It is known that conventional anti-scatter grids are limited in their ability to control scatter in general radiography. In recent years this problem has been aggravated by the use of less efficient (thin, high line density, low lead content) grids, and the increasing size of patients. As a result, radiographic image quality is often insufficient to answer questions concerning trauma and other clinical areas, and patients undergo additional higher dose, more expensive imaging exams. In many instances these additional exams could be eliminated and health care costs reduced if a better radiographic imaging system were available. We propose a coarse, high-ratio air interspace grid coupled to an orthogonally aligned low-ratio conventional grid. Together, these will effectively eliminate scatter and will have a primary transmission comparable to commonly used grids. A low-ratio grid is compatible with a range of source-to-image distances (SIDs). The coarse grid will have articulating grid slats, permitting variable SIDs and angled views. In order to build a compact and clinically acceptable system, the coarse grid can only move a short distance to blur out grid lines. It has been demonstrated that this can be accomplished by employing a quasi-trapezoidal x-ray tube current waveform. In Phase I we propose to demonstrate that an appropriate quasi-trapezoidal x-ray tube current waveform can be obtained in general radiography. In Phase II we propose to design and construct a compact and high efficiency crossed-grid system, interface it to an x-ray generator, and demonstrate that it can control scatter much more effectively than a conventional grid. The system will be able to accommodate general radiography, chest radiography, angled projections, tomography, and a range of SIDs. It can be used with either screen-film or digital image receptors, and will improve tomosynthesis and dual energy applications.
TO PUBLIC HEALTH: General radiography (x-ray images) plays an important role in health care delivery. Scattered radiation degrades image quality; social and technical trends have aggravated this problem in recent years. We propose a scatter control system that greatly increases the image quality of x- ray images without increasing patient dose.
