Variable tissue imaging systems and methods for C-arm fluoroscopic imaging systems

Abstract

A system and method (300) for performing a dual energy subtraction imaging process on a stationary or mobile fluoroscopic imaging system (100) for lung imaging applications is provided. The dual energy subtraction image processing system (300) includes a processor (146) configured to operate a radiation source (123) of a fluoroscopic imaging system (100) in a pulsed manner to obtain a plurality of high energy (HE) frames (404); forming an HE image (410) from the plurality of HE frames (404); operating the radiation source (123) of the fluoroscopic imaging system (100) in a continuous manner to obtain a plurality of low energy (LE) frames (406); forming a LE image (412) from the LE frame (406); and employing the HE image (410) and the LE image (412) in a dual energy subtraction imaging process to output a plurality of enhanced contrast images (414). The processor is further configured to operate the detector (122) in a continuous manner to obtain the HE frame (404) and the LE frame (406).

Description

Background Art

[0001] The present disclosure generally relates to a system and method for producing images with enhanced visibility on different types of tissue or implants. Specifically, the present disclosure relates to a system and method for operating a mobile fluoroscopic C-arm imaging system during a dual energy subtraction procedure.

[0002] Visual detection of lung abnormalities on radiographs is extremely challenging. The frequency of missed diagnoses due to interpretation errors has been reported to be as high as 54%. The complex nature of the superimposed background anatomy is one of the main reasons for such interpretation errors.

[0003] Dual-energy subtraction (DES) imaging increases the sensitivity and specificity of pulmonary nodule detection in chest radiographs by reducing the contrast of overlying bony structures. Today, DES has become a standard imaging mode on most radiographic systems.

[0004] In dual energy x-ray imaging techniques, a subject to be imaged is exposed to x-rays having different energies by a dual energy x-ray system, such as a radiographic imaging system, in order to produce x-ray images of different types of tissues and / or structures disposed within the subject to be imaged. The tissues and / or structures located within the subject have varying x-ray attenuation, such that x-rays of different energies will be absorbed differently by different types of tissues and / or structures. An example of a radiographic imaging system capable of performing a dual energy subtraction imaging process is an exemplary embodiment of system 10, such as the system disclosed in U.S. Patent No. 6,683,934, entitled "Dual Energy X-Ray Imaging System And Method For Radiography And Mammography," the entire contents of which are expressly incorporated herein by reference for all purposes.

[0005] When used to obtain images of a mammalian subject (e.g., a human), differences in the absorption of low energy x-ray and high energy x-ray images by various tissues of the subject (e.g., denser or hard tissue (i.e., bone) and less dense or soft tissue (i.e., internal organs)) enable the dual energy x-ray system to produce images that primarily show one type of tissue or the other. This subtraction or decomposition of the anatomical structure of the scanned patient enables each type of tissue to be presented in a separate image, a soft tissue image or a bone image, in which one type of tissue is shown in a manner that more clearly shows the tissue, while the other type of tissue is removed or subtracted to prevent the structure of the desired tissue from being obscured by the structure of the undesired tissue.

[0006] In a prior art radiographic imaging system for a dual energy subtraction imaging process, the radiographic imaging system can be easily operated to obtain each of a high energy (HE) image and a low energy (LE) image of a patient because the radiographic imaging system is capable of operating to obtain a static image of the patient using each of the voltage requirements of the HE image and the LE image.

[0007] However, while capable of providing images that enable clearer visualization and diagnosis of different types of tissue, dual energy subtraction imaging systems and processes raise questions regarding their specific implementation on fixed or mobile C-arm fluoroscopic imaging systems. More specifically, fixed and mobile C-arm fluoroscopic imaging systems have an operating configuration that differs from radiographic imaging systems to facilitate fluoroscopic or moving images of anatomical structures. For example:

[0008] 1) In an x-ray radiography system, the duration of both low energy x-ray exposure and high energy x-ray exposure is controlled by AEC (Automatic Exposure Control). A mobile C-arm fluoroscopic imaging system uses AERC (Automatic Exposure Rate Control) instead of AEC.

[0009] 2) Tube current (mA) adjustment in x-ray radiography systems is instantaneous, but in a typical mobile C-arm fluoroscopy imaging system it takes much longer, eg, 1 second.

[0010] 3) The maximum power of the x-ray generator and tube in the mobile C-arm fluoroscopic imaging system is much smaller than that in the x-ray radiography system, for example 1 / 5.

[0011] 4) The detector dynamic range of a mobile C-arm fluoroscopic imaging system is also much smaller than that of an x-ray radiography system, for example 1 / 20.

[0012] Due to these limitations, fixed and mobile C-arm fluoroscopic imaging systems are unable to acquire two exposures (LE exposure and HE exposure) within a short period of time, which is critical for lung imaging applications due to, for example, respiratory motion of the imaged patient.

[0013] Therefore, there is a need for a system and method that can be used on a fixed or mobile C-arm fluoroscopic imaging system to enable the C-arm imaging system to obtain LE images and HE images for a dual energy subtraction imaging process that overcomes these deficiencies of the prior art. Summary of the invention

[0014] According to an exemplary aspect of the present disclosure, a method for performing a dual-energy subtraction imaging process on a fluoroscopic imaging system comprises the following steps: operating a radiation source of the fluoroscopic imaging system to obtain a plurality of high-energy (HE) frames; forming a HE image from the plurality of HE frames; operating the radiation source of the fluoroscopic imaging system to obtain a plurality of low-energy (LE) frames; forming a LE image from the plurality of LE frames; and employing the HE image and the LE image in the dual-energy subtraction imaging process.

[0015] According to an exemplary non-limiting aspect of the present disclosure, a fluoroscopic imaging system includes a radiation source; a detector spaced apart from the radiation source; a processing device operably connected to the detector for receiving image data from the detector in response to operation of the radiation source and processing the image data to form an image; an electronic storage device operably connected to the processing device, on which instructions for operation of the processing device can be stored; and a dual-energy subtraction image processing system operably connected to the processing device for performing a dual-energy subtraction imaging process and having a processor, the processor being configured to operate the radiation source of the fluoroscopic imaging system in a pulsed manner to obtain a plurality of high-energy (HE) frames; form HE images from the plurality of HE frames; operate the radiation source of the fluoroscopic imaging system in a continuous manner to obtain a plurality of low-energy (LE) frames; form LE images from the LE frames; and employ the HE images and the LE images in the dual-energy subtraction imaging process to output a plurality of contrast-enhanced images.

[0016] According to another exemplary non-limiting aspect of the present disclosure, a dual energy subtraction image processing system for performing a dual energy subtraction imaging process includes a processor configured to operate a radiation source of a fluoroscopic imaging system to obtain a sequence of alternating high energy (HE) frames and low energy (LE) frames, and to employ HE image frames and LE image frames in the dual energy subtraction imaging process to output a sequence of feature enhanced images.

[0017] It should be understood that the brief description above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings illustrate the best mode currently contemplated for carrying out the present disclosure. In the drawings:

[0019] Figure 1 is a schematic diagram of an exemplary fixed C-arm fluoroscopic imaging system according to an exemplary non-limiting embodiment of the present disclosure.

[0020] Figure 2 is a side elevation view of an exemplary mobile C-arm fluoroscopic imaging system according to an exemplary non-limiting embodiment of the present disclosure.

[0021] Figure 3 According to an exemplary non-limiting embodiment of the present disclosure Figure 1 and Figure 2 Block diagram of the control mechanism of the C-arm fluoroscopic imaging system.

[0022] Figure 4 According to an exemplary non-limiting embodiment of the present disclosure Figure 1 and Figure 2 Block diagram of the computing device of a C-arm fluoroscopic imaging system.

[0023] Figure 5 is an exemplary non-limiting embodiment according to the present disclosure, in Figure 1 and Figure 2 Flow chart of the operation of the dual-energy subtraction image processing system employed on a C-arm fluoroscopic imaging system.

[0024] Figure 6 is a schematic diagram of the operation of a dual energy subtraction image processing system according to an exemplary non-limiting embodiment of the present disclosure.

[0025] Figure 7 is a soft tissue image produced by a dual energy subtraction image processing system according to an exemplary non-limiting embodiment of the present disclosure.

[0026] Figure 8 is a bone tissue image generated by a dual energy subtraction image processing system according to an exemplary non-limiting embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] One or more specific embodiments will be described below. In order to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be understood that, as in any engineering or design project, in the development of any such actual implementation, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as complying with system-related and business-related constraints that may differ between implementations. In addition, it should be understood that such development efforts may be complex and time-consuming, but are still routine tasks of design, fabrication, and manufacturing for ordinary technicians who benefit from this disclosure.

[0028] When introducing the elements of various embodiments of the present disclosure, the articles "one", "a kind of" and "the" are intended to mean that there are one or more such elements. The terms "first", "second", etc. do not represent any order, amount or importance, but are used to distinguish one element from another element. The terms "include", "comprises", and "have" are intended to be inclusive, and mean that additional elements may also exist in addition to the listed elements. As used herein, the terms "connected to", "coupled to", etc., an object (that is, a material, element, structure, member, etc.) can be connected to or coupled to another object, regardless of whether the one object is directly connected or coupled to another object, or whether there are one or more intervening objects between the one object and another object. In addition, it should be understood that reference to "one embodiment" or "embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of additional embodiments that also combine the cited features.

[0029] As used herein, "electrically coupled," "electrically connected," and "electrically communicating" means that the referenced elements are directly or indirectly connected such that current can flow from one to the other. The connection may include a direct conductive connection (i.e., without intervening capacitors, inductors, or active elements), an inductive connection, a capacitive connection, and / or any other suitable electrical connection. There may be intervening components.

[0030] When read in conjunction with the accompanying drawings, the following specific implementation of certain embodiments will be better understood. To the extent that the figures of the functional blocks of the various embodiments are shown in the accompanying drawings, these functional blocks do not necessarily represent the division between hardware circuits. For example, one or more functional blocks (e.g., processors or memories) can be implemented in a single piece of hardware (e.g., a general signal processor or random access memory block, a hard disk, etc.) or multiple pieces of hardware. Similarly, a program can be a stand-alone program, can be incorporated into an operating system as a subroutine, can be a function in an installed software package, etc. It should be understood that the various embodiments are not limited to the arrangements and tools shown in the accompanying drawings.

[0031] As used herein, the terms "system," "unit," or "module" may include hardware and / or software systems that operate to perform one or more functions. For example, a module, unit, or system may include a computer processor, a controller, or other logic-based device that performs operations based on instructions stored on a tangible and non-transitory computer-readable storage medium (such as a computer memory). Alternatively, a module, unit, or system may include a hard-wired device that performs operations based on the hard-wired logic of the device. The various modules or units shown in the figures may represent hardware that operates based on software or hard-wired instructions, software that instructs hardware to perform operations, or a combination thereof.

[0032] A “system,” “unit,” or “module” may include or represent hardware and associated instructions (e.g., software stored on a tangible and non-transitory computer-readable storage medium, such as a computer hard drive, ROM, RAM, etc.) that performs one or more operations described herein. The hardware may include electronic circuitry that includes and / or is connected to one or more logic-based devices, such as microprocessors, processors, controllers, etc. These devices may be off-the-shelf devices that are appropriately programmed or instructed to perform the operations described herein in accordance with the instructions described above. Additionally or alternatively, one or more of these devices may be hardwired with logic circuitry to perform these operations.

[0033] Referring generally to the accompanying drawings, the present disclosure describes systems and methods for medical imaging systems having a C-arm. The medical imaging systems described herein (e.g., Figure 1 The medical imaging system shown) may generally be referred to as a fluoroscopic medical imaging system, and specifically a C-arm fluoroscopic imaging system. Figure 1 An example of a fixed C-arm fluoroscopic imaging system 10 is shown, which includes an X-ray fluoroscopic system 46 for acquiring and processing image data. As shown, the fixed C-arm fluoroscopic imaging system 10 includes a controller 48 and a workstation 34. The X-ray fluoroscopic system 46 is shown as a C-arm system, which includes a C-arm 50, an X-ray radiation source 16, and an X-ray detector 22. The X-ray radiation source 16 is mounted on the C-arm 50, and the X-ray detector 22 is mounted on the C-arm 50 at a position opposite to the X-ray radiation source 28. Although in some systems, the X-ray radiation source 16 and the X-ray detector 22 can be fixed, in a typical fluoroscopic system, the C-arm 50 allows the X-ray radiation source 16 and the X-ray detector 22 to move around the patient 20. In operation, the X-ray radiation source 16 emits a radiation stream suitable for X-ray fluoroscopy. The X-ray detector 22 receives a portion of the radiation stream from the X-ray source 16 that passes through the patient 20 positioned on the workbench 28. The X-ray detector 22 generates an electrical signal representing the intensity of the radiation stream. As will be understood by one of ordinary skill in the art, these signals are appropriately acquired and processed to reconstruct an image of the features within the subject.

[0034] As previously mentioned, the fixed C-arm fluoroscopic imaging system 10 also includes a controller 48. In the illustrated embodiment, the controller 48 includes an interface circuit 52 for receiving imaging and tracking data (e.g., tracking a medical device 54, such as a surgical device or any other suitable device for a medical procedure), a processing circuit 56, a memory circuit 58, and a workstation interface circuit 60 for communicating with the workstation 34. As will be appreciated, one or more computers may be used to implement the controller 48. Generally speaking, the processing circuit 56, which may typically include a digital signal processor, a CPU, etc., may process the tracking data so that the position of the device 54 can be projected onto the reconstructed image. In addition, the processing circuit 42 may also process the imaging data (e.g., image data and offset data) to reconstruct the data into a meaningful diagnostic image. The memory circuit 58 may be used to store the imaging and tracking data and other system parameters.

[0035] As shown, the fixed C-arm fluoroscopic imaging system 10 also includes a workstation 34, which includes a user interface 62 and a display 36. The user interface 62 may include a keyboard and / or a mouse, as well as other devices such as a printer or other peripherals for reproducing a hard copy of the reconstructed image. The display 36 may include one or more screens. For example, the display 36 may include a first screen for displaying a previously acquired image and a second screen for displaying one or more intraoperative images.

[0036] Reference now Figure 2, shows a mobile C-arm fluoroscopic imaging system 100 according to an exemplary embodiment, such as the mobile C-arm fluoroscopic imaging system disclosed in U.S. published patent application serial number US2022 / 0401048 entitled "Imaging System With Carbon Fiber C-Arm", the entire contents of which are expressly incorporated herein by reference for all purposes. The mobile C-arm fluoroscopic imaging system 100 includes a rotatable C-arm 102 connected to a base 104. The base 104 supports the C-arm 102 when the C-arm 102 is stationary and when rotating. The base 104 supports the C-arm 102 on a surface 106 on which the mobile C-arm fluoroscopic imaging system 100 is located via a plurality of wheels 105 or similar rotatable supports that enable the base 104 to be easily moved on and / or along the surface 106 by an operator, such as by grasping a handle 107 on the base 104 and pulling or pushing the mobile C-arm fluoroscopic imaging system 100 into a desired position to operate the mobile C-arm fluoroscopic imaging system 100. The C-arm 102 includes a C-shaped portion 108 connected to an extension portion 110. The extension portion 110 is rotatably coupled to the base 104, which allows the C-arm 102 to rotate about an examination region 112 and an axis of rotation 114. For example, the C-arm 102 can be configured to rotate at least 180° in opposite directions relative to the base 104, but in some embodiments, the C-arm 102 can be configured to rotate at least 220°. Configuring the C-arm 102 to rotate at least 220° can allow a physician to have greater access to the patient being imaged. Although the rotation of the C-arm 102 is described below as rotating in the X and Y directions of the Cartesian coordinate system 115 (i.e., rotating the C-shaped portion 108 so that the opposite ends of the C-shaped portion 108 are closer to or farther away from the extension portion 110 in various positions), it should be understood that the C-arm 102 can also be rotated in the Z direction (i.e., rotating the C-shaped portion 108 so that the opposite ends of the C-shaped portion 108 are closer to or farther away from the patient's head in the examination area 112 in various positions, and / or using a suitable vertical translation mechanism (not shown) disposed on the base 104 and engaged with the extension portion 110 to change the height of the extension portion 110 relative to the base 104.

[0037] The mobile C-arm fluoroscopic imaging system 100 also includes a patient support 116 (i.e., a couch, bed, table, etc.) that supports an object or a patient such as the patient 118 when at least a portion of the patient 118 is located within the examination area 112. The mobile C-arm fluoroscopic imaging system 100 additionally includes a radiation source 120 and a radiation detector 122. The radiation source 120 and the radiation detector 122 are supported by the C-arm 102 and rotate therewith. In addition, the radiation source 120 and the radiation detector 122 are positioned at opposite ends of the C-shaped portion 108 of the C-arm 102 along an axis 124, wherein the axis 124 intersects the rotation axis 114 and extends radially relative to the rotation axis. The C-shaped portion 108 can be rotated as described above to adjust the position of the radiation source 120 and the radiation detector 122, thereby obtaining a 2D projection image of the subject 118 at each selected orientation of the radiation source 120 relative to the detector 122 to form a 2D projection data set. In addition, in Figure 2 In the illustrated embodiment, the position of the radiation detector 122 may be changed such that the radiation detector 122 is placed farther away from or closer to the radiation source 120 .

[0038] During a medical imaging procedure, a portion of a patient 118 is located within an examination region 112, and a radiation source 120 emits radiation 126. In one embodiment, the radiation source 120 may include an X-ray tube 123 housed within a housing 128. The X-ray tube 123 generates radiation 126, which escapes the housing 128 via an outlet 130. The radiation 126 traverses the examination region 112 and is attenuated by the portion of the patient 118 located within the examination region 112. Specifically, the radiation source 120 emits radiation 126 toward a radiation detector 122 located on an opposite end of the C-arm 102. The radiation source 120 emits a cone of radiation that is collimated to be located within an XYZ plane of a Cartesian coordinate system 115, which is generally referred to as an "object plane," which is parallel to the radiation detector 122 at the isocenter of the C-arm 102.

[0039] After passing through a portion of the patient 118, the attenuated radiation is captured by a radiation detector 122. In some embodiments, the radiation detector 122 includes a plurality of detector elements (not shown) that collect projection data. Each detector element generates an electrical signal that is a measure of the attenuation at the location of the detector element. The attenuation measurements from all detector elements in the detector 122 are collected individually to generate a transmission profile. In one embodiment, the radiation detector 122 is fabricated into a flat panel configuration that includes a plurality of detector elements.

[0040] As the radiation source 120 and the radiation detector 122 rotate with the C-arm 102 within the object plane and around the patient 118, the angle at which the radiation 126 intersects the patient 118 changes. A set of attenuation measurements (i.e., projection data) from the radiation detector 122 at one C-arm angle is referred to as a "view." A "scan" of the patient 118 includes a set of projection views made at different angles or viewing angles during the rotation of the C-arm 102. As used herein, the term view is not limited to the uses described herein with respect to projection data obtained from or from a C-arm 102 angle. The term view is used to represent a data acquisition whenever there are multiple acquisitions from different angles, for example, to form a 2D projection data set.

[0041] The mobile C-arm fluoroscopic imaging system 100 also includes a control mechanism 132 housed within the base 104. The control mechanism 132 is connected to the C-arm 102, the radiation source 120, and the radiation detector 122 via cables 134 that allow the control mechanism to send / receive data to / from the C-arm 102, the radiation source 120, and the radiation detector 122. The control mechanism 132 controls the rotation of the C-arm 102 and the operation of the radiation source 120. Although Figure 2 The base 104 is shown as including the control mechanism 132 , but in other embodiments, the control mechanism may be separate from the base 104 (ie, in a different room).

[0042] The C-arm 102 can be adjusted to a plurality of different positions by rotation of the C-shaped portion 108. For example, the radiation detector 122 can be positioned vertically above the radiation source 120 relative to the surface 106 on which the mobile C-arm fluoroscopic imaging system 100 is located, wherein the axis 124 is arranged perpendicular to the surface 106 intersecting the midpoint of the outlet 130 of the radiation source 120 and the midpoint of the detector surface 142 of the radiation detector 122. The C-arm motor controller 138 and the guide system within the extension portion 110 can adjust the C-shaped portion 108 from a first position to a different second position by rotating the C-shaped portion 108 via the coupling between the guide system and the C-shaped portion 108. In one example, the second position may be a position in which the radiation source 120 and the detector 122 are rotated together 180° relative to the first position, such that the radiation source 120 is vertically positioned above the radiation detector 122, wherein the axis 124 intersects the midpoint of the outlet 130 of the radiation source 120 and the midpoint of the detector surface 142 of the radiation detector 122. When adjusted to the second position, the radiation source 120 may be vertically positioned above the rotation axis 114 of the C-shaped portion 108, and the radiation detector 122 may be vertically positioned below the rotation axis 114.

[0043] The mobile C-arm fluoroscopic imaging system 100 also includes a computing device 144 housed within the base 104 that is operable to generate images for presentation on the display 150. Figure 2 The computing device 144 is shown housed within the base 104, but in other embodiments, the computing device 144 may be remote from the rest of the mobile C-arm fluoroscopic imaging system 100. As used herein, a computing device (or system) is any device / system (i.e., a tablet computer, handheld device, smart phone, personal computer, laptop computer, network computer, server, mobile communication device, etc.) capable of processing, storing and / or transmitting data. The computing device 144 may be connected to a network (i.e., a wide area network (WAN), a local area network (LAN), a public network (Internet), etc.) that allows the computing device 144 to communicate with other devices on the same network. In some embodiments, the network may be considered a private network and may include, for example, a virtual private network.

[0044] Then go to Figure 3 , which shows a block diagram of a computing device 144 according to an exemplary embodiment. The computing device 144 includes a processing device 146 and a system memory 148. In some embodiments, the computing device is connected to a display 150 and one or more user input devices such as a touch screen, a keyboard, a mouse, and / or an external device 152. The processing device 146 communicates with the system memory 148 and can execute computer-readable program instructions stored in the system memory 148. As used herein, a processor may include a central processing unit (CPU) or other electronic components capable of executing computer-readable program instructions (i.e., a digital signal processor, a field programmable gate array (FPGA), a graphics processing unit (GPU), etc.). In addition, as used herein, a processor may include two or more of a CPU, a digital signal processor, an FPGA, and a GPU.

[0045] System memory 148 is a computer-readable storage medium. As used herein, a computer-readable storage medium is any device that stores computer-readable program instructions for execution by a processor, and is not interpreted as being transient in itself. Computer-readable program instructions include programs, logic, data structures, modules, etc. that create means for implementing functions / actions when executed by a processor. When stored in a computer-readable storage medium and executed by a processor, the computer-readable program instructions instruct a computer system and / or another device to function in a particular manner, so that the computer-readable storage medium includes an article of manufacture. System memory as used herein includes volatile memory (i.e., random access memory (RAM) and dynamic RAM (DRAM)) and non-volatile memory (i.e., flash memory, read-only memory (ROM), magnetic computer storage device, etc.). In some embodiments, system memory 148 may also include a cache.

[0046] In one embodiment, various methods and processes may be stored as computer readable program instructions in the system memory 148. In this embodiment, the system memory 148 includes computer readable program instructions for imaging a patient using a medical imaging system (ie, the radiographic imaging system 100).

[0047] The external device 152 includes a device that allows a user to interact with / operate the computing device 144 (e.g., a mouse, keyboard, touch screen, speaker, etc.), and when configured as a touch screen device, may include a display 150. In some embodiments, the display 150 displays a graphical user interface (GUI). The GUI includes editable fields for entering data (i.e., patient data, imaging parameters, etc.), and also includes selectable icons. Selecting an icon and / or entering data causes the processing device 146 to execute computer-readable program instructions stored in the system memory 148, which causes the processor to perform a task. For example, according to one or more embodiments disclosed herein, a user of the computing device 144 can use the external device 152 or the touch screen display 150 to select a "start" icon, etc., that causes the processing device 146 to start a medical imaging process and / or analysis.

[0048] The mobile C-arm fluoroscopic imaging system 100 may include a computing device 144. The computing device 144 may be used to input or output imaging parameters, request an examination, plot data, and / or view images. In addition, in certain embodiments, the mobile C-arm fluoroscopic imaging system 100 may be connected to multiple displays, printers, workstations, and / or similar devices located locally or remotely (i.e., within an institution or hospital or in a completely different location, etc.) via one or more configurable wired and / or wireless networks. In addition, in some embodiments, the base also accommodates an internal power supply (not shown) that provides power to operate the mobile C-arm fluoroscopic imaging system 100. Alternatively, the base 104 may be connected to an external power supply to power the mobile C-arm fluoroscopic imaging system 100. A plurality of connecting cables (i.e., cables 134) may be provided to transmit power to the radiation source 120, the radiation detector 122, etc.

[0049] The computing device 144 communicates with the radiation source controller 136, the C-arm motor controller 138, and the DAS 140 and provides commands to them to control system operations, such as data acquisition and / or data processing. In some embodiments, the computing device 144 controls the operation of the radiation source controller 136, the C-arm motor controller 138, and the DAS 140 based on user input.

[0050] The computing device 144 also includes a dual energy subtraction (DES) image processing system 160 configured to receive an image dataset, such as a 2D projection image dataset / transmission dataset (not shown), from the detector 120 and implement the dual energy subtraction process described herein to generate images 200, 202 ( Figure 7 and Figure 8 ), each enhancing a different type of tissue and / or material present in the 2D projection image dataset / transmission dataset. The DES image processing system 160 may be implemented as a piece of hardware installed in the processing device 146. Optionally, the DES image processing system 160 may be implemented as a set of instructions installed on the processing device 146. The set of instructions may be a stand-alone program, may be incorporated as a subroutine into an operating system installed on the processing device 146 and / or into a system memory 148 accessed by the processing device 146, may be a function in a software package installed on the processing device 146, or may be a combination of software and hardware. It should be understood that the various embodiments are not limited to the arrangements and tools shown in the accompanying drawings.

[0051] See now Figures 4 to 6 , the DES image processing system 160 operates the radiation sources 16, 120 to emit radiation 126, which passes through the patient 20, 118 before reaching the detectors 22, 122. In operation of the DES image processing system 160, the radiation sources 16, 120 are operated at two different voltages in a range between about 30 kVp and about 140 kVp to obtain low energy (LE) images, such as 60 kVp, and high energy (HE) images, such as 120 kVp. In another embodiment, the LE image and the HE image can be obtained by applying different filters to the x-ray beam generated with the same kVp. These images can be used by the computing device 144 within a subtraction process to generate one or more enhanced contrast images, providing a better representation of the different types of tissues and / or materials present within the LE image and the HE image. While many subtraction processes are currently used for this purpose, one example of such a subtraction process is disclosed in U.S. Patent No. 10,147,171, entitled "System and Methods For Generating Subtracted Images," the entire contents of which are expressly incorporated herein by reference for all purposes.

[0052] The types of tissues and / or materials that may be represented within the contrast-enhanced images produced by the subtraction process may include, but are not limited to, soft tissue of the patient's anatomy, bone tissue of the patient's anatomy, and different types of materials and / or medical devices positioned within the patient's anatomy, such as stents, which may be formed of those different materials, e.g., metals and polymeric materials, including nylon. For example, in one exemplary embodiment, a dual energy subtraction process employed on an LE image and a HE image may produce a contrast-enhanced image that enhances the contrast and visibility of certain structures (e.g., lung cancer nodules) in the soft tissue image, such that the contrast-enhanced image output by the DES image processing system 160 includes a contrast-enhanced soft tissue image 416 ( Figure 7 ) and enhanced contrast bone image 418 ( Figure 8 ). In another exemplary embodiment, the DES image processing system 160 may output an enhanced contrast image to enhance the contrast and visibility of a nylon stent, which has been increasingly used in vascular procedures and is difficult to visualize in a conventional fluoroscopic image. In another exemplary embodiment, the DES image processing system 160 may output an image to enhance the visualization of metal within the imaged patient anatomy as compared to a bone and / or soft tissue background, such as where a stent in the imaged patient anatomy is formed of metal. To provide such enhanced visualization, the enhanced contrast image output by the DES image processing system 160 may include enhanced contrast material, such as metal, an image, and a background (soft tissue and / or bone) enhanced contrast image.

[0053] To obtain the LE and HE images used by the DES image processing system 160 to generate the enhanced contrast image, reference is now made to Figure 5 and Figure 6 In the exemplary embodiment shown, according to method 300, when a dual energy imaging process is initiated by a user, in step 302, the DES image processing system 160 will preheat the filaments within the radiation source 16, 120 before the exposure begins to ensure that the filaments are heated to the desired temperature so that the tube mA produced is close to the recommended value. The preheating in step 302 compensates for the slower mA response in the C-arm fluoroscopic imaging system 10, 100 before exposure and maximizes the radiation source 120 / X-ray tube 123 capacity by setting the maximum mA during exposure. In addition, detector saturation can be avoided by adjusting the high energy shot pulse width based on the acquired patient size determined by a previously acquired fluoroscopic process, or if there is no previous fluoroscopic image / activity available and due to the lack of an automatic exposure control (AEC) system on the C-arm fluoroscopic imaging system 10, 100.

[0054] After warming up, in step 304, the DES image processing system 160 performs one or more pulses 402 of the radiation source 16, 120 at a high energy or voltage (e.g., approximately 120 kVp) to emit radiation / X-rays from the radiation source 16, 120 during the pulses to obtain one or more HE frames 404. Figure 6 As shown, during the interval 407 between each HE pulse 402 , the detector 20 , 122 is read to obtain the corresponding HE frame 404 .

[0055] After reading the detector following the final HE pulse 402 to obtain the final HE frame 404, in step 306, the DES image processing system 160 operates the radiation source 16, 120 at a low energy or low voltage (e.g., about 60 kVp) to obtain one or more LE frames 406. In step 306, the operation of the radiation source 16, 120 is continuous to minimize the total X-ray duration, that is, the emission of radiation / X-rays from the radiation source 16, 120 is continuous throughout step 306. At designated time intervals 408 during the continuous operation of the radiation source 16, 120 at low energy, the DES image processing system 160 reads the detector 22, 122, such as at predetermined intervals, to obtain the LE frame 406. Figure 6 As shown in the exemplary embodiment of FIG. 4 , the obtained initial LE frame 406 and the final LE frame 406 may be partial frames that can be combined to form the complete LE frame 406. In an exemplary embodiment, the interval 407 between the HE pulses 402 of the HE frame 404 read by the detector 22, 122 is equivalent to the interval 408 between the LE frames 406 read by the detector 22, 122, so that the detector 22, 122 is operated or read in a continuous and / or consistent manner throughout the imaging process for obtaining the HE frame 404 and the LE frame 406.

[0056] In step 308, which may be performed during or after obtaining the LE frame 406 in step 306, the HE frame 404 is formed into a HE image 410 by the DES image processing system 160. Figure 5 and Figure 6 In the exemplary embodiment shown, HE image 410 is formed from the combination of two HE frames 404 , such as by accumulating image information in each HE frame 404 into a single HE image 410 in any suitable known manner.

[0057] In step 310, which may occur simultaneously or consecutively with the formation of HE image 410 in step 308, LE frames 406 are similarly combined with one another by DES image processing system 160 to form LE image 412. HE image 410 and LE image 412 may then be subsequently employed in a dual energy subtraction process performed by DES image processing system 160 in step 312, such as previously described, to output one or more contrast-enhanced images 414 in step 314. Also as previously described, contrast-enhanced image 414, having Figure 7 and Figure 8 The illustrated examples of soft tissue images 416 and bone tissue images 418 may be formed to provide a desired enhanced contrast between a variety of different types of tissues and / or materials present within the patient's anatomy contained within the HE image 410 and the LE image 412. The output enhanced contrast images 414, 416, 418 may be presented by the DES image processing system 160 to the C-arm fluoroscopic imaging system 10, 100 on the display 36, 150, e.g., simultaneously for viewing by a user.

[0058] In an alternative exemplary embodiment, the DES image processing system 160 may operate the radiation sources 16, 120 in a manner that the LE frames 406 are obtained before the HE frames 404. In another alternative exemplary embodiment, again referring to Figure 5 , the DES image processing system 160 may operate the radiation source 16, 120 (e.g., in a pulsed manner) to obtain a sequence of alternating high energy (HE) frames 404 and low energy (LE) frames 406, or vice versa, to form an associated pair of a single HE frame 404 and a single LE frame 406, and then perform an image processing step 311 on the pair of HE frames 404 and / or LE frames 406. The image processing performed on the pair of frames 404 and 406 in step 311 may be any suitable image processing step, such as, but not limited to, noise reduction of the frames 404, 406. Then, in a subsequent dual energy subtraction step 312, each pair of associated and image processed HE frames 404 and LE frames 406 is used as a HE image 410 and a LE image 412, respectively, to produce one or more feature enhanced images 414, 416, 418 for each pair of associated frames 404, 406 that are output in step 314.

[0059] Using the DES image processing system 160 and the associated method 300, the process for obtaining the HE frames 404 and the LE frames 406 performed by the C-arm fluoroscopic imaging system 10, 100 is reduced by operating the detector 22, 122 at a constant rate without switching the operating mode of the detector 22, 122 between pulsed high energy x-ray exposure and continuous low energy x-ray exposure. Figure 6The duration of the process is minimized. In an exemplary embodiment, the total duration of the X-ray exposure in the method 300 is no longer than 200 milliseconds, which is critical to ensuring image quality in the presence of respiratory motion of the patient 20, 118. In addition, the DES image processing system 160 and the associated method 300 accommodate each of the operational differences or shortcomings of the C-arm fluoroscopic imaging system 10, 100 and the radiographic system, including slower tube mA response, lower detector dynamic range, lower tube power, and lack of hard-wired AEC (automatic exposure control) to enable the use of the C-arm fluoroscopic imaging system 10, 100 to perform dual energy subtraction imaging procedures, particularly with respect to lung imaging applications.

[0060] This written description uses examples to disclose the invention, including the best mode, and also to enable those skilled in the art to practice the invention, including making and using any devices or systems and performing any included methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with minor differences from the literal language of the claims.

Claims

1. A method for performing a dual energy subtraction imaging process on a fluoroscopic imaging system (100), the method comprising the following steps: a. operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of high energy (HE) frames (404); b. forming a HE image (410) from the plurality of HE frames (404); c. operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of low energy (LE) frames (406); d. forming an LE image (412) from the plurality of LE frames (406); and e. Using the HE image (410) and the LE image (412) in a dual energy subtraction imaging process.

2. The method of claim 1, wherein the step of operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain the plurality of HE frames (404) comprises operating the radiation source (123) of the fluoroscopic imaging system (100) in a pulsed manner to obtain the plurality of HE frames (404).

3. The method of claim 2, wherein the step of operating the radiation source (123) of the fluoroscopic imaging system (100) in a pulsed manner to obtain the plurality of HE frames (404) further comprises reading a detector (122) between pulses (402) to obtain the plurality of HE frames (404).

4. The method of claim 2, wherein the step of operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of low energy (LE) frames (406) comprises operating the radiation source (123) of the fluoroscopic imaging system (100) in a continuous manner to obtain the plurality of LE frames (406).

5. The method according to claim 4, wherein the step of operating the radiation source (123) of the fluoroscopic imaging system (100) in a continuous manner to obtain the multiple LE frames (406) also includes reading the detector (122) at predetermined intervals (408) to obtain the multiple LE frames (406).

6. The method of claim 5, wherein the predetermined interval (408) is equivalent to the interval between HE pulses (402) during operation of the radiation source (123) of the fluoroscopic imaging system (100) in a continuous manner to obtain the plurality of LE frames (406).

7. The method according to claim 2, wherein the total length of time for operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain the multiple HE frames (404) and for operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain the multiple LE frames (406) does not exceed 200 ms.

8. The method of claim 1, wherein the step of forming the HE image (410) from the plurality of HE frames (404) comprises combining the HE frames (404) into the HE image (410).

9. The method of claim 8, wherein the step of forming the LE image (412) from the plurality of LE frames (406) comprises combining the LE frames (406) into the LE image (412).

10. The method according to claim 1, further comprising the step of outputting at least one contrast-enhanced image (414, 416, 418) after using the HE image (410) and the LE image (412) in a dual energy subtraction imaging process.

11. The method of claim 10, wherein the at least one contrast-enhanced image (414, 416, 418) comprises: a. Enhanced contrast material image (414); as well as b. Enhance the contrast of the background image (416, 418).

12. The method according to claim 1, further comprising the steps of: a. alternating the operation of the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of associated pairs of high energy (HE) frames (404) and low energy (LE) frames (406); b. performing image processing on the high energy (HE) frame (404) and the low energy (LE) frame (406) of each associated pair; c. Forming a HE image (410) from the processed HE frame (404); d. forming an LE image (412) from the processed LE frame (406); e. performing a subtraction imaging process on the HE image (410) and the LE image (412) to produce an enhanced image (414); and f. Displaying the enhanced image (414).

13. A dual energy subtraction image processing system (144) for performing a dual energy subtraction imaging process, the dual energy subtraction image processing system comprising a processor (146), the processor being configured to: a. operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of high energy (HE) frames (404); b. forming a HE image (410) from the plurality of HE frames (404); c. operating the radiation source (123) of the fluoroscopic imaging system (100) to obtain a plurality of low energy (LE) frames (406); d. forming an LE image (412) from the LE frame (406); and e. Using the HE image (410) and the LE image (412) in a dual energy subtraction imaging process to output a plurality of contrast-enhanced images (414).

14. The dual energy subtraction image processing system according to claim 13, wherein the processor (146) is configured to: a. operating the radiation source (123) of the fluoroscopic imaging system (100) in a pulsed manner to obtain the plurality of HE frames (404); and b. Operating the radiation source (123) of the fluoroscopic imaging system (100) in a continuous manner to obtain the plurality of LE frames (406).

15. The dual energy subtraction image processing system according to claim 14, wherein the processor (146) is configured to read the detector (122) at predetermined intervals to obtain the plurality of HE frames (404) and the plurality of LE frames (406).

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