David M. Gauntt PhD, Presenter: Co-owner, X-Ray Imaging Innovations, LLC Patent holder, BRAGA system

Gary T. Barnes PhD, Abstract Co-Author: Owner, X-Ray Imaging Innovations, LLC Patent holder, BRAGA system

Colleen Sanders MD, Abstract Co-Author: Nothing to Disclose

BRAGA (Bedside Radiography Automatic Grid Alignment) is a system that allows a technologist to easily achieve excellent focal spot/grid alignment in bedside radiography, allowing the use of high-ratio grids and therefore producing vastly improved image quality. We will present quantitative results comparing the accuracy of focal spot/grid alignment achieved with manual alignment to the accuracy achieved with the BRAGA system.

We modified a GE AMX4+ to incorporate the BRAGA system. This system includes a custom built grid tunnel, a digital camera mounted on the collimator, an embedded computer, and a motion control system (MCS) with 6 motors and encoders. A detachable arm with an optical target is mounted rigidly to the grid tunnel; the arm extends out from under the patient so the optical target is visible from the digital camera. To position the focal spot automatically, the technologist places the tube housing in roughly the right position, then pushes and holds a button. The camera acquires an image of the optical target, the computer processes this image, then directs the MCS to move the tube housing and collimator to the center of the grid focal axis. Several experienced technologists used the system in a laboratory setting (with a torso phantom) and in a clinical setting (with patients). For each alignment, we recorded the initial (manual) positioning error, the final (automatic) positioning error, and the time it took BRAGA to complete positioning.

The technologists positioned the focal spot within 7 cm (RMS) of the center of the focal axis, while BRAGA positioned the focal spot within 0.4 cm (RMS) of the center of the focal axis. The automatic positioning took an average of 8.5 sec, and never more than 15 sec.

BRAGA can rapidly position the focal spot of a mobile radiographic system to within 3 mm of the center of the grid focal axis with a minimum of operator intervention. This is approximately a factor of 20 times better than the performance of an experienced technologist.

BRAGA allows the practical use of precisely aligned high ratio grids in bedside radigraphy with a minimum of operator effort, resulting in vastly improved image contrast.

Gauntt, D, Barnes, G, Sanders, C, BRAGA: An Easy to Use System for Improved Focal Spot/Grid Alignment in Bedside Radiography.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5008084.html