Objective: Axial rotation is a known confounder for clinicians seeking to measure the pelvis on the anteroposterior radiograph. This study examines if the y-axis rotation of a model, as seen on an anteroposterior radiograph, could be calculated by a mathematical method using a computer application.
Methods: A model was used to show 2 points, used in a previous study, to calculate anteroposterior radiographic y-axis pelvic rotation. The model was rotated 0 to 10 degrees in 2-degree increments. An anteroposterior radiograph of the model was obtained at each rotation point. A 3-member team worked together to determine the location of the 2 points of the model on each digital radiograph. The distance between the points along with the source image receptor distance and the distance of the model from the image receptor were entered into a computer application to calculate the y-axis (axial) rotation of the model. The degree of rotation of the model was compared to the rotation calculated by the computer.
Results: The difference between the 2 methods was less than 1 degree in all y-axis rotations measured.
Conclusion: The mathematical method appears applicable to clinical practice as it was able to calculate y-axis rotation of the model on the anteroposterior radiographs when compared to the mechanical rotation of the model on the y-axis to an accuracy of less than one degree.
Author keywords: Radiography; Chiropractic; Spine; Pelvis; Projection
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