EXTREMITY IMAGING APPARATUS FOR CONE BEAM COMPUTED TOMOGRAPHY
An apparatus for cone beam computed tomography can include a support structure, a scanner assembly coupled to the support structure for controlled movement in at least x, y and z orientations, the scanner assembly can include a DR detector configured to move along at least a portion of detector path that extends at least partially around a scan volume with a distance D 1 that is sufficiently long to allow the scan volume to be positioned within the detector path; a radiation source configured to move along at least a portion of a source path outside the detector path, the source path having a distance D 2 greater than the distance D 1, the distance D 2 being sufficiently long to allow adequate radiation exposure of the scan volume for an image
1 . An apparatus for cone beam computed tomography, the apparatus comprising:
a support structure;
a scanner assembly coupled to the support structure, comprising:
a digital radiation detector, the detector configured to move along at least a portion of a detector path, the at least a portion of the detector path extending so that the detector is configured to move at least partially around a scan volume, the detector path having a distance D 1 that is sufficiently long to allow the scan volume to be positioned within the detector path;
a radiation source, the source configured to move along at least a portion of a source path outside the detector path, the source path having a distance D 2 greater than the distance D 1 , the distance D 2 being sufficiently long to allow adequate radiation exposure of the scan volume for an image capture by the detector;
a gap in the detector path and the source path to provide radial access to the scan volume; and
a control panel coupled to the support structure to provide an operator interface for entering instructions for operation of the apparatus;
where a first mode of the imaging apparatus is configured to perform CBCT imaging of the scan volume and a second mode of the imaging apparatus is configured to perform tomography imaging of the scan volume.
2 . The apparatus according to claim 1 , where in the second tomography imaging mode an extremity is longitudinally oriented in the scan volume and gap or the extremity is radially oriented in the scan volume and the gap.
3 . The apparatus according to claim 1 , wherein the radiation source has a radiation source actuator that is operable independently and separate from a detector actuator to reduce weight.
4 . The apparatus according to claim 1 , where in the second tomography imaging mode the source and the detector travel at least a corresponding 30 degree path.
5 . The apparatus according to claim 1 , where the scanner assembly comprises a retractable door to cover a detector path gap, where in the second tomography imaging mode the door is retracted or where the scanner assembly comprises a removable door to cover a detector path gap, where in the second tomography imaging mode the door is removed from the scanner assembly.
6 . The apparatus according to claim 1 , where in the second tomography imaging mode a subset of the CBCT projections are exposed to generate a topographic imaging data set to reduce metal artifacts.
7 . The apparatus according to claim 1 , further comprising:
a first device configured to move the scanner assembly along a vertical direction of the support column;
a second device configured to revolve the scanner assembly to a vertical or other angular orientation; and
a third device configured to orient the scanner assembly by revolving the scanner assembly about a different axis that the second device.
8 . The apparatus according to claim 1 , wherein radiation absorbent shielding is added to at least portions of surfaces of the housing or a door for absorbing radiation during exposure, wherein the detector is coupled to a radiation-absorbent backing plate.
9 . The apparatus according to claim 1 , wherein the detector is coupled to a radiation-absorbent backing plate, where the weight of the radiation-absorbent backing plate is configured to position a center of mass for the gantry is on the beta axis.
10 . An imaging apparatus for cone beam computed tomography imaging of an extremity, the apparatus comprising a scanner that scans a scan volume about a β axis, the scanner comprising:
a) a housing that defines an opening for patient extremity access to the scan volume;
b) a detector for acquiring image data from the scan volume according to received radiation, wherein the detector has a detector actuator and is translatable to orbit the scan volume along a detector path that lies at a first radius R 1 about the β axis;
c) a radiation source that is energizable to direct radiation through the scan volume and toward the detector, wherein the radiation source has a radiation source actuator that is operable independently of the detector actuator and wherein the radiation source is moveable to orbit the scan volume at a second radius R 2 about the β axis.
11 . The imaging apparatus of claim 1 , where the independent operation of the radiation source actuator and the detector actuator operate to position the source and the detector in a first relative position before imaging and in a second relative position during imaging.
12 . An apparatus for cone beam computed tomographic imaging of one extremity, the apparatus comprising:
a digital radiation detector;
a detector mechanism attached to the detector and configured to move the detector along a detector path, a shape of the detector path comprising a first circular arc, the detector path defining a detector axis whereat at least a portion of the one extremity is positioned to be imaged by the apparatus;
a radiation source; and
a source mechanism separate from the detector mechanism, the source mechanism attached to the source and configured to move the source along a source path, the source mechanism controllable to move the source independent of the detector movement, a shape of the source path comprising a second circular arc, the source path defining a source plane and a source axis, the source axis coaxial with the detector axis, wherein a distance from the detector path to the detector axis is shorter than a distance from the source path to the source axis.
13 . The apparatus of claim 12 , wherein the source mechanism and the detector mechanism are configured to position the source and detector, respectively, in a first relative position before imaging, and in a second relative position while performing imaging.
14 . The apparatus of claim 13 , wherein the apparatus is configured to position the extremity at the detector axis while the source and detector are disposed in the first relative position.
15 . The apparatus of claim 14 , wherein the apparatus is configured to image the extremity at the detector axis while the source and detector are disposed in the second relative position.
16 . The apparatus of claim 13 , wherein the source and detector are diametrically opposite the detector axis in the second relative position.
17 . The apparatus of claim 12 , wherein the source mechanism includes a rigid C-shaped assembly to provide mechanical support for the source as the source is moved along the source path.
18 . The apparatus of claim 17 , wherein the detector mechanism includes the rigid C-shaped assembly to provide mechanical support for the detector as the detector is moved along the detector path.
19 . The apparatus of claim 18 , wherein the source mechanism further includes a source support arm, a proximate end of the source support arm attached to the C-shaped assembly and a distal end of the source support arm attached to the source to provide mechanical support for the source as the source is moved along the source path.
20 . The apparatus of claim 12 , further comprising a C-shaped housing to enclose the source and the source mechanism as the source moves along the source path and to enclose the detector and the detector mechanism as the detector moves along a portion of the detector path.