Variable Angle Slant Hole Collimator Leaf Alignment

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Solution Overview

Problem

Existing multi-angle collimators in radiation imaging lack accurate alignment of leaves, resulting in reduced image quality and inefficient tomographic acquisition, particularly in clinical nuclear imaging, due to inaccurate collimation angles and physical interference with the imaging target.

Innovation Solution

A variable angle slant hole (VASH) collimator with multiple leaves and a precise alignment mechanism using twin-lead screws and wedge blocks, allowing for stationary detector operation and continuous collimation angle adjustment, enabling accurate tomographic acquisition and high image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple detectors at different positions are used for multi-angle projection, then 3D image acquisition is enabled, but physical interference with the imaging target occurs

Engineering Contradiction:

Improvemulti-angle projection capabilityVSAvoidphysical interference with imaging target

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The collimator is divided into multiple independent leaves that can be individually positioned at different angles. Each leaf contains apertures that can be independently aligned, allowing multi-angle projection capability while maintaining a single detector position, thus avoiding physical interference with the imaging target.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If variable angle slant hole collimator with adjustable leaf alignment is used, then multiple projection angles are achieved, but alignment accuracy is reduced resulting in lower image quality

Engineering Contradiction:

Improveadjustable collimation angleVSAvoidleaf alignment accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The alignment mechanism incorporates feedback through precision mechanical guides and alignment features that ensure each leaf is positioned at the exact desired angle. The system includes alignment marks and mechanical stops that provide visual and physical feedback to confirm accurate positioning, thereby maintaining high alignment precision despite adjustable angles.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention replaces manual or crude mechanical alignment methods with a precision engineered mechanical system featuring guided rails, precision-machined surfaces, and interlocking features. This substituted mechanical system provides repeatable, accurate alignment without requiring complex adjustment procedures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If detector rotation is used for tomographic acquisition, then 3D imaging is achieved, but acquisition time is increased

Engineering Contradiction:

Improvetomographic acquisition capabilityVSAvoiddata acquisition time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The collimator leaves are designed to be dynamically adjustable during the imaging process. Multiple leaves can be repositioned to different angles rapidly and independently, enabling the system to acquire multi-angle projections without rotating the detector, thereby significantly reducing acquisition time while maintaining tomographic imaging capability.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If multi-leaf collimator with adjustable angles is used, then collimation angle can be changed, but aperture alignment may be compromised

Engineering Contradiction:

Improvevariable collimation angleVSAvoidaperture alignment stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The collimator leaves are pre-aligned during manufacturing with precision-machined reference surfaces and alignment features. Before use, the leaves are assembled in a predetermined sequence with pre-established geometric relationships, ensuring that when positioned at any angle, the apertures remain properly aligned. This preliminary preparation eliminates the need for complex realignment during operation.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9711251B2Apparatus and method for variable angle slant hole collimator

Publication Date: 2017.07.18 JEFFERSON SCIENCE ASSOCIATES LLC

AI summary

A variable angle slant hole (VASH) collimator for providing collimation of high energy photons such as gamma rays during radiological imaging of humans. The VASH collimator includes a stack of multiple collimator leaves and a means of quickly aligning each leaf to provide various projection angles. Rather than rotate the detector around the subject, the VASH collimator enables the detector to remain stationary while the projection angle of the collimator is varied for tomographic acquisition. High collimator efficiency is achieved by maintaining the leaves in accurate alignment through the various projection angles. Individual leaves include unique angled cuts to maintain a precise target collimation angle. Matching wedge blocks driven by two actuators with twin-lead screws accurately position each leaf in the stack resulting in the precise target collimation angle. A computer interface with the actuators enables precise control of the projection angle of the collimator.