Abstract:
A SPECT imaging system has at least one detector head, adapted for detecting a radioisotope emission from a patient, and a collimator, which directs said radioisotope emission towards said detector head, a movement subsystem, which moves at least one of a patient being imaged, or said detector heads, relative to the other. A controlling computer, includes a user interface receiving output from the at least one detector head, and controls said movement subsystem, said controlling computer including a user interface, receiving information said output from the detector head, and controls at least one parameter associated with the reception of information by the detector head. The controller displays information about a region of interest within a image to be determined, and automatically determines at least one recommended parameter for the scan based on said region of interest.

Description:
CLAIM OF PRIORITY  
       [0001]     This application claims priority from provisional application Ser. No. 60/613,781, filed Sep. 27, 2004. 
     
    
     BACKGROUND  
       [0002]     Medical imaging systems may use nuclear materials, called radiopharmaceuticals, for the imaging. One such imaging system is single photon emission computed tomography, abbreviated as SPECT. Other techniques may include other kinds of nuclear medicine, positron emission tomography (“PET”) as well as magnetic resonance imaging.  
         [0003]     Imaging systems of this type may be dependent on many variables including, but not limited to, characteristics of the specific patient, also called patient demographics, selection of the collimator which is used for the photon emission, the kind of radiation detector which is used, and the uptake of the radiopharmaceutical in the patient. Exemplary patient demographics that may lead to image inconsistencies may include patient variables such as patient size and weight, as well as normal differences between the locations of organs in different people. The different ways in which these variables are carried out may affect the image quality that is achieved in the nuclear medical image acquisition.  
         [0004]     Importantly, the variation in image quality may result itself in quality variations that may lead to inconsistencies in interpretation. Any such inconsistencies may be undesirable, since they may reduce the confidence in image interpretation. Attempts have been made to improve the consistency of the images. However, these improvement attempts are often relatively slow, and may interrupt the flow and workload of the organization that obtains the images.  
         [0005]     The American Society of Nuclear Cardiology (ASNC), the largest Nuclear Cardiology organization, developed and approved imaging guidelines, entitled “Imaging Guidelines for Nuclear Cardiology Procedures, Part 1”, Revised in 2000. These were published as “Updated Imaging Guidelines for Nuclear Cardiology Procedures, Part 1” (Journal of Nuclear Medicine, January/February 2001, part 1, volume 8, number 1). These guidelines are designed to help standardize SPECT acquisition protocols. These protocols pertain directly to recommended acquisition times and procedures, describing the desired minimum and maximum number of “counts” accumulated in the desired area of imaging, e.g., the heart. The “counts” refer to the amount of detected emission from the heart, responsive to the incoming radiation. In one embodiment, the incoming radiation may be gamma radiation.  
         [0006]     One guideline is used for determining if the imaging of the heart has received enough “counts” of gamma radiation, that is, is the heart “count sufficient” or “count starved”. However, the practical implementation of these guidelines suggests that the operators of the imaging system perform manual calculations. Because of the additional time needed to perform these calculations and the corresponding effect on throughput of the imaging process, many operators have opted not to use them.  
         [0007]     Other, less precise indicia, such as generic acquisition time recommendations are often used. These indicia do not account for important variables such as patient size and or weight.  
       SUMMARY  
       [0008]     The present application teaches techniques to identify a region of interest, within an image to be scanned, prior to acquisition of that image. In an embodiment, the region of interest is identified within an image that represents the human body part or area, of which an image will be obtained. An aspect allows using a user interface to interact with and /or change the region of interest, and to change characteristics of the eventual scanning. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     These and other aspects will now be described in detail with reference to the accompanying drawings, wherein:  
         [0010]      FIG. 1  shows a persistence display of a patient, including the projection image of an organ of interest, and an exemplary box shown as drawn around that organ of interest;  
         [0011]      FIG. 2  shows a user interface display which may display information to a user;  
         [0012]      FIG. 3  illustrates a block diagram of the controlling system; and  
         [0013]      FIG. 4  shows a flowchart of operation. 
     
    
     DETAILED DESCRIPTION  
       [0014]     The general structure and techniques, and more specific embodiments which can be used to effect different ways of carrying out the more general goals are described herein.  
         [0015]     One embodiment describes identifying a region of interest within an image to be scanned prior to its acquisition.  FIG. 3  illustrates an exemplary system. A patient, shown as  300 , is illustrated along with an organ of interest which may be the heart. A radiopharmaceutical, e.g., a radioisotope  305  is within the patient body. A collimator  305  is used to focus the emission along a path  310  as a radiation beam. The emission is detected by a detector head  320 , so long as the detector head  320  is along the path  310  formed by the collimator. If parallel-beam collimators are used, the path  310  should be perpendicular to the surface of the detector head  320  surface. Of course, other collimator types may also be used. The beam  31  is collected by at least one detector head  320  after passage through the patient  300 . While the above has described an emission study type image, it should be understood that this can also be applied to transmission type studies.  
         [0016]     The output of the detector head  320  is processed by a processing element/controller  330 . The processing element may be a computer. This may be any kind of computer, either general purpose, or some specific purpose computer such as a workstation. The computer may be a Pentium class computer, running Windows XP or Linux, or may be a McIntosh computer. The programs may be written in C, or Java, or any other programming language. The programs may be resident on a storage medium, e.g., magnetic or optical, e.g. the computer hard drive, a removable disk or other removable medium. The programs may also be run over a network.  
         [0017]     The processing element may also control the movement of at least one of the detector head  320 , or the patient  300  using a movement subsystem  335 . For example, either the patient  300  may be rotated or the heads may be rotated to receive information from the patient.  
         [0018]     In an embodiment, the controlling unit  330  may include the ability to identify a region of interest in the image to be scanned prior to its acquisition. The techniques for doing this may be carried out in software, firmware or hardware. The controller  330  may include a general-purpose processor, such as an Intel Pentium class processor, or any other type of processor as may be understood by those having ordinary skill in the art. The controller  330  may have an associated user interface  331 .  
         [0019]     In operation, the controller may run a routine shown in the flowchart of  FIG. 4  prior to image acquisition time. A region of the patient is in a specific condition at that time, for example the region may be resting or under stress, and the routine may use a particular radiation imaging system. In the embodiment, the system may be a gamma ray imaging system used to generate single photon emission computed tomography images. At  400 , the imaging target, typically the patient is positioned into the specific location where the patient will be imaged. A display on the user interface  331  is formed at  405 ; for example, a persistence display that shows the imaging target. The display may be formed from an initial medical imaging scan of the patient, using an emission or transmission scan, an xray scan, MRI or any other technique. At  410 , the user interface is used to draw a rectangle around the display of the region of interest. The operator can readily identify the scan, thereby facilitating the drawing. For example, the computer mouse or other pointing device can be used for this purpose. The embodiment, as shown in  FIG. 1 , draws a corresponding rectangle on the display, surrounding the target.  
         [0020]     In another embodiment, other types of user interface devices may be used to draw on the target. For example, a pointing device may be used to point directly at the target, draw a circle around the target, or may be used with other ways of identifying the region of interest. Using conventional techniques, the image within that region of interest may be smoothed and reshaped.  
         [0021]     According to another embodiment, an image processing system may include kernels indicative of usual shapes of regions of interest at display  405 . For example, a database of usual heart shapes in the display  405  may be maintained, and correlated against the image in  FIG. 1 . This correlation may be used to automatically identify the heart in the display, as the region of interest. By actually selecting the region of interest, image inconsistencies may be reduced.  
         [0022]     At  420 , the count rate within the identified region of interest is calculated. The count rate within the entire field of view may also be calculated.  
         [0023]     At  430 , a database of common imaging targets is accessed. This database includes information about imaging targets such as the heart, liver, bone, and other targets. Based on the information from the database, the embodiment may then determine a recommended acquisition time at  440 . For example, this may be done by using a local table that correlates the organs to the acquisition time calculation. Alternatively, the computer may calculate the information, using either a formula, or model, or any other technique. It may use any other type of data detection and/or analysis system.  
         [0024]     The selected working, as well as the count rate in the region of interest, are used to display a recommended acquisition time.  FIG. 2  illustrates an exemplary dialog box that shows the organ, as well as different information about the display. In  FIG. 2 , the organ is shown as  200 , and the orientation shown as  205 . The measuring isotope, here tc-99m is selected. The entry settings and projections may also be analogously selected. The system then displays this recommended time at  230  which may be used for the imaging. The operator may choose to adopt the recommendation, or alternatively may choose to ignore it. If the operator chooses to adopt the recommendation, of that time can be automatically accepted by clicking the button  240  on the display.  FIG. 2  illustrates an exemplary stop condition window for an exemplary heart image acquisition  232  represents the stop condition initially entered by the operator, of 40 seconds. The calculated stop condition at  230  is shown as 33 seconds. The operator can then click a button  232  to copy the entry in the recommended time box into the final value. The user can then proceed with the acquisition using the recommended time.  450  illustrates the user clicking the button to accept the recommended time.  
         [0025]     This embodiment allows count rate and count density on a persistence mode display to be used as a basis for quantified quality control prior to the actual image acquisition. Unlike post-acquisition processes, this system may enhance compliance with guidelines without significantly compromising the throughput of patients through the imaging process. Moreover, the techniques disclosed herein may be used along with a post-acquisition tool, and also may be used with other kinds of imaging that are used in place of or in addition to the SPECT imaging.  
         [0026]     Although only a few embodiments have been disclosed in detail above, other embodiments are possible and the inventor(s) intend these to be encompassed within this specification. The specification describes specific examples to accomplish a more general goal that may be accomplished in other way. This disclosure is intended to be exemplary, and the claims are intended to cover any modification or alternative which might be predictable to a person having ordinary skill in the art. For example, this may be used with different kinds of imaging than that disclosed; it may be used with multiple different imaging techniques, and it may be used with other ways of selecting the area of interest, including automatic techniques of detecting the area of interest. One exemplary way of determining the region of interest is to store a number of image “kernels”, each kernel representing an exemplary view of a specified organ. For example, views of the most common kinds of organs can be stored. The way the heart looks from many different directions and/or in many different patients and/or with many different machines can be stored. Each of the kernels may be correlated over the entire image, using least mean squares matching, to find the closest match to the kernels. For example, if a close match to the heart kernel is found, then the area of that match is determined to be a heart, and may be automatically outlined by the computer as the region of interest.  
         [0027]     While the above describes a single detector head, it should also be understood that there can be multiple separated detector heads.  
         [0028]     Also, the inventors intend that only those claims which use the words “means for” are intended to be interpreted under 35 USC 112, sixth paragraph. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims.