projection angles at which the imaging system 100 can operate.

[0039] For an imaging system that can operate between + / -30 degrees, the reference detector count map generation module 204 can acquire a reference image and generate a reference detector count map for each of the 61 discrete projection angles between +30 degrees and -30 degrees, in increments of 1 degree. In some examples, the reference detector count map generation module 204 can also acquire reference detector count maps at intermediate projection angles. In other examples, the reference detector count maps for intermediate projection angles can be pre-calculated and stored or calculated in real time using a curve fitting operation that fits the reference detector count maps with respect to the intermediate projection angles. Figure 6 Described in further detail.

[0040] The reference detector count map generation module 204 can cause the imaging system 100 to generate a reference detector count map at each of a plurality of projection angles by exposing a phantom of uniform thickness with a reference dose of x-ray radiation, acquiring a resulting reference image, determining a detector count value for each pixel within the reference image, and generating a map associating the determined detector count values ​​with each pixel within the reference image.

[0041] The reference dose used to generate the reference image may be an x-ray dose known to result in x-ray images with sufficient clarity and commonly used in a clinical setting. For example, for a 4 cm thick uniform phantom, a typical reference x-ray radiation dose may be between 5 mGy and 10 mGy.

[0042] Once a reference detector count map is generated for each of the plurality of projection angles, the reference detector count map is stored in a local data repository or an external data repository communicatively connected to the imaging system 100. As described below with respect to the AEC dose calibration module 206 and Figure 7 As described above, the reference detector count map for each projection angle can then be used by the AEC dose calibration module 206 to calculate the AEC x-ray dose required for the wide-angle tomosynthesis imaging process. As described above, the term "AEC x-ray dose" is defined as the x-ray dose that balances the need to reduce the amount of radiation to which a patient is exposed and the need to obtain images clear enough to detect potential abnormal areas within the patient's breast. In other words, the "AEC x-ray dose" as used in this application is the minimum amount of x-ray dose required to obtain an x-ray image with image quality sufficient to detect potential abnormalities within a patient's breast. About Figure 3-6 The process of generating a reference detector count map is described in more detail in .

[0043] The AEC dose calibration module 206 is configured to automatically calculate the AEC x-ray dose required to acquire sufficiently clear x-ray images of a patient's breast during a tomosynthesis sweep process. The AEC dose calibration module 206 may calculate the AEC x-ray dose using a stored reference detector count map.

[0044] In some examples, the AEC dose calibration module 206 may move the components of the imaging system 100 to a particular projection angle to initiate the dose calibration process. In other examples, the AEC dose calibration module 206 may initiate the dose calibration process from any projection angle at which the components of the imaging system 100 are currently located.

[0045] The AEC dose calibration process may begin by acquiring a scout image of the patient's breast using a low x-ray dose. The low x-ray dose may be a small fraction of a typical x-ray dose, such as 5% or 10% of a typical x-ray dose. The AEC x-ray dose to be used during the tomosynthesis process may be calculated by comparing detector count values ​​associated with the scout image to reference detector count values ​​associated with a reference image, the reference detector count values ​​being derived from a reference detector count map acquired and stored by the reference detector count map generation module 204. The process of calculating the AEC calibrated x-ray radiation dose to be used during the tomosynthesis process is described with respect to Figure 6-7 Describe in more detail.

[0046] Figure 3 An example schematic diagram 300 of the imaging system 100 during the generation of a reference image is illustrated. The imaging system 100 locks a phantom 302 simulating a patient's breast so that the patient can be compressed via a breast compression locker unit 104 ( Figure 3 The support arm enables the x-ray source 122 (not shown) to perform x-ray imaging. Figure 3 The support arm 100 (not shown) rotates about an axis relative to the locking unit 104 including the movable paddle 108 and the phantom 302. When the support arm rotates the x-ray source 122 along each of the plurality of projection angles 304, the image receiver 116 generates imaging information in response to the illumination of the imaging beam 120 from the x-ray source 122. Thus, the imaging system 100 can acquire a plurality of reference images 306, wherein there is at least one reference image at each corresponding projection angle 304.

[0047] Although Figure 3 The projection angle 304 is illustrated as being from -30 degrees to +30 degrees, but the projection angle may extend to a greater or lesser range, depending on the type of imaging system 100. Figure 4 Generating a reference detector count map from each reference image in the plurality of reference images 306 is described in further detail.

[0048] Figure 4 An example diagram 400 of a reference image and a corresponding reference detector count map generated by the reference detector count map generation module 204 of the imaging system 100 is illustrated.

[0049] Each reference image 402 in the plurality of reference images 306 generated by the imaging system 100 includes a plurality of pixels 404. Figure 4 The plurality of pixels 404 within the reference image 402 in FIG. 4 are labeled with numbers from 1 to 100, but in practice, the plurality of pixels 404 may extend to a larger or smaller range of pixels.

[0050] In about Figure 3 After acquiring the reference image 402 as described, the reference detector count map generation module 204 of the AEC engine 202 can determine the reference detector count value associated with each of the plurality of pixels 404 by communicating with the image receiver 116 and the image processor 132 to determine a digital count of x-ray signals received by the image receiver when the phantom 302 is exposed to x-ray radiation from the x-ray source 122.

[0051] The reference detector count map generation module 204 of the AEC engine 202 can generate a reference detector count map 406 for each reference image 402 based on the reference detector count values ​​transmitted by the image receiver 116 and the image processor 132. In some examples, the reference detector count map 406 may include a table in which each pixel in the plurality of pixels 404 is listed in one column and the corresponding detector count values ​​are listed in a second column. In other examples, the plurality of pixels 404 and the corresponding detector count values ​​can be organized in a different manner. Once generated, the reference detector count map 406 can be stored in a local data repository within the imaging system 100 or in an external data repository that is communicatively connected to the imaging system 100.

[0052] Figure 5 An example diagram 500 of a curve fitting operation for estimating reference detector count values ​​at intermediate projection angles is illustrated. Figure 3 As described, the reference image 306 is captured only at certain projection angles. The reference image 306 is typically captured at projection angles in 1 degree increments within the range of projection angles in which the imaging system can operate. For intermediate projection angles, the reference image 306 and the corresponding reference detector count map 406 may not be acquired or generated. In order to calculate the AEC dose, the AEC dose calibration module 206 of the AEC engine 202 may require the reference detector count map 406 at the intermediate projection angle, for which the reference detector count map generation module 204 may not have acquired the reference detector image 306. In such cases, the reference detector count value for the intermediate projection angle can be estimated based on the stored reference detector count map 406 for adjacent discrete projection angles by performing a curve fitting operation on the data from the stored reference detector count map.

[0053] The example schematic diagram 500 illustrates a pixel ( Figure 4 65). The example schematic diagram 500 includes a graph 502 having an x-axis and a y-axis. The x-axis may include a range of projection angles. In this example, the range of projection angles may be -30 to +30 degrees. The y-axis may include a range of detector count values.

[0054] To perform the curve fitting operation, for each pixel in the plurality of pixels 404, the reference detector count value corresponding to each of the plurality of projection angles on the x-axis may be plotted as a graphical representation. For each pixel in the plurality of pixels 404. For example, Figure 5 As shown in , map 502 associated with pixel number 65 may include a map of each detector count value 504 corresponding to each of a plurality of projection angles, where each detector count value 504 may be extracted from a reference detector count map 406 corresponding to the particular projection angle.

[0055] For example, when the projection angle is -30 degrees, the reference detector count map 406 for -30 degrees may be retrieved from the data repository and the reference detector count value associated with pixel number 65 may be identified. This process may be repeated using each reference detector count map 406 for each projection angle ranging from -30 degrees to +30 degrees to populate the map 502 with the detector count values ​​504.

[0056] Once the graph 502 is generated, a curve fitting function may be used to generate a curve 506 that fits the detector count values ​​504. Curve fitting may be the process of constructing a curve or mathematical function that best fits a series of data points. In some examples, the curve fitting may be performed using an interpolation function or an extrapolation function. In other examples, the curve 506 may be generated using a polynomial curve fit, where a polynomial function is fitted to the series of data points.

[0057] In the case of using a polynomial curve fit, the order of the polynomial function can range from a low order (such as first order) to a high order (such as fifth order or sixth order). Generally speaking, in the case of generating a curve 506 that fits the detector count values ​​504, a fourth order polynomial function can be used, such as "y = ax 4 +bx 3 +cx 2 +dx+e". Once a polynomial function representing a curve 506 that fits the detector count values ​​504 is generated using regression analysis, the coefficients of the generated polynomial function may be stored in a data repository. The polynomial coefficients may then be used by the AEC dose calibration module 206 to estimate detector count values ​​at intermediate projection angles or angles outside the + / - 30 degree scan angle range in near real time.

[0058] Figure 6 An example method 600 is illustrated for generating a reference detector count map 406 at each of the plurality of projection angles 304 using the reference detector count map generation module 204 of the imaging system 100. The method 600 begins at operation 602. In operation 602, the reference detector count map generation module 204 of the imaging system 100 may acquire a reference image 306 of the phantom 302 at each of the plurality of projection angles 304. For example, the reference detector count map generation module 204 may cause the imaging system 100 to expose the phantom 302 with a reference x-ray dose and acquire a resulting x-ray image for each of the plurality of projection angles 306.

[0059] The reference x-ray dose may include any radiation dose effective to produce an x-ray image that at least meets the threshold image quality level. The phantom 302 used to generate the reference image may generally be made of a uniform material and have a uniform thickness. In some examples, a phantom 302 having a thickness that mimics an average patient breast may be used to generate a reference detector count map 406 for each of the plurality of projection angles 304. In other examples, a phantom having a different thickness may be used to generate the reference detector count map 406.

[0060] Although reference detector count maps 406 for each of the plurality of projection angles 304 are generated using a phantom 302 of a particular thickness, reference detector count maps corresponding to other breast thicknesses may be derived from reference detector count maps acquired using a phantom 302 of an average thickness by applying a scaling factor from a previously generated lookup table. Figure 7 The process of obtaining reference detector count maps for different breast thicknesses is further described in .

[0061] In some examples, the plurality of projection angles 404 at which the reference image 306 is acquired to generate the reference detector count map may include each discrete projection angle within a range of projection angles included in a tomosynthesis sweep performed by the imaging system 100. In some examples, the range of projection angles may be +30 degrees to -30 degrees. In this case, the discrete projection angles may include each of 61 discrete projection angles between +30 degrees and -30 degrees. In other examples, the range of projection angles may be +60 degrees to -60 degrees, in which case the discrete projection angles may include each of 121 discrete projection angles between +60 degrees and -60 degrees. In other examples, rather than acquiring reference images in increments of 1 degree, reference images may be acquired at other regular intervals, such as every 2 degrees or every 5 degrees.

[0062] In some examples, the plurality of projection angles at which the reference image is acquired in order to generate the reference detector count map may include a greater or lesser number of projection angles, and may include intermediate angles between discrete angles, such as projection angles in increments of 0.5 degrees; or may include angles outside the range of angles at which the reference image is acquired. In other examples, the above may be performed as described with respect to Figure 5 The curve fitting operations described herein, and in the case of a polynomial curve fitting operation, the corresponding polynomial coefficients may be stored and used to generate estimated detector count values ​​at intermediate projection angles or out-of-range scan angles in real time or near real time.

[0063] In operation 604 , the reference detector count map generation module 204 of the imaging system 100 may determine, for each reference image 306 acquired in operation 602 , a reference detector count value associated with each pixel of a plurality of pixels within each reference image 306 .

[0064] Each reference image acquired in operation 602 includes a plurality of pixels 404. For example, the reference detector count map generation module 204 may communicate with the image receiver 116 and the image processor 132 to determine a digital count of x-ray signals received by the image receiver 116 when the phantom 302 is exposed to the reference x-ray dose in operation 602. The count of x-ray signals associated with a particular pixel of the reference image 402 is determined as a reference detector count value associated with the particular pixel of the reference image 402. Thus, a reference detector count value for each of the plurality of pixels 404 within each reference image 306 acquired in operation 602 may be determined in operation 604.

[0065] In operation 606, the reference detector count map generation module 204 may generate a reference detector count map for each of the plurality of projection angles 304 based on the reference detector count values ​​determined in operation 604 for each reference image 306 acquired in operation 602. The reference detector count map 406 may include a map between each pixel within the reference image and a corresponding reference detector count value measured at the image receptor 116 when a reference x-ray dose is emitted onto the phantom.

[0066] In operation 608, the reference detector count map generation module 204 may store the reference detector count map 406 generated for each of the plurality of projection angles 304, the corresponding projection angle information, and the reference x-ray dose information in a data repository local to the imaging system 100 or in a data repository external to the imaging system 100 while being communicatively connected to the imaging system 100. The stored reference detector count map and reference x-ray dose information may be retrieved and used to calculate the AEC x-ray dose, such as Figure 7Described in .

[0067] When reference detector count values ​​for intermediate projection angles (for which no reference images and corresponding reference detector count maps are acquired) are needed to calculate the AEC x-ray dose, a curve fitting operation may be performed to obtain the reference detector count values, as described above. Figure 5 As further described in .

[0068] Figure 7 An example method 700 for calculating the AEC x-ray dose required to perform x-ray imaging (including wide-angle tomosynthesis sweeps of a patient's breast) using the imaging system 100 is illustrated. In operation 702, the AEC dose calibration module 206 may cause the imaging system 100 to acquire a scout image of the patient's breast at a first projection angle. In some examples, and in a typical tomosynthesis system, the first projection angle may be a specific projection angle among the plurality of projection angles 304, such as 0 degrees. However, the AEC dose calibration module 206 may cause the imaging system 100 to acquire the scout image from the current position of the support arms 124 and 126, rather than moving the support arms 124 and 126 of the imaging system 100 to the specific projection angle. The current position of the support arms 124 and 126 may simply be based on whatever position the support arms 124 and 126 were in after a previous operation of the imaging system 100. Moving the support arms 124, 126 and resetting the support arms 124, 126 to a 0 degree angle or a specific angle each time before starting a tomosynthesis process requires time and effort. Furthermore, moving the support arms 124, 126 to an exact position is difficult to achieve and often results in an error margin of several degrees. Thus, being able to acquire a scout image from any current position results in acquiring a more accurate scout image.

[0069] A scout image of the patient's breast may be acquired using a low x-ray dose. Typically, a scout image may be acquired using 5% or 10% of a reference x-ray dose. The scout image is used as a starting point for calculating the actual dose required to perform a full tomosynthesis sweep based on the AEC process. Thus, the scout image is acquired using a low x-ray dose to limit radiation exposure to the patient.

[0070] In operation 704, the AEC dose calibration module 206 may identify a first region on the scout image acquired during operation 702 as corresponding to the densest portion of the patient's breast. Generally speaking, the densest portion of the patient's breast is identified in order to determine the minimum amount of x-ray dose required to obtain an acceptable detector count value even at the densest portion of the patient's breast. In other words, the densest portion of the patient's breast is typically the area that is most difficult for x-rays to penetrate, and therefore requires the largest amount of dose to generate an image of sufficient quality. Therefore, if the x-ray radiation dose is calibrated for the densest area of ​​the patient's breast, the x-ray radiation dose is typically sufficient for the remaining areas of the patient's breast.

[0071] The densest area of ​​the patient's breast may be determined by first flattening the scout image by applying a gain map associated with a first projection angle in order to calibrate the scout image for angle effects and heel effects.

[0072] When using a digital flat-panel x-ray imaging receptor, one of the practical requirements is to provide gain calibration. The imaging receptor may include a two-dimensional array of millions of imaging pixels, and there may be inherent differences in the response of different imaging pixels to incident x-rays. When all imaging pixels receive the same x-ray exposure, each pixel should ideally provide the same electrical output signal (pixel value). However, this may not be the case in practice, and there are often differences between the pixel values ​​provided by different imaging pixels when exposed to the same x-ray input. In addition, the incident x-ray intensity on the detector surface is often non-uniform; for example, due to the "heel effect", the x-ray intensity decreases along the direction from the chest wall to the nipple. In order to correct the pixel value differences in response to uniform x-ray exposure, and to correct the non-uniform x-ray intensity distribution on the surface area of ​​the x-ray imaging detector, various gain calibration and image correction techniques are used. Typically, in conventional x-ray mammography, a flat-panel imager is exposed to an x-ray field through a "flat-field" phantom that simulates a patient's breast but is of uniform thickness and made of uniform material, the differences between the pixel values ​​are recorded, and a gain correction map resulting in such differences at each projection angle is generated. Each gain correction map corresponding to each projection angle may be stored locally in a data repository within the imaging system 100 or in an external data repository communicatively coupled to the imaging system 100 .

[0073] Once a scout image is generated while exposing the patient's breast to x-ray radiation at a first projection angle, a gain correction map corresponding to the first projection angle is retrieved from a data repository and applied to the scout image to flatten the scout image and minimize angle and heel effects. The angle-corrected scout image can then be used to identify the densest portion of the patient's breast.

[0074] For example, the densest portion of a patient's breast is typically located in the center of the breast and is associated with the lowest detector count value. Thus, a simplified method of identifying the densest portion of a patient's breast includes identifying a first region having a group of pixels having the lowest corresponding detector count value within a particular region of the scout image that may include the center of the breast. Once the first region including the group of pixels having the lowest detector count value is identified, the particular location on the scout image that includes the first region is determined to be the densest portion of the patient's breast.

[0075] In operation 706, the AEC dose calibration module 206 may calculate an average detector count value associated with the pixel group within the first region of the scout image. For example, the average detector count value may be calculated by determining a detector count value associated with each pixel within the pixel group located within the first region identified in operation 704 and averaging the detector count values ​​to obtain an average detector count value.

[0076] In operation 708, the AEC dose calibration module 206 of the AEC engine 202 may retrieve a reference image and a reference detector count map corresponding to the first projection angle from a data repository, wherein Figure 6 The reference detector count map generated by the reference detector count map generation module 204 is stored in operation 608 of the AEC dose calibration module 206. When the reference image and the reference detector count map for the first projection angle are not available in the data repository because the first projection angle is an intermediate angle or is out of the scanning range for which the reference detector count map generation module 204 has not yet generated a reference image or a reference detector count map, the AEC dose calibration module 206 may proceed to operation 712, where a polynomial curve fitting operation or an interpolation or extrapolation operation may be used to generate the reference detector count values ​​required in real time or near real time.

[0077] In operation 710, the AEC dose calibration module 206 of the AEC engine 202 may identify a second region on the retrieved reference image that corresponds in position to the first region from the scout image, as identified in operation 704. As an example, if in operation 704, the identified first region includes pixels corresponding to pixel numbers 56, 57, 66, 67 on the scout image, then the second region associated with the reference image may also include pixels corresponding to pixel numbers 56, 57, 66, 67.

[0078] In operation 712 , the AEC dose calibration module 206 , after identifying the second region corresponding to the reference image, may determine reference detector count values ​​corresponding to pixels within the second region.

[0079] If the first projection angle is an intermediate angle for which no reference image and corresponding reference detector count map are acquired or generated, the AEC dose calibration module 206 may estimate reference detector count values ​​for pixels within the second region in real time or near real time using a polynomial curve fitting function or an interpolation function, such as Figure 5 In other examples, rather than using curve fitting to generate only reference detector count values ​​for pixels within the second region, a curve fitting function may be applied to generate a complete reference image and a corresponding reference detector count map.

[0080] In operation 714, the AEC dose calibration module 206 may also adjust the detector count values ​​based on the patient's breast size. As described above, the reference image and the corresponding reference detector count map are based on the phantom 302 corresponding to an average patient breast thickness. In some examples, the thickness of the phantom 302 may have a thickness of 4 cm, and the reference detector count values ​​included in the reference detector count map may serve as reference values ​​for patients having a breast thickness of approximately 4 cm. However, when the patient's breast thickness is significantly higher or lower, the reference detector count values ​​may need to be adjusted.

[0081] In general, reference detector count values ​​associated with pixels of the second region may be adjusted using a lookup table that includes a scaling factor that corresponds to how the detector count values ​​are adjusted when the patient's breast thickness is different from the thickness of the phantom 302. For example, the lookup table may indicate that a scaling factor associated with a patient's breast thickness of 6 cm may be 1.2. In this case, the reference detector count values ​​for pixels within the second region determined by the AEC dose calibration module 206 (as determined in operation 712) may be multiplied by the factor 1.2 to yield adjusted reference detector count values.

[0082] Alternatively, reference images and corresponding reference detector count maps may be acquired, generated, and stored for phantoms of different sizes. In other words, rather than simply acquiring a reference image and generating a reference detector count map based on the phantom 302 corresponding to an average patient breast thickness, the process may be repeated for different phantom thicknesses. Figure 6 The process described in , and the reference image and reference detector count map corresponding to each phantom thickness may be stored. In this case, in operation 708, the reference image and reference detector count map corresponding to the phantom thickness that matches the patient's breast thickness may be retrieved, and the adjustment operation outlined above with respect to operation 714 may be skipped because the reference detector count value already takes into account the factor corresponding to the patient's breast thickness.

[0083] In operation 716, the AEC dose calibration module 206 may calculate an average reference detector count value associated with the pixels of the second region. The calculation of the average reference detector count value may be based on the adjusted reference count value determined in operation 714. To calculate the average reference detector count value, the AEC dose calibration module 206 may simply calculate a mean value corresponding to the adjusted reference detector count values ​​corresponding to the pixels within the second region of the reference image.

[0084] In operation 718, the AEC dose calibration module 206 may calculate a dose to be used in the full tomosynthesis scan based on a ratio of the average reference detector count value to the average detector count value. For example, an AEC-calibrated x-ray radiation dose for a full tomosynthesis sweep may be calculated based on the following formula:

[0085]

[0086] Wherein, the average reference detector count value is the average reference detector count value calculated in operation 716 based on the adjusted detector count value from operation 714, the average detector count value is the average detector count value calculated in operation 706, and the scout dose is the radiation dose used to acquire the scout image in operation 702. K is a global scaling factor that can be adjusted based on different clinical needs.

[0087] In operation 720, the AEC dose calibration module 206 may set the AEC-calibrated x-ray radiation dose level of the imaging system 100 to the value calculated in operation 718 and cause the imaging system 100 to perform a tomosynthesis sweep over the entire projection angle range using the set AEC-calibrated x-ray radiation dose. The AEC-calibrated x-ray radiation dose calculated in operation 718 balances the need to minimize the amount of radiation exposure for the patient while also generating adequately exposed tomosynthesis x-ray images at multiple projection angles.

[0088] Figure 8 An example of a suitable operating environment 800 in which one or more of the present examples may be implemented is illustrated. The operating environment may be incorporated directly into the virtualization system disclosed herein, or may be incorporated into a computer system separate from the breast imaging system described herein but used to control the breast imaging system described herein. For example, such a computer system may be Figure 1AThe workstation depicted in . This is only one example of a suitable operating environment and is not intended to imply any limitation as to the scope of use or functionality. Other well-known computing systems, environments, and / or configurations that may be suitable for use include, but are not limited to, imaging systems, personal computers, server computers, handheld or laptop devices, multiprocessor systems, microprocessor-based systems, programmable consumer electronics such as smartphones, network PCs, minicomputers, mainframe computers, tablet computers, distributed computing environments including any of the above systems or devices, and the like.

[0089] In its most basic configuration, the operating environment 800 typically includes at least one processing unit 802 and memory 804. Depending on the exact configuration and type of computing device, the memory 804 (which stores, among other things, instructions (for reading from a data storage device or sensor, or performing other methods disclosed herein)) may be volatile memory 808 (such as RAM), non-volatile memory 810 (such as ROM, flash memory, etc.), or some combination of the two. The instructions 806 may include AEC engine instructions that, when executed by the processing unit 802, cause the processing unit 802 to cause the AEC engine 202 to perform operations related to the AEC engine 202. Figure 2-7 This most basic configuration is as follows Figure 8 812 in the figure. In addition, the environment 800 may also include storage devices (removable devices 814 and / or non-removable devices 816), including but not limited to magnetic or optical disks or tapes. Similarly, the environment 800 may also have (one or more) input devices 820 such as a touch screen, keyboard, mouse, pen, voice input, etc. and / or (one or more) output devices 822 such as a display, speaker, printer, etc. The environment may also include one or more communication connections 818, such as LAN, WAN, point-to-point, Bluetooth, RF, etc.

[0090] The operating environment 800 typically includes at least some form of computer-readable media. Computer-readable media can be any available media that can be accessed by the processing unit 802 or other devices having the operating environment. As an example and not limitation, computer-readable media can include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical storage device, magnetic cassette, magnetic tape, magnetic disk storage device or other magnetic storage device, solid-state storage device or any other tangible medium that can be used to store desired information. Communication media implement computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and include any information transfer medium. The term "modulated data signal" refers to a signal having one or more characteristics set or changed in a manner that encodes information in the signal. By way of example and not limitation, communication media include wired media such as a wired network or direct wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Any combination of the above should also be included within the scope of computer-readable media. A computer-readable device is a hardware device that incorporates a computer storage medium.

[0091] Operating environment 800 can be a single computer that operates in a networked environment using a logical connection to one or more remote computers. The remote computer can be a personal computer, a server, a router, a network PC, a peer device or other public network node, and generally includes many or all of the above elements and other elements not mentioned. The logical connection can include any method that can be supported by a communication medium. Such a networked environment is common in offices, enterprise-wide computer networks, intranets and the Internet.

[0092] In some examples, the components described herein include such modules or instructions that can be executed by the computer system 800, which can be stored on computer storage media and other tangible media and transmitted in communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer readable instructions, data structures, program modules or other data. Any combination of the above should also be included in the scope of readable media. In some embodiments, the computer system 800 is part of a network that stores data in a remote storage medium for use by the computer system 800.

[0093] Fig. 9900 in which the various systems and methods disclosed herein may operate. In an example, a client device such as client device 902 may communicate with one or more servers (such as servers 904 and 906) via network 900. In an example, the client device may be a stand-alone imaging system (e.g., Figure 1A The client device may also include or be combined with a laptop, a personal computer, a smart phone, a PDA, a netbook, or any other type of computing device, such as Figure 8 In the example, such a client device can be connected to the imaging system. In the example, the servers 904 and 906 can also be any type of computing device, such as Figure 8 The computing device shown. Network 900 can be any type of network capable of facilitating communication between a client device and one or more servers 904 and 906. For example, surface image data and internal image data can be acquired locally via an imaging system and transmitted to another (or more) computing device for further processing, such as an image acquisition workstation or a cloud-based service. Examples of such networks include, but are not limited to, a LAN, a WAN, a cellular network, and / or the Internet.

[0094] In examples, various systems and methods disclosed herein can be performed by one or more server devices. For example, in one example, a single server such as server 904 can be used to perform the systems and methods disclosed herein, such as the imaging methods discussed herein. Client device 902 can interact with server 904 via network 900. In other examples, client device 902 can also perform functions disclosed herein, such as scanning and image processing, which can then be provided to server 904 and / or 906.

[0095] The present disclosure describes some examples of the present technology with reference to the accompanying drawings, of which only some possible examples are shown. However, other aspects may be implemented in many different forms and should not be construed as limited to the examples set forth herein. Instead, these examples are provided to make the present disclosure thorough and complete and to fully convey the scope of possible examples to those skilled in the art.

[0096] Although specific examples are described herein, the scope of the present technology is not limited to those specific examples. Those skilled in the art will recognize other examples or improvements within the scope of the present technology. Therefore, specific structures, actions, or media are disclosed only as illustrative examples. Unless otherwise specified herein, elements or components that are generally disclosed but not explicitly combined and illustrated may also be combined according to examples of the present technology. The scope of the present technology is limited by the attached claims and any equivalent forms therein.

[0097] Illustrative examples of the systems and methods described herein are provided below. Embodiments of the systems or methods described herein may include any one or more of the following clauses and any combination thereof:

[0098] Clause 1. A tomosynthesis system for performing an automatic exposure control (AEC) operation, the system comprising: a processor; a memory, the memory comprising instructions that, when executed by the processor, cause the processor to: acquire a scout image of a patient's breast at a first projection angle relative to a 0 degree normal direction to the patient's breast by emitting a scout x-ray dose toward the patient's breast with the tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel in the plurality of pixels is associated with a detector count value in a plurality of detector count values; identify a first region on the scout image as corresponding to a densest portion of the patient's breast; and average one or more detector count values ​​corresponding to one or more pixels within the first region to obtain a scout image of the patient's breast. calculating an average detector count value; identifying a second region on the first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches the location of the first region on the scout image; obtaining one or more reference detector count values ​​associated with one or more reference pixels within the second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and setting a radiation dose for a tomosynthesis sweep at multiple projection angles on a patient's breast to the AEC-calibrated dose.

[0099] Clause 2. A tomosynthesis system as described in Clause 1, wherein obtaining the one or more reference detector count values ​​includes: extracting the one or more reference detector count values ​​from a reference detector count map associated with a first projection angle, wherein the reference detector count map associated with the first projection angle is one of a plurality of reference detector count maps generated in a calibration process prior to acquiring the reconnaissance image.

[0100] Clause 3. A tomosynthesis system as described in Clause 2, wherein the calibration comprises: acquiring multiple reference images of a phantom, wherein each of the multiple reference images is acquired using the tomosynthesis system at each of the multiple projection angles, and each of the multiple reference images includes multiple reference image pixels; determining a detector count value corresponding to each of the multiple reference image pixels within each of the multiple reference images; and generating the multiple reference detector count maps corresponding to each of the multiple projection angles by compiling the multiple reference image pixels and the corresponding detector count values ​​associated with each of the multiple projection angles.

[0101] Clause 4. A tomosynthesis system as described in clauses 2-3, wherein when the first projection angle is not one of the plurality of projection angles comprising the reference detector count map, obtaining reference detector count values ​​associated with the one or more reference pixels from a second region of the first reference image comprises estimating the reference detector count values ​​by performing (i) an interpolation function, (ii) an extrapolation function, or (iii) a polynomial curve fitting function.

[0102] Clause 5. The tomosynthesis system of Clause 1, wherein the plurality of projection angles comprises an angle range between approximately -60 degrees and approximately +60 degrees relative to the patient's breast.

[0103] Clause 6. The tomosynthesis system of Clause 1, wherein calculating the dose for the AEC calculation comprises multiplying the scout x-ray dose by a ratio between an average reference detector count value and an average detector count value and a global scaling factor.

[0104] Clause 7. The tomosynthesis system of Clause 1, wherein the scout x-ray dose comprises a combination of the voltage used to generate radiation from the x-ray source (kV), the x-ray cathode to anode tube current (mA), and the length of time (s) the patient is exposed to the radiation.

[0105] Clause 8. The tomosynthesis system of Clause 1, wherein the scout x-ray dose is less than 10% of the AEC calculated dose.

[0106] Clause 9. The tomosynthesis system of clause 1, wherein identifying the densest portion of the patient's breast comprises: applying a gain map associated with the first projection angle to the scout image to compensate for angle effects; and identifying pixels within a pre-identified central region that includes a lowest detector count value.

[0107] Clause 10. A method of performing an automatic exposure control (AEC) operation using a tomosynthesis system, the method comprising: acquiring a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dose toward the patient's breast with the tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel in the plurality of pixels is associated with a detector count value in a plurality of detector count values; identifying a first region on the scout image as corresponding to a densest portion of the patient's breast; calculating an average detector count value by averaging one or more detector count values ​​corresponding to the one or more pixels within the first region; identifying a second region on a first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image; obtaining one or more reference detector count values ​​associated with one or more reference pixels within the second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and setting a radiation dose for a tomosynthesis sweep over the patient's breast at the plurality of projection angles to the AEC-calibrated dose.

[0108] Clause 11. A method as described in Clause 10, wherein obtaining the one or more reference detector count values ​​includes: extracting the one or more reference detector count values ​​from a reference detector count map associated with a first projection angle, wherein the reference detector count map associated with the first projection angle is one of a plurality of reference detector count maps generated in a calibration process prior to acquiring the reconnaissance image.

[0109] Clause 12. A method as described in Clause 11, wherein the calibration process includes: acquiring multiple reference images of the phantom, wherein each of the multiple reference images is acquired using a tomosynthesis system at each of the multiple projection angles, and each of the multiple reference images includes multiple reference image pixels; determining a reference image detector count value corresponding to each of the multiple reference image pixels within each of the multiple reference images; and generating the multiple reference image detector count maps corresponding to each of the multiple projection angles by compiling the multiple reference image pixels and the corresponding reference image detector count values ​​associated with each of the multiple projection angles.

[0110] Clause 13. A method as described in clauses 11-12, wherein when the first projection angle is not one of the multiple projection angles comprising the reference detector count map, obtaining the reference detector count value associated with the one or more reference pixels from the second area of ​​the first reference image includes: estimating the reference detector count value by executing (i) an interpolation function, (ii) an extrapolation function, or (iii) a polynomial curve fitting function.

[0111] Clause 14. The method of Clause 10, wherein the plurality of projection angles comprises a range of angles between approximately -60 degrees and approximately +60 degrees corresponding to a breast of the patient.

[0112] Clause 15. The method of Clause 10, wherein calculating the AEC-calculated dose comprises multiplying the scout x-ray dose by a ratio between an average reference detector count value and an average detector count value and a global scaling factor.

[0113] Clause 16. The method of clause 10, wherein the first projection angle is based on a current position of the tomosynthesis system prior to acquiring the scout image.

[0114] Clause 17. The method of Clause 16, wherein the current position is different from an angle of 0 degrees relative to the patient's breast.

[0115] Clause 18. The method of Clause 10, further comprising acquiring a scout image of the patient's breast at a second projection angle different from the first projection angle.

[0116] Clause 19. The method of clause 10, wherein identifying the densest portion of the patient's breast comprises: applying a gain map associated with the first projection angle to the scout image to compensate for angle effects; and identifying pixels within a pre-identified central region that includes a lowest detector count value.

[0117] Clause 20. A method of performing a calibration operation associated with an automatic exposure control (AEC) operation using a tomosynthesis system, the method comprising: acquiring a plurality of reference images of a phantom at a plurality of projection angles, wherein each of the plurality of reference images comprises a plurality of reference image pixels; generating a plurality of reference image detector count maps corresponding to each of the plurality of reference images by compiling the plurality of reference image pixels and corresponding reference image detector count values ​​associated with each of the plurality of reference images; storing the plurality of reference image detector count maps; acquiring a scout image of a patient's breast at a first projection angle by emitting a scout x-ray dose toward the patient's breast with the tomosynthesis system, the scout image comprising a plurality of pixels, wherein each of the plurality of pixels is associated with a detector count value from a plurality of detector count values; identifying a first region on the scout image as corresponding to a densest portion of the patient's breast; Averaging one or more detector count values ​​corresponding to one or more pixels within the first region to calculate an average detector count value; identifying a second region on the first reference image associated with a first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image, and the first projection angle is one of the plurality of projection angles, and the first reference image is one of the plurality of reference images; obtaining one or more reference detector count values ​​associated with one or more reference pixels within the second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; and setting a radiation dose for a tomosynthesis sweep at the plurality of projection angles over the patient's breast to the AEC-calibrated dose.

Claims

1. A tomosynthesis system for performing an automatic exposure control (AEC) operation, the system comprising: processor; a memory comprising instructions that, when executed by a processor, cause the processor to: acquiring a scout image of a breast of the patient at a first projection angle relative to a 0 degree normal direction to the breast of the patient by transmitting a scout x-ray dose toward the breast of the patient with a tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel of the plurality of pixels is associated with a detector count value of a plurality of detector count values; identifying a first region on the scout image as corresponding to the densest portion of the patient's breast; calculating an average detector count value by averaging one or more detector count values ​​corresponding to one or more pixels within the first region; identifying a second region on the first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image; obtaining one or more reference detector count values ​​associated with one or more reference pixels within a second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; as well as The radiation dose used for tomosynthesis sweeps at multiple projection angles over the patient's breast was set to the AEC-calibrated dose.

2. The tomosynthesis system of claim 1 , wherein obtaining the one or more reference detector count values ​​comprises: extracting the one or more reference detector count values ​​from a reference detector count map associated with the first projection angle, Wherein the reference detector count map associated with the first projection angle is one of a plurality of reference detector count maps generated in a calibration process prior to acquiring the scout image.

3. The tomosynthesis system of claim 2, wherein the calibration comprises: acquiring a plurality of reference images of the phantom, wherein each reference image of the plurality of reference images is acquired using a tomosynthesis system at each of the plurality of projection angles, and each reference image of the plurality of reference images comprises a plurality of reference image pixels; determining a detector count value corresponding to each of the plurality of reference image pixels within each of the plurality of reference images; as well as The plurality of reference detector count maps corresponding to each of the plurality of projection angles are generated by compiling the plurality of reference image pixels and corresponding detector count values ​​associated with each of the plurality of projection angles.

4. The tomosynthesis system of claims 2-3, wherein when the first projection angle is not one of the plurality of projection angles comprising the reference detector count map, obtaining reference detector count values ​​associated with the one or more reference pixels from the second region of the first reference image comprises: The reference detector count value is estimated by performing (i) an interpolation function, (ii) an extrapolation function, or (iii) a polynomial curve fitting function.

5. The tomosynthesis system of claim 1, wherein the plurality of projection angles comprises an angle range between approximately -60 degrees and approximately +60 degrees relative to a breast of the patient.

6. The tomosynthesis system of claim 1 , wherein calculating the AEC-calculated dose comprises multiplying the scout x-ray dose by a ratio between an average reference detector count value and an average detector count value and a global scaling factor.

7. The tomosynthesis system of claim 1 , wherein the scout x-ray dose comprises a combination of a voltage (kV) used to generate radiation from an x-ray source, an x-ray cathode to anode tube current (mA), and a length of time (s) the patient is exposed to the radiation.

8. The tomosynthesis system of claim 1, wherein the scout x-ray dose is less than 10% of the AEC calculated dose.

9. The tomosynthesis system of claim 1 , wherein identifying the densest portion of the patient's breast comprises: applying a gain map associated with the first projection angle to the scout image to compensate for angle effects; as well as Pixels within the pre-identified center region that include the lowest detector count value are identified.

10. A method of performing an automatic exposure control (AEC) operation using a tomosynthesis system, the method comprising: acquiring a scout image of a breast of the patient at a first projection angle by transmitting a scout x-ray dose toward the breast of the patient with a tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel of the plurality of pixels is associated with a detector count value of a plurality of detector count values; identifying a first region on the scout image as corresponding to the densest portion of the patient's breast; calculating an average detector count value by averaging one or more detector count values ​​corresponding to one or more pixels within the first region; identifying a second region on the first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image; obtaining one or more reference detector count values ​​associated with one or more reference pixels within a second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; as well as The radiation dose used for tomosynthesis sweeps at multiple projection angles over the patient's breast was set to the AEC-calibrated dose.

11. The method of claim 10, wherein obtaining the one or more reference detector count values ​​comprises: extracting the one or more reference detector count values ​​from a reference detector count map associated with the first projection angle, Wherein the reference detector count map associated with the first projection angle is one of a plurality of reference detector count maps generated in a calibration process prior to acquiring the scout image.

12. The method of claim 11, wherein the calibration process comprises: acquiring a plurality of reference images of the phantom, wherein each reference image of the plurality of reference images is acquired using a tomosynthesis system at each of the plurality of projection angles, and each reference image of the plurality of reference images comprises a plurality of reference image pixels; determining a reference image detector count value corresponding to each of the plurality of reference image pixels within each of the plurality of reference images; as well as The plurality of reference image detector count maps corresponding to each of the plurality of projection angles are generated by compiling the plurality of reference image pixels and corresponding reference image detector count values ​​associated with each of the plurality of projection angles.

13. The method of claims 11-12, wherein when the first projection angle is not one of the plurality of projection angles comprising the reference detector count map, obtaining reference detector count values ​​associated with the one or more reference pixels from a second region of the first reference image comprises: The reference detector count value is estimated by performing (i) an interpolation function, (ii) an extrapolation function, or (iii) a polynomial curve fitting function.

14. The method of claim 10, wherein the plurality of projection angles comprises a range of angles between approximately -60 degrees and approximately +60 degrees relative to the patient's breast.

15. The method of claim 10, wherein calculating the AEC-calculated dose comprises multiplying the scout x-ray dose by a ratio between an average reference detector count value and an average detector count value and a global scaling factor.

16. The method of claim 10, wherein the first projection angle is based on a current position of the tomosynthesis system prior to acquiring the scout image.

17. The method of claim 16, wherein the current position is different from an angle of 0 degrees relative to the patient's breast.

18. The method of claim 10, further comprising: A scout image of the patient's breast is acquired at a second projection angle different from the first projection angle.

19. The method of claim 10, wherein identifying the densest portion of the patient's breast comprises: applying a gain map associated with the first projection angle to the scout image to compensate for angle effects; as well as Pixels within the pre-identified center region that include the lowest detector count value are identified.

20. A method of performing a calibration operation associated with an automatic exposure control (AEC) operation using a tomosynthesis system, the method comprising: acquiring a plurality of reference images of the phantom at a plurality of projection angles, wherein each reference image of the plurality of reference images comprises a plurality of reference image pixels; generating a plurality of reference image detector count maps corresponding to each of the plurality of reference images by compiling a plurality of reference image pixels and corresponding reference image detector count values ​​associated with each of the plurality of reference images; storing the plurality of reference image detector count maps; acquiring a scout image of a breast of the patient at a first projection angle by transmitting a scout x-ray dose toward the breast of the patient with a tomosynthesis system, the scout image comprising a plurality of pixels, wherein each pixel of the plurality of pixels is associated with a detector count value of a plurality of detector count values; identifying a first region on the scout image as corresponding to the densest portion of the patient's breast; calculating an average detector count value by averaging one or more detector count values ​​corresponding to one or more pixels within the first region; identifying a second region on the first reference image associated with the first projection angle, wherein the second region corresponds to a location on the first reference image that matches a location of the first region on the scout image, and the first projection angle is one of the plurality of projection angles, and the first reference image is one of the plurality of reference images; obtaining one or more reference detector count values ​​associated with one or more reference pixels within a second region of the first reference image; calculating an average reference detector count value by averaging the one or more reference detector count values; calculating an AEC-calibrated dose to be used in a tomosynthesis scan based on a ratio between the average reference detector count value and the average detector count value; as well as The radiation dose used for tomosynthesis sweeps at multiple projection angles over the patient's breast was set to the AEC-calibrated dose.

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