# US 2014/0192952 A1 · Modulating gantry rotation speed and image acquisition in respiratory correlated (4d) cone beam ct images

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- Number: US 2014/0192952 A1
- Document ID: US20140192952A1
- Status: Published application
- Kind: A1
- Application number: 14/131,896
- Filed: 2012-07-27
- Published: 2014-07-10
- Earliest claimed: 2011-07-28
- Assignees: The University of Sydney; The Board of Trustees of the Leland Stanford Junior University
- Inventors: Paul J. Keall; Ricky O'Brien; Benjamin J. Cooper; Jun Lu; Jeffrey F. Williamson
- Web page: https://patentgrep.com/patent/US20140192952A1

## CPC

- A61B 6/541: {involving acquisition triggered by a physiological signal}
- A61B 6/4085: {Cone-beams}
- A61B 6/486: {involving generating temporal series of image data}
- A61B 6/5205: {involving processing of raw data to produce diagnostic data}
- A61B 6/5264: {due to motion}
- A61B 6/583: {using calibration phantoms}
- A61N 2005/1061: {using an x-ray imaging system having a separate imaging source}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)

## Abstract

A method of optimizing 4D cone beam computed tomography (4DCBCT) imaging is provided that includes using a scanner to generate projections of a target, where the projections are used to form a cone beam computed tomography (CBCT) scan of the target, where the CBCT includes a 3D image of the target, and using an appropriately programmed computer to control rotation speed of a gantry and projection acquisition of the CBCT in real-time according to a measured patient respiratory signal, where the real-time acquisition of the CBCT forms an optimized 4DCBCT image set.

## Claims

### Claim 1

A method of optimizing 4D cone beam computed tomography (4DCBCT) imaging, comprising:
a. generating by a scanner projections of a target;
b. forming by said scanner a cone beam computed tomography (CBCT) scan of said target from said projections, wherein said CBCT comprises a 3D image of said target; and
c. controlling by an appropriately programmed computer a rotation speed of a gantry and projection acquisition of said CBCT in real-time according to a measured patient respiratory signal, wherein said real-time acquisition of said CBCT forms an optimized 4DCBCT.

### Claim 2 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein a time interval between projections of said CBCT is varied.

### Claim 3 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein acceleration and a velocity of said gantry are varied.

### Claim 4 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein a breathing trace is used to optimize a projection schedule.

### Claim 5 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein said optimized projection schedule comprises regulating a gantry angle and regulating a projection pulse rate.

### Claim 6 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein said control of said gantry rotation speed and projection acquisition of said 4DCBCT in real-time comprises:
a. analyzing by sensors a patient's breathing pattern to determine a representative breathing trace;
b. separating the patients representative breathing trace into a number of phase or displacement based respiratory bins;
c. determining and applying by mathematical optimization techniques on said computer a gantry angle and a projection pulse rate schedule from said representative breathing cycle;
d. recomputing by said computer said gantry angle and a projection pulse rate schedule if said patient's breathing deviates from said representative breathing cycle; and
e. continuing said projection acquisition according to said recomputed gantry angle and projection pulse rate schedule.

### Claim 7 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein motion of said gantry is regulated within specified limits, wherein said limits are selected from the group consisting of minimum and maximum velocity, minimum and maximum acceleration, minimum and maximum jerk, minimum and maximum time between projections, minimum and maximum number of projections, minimum and maximum number of projections per respiratory bin, maximum imaging radiation dose, minimum and maximum image quality, minimum and maximum probability on the robustness of the schedule to irregular breathing, minimum and maximum likelihood of reconstructing a suitable schedule when a patients breathing becomes irregular, minimum and maximum number of respiratory bins and total imaging time.

### Claim 8 (depends on 1)

The method of optimizing 4DCBCT imaging of claim 1, wherein said patient respiratory signal is used to modulate a speed of said gantry and modulate said projection acquisition to yield images for each phase of a breathing trace at a predetermined and optimized angular spacing.

### Claim 9 (depends on 8)

The method of optimizing 4DCBCT imaging of claim 8, wherein optimizing said gantry angle comprises operations selected from the group consisting of minimizing the time required to acquire the 4DCBCT projections, minimizing the angular separation between the gantry angles for each projection, minimizing the root mean squared of the angular separation between the projections, maximizing the image quality in each respiratory bin, maximizing a number of images acquired, maximizing a number of respiratory bins, maximizing a likelihood of acquiring suitable quality images when a patients breathing becomes irregular, maximizing a robustness of a schedule, and minimizing a radiation dose to said patient.