Detector arm systems and assemblies

A detector arm assembly is provided that includes a stator, a detector head, a radial motion motor, and a detector head belt. The stator is configured to be fixedly coupled to a gantry having a bore. The detector head includes a carrier section that is slidably coupled to the stator and configured to be movable in a radial direction in the bore relative to the stator. The radial motion motor is operably coupled to at least one of the detector head or the stator. The detector head belt is operably coupled to the radial motion motor and the carrier section. Rotation of the radial motion motor causes movement of the detector head in the radial direction.

BACKGROUND

The subject matter disclosed herein relates generally to medical imaging systems, and more particularly to Nuclear Medicine (NM) imaging systems which can be Single Photon Emission Computed Tomography (SPECT) imaging systems.

In NM imaging, such as SPECT imaging, radiopharmaceuticals are administered internally to a patient. Detectors (e.g., gamma cameras), typically installed on a gantry, capture the radiation emitted by the radiopharmaceuticals and this information is used to form images. The NM images primarily show physiological function of, for example, the patient or a portion of the patient being imaged.

Conventional SPECT imaging systems include one, two or three gamma cameras mounted to a single gantry. These systems are generally not physically reconfigurable. The gamma cameras (also referred to as heads) are formed from particular materials. In the selection of material, tradeoffs must be made, such as imaging sensitivity, size, cost, etc. Additionally, specific collimation may be provided, which typically limits the application of the scanner to a particular type of scan, such as whole body bone exams, cardiac exams, etc. Thus, conventional SPECT imaging systems have limitations in design and/or operational characteristics. Moreover, there is limited flexibility in these imaging systems. There is a need for flexibility of an imaging system to be customizable based on specific patient need and operator cost constraints. There is also a need for imaging systems to automatically adjust imaging operations in systems that have changes in configurations.

BRIEF DESCRIPTION

In accordance with an embodiment, a detector arm assembly is provided that includes a stator, a detector head, a radial motion motor, and a detector head belt. The stator is configured to be fixedly coupled to a gantry having a bore. The detector head includes a carrier section that is slidably coupled to the stator and configured to be movable in a radial direction in the bore relative to the stator. The radial motion motor is operably coupled to at least one of the detector head or the stator. The detector head belt is operably coupled to the radial motion motor and the carrier section. Rotation of the radial motion motor causes movement of the detector head in the radial direction.

In accordance with an embodiment, a detector arm assembly is provided that includes a stator, a detector head, a slider block, and a detector head belt. The stator is configured to be fixedly coupled to a gantry having a bore. The detector head includes a carrier section that is slidably coupled to the stator and configured to be movable in a radial direction in the bore relative to the stator. The slider block is interposed between the detector head and the stator. The slider block is slidably coupled to the stator and configured to be moveable in the radial direction with respect to the stator. The carrier section of the detector head is slidably coupled to the slider block and configured to be moveable in the radial direction with respect to the slider block. The detector head belt is operably coupled to the carrier section. Movement of the detector head belt causes movement of the detector head in the radial direction.

In accordance with an embodiment, an imaging system is provided that includes a gantry and plural detector arm assemblies. The gantry defines a bore. The plural detector arm assemblies are distributed about the bore. At least some of the detector arm assemblies include a stator, a detector head, a radial motion motor, a detector head belt, and a slider block. The stator is configured to be fixedly coupled to the gantry having a bore. The detector head includes a carrier section that is slidably coupled to the stator and configured to be movable in a radial direction in the bore relative to the stator. The radial motion motor is operably coupled to at least one of the detector head or the stator. The detector head belt is operably coupled to the radial motion motor and the carrier section. Rotation of the radial motion motor causes movement of the detector head in the radial direction. The slider block is interposed between the detector head and the stator. The slider block is slidably coupled to the stator and is configured to be moveable in the radial direction with respect to the stator. The carrier section of the detector head is slidably coupled to the slider block and configured to be moveable in the radial direction with respect to the slider block.

DETAILED DESCRIPTION

Various embodiments provide a medical imaging system, and in particular, a Nuclear Medicine (NM) imaging system having a gantry with a plurality of different types of imaging detectors mounted thereto. For example, in various embodiments of an NM imaging system, a Single Photon Emission Computed Tomography (SPECT) imaging scanner is provided that includes a plurality of detectors with a combination of different types of detectors that acquire SPECT image information. The various embodiments may include detectors formed from different materials, having different configurations or arrangements, having different collimation, etc. The system may be configured to perform single isotope or multi-isotope imaging.

It should be noted that although the various embodiments are described in connection with a particular NM imaging system, such as a SPECT detector system, the various embodiments may be implemented in connection with other imaging systems, such as a Positron Emission Tomography (PET) imaging system. Additionally, the imaging system may be used to image different objects, including objects other than people.

A medical imaging system10may be provided as illustrated inFIG. 1. A subject18can be a human patient in one embodiment. It should be noted that the subject18does not have to be human. It can be some other living creature or inanimate object in various embodiments. The subject18can be placed on a pallet14that can move a subject horizontally for locating the subject in the most advantageous imaging position. The bed mechanism16can raise and lower the pallet14vertically for locating the subject in the most advantageous imaging position. The gantry12is shown as circular in one embodiment. In other embodiments the gantry12may be of any shape such as square, oval, “C” shape, or hexagonal.

FIG. 2shows the medical imaging system20in accordance with another embodiment. The medical imaging system20may be provided having a plurality of NM cameras configured as SPECT detector columns22a-22f. It should be noted that the various embodiments are not limited to the medical imaging system20having six detector columns22as shown or to the sizes or shapes of the illustrated detector columns22. For example, the medical imaging system20may include more or less detector columns22having different shapes and/or sizes, or formed from different materials. The medical imaging system20in various embodiments is configured as a hybrid SPECT system having a plurality of detector columns22, wherein at least two of the detectors are formed from different materials, have different configurations or arrangements, have different collimation, or are otherwise different. Detector columns can be called detector units in some embodiments.

In operation, a subject, such as a patient24, is positioned in proximity to the one or more of the detector columns22for imaging. The imaging system20can then re-adjust the detector columns22further from or closer to the patient24or patient area of interest as needed, which is heart28in an example embodiment. Imaging of the patient24is performed by one or more of the detector columns22. The imaging by each of the detector columns22may be performed simultaneously, concurrently, or sequentially.

The position of the detector columns22may be varied, including the relative position between detector columns22, tilt, angle, swivel, etc. of the detector columns22. Additionally, each of the detector columns22may have a corresponding collimator26a-26fmounted or coupled thereto. The collimators26a-26flikewise may be of different types. One or more detector columns22may be coupled to a different type of collimator26(e.g., parallel hole, pin-hole, fan-beam, cone-beam, etc.). Accordingly, in various embodiments, the detector column22wholly includes collimator26.

The detector columns22may include single crystal, or multi-crystal, detectors or pixelated detectors or scintillator based detectors that are configured to acquire SPECT image data. For example, the detector columns22may have detector elements formed from different materials, such as semiconductor materials, including Cadmium Zinc Telluride (CdZnTe), often referred to as CZT, Cadmium Telluride (CdTe), and Silicon (Si), among others, or non-semiconductor scintillator materials such as different types of crystal scintillators, for example, Sodium Iodide (Nap, Bismuth Germanate (BGO), Cerium-doped Lutetium Yttrium Orthosilicate (LYSO), Gadolinium Oxyorthosilicate (GSO), Cesium Iodide (CsI), Lanthanum(III) bromide (LaBr3), among others. Additionally suitable components may be provided. For example, the detector columns22may be coupled to photosensors, such as an array of Photo-Multiplier Tubes (PMTs), an Avalanche Photodiode Detector (AFD), etc.

The imaging system20can also include a detector controller30that operates to control the movement of the detector columns22and/or the collimators26. For example, the detector controller30may control movement of the detector columns22, such as to rotate or orbit the detector columns22around a patient24, and which may also include moving the detectors closer or farther from the patient24and pivoting/swiveling the detector columns22, such that more localized movements or motions are provided. The detector controller30additionally may control the orbital rotation of the detector columns22around the edges of the gantry bore, such that the detector columns22are at a new angle to the patient24than previously. The detector controller30may also optionally control movement of the collimators26, such as independently of the detector columns22. It should be noted that one or more the detector columns22and/or the collimators26may move during imaging operation, move prior to, but remain stationary during imaging operation, or may remain in a fixed positioned or orientation. In various embodiments, the detector controller30may be a single unit controlling movement of both the detector columns22and the collimators26, may be separate units, or may be a single unit controlling only operation of the detector columns22or may be a single unit controlling only operation of the collimators26.

The imaging system20also includes an image reconstruction module34configured to generate images from acquired image information36received from the detector columns22. For example, the image reconstruction module34may operate using NM image reconstruction techniques to generate SPECT images of the patient24, which may include an object of interest, such as the heart28of the patient. The image reconstruction techniques may be determined based on the installation status of detector column22acquiring the image information36and sending to image reconstruction module34and/or processor32.

Variations and modifications to the various embodiments are contemplated. For example, in a multi-headed system, namely a system having two or more detector columns22, each detector column22may be formed from different materials and have different collimators26. Accordingly, in at least one embodiment, one detector combination may be configured to obtain information for an entire field of view (FOV), such as the entire spine, while another detector combination is configured to focus on a smaller region of interest (ROI) to provide higher quality information (e.g., more accurate photon counting). Additionally, information acquired by one detector combination may be used to adjust the position, orientation, etc. of at least one other detector combination during imaging.

The image reconstruction module34may be implemented in connection with or on a detector controller30and/or processor32that is coupled to the imaging system20. Optionally, the image reconstruction module34may be implemented as a module or device that is coupled to or installed in the detector controller30and/or processor32. Each processing module may be a separate hardware module or software module, or combined together into one chip or module in various embodiments.

The image information36received by the processor32and/or image reconstruction module34may be stored for a short term (e.g., during processing) or for a long term (e.g., for later offline retrieval) in a memory38. The memory38may be any type of data storage device, which may also store databases of information. The memory38may be separate from or form part of the processor32. A user input39, which may include a user interface selection device, such as a computer mouse, trackball and/or keyboard is also provided to receive a user input. The user input may direct the processor32to send a detector control signal to the detector controller30for alteration of the detector column22arrangement in the gantry bore. Optionally, the user input39may be considered by the processor32as a suggestion and the processor32may choose to not execute the suggestion based on criteria.

Thus, during operation, the output from the detector columns22, which may include the image information36, such as projection data from a plurality of detector/gantry angles is transmitted to the processor32and the image reconstruction module34for reconstruction and formation of one or more images. The reconstructed images and other user output can be transmitted to a display40such as a computer monitor or printer output. The reconstructed images and other user output can also be transmitted to a remote computing device via network42.

Different combinations and variations of detector columns22and/or collimators26will now be described. It should be noted that the various embodiments are not limited to a particular detector, collimator, or detector combination, but may include any imaging system having a plurality of different types of detector columns22and/or collimators26, for example, having at least two detector columns22of a different type or design. Additionally, the number of detector columns22and the arrangement thereof may be varied as desired or needed, for example, based on the type of imaging to be performed or the type of image information to be acquired. Accordingly, various embodiments include the imaging system20having a plurality of detector columns22, wherein at least two of the detector columns22are different and are configured to perform imaging of the patient24(or other object).

For example, in one embodiment, illustrated inFIG. 2, a configuration is provided having one detector column22aformed from one material and the remaining detector columns22b-221formed from a different material. In the illustrated embodiment, the detector column22ais formed from a NaI material and the remaining detector columns22b-221are formed from a CZT material. Accordingly, in this configuration, a single NaI detector column22aand a plurality of CZT detector columns22b-221are provided. The detector columns22a-221may be sized and shaped the same or differently. For example, in the embodiment illustrated inFIG. 2, the NaI detector column22ais larger than each of the CZT detector columns22b-221, such that the NaI detector column22acan image the entire patient24and the CZT detector columns22b-221are configured to focus on a portion of the patient24, such as the heart28. In this embodiment, one or more of the CZT detector columns22b-221may be positioned and oriented at different angles or tilted differently to provide focused imaging. However, one or more of the CZT detector columns22b-221may be angled or tilted the same. In the embodiment ofFIG. 2, the CZT detector columns22b-221are angled such that together the CZT detector columns22b-221focus on the overall body of the patient24, instead of on a particular ROI, such as the heart28. Thus, one or more detector columns22may be arranged and configured to cover an entire FOV of an imaged, while one or more other detectors are arranged and configured to cover a focused FOV within the object.

It should be noted that as used herein, a set of detectors is generally referred to as the detector columns22and a set of collimators is generally referred to as the collimators26. Moreover, the use of letter designations after the numeral designation for the detector columns22and collimators26are used for ease of illustration and do not necessarily represent the same detector columns22or collimators26in the various embodiments or figures. Thus, the letter designation represents the relative positioning of the detector columns22or collimators26and not necessarily the type or kind of detector. Additionally, the size and shape of the detector columns22may be varied as desired or needed.

InFIG. 2, the collimators26a-261may be the same or may be different. For example, the collimator26amay be of a first type, such as a parallel hole collimator, while the collimators26b-261may have different types (e.g., converging, diverging or pinhole) based on a desired or required sensitivity or resolution, as well as the position and orientation of the detector column22on which the collimator26is coupled. Thus, the collimators26may be of any type.

FIG. 3shows a more detailed implementation of detector column22in accordance with an embodiment. Column arm44attaches to a gantry and provides support for and includes a radial motion rail46, radial motion motor48, and detector head50. The radial motion motor48controls the movement of the detector head50by extending or retracting the detector head50along the radial motion rail46. This provides customizability and flexibility to the imaging system. The detector column can include telescopic covers that allow it to extend and contract as it moves radially in and out.

The detector head50includes a sweep motor52, detector elements54, and collimator56. The detector elements54can be CZT modules or other detector element modules discussed throughout for detecting imaging data. Sweep motor52controls the rotation angle of the detector head50in relation to the arm44. The sweep pivoting axis53shows the rotation angle axis of the detector head50. The detector controller30can provide instruction and control to either or both of the radial motion motor48and sweep motor52. Thus, each detector column22is independently controllable in the radial location as well as the angle of tilt of the detector head50. The radial motion motor48and sweep motor52can be two separate motors as shown in the embodiment ofFIG. 3. Alternatively, the functionality of the two motors may be provided by one motor.

FIG. 4Ashows a radial construction of an imaging system where twelve detector columns22are placed at a consistent angle, thirty degrees in this example, from each other along the inside of a gantry bore. Thus, the detector columns22are uniformly distributed in this example. Each detector column22is movable along a radial axis. This allows the detector columns22to be closer or further from a subject18for imaging. The circles in the figure depict the location of the detector head50of detector column22. The detector columns are shown along the dotted line as their outer limit position in this view of one embodiment. The dual head radial arrows depict the in-out direction of motion of the detector columns22.

FIG. 4Bshows a radial construction where twelve detector columns22have their heads placed at a consistent angle and have been moved radially inward to be in positions close to a patient24. AsFIG. 4Bshows, some of the detector heads are further towards the center of their radial axis than others. This allows for high-quality imaging results with varied-sized objects.

FIG. 5shows a NM medical imaging system60scanning the mid-section of a patient24where the detector columns22including detector heads50are only partially populated, according to one embodiment. Compared to a fully populated system, such asFIG. 4AandFIG. 4B, a partially populated system includes the installation of a partial amount of detector columns22that an imaging system is configured to support.FIG. 5also demonstrates the planes of scanning including the sagittal plane, coronal plane, and transverse plane. Based on the specific ROI or type of image scan selected, imaging of a patient may only need to be focused in areas of these planes. Some embodiments herein are directed towards tailoring partially populated imaging systems, such as NM imaging system60for maximal image quality and lowest scan time given the situation and installation information constraints.

FIG. 6shows a gantry62that can support twelve detector columns22. The gantry62can contain all of the features of theFIG. 2system in one embodiment. Only six detector columns22have been installed in gantry62. This could be for lower cost of the system, easier maintenance, or other reasons, for example. Thus, the system ofFIG. 6is a partially populated NM imaging system. It is partially populated because the installation information for the system indicates that the system can support twelve detector columns22, but only six detector columns22are installed. The locations where a detector column can be installed or attached can be called receiver locations64in some embodiments. The detector columns22inFIG. 6are shown in a radially extended position. The detector columns22of this embodiment can be detached by a non-technical operator. They can be detached from one of the twelve receiver locations64and snapped, screwed, clamped, or otherwise attached, to one of the open receiver locations64around the gantry62. Thus, detector columns22are detachable and attachable to create further system configurations. This system, in some embodiments, can be considered a modular system. A non-technical operator can be one who has not had specialized or advanced training on the installation and adjustment of the imaging system. A technical operator could be a field engineer, for example.

Installation information can be dynamically updated by processor32or detector controller30based on information from installation verification elements in receiver locations64, and stored in memory38in one embodiment. Installation verification elements can be any sort of switch, button, sensor, or other device that detects the presence of hardware installed or not installed in the system. Installation verification elements of receiver locations64are one way that the system can detect and update installation information. Installation information in one embodiment relates to the detector column arm44being physically attached to gantry62. Further, installation information in another embodiment detects both physical attachment plus a fully functioning arm. In this embodiment, if any of the radial motion motor48, sweep motor52, and/or detector elements54are inoperable, even though the detector column22is attached to the gantry62, the installation information could indicate the detector column as uninstalled and/or inoperable. Installation information can also indicate the population of specific detector elements54, as further discussed below.

Installation information is also called configuration information in some embodiments. This is because installation information gives information related to the current hardware configuration in the imaging system, and can be dynamically updated. Thus, installation information, sometimes called configuration information, is not just the initial setup information of the system when delivered to a customer, but is information dynamically updated based on many hardware factors throughout the lifetime of the system.

FIG. 7Ashows a gantry62that can support the installation and operation of twelve detector columns22. Only seven detector columns22have been installed in gantry62. This is an example of a partially populated imaging system. The detector columns22inFIG. 7Aare shown in a radially extended manner, but not as radially extended as shown inFIG. 6. This configuration may be best for a supine patient where the heart, as an example of a ROI, is near the top and side of the gantry. The detector controller30can identify from the installation information that there are seven installed detector columns22and in which receiver locations64they reside around the bore of gantry62. Then the detector controller30rotates the detector columns22around the bore to the ideal position for the particular region of interested based on user input39or information of the test and patient from other sources, such as memory38or network42. This ideal position can also be called the position location essential for imaging information. Thus, moving the detector columns22and detector heads50into the best position for capturing essential imaging information for each type of procedure is important and is done by the embodiments.

FIG. 7Bshows a gantry62where the seven detector columns22have been rotated by machinery in an orbital manner inside the gantry62that is controlled by the detector controller30to move the detector columns22into positions with new radial axes to a patient. The detector columns can be rotated rotate three-hundred sixty degrees around a subject to be imaged, which is patient24in this example. As can be seen from comparingFIG. 7AtoFIG. 7B, detector column22ahas been rotated from an axial position below a patient24to an axial position above the patient24. Detector column22g, consequently, has moved from above to below the patient in this example. The example inFIG. 7Bmay be best for prone patients where the heart, as an example of a ROI, is near the bottom and side of the gantry.

FIG. 8is a flowchart depicting a method of operation with respect to one embodiment. The steps as shown do not necessarily have to flow in the order as listed, but are shown in this order just as an example.

In step80, the system determines installation information. This helps determine what operations and features are available in the system. Installation information, in some embodiments, can included detector column attachment status71which indicates in which receiver locations64detector columns22are installed and in which receiver locations64detector columns22are not installed. This can tell the system both how far each detector unit can be extended radially as well as how much orbital movement of the detector units will need to occur during operation. Installation information can further include sweep motor status72. This status can indicate whether each detector column22has a sweep motor52for head rotation capability, whether the sweep motor52is operable, and its range of motion (in circumstances when some detector heads50are configured to rotate further than others), or not responding. Installation information can further include radial motion motor status73. This status can indicate whether each detector column22has a radial motion motor48, its radial motion distance, radial location status, and whether or not the motor is currently operable. Installation information can further include detector element configuration status74. This status can indicate the specific locations where detector elements54are installed and specific locations where detector elements54could be installed but are not installed. SeeFIGS. 16-17for example. This status can also indicate what materials are being used to detect the imaging data. Each detector column or detector element could have different scintillator or semi-conductor materials installed. This detector element configuration status74can also indicate what collimator56structure is used in the detector head. As mentioned above, different collimators56can be utilized in different detector heads50. Installation information can further include other installation factors75, including gantry rotation ability. This is an indication of how many degrees of rotation (or how many ‘steps’) the gantry can rotate detector columns around the orbit of the gantry. Installation information can further include other installation factors75such as the room the imaging system is set up in, factors input by a user, safety information, and other types of information about the installation of the system overall, not just the installation status of the components in the imaging system. For example, many SPECT systems are placed in SPECT/CT (computed tomography) combined system, and the system may also acquire information related to what CT setup is installed.

In step82, the system compares the installation information with what a specific imaging scan will be and subject information. The imaging scan type information76(such as CT, SPECT, PET, MRI, or can be related to the specific radiopharmaceutical being used or the type of medical examination performed) can be considered. The region of interest information77(such as cardiac, brain, thyroid) can be considered. The patient position information78on the pallet or bed can be considered. The subject size, age, gender, weight, and other medical characteristics (patient body-type information or patient medical information or subject specific information) can impact the process relating to other user input factors79. The imaging scan is generally a NM imaging scan based on acquiring SPECT data, but the system could be used in other scanning arrangements for other types of imaging information.

In step84, the imaging system20develops an optimal scanning scenario based on the installation information compared with the subject scan information. For example, if the scan is a cardiac scan and the subject patient is small, a selected scenario would set the radial extension of the arms to high and the arms will be recommended to move orbitally towards the sides of the gantry closest to the heart. If the angle of the subject is difficult, the scenario may include rotating some of the detector heads50to be more accurately aligned towards the subject.

In step86, the system makes a decision whether the scanning scenario can be performed within a threshold time. This can also be called a total imaging operation time prediction. This determination considers how long it will take the system to do the full requested imaging based on the imaging time plus system rearrangement time when it is being reconfigured to get additional scanning data. The threshold can be based on an ‘acceptable’ time set by a user, a subject patient preferred time, a normalized time compared to most scans of the type being done, and/or related to a threshold of safety. The total imaging operation time prediction also considers how long it may take to adjust the patient and how long it takes to adjust the detector columns, detector heads, and/or detector elements. If the time to complete the optimal scanning scenario is higher than a threshold, the system goes to step88, otherwise continuing on to step86.

In step88, a user is notified that the current installation setup of the system may not be able to complete the requested scan in a threshold time. A list of options may also be presented to the user relating to steps the user can take to mitigate any issues or override the issue.

In step90, the user decides whether to alter the installation arrangement/setting of the system or not. The user can input a response back to the system of their intention. The user can adjust the system manually, in some respects, and automatically through computer control in other respect. If a user adjusts the system, thus altering installation information, the method returns to step80to re-evaluate the installation information. If the user is OK with the time threshold being met or exceeded, the system can proceed to step92.

In step92, the system performs the physical modifications recommended in the optimal scanning scenario. This can include configuring the detector column axial position around the gantry orbit, the axial radius location for scanning (how far or close to patient along the axial radius), detector head angle as controlled by the sweep motor, and other physical adjustments discussed throughout.

In step94, the subject is in the system and the images are acquired. If multiple physical positions of the detector columns22, detector heads50, and/or detector elements54are needed, the system adjusts them during the imaging operation at step96. This is an example of dynamically adjusting of the physical system.

In step98, the final requested image data is output. A reconstruction algorithm may be applied after the image data acquisition or proactively during the image data acquisition. The output can be to a display, network connected computing device, a printer, picture archive and communication system (PACS) or other output location.

Because the imaging system of at least one embodiment can start with limited installation equipment, the system can perform lower-cost imaging, while also providing upgradability. For example, if a hospital has a small budget and only will perform cardiac scans, they can purchase a system with detector columns setup best for cardiac and not including additional detector columns that can add additional cost. The hospital can still do other types of scans, but will have to wait longer for the system to re-adjust to different image scan scenarios to handle the different scan type. This can add time and sometimes provide a lower quality image than a fully populated or otherwise customized system. The hospital can upgrade and purchase more detector columns, or detector columns with the optional detector head sweep feature, or detector columns with the optional detector radius extension feature, or detector columns with multiple types of image acquisition materials and install them into the system for improved performance. This also applies to detector elements. Detector elements are a driver of cost as well. So a hospital, for example, could purchase one with lower detector element count (with longer scan time, seen for example inFIG. 16B) and upgrade later.

FIG. 9shows the front view of an imaging system specifically set to target a cardiac image. A patient100lies on a bed102, which could also be similar to the pallet14and bed mechanism16ofFIG. 1, with their heart104on the left side of the system in this view. For this cardiac application, distant locations106can either be un-populated (empty) of any detector columns or they can be set to not receive images (such as, to save electricity). In this case, the unused detector columns may be retracted and not advance towards the patient. This can also be beneficial when one of the detector columns in the system has a broken aspect, such as one of its motors, wires, arm, or detector elements. They system can orbitally move that broken detector column into a distant location106to not be used in the current scan. A notification can be sent to the user or operator regarding the issue, the user or operator can be at a local display or remote facility. The system, in this embodiment, does not need to use any detector columns in distant locations106because they are too far from the subject, for example, and the distance reduces resolution of the image and adds attenuation from the gamma ray source, patient heart104in this example. Thus, the image contribution of any detector columns in distant locations106is negligible.

FIG. 10shows the front view of an imaging system specifically set to target a small subject such as a brain, a limb, or pediatric image. In this imaging operation, the patient area108is smaller than a full body. The detector columns22have their heads extend radially from their starting position on the outer limits of the gantry towards the patient108to get the best image resolution by being closer, in this example. This example shows a case where a fully populated, all twelve detector column receiver locations in the gantry are filled with detector columns, system is not necessarily ideal, because the arms collide as they try to get the closest distance from the patient area108.

FIG. 11shows another front view of an imaging system specifically set to target a brain or pediatric image. This is a similar situation toFIG. 10, but the system, following the flowchart steps ofFIG. 8orFIG. 13, determines the installation information (in this case, as an example, a fully populated system with twelve detector columns where the radial motion motors are all in operation), takes in the subject scan information (either the fact that the scan type is a head—small in size, or the subject type is a child—small in size), and develops an optimal scanning scenario. This case includes some fully extended detector columns110, in this case every other, with some not-fully extended detector columns112. InFIG. 10, an implementation with fully extended detector columns110was not possible because of detector column collision. By not uniformly extending the detector columns, such an implementation is possible in the scenario ofFIG. 11.

FIG. 12shows another front view of an imaging system specifically set to target a brain or pediatric image. In this system, similar toFIG. 6, only half of the possible receiver locations for detector column installation have detector columns installed. A user, either technically savvy or not technically savvy depending on specific hardware implementation, could have removed the detector columns that were not needed from the system. A customer could order from the supplier an imaging system with only some of the detector columns installed, for cost reasons for example. Or, a customer could purchase a fully populated system ofFIG. 10orFIG. 11, and some of the detachable detector columns can be removed at a later time. This creates flexibility and upgradability for users and owners of the system. If a particular imaging system user simply focuses on brain imaging in their imaging operations, they may never need the extra detector columns, with related cost and maintenance, of a fully populated system ofFIG. 10orFIG. 11.

FIG. 13shows a flowchart of the operation of the system in an embodiment. In step130, the system operator gives a user input39indicating the procedure type, such as a brain scan, breast scan, cardiac scan, or other object scan.

In step132, the system creates an optimal scanning technique of how the detector columns22, detector heads50, and detector elements54should be arranged. This optimal scanning technique can be based on organ type, patient size, desired acquisition time, for example. These can be user input values for each, or system detected values. For example, the patient size could be automatically determined by a quick scan of the environment.

In step133, the system determines if the hardware installed in the system can perform the optimal scanning technique. This can also be thought of as a determination if the optimal hardware setup is in place for the current situation based on installation information. If the system has all of the hardware installed for an optimal result (meaning the installation information matches the optimal scanning arrangement), the system proceeds to step135. Otherwise, it proceeds to step134.

If the system reaches step134, the system has used the installation information to determine that the optimal scanning technique cannot be performed. This could be, for example, that one detector column is missing so the optimal arrangement cannot be accomplished and the scan time will necessarily be longer. In step134, the system, using the installation information and/or other factors related to the scan type or scan object, creates a new adaptive scanning technique to meet the situation or retrieves a previously saved adaptive scanning technique from memory that can apply to the current situation. The adaptive scanning technique can add time to the scan, but can be lower cost because the operator or customer does have to pay for a fully populated or fully featured system. Optionally, the adaptive scanning technique may comprise gantry motion or rotation or both in order to bring an operating detector to a location where a missing or inoperative detector should have been.

In step135, the system performs an imaging operation on the subject. The imaging operation is completed by controlling the hardware elements of the system in a manner fitting the selected scanning technique (either optimal or adaptive). This controlling can include, but is not limited to, extending or retracting detector columns22, rotating detector heads50to different scan angles, or moving detector columns22around the gantry orbitally to a new radial angle to the subject (such as the orbital movement of detector columns betweenFIG. 7AandFIG. 7B).

In step136, the system adapts a reconstruction algorithm based on an image acquisition scenario and reconstructs the imaging information picked up on the detector elements54using image reconstruction module34. The image reconstruction process or algorithm can be adapted to be more compatible with the selected scanning technique. This creates the highest quality image possible given the hardware constraints of the system.

In step138, the system displays an image output to a user, operator, patient, or other party. This can be on display40or at some remote location after the image output has been transmitted over network42.

FIG. 14shows the ability of the gantry to rotate the detector columns in an orbital manner. Detector columns22are placed at even angles from each other in this fully populated example. The gantry rotation range146is a full three-hundred sixty degree rotation in some embodiments, as low as zero degrees in other embodiments, and may be anywhere in between. Again, this is an upgradeable feature and related to installation information. The gantry can be initially installed with hardware only supporting thirty degree rotation, for example. The customer could then purchase an upgrade with a few additional motors or hardware components to be installed to give the gantry one-hundred eighty or three-hundred sixty degree rotation ability.FIG. 14shows a system with a thirty degree gantry rotation range146. This allows a twelve detector column system to give coverage every ten degrees.FIG. 14shows detector column148A at an initial position140, step1of rotation. Detector columns148B and148C are the same physical detector column as148A, just in new orbital positions142and144, respectively.FIG. 14further shows detector column150A rotated to different orbital positions150B and150C. Thus, the system can rotate orbitally to move all detector columns to a new radial angle from a subject, or just move specific detector columns to new locations without rotating all of the detector columns in the system.FIG. 14shows the latter arrangement, when only detector columns148A and150A are rotated an all other detector columns22remain at the same radial angle with respect to a subject.

FIG. 15shows the ability of a partially populated gantry to rotate the detector columns, such as detector column154, in an orbital manner. In this example, the column detectors only partially populate the gantry locations. Six gantry locations, at sixty degree intervals have detector columns installed, while alternating six locations are vacant. The gantry rotation range152is sixty degrees in this example, and a detector column152has six ‘steps’ or locations of scanning, each set at a ten degree offset.

FIG. 16Ais a detailed view of a fully populated detector head50. It shows detector elements54that include the detector materials to pick up photons or other imaging indicators in an imaging operation. The detector head50ofFIG. 16Ais considered fully populated because all seven of the locations where detector elements can be installed have installed detector elements54. Whether a detector element54is installed or vacant can be one type of installation information. Also, the type of materials embedded in each detector element54can be one type of installation information. The head may have any number of detector element locations; seven is just the example of this particular embodiment.

FIG. 16Bis a detailed view of a partially populated detector head160. The detector elements54are installed in a staggered fashion, with vacant detector element locations162. This installment configuration provides for a lower cost detector column22, because much of the cost of a detector column comes from the detector element54. The collimator may be sized to the number of populated detector elements. In this case, even locations are vacant, and odd locations are populated.

FIG. 16Cis a detailed view of a partially populated detector head164. The detector elements54are all installed towards one side of the detector head164. Vacant detector element locations162are towards the other side of the detector head164. This installation configuration can be good for narrow field of view imaging operations. The narrow field of view installation configuration can be good for small organ scanning, such as having five detector elements54installed for brain scans (20 cm coverage), four detector elements54installed for heart scans (16 cm coverage), or two detector elements54installed for thyroid scans (8 cm coverage). As an example, if a system including only two detector elements54per detector column22was trying to complete a brain scan, the time to do the brain scan could be much longer or the image result could be much worse. Step86ofFIG. 8could determine this and notify the user at step88. The user could then swap out the current detector columns with others that have five detector elements per detector column. The system would then dynamically update the installation information in step80. Thus, the system is reconfigurable and customizable to fit user needs and imaging situations. A medical facility, for example, in which the majority of scans are of limited axial extend, such as brain, thyroid, heart, and the like may choose the appropriate population for their system to reduce cost. Axial FOV larger than the width of the populated section of the heads, for example, whole body scanning, may be achieved with axial motion of the patient table.

FIG. 17AandFIG. 17Bshow detailed views of partially populated detector heads. In a system, such asFIG. 20, where a gantry has fully populated detector columns22, the odd numbered detector columns could have odd populated detector elements, such as in detector head170. The even numbered detector columns could have even populated detector elements, such as detector head172. Thus, the installation information can vary from one detector column to the next detector column.

Optionally, the populated detector elements in the detector columns are arranged in an alternating fashion such that a combination of detector elements in two adjacent detector columns creates a full set. This allows for acquiring a full data set by positioning odd columns in the position where an even column was before, and combining the data acquired from the two columns from at the same position. It should be noted that positions may not be identical, but only proximate to enable successful reconstruction. Optionally, adjacent columns may have at least one common populated element or a common missing element and yet enable successful reconstruction. Generally, “over sampling” as created by common populated element is easily compensated in the reconstruction and reduces the noise in the parts of the scanned body which was over sampled. Under sampling as created by common unpopulated element may also be compensated in the reconstruction, but it may increase the noise in the parts of the scanned body which was under sampled. However, not all parts of the body need to be scanned at the same accuracy, and thus under sampling may be tolerated if aimed at less critical organs.

FIG. 18shows a detailed view of a detector head design of another embodiment. The detector elements of detector head180are arranged in a grid. When targeting a specific organ or subject, the direct detector elements are most important for image quality, and the detector elements further to the side are only necessary for peripheral information. Thus, to save cost, detector heads can be configured as shown. The middle region with fixed detector elements184give five times better sensitivity than the detector elements182. This is because sliding detector elements184move behind the collimator during the imaging operation to collect data at various points. This movement can be controlled by a motor such as the sweep motor52or additional motor installed. The organ or subject, such as a heart, could be centered in the middle of the detector head in an optimal scanning scenario. An effective field of view for such a system could be 36 by 20 centimeters. A quality field of view for such a system could be 20 by 20 centimeters. The installation information for this embodiment can include the number, location, and movement ability of each detector element. The detector head180is very useful in system installation configurations where the number of total detector columns is low, because each detector column would be able to handle more detection information. In this embodiment, the collimator could be attached to the detector head itself or individual detector elements. Thus, the movable detector elements182could have a collimator attached thereto so that a collimator would not have to be manufactured for the whole space, saving cost.

FIG. 19is a flowchart of one embodiment in which different detector element configurations are applicable to the installation information. Dotted box185indicates that the steps186-194are examples of the types of determinations that could be made in step80ofFIG. 8. Step200is an example of type of determination that could be made in step82ofFIG. 8. And dotted box198indicates that the steps202-208are examples of the types of determinations that could be made in step84ofFIG. 8.

In step186, the system collects data from various parts of the overall system (such as shown in steps71-75ofFIG. 8). Based on that data, the system determines whether the system has a staggered setup, in step188, a sliding setup, in step190, a narrow FOV setup, in step192, or a custom detector element setup, in step194. A staggered setup could be one such as demonstrated inFIGS. 17A and 17B. A sliding setup could be one such as demonstrated inFIG. 18. A narrow FOV setup could be one such as demonstrated inFIG. 16C.

In step200, the system compares the determined detector element setup from the steps of dotted box185with subject scan information. This information is based on the subject of the scan (i.e. heart, thyroid, brain, breast, etc.) as well as the type of scan being performed.

In the steps of dotted box198, an imaging operation is performed based on the installation information compared with the subject scan information. If there is a good fit between the installation information, the corresponding scan to the detector element is selected. This is indicated by the horizontal lines. Step202to scan with each detector column across sixty degrees of the total range (such as inFIGS. 20A-20C) is generally performed when the staggered setup is determined in step188and that matches well with the subject scan information. Step204to scan including sliding edge detector elements is generally performed when the sliding setup is determined in step190and that matches well with the subject scan information. Step206to scan focusing with edge of a detector head with installed elements is generally performed when the narrow FOV setup is determined in step192and that matches well with the subject scan information. Step208to scan using a custom scan scenario is generally performed when the installation setups do not match with the subject scan information or are not in any predefined arrangement.

FIGS. 20A-20Cshow the details of an imaging operation of step202where each detector column scans across sixty degrees across the total range. This could be best executed for a system ofFIGS. 17A and 17Bas discussed in detail above. Odd detector columns have odd detector elements installed and even detector columns have even detector elements installed. Therefore, to get a full scan of the subject, the system would have to orbitally rotate each detector column sixty degrees during the total imaging operation.

FIG. 20Ashows a system with fully populated detector columns22with a gantry orbital rotation range210of sixty degrees. The detector arms can be extended radially in the system. While the detector columns are fully populated, the detector elements in each detector column are not, as discussed above.

FIG. 20Bshows a staggered imaging operation during the first three movement locations, covering a gantry orbital rotation range212of thirty degrees.

FIG. 20Cshows a staggered imaging operation during the final three movement locations, covering an additional gantry orbital rotation range214of thirty degrees. Thus, each angle of a scanning operation is covered by an even and an odd detector element. The imaging operation may take longer than a system with fully populated detector elements, but the system can be cheaper due to having only half of the total detector elements in the system.

As contemplated, the various embodiments provide a lower cost, upgradable, and customizable system for imaging operations. All functionality can be preserved, yet with a tradeoff of cost vs. acquisition time.

The configurable and controllable system of some embodiments could be controlled by user input. Thus, the user can override the automatic operation of the system and take full specific control of components of the system through a user interface.

Various embodiments provide configurations for arm assemblies that may be used with an NM camera having pivoting heads. In some embodiments, a telescopic in/out motion for columns holding heads may be provided. The telescopic in/out motion in various embodiments allows for a smaller outside diameter of a gantry while allowing a desired range of motion. Further, counterbalancing of the telescopic in/out motion for the columns may be provided. Counterbalancing may allow for the use of weaker motors to articulate detector heads, and also provide improved safety (for example, in the case of motor failure or power outage).

Various embodiments may utilize detector arms that are arranged in telescopic configurations to provide for a desired range of radial motion in a compact package.FIG. 21Aprovides a perspective schematic view of a detector arm assembly1000in an extended position, andFIG. 21Bprovides a perspective schematic view of the detector arm assembly1000in a retracted position. As seen inFIGS. 21A and 21B, the detector arm assembly1000includes a stator1010, a detector head1020, a radial motion motor1030, and a detector head belt1040.

The stator1010is configured to be fixedly coupled to a gantry having a bore. As used herein, “fixedly coupled” may be understood to mean that the stator1010does not move with respect to the gantry when mounted in its intended fashion and an imaging system using the detector arm assembly1000is used in its intended fashion. One stator1010and one detector arm assembly1000are shown inFIGS. 21A and 21B; however, it may be noted that plural stators1010may be mounted about the bore of a gantry for which plural corresponding detector heads1020may be utilized to image an object within the bore.

The detector head1020includes a carrier section1022that is slidably coupled to the stator1010and configured to be movable along a radial direction1001in the bore relative to the stator1010. Thus, the detector head1020may be articulated radially inwardly (toward the center of the bore) or radially outwardly (away from the center of the bore) to place the detector head1020in a desired position for imaging. It may be noted that the carrier section1022and the stator1010may be directly or indirectly slidably coupled to each other. For example, in some embodiments, the carrier section1022and stator1010may be directly slidably coupled to each other, for instance, with one of the carrier section1022or stator1010including a guide that slidably accepts a rail of the other. In other embodiments, for increased compactness in the retracted position, the detector arm assembly1000may be configured as a telescoping assembly with an intermediate member (e.g., slider block1050) interposed between the stator1010and carrier section1022, with the intermediate member slidably coupled to the stator1010and carrier section1022separately, providing an example of an indirect slidable coupling between the stator1010and carrier section1022. As seen inFIG. 21A, the detector head1020may be understood as being distally positioned (e.g., positioned more radially inwardly than the stator1010). One or more detectors (e.g., one or more CZT detectors), which may be pivoted or tilted within the detector head1020, may be positioned in a distal portion of the detector head1020. It may be noted that the detector head1020may include one or more shielding members (e.g., for shielding electronics of a detector module from radiation), and may be configured to provide cooling (e.g., by passing a flow of air over cooling fins) to dissipate heat generated by electronics associated with the detectors.

In various embodiments, the radial motion motor1030is operably coupled to at least one of the detector head1020or the stator1010. In the embodiment depicted inFIGS. 21A and 21B, the radial motion motor1030is mounted to the carrier section1022of the detector head1020. Generally, the radial motion motor1030is used to drive the detector head belt1040to articulate the detector head1020radially (e.g., inwardly toward the center of the bore or outwardly away from the center of the bore). For example, a drive shaft of the radial motion motor1030may be rotated to drive the detector head belt1040. The radial motion motor1030may also be used to help secure or maintain the detector head belt1040in a desired position (e.g., by being prevented or inhibited from rotating). It may be noted that, while a motor and belt are used in the depicted embodiment (e.g., radial motion motor1030is utilized to drive the detector head belt1040and to articulate the detector head1020radially), other devices, systems, or mechanisms may be utilized to articulate the detector head1020radially in other embodiments.

The depicted detector head belt1040is operably coupled to the radial motion motor1030and to the carrier section1022of the detector head1020, with rotation of the radial motion motor1030(e.g., rotation of a drive or output shaft of the radial motion motor) causing movement of the detector head1020along the radial direction1001. In the illustrated embodiment, the detector head belt1040passes around a drive shaft and/or gear of the radial motion motor1030and around a detector head gear1042mounted to the carrier section1022. The depicted detector head gear1042is mounted to an opposite end of the carrier section1022than the radial motion motor, with the detector head belt1040extending along most or all of the length of the carrier section1022in the radial direction1001.

As mentioned above, for increased compactness in the retracted position, the detector arm assembly1000may be configured as a telescoping assembly with an intermediate member (e.g., slider block1050) interposed between the stator1010and carrier section1022, with the intermediate member slidably coupled to the stator1010and carrier section1022separately, providing an example of an indirect slidable coupling between the stator1010and carrier section1022. As seen inFIG. 21A, the detector arm assembly1000includes a slider block1050interposed between the detector head1020(e.g., the carrier section1022of the detector head1020) and the stator1010. The slider block1050is slidably coupled to the stator1010and configured to be moveable in the radial direction1001with respect to the stator1010. For example, one of the slider block1050and stator1010may include a guide that accepts a rail of the other. Also, the carrier section1022of the detector head1020is slidably coupled to the slider block1050and configured moveable in the radial direction1001with respect to the slider block1050. For example, one of the slider block1050and carrier section1022may include a guide that accepts a rail of the other.

In various embodiments, one or more belts may be fixed or coupled to the one or more of the stator1010, slider block1050, or carrier section1022to articulate the detector head1020in the radial direction1001, or to articulate the detector arm assembly1000between extended and retracted positions.FIG. 22provides a side perspective view of the detector arm assembly1000, andFIG. 23provides an opposite side perspective view of the detector arm assembly1000.

As best seen inFIGS. 22 and 23, the slider block1050is fixed to the detector head belt1040at point1051. Accordingly, the slider block1050moves in the radial direction1001with a portion1041of the detector belt. It may be noted that portion1043of the detector belt1040, disposed on that opposite side of detector head gear1042from the portion1041, moves oppositely in or along the radial direction1001as the slider block1050. The point1051where the slider block1050is fixed to the detector head belt1040may be the location of mounting to a bracket or clip1052used to fix the slider block1050to the detector head belt1040.

As also seen inFIGS. 22 and 23, the detector arm assembly1000also includes an idler belt1060. The depicted idler belt1060is mounted to idler gears1062,1064disposed on the slider block1050. In the illustrated embodiment, the idler gears1062,1064are mounted on opposite ends1063,1065, respectively, of the slider block1050. The idler belt1060is fixed to the carrier section1022at point1067(e.g., via a clip or bracket as discussed in connection with point1051) and to the stator1010at point1068(e.g., via a clip or bracket as discussed in connection with point1051). The slider block1050moves in the radial direction1001with a portion1073of the idler belt1060relative to the stator1010. Also, the carrier section1022moves in the radial direction1001with a portion1071of the idler belt1060relative to the slider block1050. With the portion1073and the portion1071on opposite sides of the idler gears1062,1064as shown inFIG. 23, the stator1010and the carrier section1022move oppositely to each other along the radial direction1001with respect to the slider block1050. Use of the idler belt1060thus results in about twice the total movement of the detector head1020with respect to the stator1010for the same motor rotation and/or similar retracted length compared to examples that do not use the idler belt1060and slider block1050(see also, e.g.,FIG. 3and related discussion). It may be noted that electrical cables1080may be disposed about the idler belt1060, with the electrical cables1080extending along with the detector head1020to provide electrical communication with the detector head1020in the various positions at which the detector head1020may be disposed.

In various embodiments, all or a portion of the stator1010, detector head1020, and/or slider block1050may be protected or contained within a cover. The cover may telescope with the detector arm assembly1000to provide coverage over a range of motion while still providing compactness in a retracted position.FIG. 24Aprovides a perspective view of a cover system1100in an extended position, andFIG. 24Bprovides a perspective view of the cover system1100in a retracted position. The illustrated cover system1100includes a distal cover1110and an outer cover1120. As seen inFIGS. 24A and 24B, the distal cover1110is mounted to and moves with the detector head1020. The distal cover1110nests inside the outer cover1120in the retracted position (seeFIG. 24B) and extends from the outer cover1120in the extended position (seeFIG. 24A).

As indicated herein, in various embodiments a plurality of detector arm assemblies (e.g., detector arm assemblies1000) may be distributed about a bore of a gantry.FIG. 25provides a perspective view of an imaging system1200. The imaging system includes a gantry1210and detector arm assemblies1220. It may be noted that the detector arm assemblies may be generally similar to the detector arm assembly1000discussed herein.

As seen inFIG. 25, the gantry1210is a radial gantry and includes a bore1222about which the detector arm assemblies1220are distributed. As also seen inFIG. 25, some of the detector arm assemblies1220are in an extended position, and some are in a retracted position. It may be noted that, in various embodiments, counterweights may be employed, for example, to improve safety and/or to reduce an amount of power or energy required to articulate detector arm assemblies. In various embodiments, a counterweight may be coupled to at least one of the slider block or the detector head, with the counterweight configured to move oppositely in a radial direction to the detector head. For example, if the detector head moves radially inward, the counterweight may move radially outward. As another example, if the detector head moves radially outward, the counterweight may move radially inward.

FIG. 26Aprovides a schematic view of a detector arm assembly1300in a retracted position, andFIG. 26Bprovides a schematic view of the detector arm assembly1300in an extended position. The detector arm assembly1300may be generally similar in certain respects to the detector arm assembly1000disclosed herein. The depicted detector arm assembly1300includes a stator1310, a detector head1320, a slider block1330, and an idler belt1340. The detector arm assembly1300also includes a counterweight1350, a counterweight pulley1360, a stator pulley1370, and a cable1380. The counterweight1350may be slidably coupled to the stator1310via rail1351. The counterweight pulley1360is mounted to the counterweight1350, and the stator pulley1370is mounted to the stator1310. As seen inFIGS. 26A and 26B, the cable1380is wrapped partially about the stator pulley1370and the counterweight pulley1360. As the detector head1320is articulated in direction1381(from the retracted position to the extended position), the cable1380is pulled around the counterweight pulley1360and the stator pulley1370, drawing the counterweight1350upward in direction1382.

In some embodiments, reduced travel of a counterweight relative to travel of a detector head may be provided, for example, with one or more additional pulleys.FIG. 27Aprovides a schematic view of a detector arm assembly1400in a retracted position, andFIG. 27Bprovides a schematic view of the detector arm assembly1400in an extended position. The detector arm assembly1400may be generally similar in certain respects to the detector arm assembly1000disclosed herein. The depicted detector arm assembly1400includes a stator1410, a detector head1420, a slider block1430, and an idler belt1440. The detector arm assembly1400also includes a counterweight1450, counterweight pulley1460, a first stator pulley1470, a second stator pulley1471, and a cable1480. The counterweight1450may be slidably coupled to the stator1410via rail1451. The counterweight pulley1460is mounted to the counterweight1450, and the first stator pulley1470and second stator pulley1471are mounted to the stator1410. As seen inFIGS. 27A and 27B, the cable1480is wrapped partially about the first stator pulley1470, the second stator pulley1471, and the counterweight pulley1460. As the detector head1420is articulated in direction1481(from the retracted position to the extended position), the cable1480is pulled around the counterweight pulley1460, and the first stator pulley1470and second stator pulley1471, drawing the counterweight1450upward in direction1482.

It may be noted that, in various embodiments, other arrangements may be employed additionally or alternatively to the use of pulleys and counterweights. In some embodiments, counter-balancing may be provided that may be utilized in a number of different orientations, instead of just up-and-down with respect to a gravitational field. For example,FIG. 28Aprovides a schematic view of a detector arm assembly1500in a retracted position, andFIG. 28Bprovides a schematic view of the detector arm assembly1500in an extended position. The detector arm assembly1500may be generally similar in certain respects to the detector arm assembly1000disclosed herein. The depicted detector arm assembly1500includes a stator1510, a detector head1520, a slider block1530, and an idler belt1540. The detector arm assembly1500also includes a counterweight1550, a first stator pulley1570, a second stator pulley1571, and a cable1580. The counterweight1550may be slidably coupled to the stator1510via rail1551. The first stator pulley1570and second stator pulley1571are mounted to opposite ends (in the radial direction) of the stator1510, with the cable1580forming a loop1590around the stator1510. The cable1580is attached to the counterweight1550at point1591and to the slider block1530at point1592. As the detector head1520is articulated in direction1581(from the retracted position to the extended position), the downward motion of the slider block1530causes a clockwise rotation of the cable1580about the stator1510, drawing the counterweight1550upward in direction1582. It may be noted that, via the use of the cable1580forming the loop1590, the detector arm assembly may be oriented in different directions and still provide effective counterbalancing, including oriented such that the detector head moves toward the extended position in opposition to a gravitational field. It may further be noted that, in the illustrated embodiment, the detector arm assembly1500includes a radial motion motor1502mounted to the stator1510, with the radial motion motor directly driving the cable1580at the first stator pulley1570to articulate the detector head1520and counterweight1550oppositely along a radial direction. It may be noted that generally similar loops may be implemented in additional embodiments, for example embodiments that incorporate various aspects of the previously illustrated examples.

Still other arrangements may be employed for counterbalancing in various embodiments. For example, a spring loaded spool may be employed in various embodiments.FIG. 29Aprovides a schematic view of a detector arm assembly1600in a retracted position, andFIG. 29Bprovides a schematic view of the detector arm assembly1600in an extended position. The detector arm assembly1600may be generally similar in certain respects to the detector arm assembly1000disclosed herein. The depicted detector arm assembly1600includes a stator1610, a detector head1620, a slider block1630, and an idler belt1640. The detector arm assembly1600also includes a spring-loaded spool1650and a cable1680. The spring-loaded spool1650includes a spring that resists the withdrawal of the cable1680from the spring-loaded spool1650. The free end of the cable1680(the end outside of the spring-loaded spool1650) is attached to the detector head1620. As the detector head1620is articulated in direction1681(from the retracted position to the extended position), the spring-loaded spool1650provides a force acting upward in direction1682as seen inFIGS. 29A and 29B. It may be noted that the detector arm assembly may be oriented in different directions and still provide effective counterbalancing, including oriented such that the detector head moves toward the extended position in opposition to a gravitational field. The spring force for the spring-loaded spool1650may be selected relative to the detector weight, and may be adjustable or variable depending on the orientation of the detector head with respect to gravity.

As also indicated elsewhere herein, in various embodiments a plurality of detector arm assemblies (e.g., detector arm assemblies1000) may be distributed about a bore of a gantry. It may be noted that, in various embodiments, each of the detector arm assemblies of an imaging system may be provided with counterweights. Alternatively, some detector arm assemblies may be provided with counterweights or counterbalancing while other detector arm assemblies are not provided with counterweights or counterbalancing. For example, counterbalancing may be provided for gantry locations for which counterbalancing is particularly desirable or advantageous, while counterbalancing is not provided for other locations to reduce expense and/or space requirements.

FIG. 30provides a schematic depiction of various gantry locations. InFIG. 30an oval gantry3000is depicted; however, other shapes such as circular may be employed in various embodiments. Detector arm assemblies3010, schematically depicted as arrows may be distributed about a bore3002of the gantry3000and oriented toward the center of the gantry. The detector arm assemblies may be categorized in three groups—lateral arms3020, upper vertical arms3030, and lower vertical arms3040. The lateral arms3020may include all arms oriented within 30 degrees of horizontal (with a horizontal direction defined as being normal to a gravitational field), with the remaining arms being grouped as either upper or lower vertical arms.

With the lateral arms3020acting generally normal to a gravitational field, there may be fewer safety concerns regarding an arm striking a patient while accelerated by gravity. Also, with the lateral arms extending and retracting normal to a gravitational field, relatively smaller power amounts may be required to articulate the arms. Accordingly, the lateral arms3020may be provided without counterweights or counterbalancing.

The upper vertical arms3030, however, are retracted generally against a gravitational force, and thus it may be desirable for power considerations to provide the upper vertical arms3030with counterbalancing to reduce the power requirements for retracting the detectors. Further still, because the upper vertical arms3030are disposed above the patient (with respect to gravity), it may further be desirable to provide counterbalancing for safety purposes.

The lower vertical arms3040are disposed below the patient (with respect to gravity), and thus safety may not be an issue with respect to desirability of counterbalancing the lower vertical arms. The lower vertical arms3040, however, are extended generally against a gravitational force, and thus it may be desirable for power considerations to provide the upper vertical arms with counterbalancing to reduce the power requirements for extending the detectors. Accordingly, in some embodiments, only the upper vertical arms3030may be provided with counterbalancing, while the lower vertical arms3040and lateral arms3020may not be provided with counterbalancing. In other embodiments, the upper vertical arms3030and lower vertical arms3040may be provided with counterbalancing, while the lateral arms3020are not provided with counterbalancing.

As used herein, a structure, limitation, or element that is “configured to” perform a task or operation is particularly structurally formed, constructed, or adapted in a manner corresponding to the task or operation. For purposes of clarity and the avoidance of doubt, an object that is merely capable of being modified to perform the task or operation is not “configured to” perform the task or operation as used herein. Instead, the use of “configured to” as used herein denotes structural adaptations or characteristics, and denotes structural requirements of any structure, limitation, or element that is described as being “configured to” perform the task or operation.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments of the invention without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the invention, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.