Abstract:
A multiheaded camera which is formed with a number of heads on one support structure and a different support structure with other heads. At least one of the heads is movable, so that the patient can obtain ingress and egress to the area.

Description:
The present application claims priority to provisional application No. 60/612,744, filed Sep. 24, 2004, the contents of which are herewith incorporated by reference. 

   BACKGROUND 
   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 medical imaging techniques may include positron emission tomography (“PET”) as well as magnetic resonance imaging. 
   SPECT imaging attempts to produce a three-dimensional reconstruction of the intensity of the three-dimensional distribution of a photon emitter within the body of the subject being imaged. Typically the emitted photons are gamma-rays from the radiopharmaceutical. SPECT operates by back projecting multiple projection images acquired at equal angular increments over at least 180° around the subject. One or more detector heads collect these projection images and produce a two-dimensional image of the emitted gamma rays. 
   Having multiple detector heads may increase the camera system&#39;s efficiency. This increased efficiency can either be used to improve image quality or to reduce the time of the procedure. 
   The physical size of imaging heads on current multi-head SPECT cameras has typically limited the camera to have four heads that are positioned over 360°. For a four-headed system, the heads have been typically spaced at 90° increments. One limiting factor is the size of the heads. The head size may constrain the minimum orbit radius, which is the distance from the center of rotation to the photon-sensitive face of the detector heads, for such systems to be approximately 25 cm. 
   In addition, large heads arrayed over 360° may reduce the ability for patient ingress and egress from the imaging system. The patient enters the imaging volume by being translated into the imaging volume along the axis-of-rotation of the heads. 
   SUMMARY 
   An embodiment allows a multi-head Single Photon Emission Computed Tomography (SPECT) camera system to be constructed, whereby four or more of the detector heads are positioned within 360°. The present system allows a multi-head medical camera, e.g. a Single Photon Emission Computed Tomography (SPECT) camera system, or a positron emission tomography (PET) to be constructed whereby four, or more than four of the detector heads, are positioned within 360°. For example, this system may use 4, 5 or 6 heads. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the Drawings: 
       FIG. 1  shows an embodiment with five heads on multiple different head holding arms. 
   

   DETAILED DESCRIPTION 
   Imaging gamma ray detector heads have been developed that have small dead spaces surrounding the imaging field-of-view (FOV). In addition, small field-of-view (SFOV) detector heads that have an area just large enough to cover the area of the heart have been used to perform cardiac SPECT. 
   An embodiment uses these characteristics to arrange four or more than four of these SFOV heads within 360°. An embodiment uses five heads, and still allows patient ingress into the area defined inside the heads. 
   The following illustrates an embodiment using five heads. SFOV systems with other than four or five heads. One aspect defines that the heads have an angle between them that is other than 90 degrees. 
   The use of SFOV detector heads offers many advantages, including that the imaging orbit radius may be less than 25 cm. 
     FIG. 1  shows an embodiment. The  FIG. 1  embodiment includes two separated head holding structures. The first head holding structure  100  is shown holding three heads  110 ,  112 ,  114 . Each of the heads is attached to a bracket, for example, head  110  is attached to a bracket  115 . The bracket extends at a specified angle θ relative to the axis shown as  120 . The bracket  116  which holds head  114  may extend at the same angle θ but in an opposite direction. In the embodiment, the face of head  112  is substantially perpendicular to the axis  120 . 
   The second head holding structure  130  is separated from, and separately movable relative to, the first head holding structure  110 . It also holds the heads at specified angles, where the head  132  is held at an angle γ relative to the axis, and the head  134  may be held at the same angle γ, but facing in the opposite direction, to have the same angular absolute value. At least one of the head holding structures  100 ,  130  is movable. The holding structure  100  includes a slide  102  which slides on a support  103  and allows the head holding structure to be moved in the direction of the axis  120 . And an alternative embodiment, however, the support structure  100  may be hinged, to enable it to move in a different plane, or to rotate. 
   The head holding structure  130  may also include a comparable slide structure shown as  132 . One or both of the head holding structures  100 ,  132  may be moved along the axis, to open a space at  150 . The patient may enter through the space  150 . In operation, the heads can be separated, the patient can obtain ingress, and then images can be taken, the heads are again separated, and the patient may exit the imaging area. 
   In operation, one structure is moved relative to another structure. A moving part  160  is shown. The moving part may rotate the heads relative to the patient, or may rotate the patient relative to the heads. In the embodiment, it may be simpler to rotate the patient, since otherwise both separately-supported heads will need to be rotated. However, rotation of either is possible. 
   The medical information from the heads indicates information indicative of organs or areas of interest within a patient to be viewed. That information is sent to a computer  170  for processing to determine the medical information. The computer  170  may be a general purpose computer such as a Pentium-class computer running Windows XP.  FIG. 1  shows the information from only one head being sent to the computer, but it should be understood that the information from all the heads is appropriately connected. 
   This embodiment can be used for any kind of medical imaging, but maybe preferably used for radiological based imaging such as single photon or single positron imaging. The embodiment shows imaging different body organs, but it should be understood that this can also be used for imaging the brain or some other organ, or even the entire body. 
     FIG. 1  shows the use of a fanbeam collimator. Parallel hole collimators or collimators of other configurations can also be used. The FIGURE also illustrates an upright, rotating chair gantry system whereby the subject rotates in front of the imaging heads. The imaging heads could also be affixed to a gantry that rotates the heads around the subject to be imaged. The subject may be either upright, prone or supine. 
   The following illustrates an embodiment using five heads. The invention is not limited to systems with four or five heads. 
   Another embodiment may use more than two head holding structures. 
   Although only a few embodiments have been disclosed in detail above, other embodiments are possible and are intended 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, more than 5 heads may be used, and more than 2 support structures. A 6-head system may use 3 support structures, for example, each with 2 heads, and each being either stationary, or separately movable. 
   Also, 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.