Computed tomography apparatus for odontology

Patent metadata

Field	Value
Publication number	US-9538966-B2
Application number	US-201013512148-A
Country	US
Kind code	B2
Filing date	Nov 23, 2010
Priority date	Nov 25, 2009
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

Computed tomography apparatus for odontology, which includes an arm part arranged to be turnable, to which arm part at a distance from each other a radiation source and a receiver of image information have been arranged, in which apparatus said arm part is arranged to locate or to be transferred to such location with respect to the volume desired to be imaged that when the arm part is turned during the imaging, at least over a substantial angular range only a portion of the volume arranged to become imaged is within the radiation beam, and in which the control system of the apparatus comprises a control routine which then controls said radiation source to generate radiation as pulsed.

First claim

The invention claimed is:

1. A computed tomography apparatus for odontology, which apparatus comprises an arm part arranged turnable around at least one rotation axis with the help of an actuator, to which arm part and at a distance from each other a radiation source and a receiver of image information have been arranged, said receiver of image information comprising an imaging detector which is an area sensor which during an imaging scan captures a number of frames comprising x-ray image information of the object being imaged, a control system to control said actuator, radiation source and receiver of image information, in which apparatus said arm part is arranged to be located or transferable with respect to the volume desired to become imaged to such location, and the control system to comprise such control routine that when the arm part is turned during an individual imaging scan in which information is gathered for reconstruction of a single volume, at least over a substantial angular range or over the whole angular range used for the individual imaging scan, only a portion of the volume arranged to become imaged is within the radiation beam, characterized in that said control system comprises a first control routine, which is arranged to control said radiation source to produce pulsed radiation and wherein the apparatus comprises a means to measure anode current of the radiation source during an individual radiation pulse and in the event of deviation from a preset value, said first control routine comprises adjusting duration of the radiation pulses such that anode current of the radiation source is measured and the pulse is terminated at the point when integral of the measured current reaches the preset value, whereby upon termination of said radiation pulse the capturing of x-ray image information at said imaging detector also terminates.

2. An apparatus according to claim 1 wherein said control system is arranged to control reading of information from said imaging detector to take place at those moments of time when the irradiation has been interrupted.

3. An apparatus according to claim 1 wherein duration of a single radiation pulse is arranged shorter than the maximum time it may take for the beam to turn in the volume being imaged for a distance which corresponds the voxel size one intends to use in the reconstruction, or shorter or substantially shorter than the time which lapses when said imaging detector moves during imaging a distance of one detector pixel.

4. An apparatus according to claim 1 wherein said imaging detector is a circular, a rectangular or a quadric area sensor, the diameter or the side length of which being of the order of 10-20 cm.

5. An apparatus according to claim 1 wherein said imaging detector has been arranged to save and/or forward the information it has received several times a second.

6. An apparatus according to claim 1 wherein said first control routine comprises controlling the radiation source such that a portion of the pulses is generated with a greater voltage, another portion with a lower voltage.

7. An apparatus according to claim 6 , wherein said first control routine comprises generating every other pulse with a higher voltage and every other with a lower voltage, or in consecutive periods during which always the same number of pulses is generated first by the other, then by the other voltage.

8. An apparatus according to claim 1 , wherein the apparatus includes
a first arm part arranged turnable about a substantially vertical rotation axis with the help of an actuator to which arm part and at a distance from each other and on the opposite sides of said rotation axis, a radiation source and a receiver of image information have been arranged,
a second arm part arranged turnable about a substantially vertical rotation axis with the help of an actuator which second arm part is arranged to support said first arm part, and in which
said control system comprises a second control routine which controls said at least one actuator of the apparatus such that during an imaging process, said first arm part does not rotate but remains at its place in relation to said second arm part for the duration of imaging, and said second arm part rotates about its rotation axis.

9. An apparatus according to claim 8 , wherein said second control routine comprises a step in which, prior to the actual imaging process, the first arm part is driven at a desired angle in relation to the orientation of the second arm part.

10. An apparatus according to claim 8 wherein said second control routine comprises turning the second arm part about its rotation axis substantially for 360 degrees.

11. An apparatus according to claim 8 , wherein said first arm part is supported by said second arm part via the rotation axis of the first arm part.

12. An apparatus according to claim 8 , wherein the rotation axes of said first and second arm part are substantially parallel and/or the distance between them is constant.

13. An apparatus according to claim 5 wherein said imaging detector has been arranged to save and/or forward the information it has received at least ten times a second.

14. A computed tomography apparatus for odontology, which apparatus comprises an arm part arranged turnable around at least one rotation axis with the help of an actuator, to which arm part and at a distance from each other a radiation source and a receiver of image information have been arranged in a manner to perform an asymmetric scan of at least 360°, a control system to control said actuator, radiation source and receiver of image information, in which apparatus said arm part is arranged to be located or transferable with respect to the volume desired to become imaged to such location, and the control system to comprise such control routine that when the arm part is turned during imaging, at least over a substantial angular range or over the whole angular range used for the imaging, only a portion of the volume arranged to become imaged is within the radiation beam, characterized in that said control system comprises a first control routine, which is arranged to control said radiation source to produce pulsed radiation, and the apparatus comprises a means to measure anode current of the radiation source and that said first control routine comprises adjusting duration of the radiation pulses such that anode current of the radiation source is measured and said pulse is terminated at the point when integral of the measured current reaches a preset value which is associated with an image frame to be generated.

Assignees

• Müller Timo
• Planmeca Oy

Inventors

• Müller Timo

Classifications

• A61B6/405

  Source units specially adapted to modify characteristics of the beam during the data acquisition process (A61B6/4021, A61B6/4035 take precedence) · CPC title

• A61B6/4441

  the rigid structure being a C-arm or U-arm · CPC title

• A61B6/5229

  combining image data of a patient, e.g. combining a functional image with an anatomical image · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title

• A61B6/5241

  combining overlapping images of the same imaging modality, e.g. by stitching · CPC title