X-ray motion analysis is a technique used to track the movement of objects using X-rays. This is done by placing the subject to be imaged in the center of X-ray beam and recording motion using the image intensifier and high-speed camera, allowing for high quality video that is sampled many times per second. Depending on the setting of X-rays, this technique can visualize a particular structure in an object, such as bone or cartilage. X-ray motion analysis can be used to perform gait analysis, analyze joint motion, or record bone movement obscured by soft tissue. The ability to measure skeletal movement is a key aspect to one's understanding of vertebrate biomechanics, energetics, and motor control.
Video X-ray motion analysis
Imaging Method
Planar
Many X-ray studies are done with one X-ray transmitter and camera. This type of imagery makes it possible to track movement in a two-dimensional plane of X-rays. Movements are made parallel to the field of camera imagery for movement to be accurately tracked. In gait analysis, a planar X-ray study was conducted in the sagittal field to allow for highly accurate large motion tracking. Methods have been developed to allow for estimating six degrees of freedom of movement from planar X rays and traceable object models.
Biplanar
Some movements are really planar; Planar X-ray imagery can capture most of the movement, but not all of it. Accurately capturing and measuring the three dimensions of movement requires a biplanar imaging system. Bipolar imaging is difficult because many facilities have access to only one X-ray transmitter. With the addition of an X-ray and a second camera system, the 2-D imaging field extends to 3-D imaging volumes at X-ray junction. Because the imaging volume is at the intersection of two X-ray beams, the overall size is limited by the X-ray transmitting area.
Maps X-ray motion analysis
Tracking Techniques
Markered
Motion capture techniques often use reflective markers for shooting. In X-ray imaging, blurry-looking markers in X-ray images are used. This often involves the use of radio-opa balls attached to the subject. Markers can be implanted in the bones of the subject, which will then be seen in X-ray images. This method requires a surgical procedure to infuse and healing period before the subject can undergo motion analysis. For accurate 3-D tracking, at least three markers need to be embedded into each bone to be tracked. Markers can also be placed on the subject's skin to track the movement of the bones underneath, although the markers placed on the skin are sensitive to the motion artifacts of the skin. This is a mistake in measuring the location of markers placed on the skin compared to markers grown on the bone. This happens in locations where the soft tissue moves more freely than the skin that lines. The marker is then tracked relative to the X-ray camera and movements are mapped to the local anatomical body.
No Marker
Appear techniques and software that allow to be tracked without the need for radio-blurred markers. Using the 3-D model of the tracked object, objects can be coated on X-ray video images on each frame. Translation and rotation models, as opposed to a set of markers, are then tracked relative to the X-ray camera (s). Using local coordinate systems, these translations and rotations can then be mapped to standard anatomic movements. The 3-D object model is generated from any 3-D imaging technique, such as MRI or CT scan. Unmarked tracking has the benefit of being a non-invasive tracking method, avoiding complications due to surgery. One difficulty comes from generating 3-D models in animal research, because animals are asked to be sedated or sacrificed for scanning.
Analysis
In planar X-ray imaging, marker or body movements are tracked in special software. Initial location guesses are provided by users for markers or agencies. The software, depending on its capabilities, requires users to manually locate a bookmark or body for each video frame, or it can automatically track locations across the video. Automatic tracking should be monitored for accuracy and may need to manually move the marker or body. Once the tracking data is generated for each desired marker or body, the tracking is applied to the local anatomical body. For example, a marker placed on the hip and knee will track the movement of the femur. Using the knowledge of local anatomy, these movements can then be translated into anatomical motion terms in the field of X-rays.
In biplaner X-ray imaging, movement is also tracked in special software. Similar to planar analysis, the user gives an initial location guess and tracks the marker or body manually or the software can track it automatically. However, biplanar analysis requires that all tracking be done on both video frames at the same time, positioning objects in free space. Both X-ray cameras must be calibrated using known volume objects. This allows the software to position the camera relative to each other and then allows the user to position the 3-D model of the object according to both video frames. Tracking data is generated for each marker or body and then applied to the local anatomical body. Further tracking data is defined as an anatomical term motion in free space.
Apps
An X-ray motion analysis can be used in human gait analysis to measure the kinematics of the lower extremities. Treadmill gait or gait on the surface can be measured depending on the mobility of the X-ray system. Other movement types, such as skipping maneuvers, have also been recorded. By combining an X-ray motion analysis with a power platform, a combined torque analysis can be performed. Rehabilitation is an important application of X-ray motion analysis. X-ray imaging has been used for medical diagnostic purposes immediately after its discovery in 1895. The analysis of X-ray motion can be used in joint imaging or analyzing joint-related illnesses. It has been used to measure osteoarthritis in the knee, estimate the knee cartilage contact area, and analyze the results of rotator cuff improvement with shoulder joint imaging, among other applications.
Locomosi animals can also be analyzed with X-ray imaging. As long as the animal can be placed between the X-ray producer and the camera, the subject can be imaged. Examples of reverberations that have been studied are rats, guineafowls, horses, bipedal birds, and frogs, among others. In addition to the movers, X-ray motion analysis has been used in research and other mobile morphological analysis studies, such as mastication of pigs and temporomandibular joint movement in rabbits.
See also
- Video motion analysis
- Roentgen Stereophotogrammetric Analysis
- Radiography
- Fluoroscopy
References
Source of the article : Wikipedia
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