Radiographic Reference Device for External Fixator 3D Imaging
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Solution Overview
Problem
Obtaining truly orthogonal radiographs is challenging with external fixators, as patients find it difficult to rotate their limbs 90 degrees, and existing systems struggle to align reference rings and avoid overlapping bone images, making it hard to reconstruct accurate 3D digital images.
Innovation Solution
A radiographic reference device with two surfaces separated by a specific angle, attached to an external fixation device, allows for the capture of two radiographic images at different angles, enabling the calculation of object positions in three dimensions using distances measured from these images, with adjustable struts and markers for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the patient rotates their limb 90 degrees to obtain perpendicular radiographs, then orthogonal images can be obtained for 3D reconstruction, but the operation becomes difficult when the patient is fitted with an external fixator
Solution Approach 1:
A radiographic reference device with a reference ring is introduced as an intermediary between the external fixator and the radiographic imaging system. The reference device includes reference markers that provide visual cues for alignment, allowing the operator to achieve proper angular positioning without requiring the patient to physically rotate their limb. The reference ring with angular markings serves as a mediator to establish the correct geometric relationship between successive radiographic images.
Solution Approach 2:
The solution moves from directly rotating the patient's limb in three-dimensional space to using a two-dimensional reference ring with angular markings that can be aligned visually. By projecting the three-dimensional rotational requirement onto a two-dimensional reference plane with clear angular indicators, the complexity of spatial orientation is reduced, making it easier to achieve the required 90-degree separation between radiographic images.
2Measurement precision
If the equipment is rotated 90 degrees to obtain perpendicular radiographs, then orthogonal images can be obtained, but it is difficult to align the reference ring on both images and avoid overlapping of bone image with ring image
Solution Approach 1:
The radiographic reference device serves multiple functions simultaneously: it provides angular reference markings for alignment, acts as a positioning aid during image acquisition, and serves as a verification tool to ensure proper geometric relationships. The reference ring integrates multiple reference features (angular markings, alignment indicators) into a single device that can be used throughout the imaging process, eliminating the need for separate alignment tools and reducing overall system complexity.
Solution Approach 2:
The reference device is attached to the external fixator before the radiographic imaging begins, establishing the reference frame in advance. The angular markings and alignment features are pre-positioned on the reference ring, allowing the operator to plan and execute the imaging sequence without complex real-time calculations. This preliminary setup simplifies the subsequent imaging process by providing ready-made alignment cues.
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
Facilitates the acquisition of truly perpendicular radiographs, simplifies the process for operators, and ensures accurate 3D image reconstruction even with external fixators, enhancing patient convenience and operator ease of use.
Implementation Method 1
capture a first radiographic image of the external fixation device and the one or more objects; repositioning the external fixation device to position the second surface of the radiographic reference device on the surface to capture a second radiographic image
Data Source
AI summary
A radiography aid and method of using the same comprising: attaching a radiographic reference device to the external fixation device, the radiographic reference device comprises at least two surfaces; positioning the first surface of the radiographic reference device on an imager surface to capture a first radiographic image of the external fixation device and the one or more objects; repositioning the external fixation device to position the second surface of the radiographic reference device on the imager surface to capture a second radiographic image of the external fixation device and the one or more objects that differs in position from the first radiographic image by the first angle; and calculating the position of the one or more objects in three dimensions.