Cone-Beam CT Imaging Trajectories for Large Anatomy Coverage

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Solution Overview

Problem

Current cone-beam computed tomography (CBCT) systems are limited in imaging larger anatomies due to restricted field sizes, leading to incomplete data coverage and increased radiation dose, which results in reconstruction artifacts and reduced precision in radiation therapy planning.

Innovation Solution

The implementation of advanced image acquisition trajectories and modes that allow for increased scanning diameters and imaging volumes by moving the treatment couch along orthogonal planes and rotating the gantry, enabling a fixed, centrally located or offset detector configuration without introducing imaging artifacts, while using megavoltage or kilovoltage X-ray sources with reduced field sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a larger field size is used to image larger anatomies, then the field of view is increased, but the acquisition time and radiation dose increase, and X-ray scatter artifacts are introduced

Engineering Contradiction:

Improvefield of viewVSAvoidacquisition time

Core Design Contradiction:

Area of stationary objectVSLoss of time

Solution Approach 1:

The patent divides the imaging process into multiple scanning trajectories (e.g., multiple arcs or partial rotations) that collectively cover the large anatomy. Instead of using a single large field size, the system segments the acquisition into multiple passes with reduced field sizes, thereby maintaining image quality while reducing scatter artifacts and radiation dose per trajectory.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces additional scanning dimensions by combining multiple scanning trajectories with different orientations and positions. By moving the treatment couch along orthogonal planes and rotating the gantry in multiple arcs, the system achieves comprehensive coverage of large anatomies without requiring a single large field size, thus reducing X-ray scatter and acquisition time.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a reduced field size is used, then the dose-rate at the center area increases and X-ray scatter decreases, but the size of the object that can be imaged is limited

Engineering Contradiction:

ImproveX-ray scatterVSAvoidimaging coverage

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent segments the imaging of large anatomies into multiple scanning trajectories with reduced field sizes. Each trajectory uses a smaller field size that minimizes X-ray scatter, while the combination of multiple trajectories achieves complete coverage of the entire anatomy, thus resolving the contradiction between reduced scatter and sufficient imaging coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic movement of the treatment couch and gantry to adapt the imaging field to different regions of the anatomy. By dynamically adjusting the position and orientation during multiple scanning passes, the system maintains optimal field size for each local region, reducing scatter while ensuring complete coverage of the entire object.

Inventive Principle:

Principle #15Dynamics

3Area of stationary object

If offset imager geometry is used to increase field of view, then the field of view increases, but the acquisition time and radiation dose increase, and system complexity increases

Engineering Contradiction:

Improvefield of viewVSAvoidimaging system complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

Instead of offsetting the imager to increase field of view, the patent inverts the approach by using a centrally located detector with multiple scanning trajectories. This alternative configuration achieves the same goal of imaging large anatomies without the increased system complexity, acquisition time, and radiation dose associated with offset geometry.

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables complete data coverage for CT volume reconstruction, reducing radiation dose and acquisition time, and improving image quality for anatomies larger than 50 cm in diameter, while maintaining precision and reducing X-ray scatter artifacts.

Implementation Method 1

A cone-beam computed tomography (CBCT) system acquires a plurality of projection images of a target volume by moving an X-ray source around an arc segment

Methodology Applied

Scientific EffectX-ray transmission: X-Ray