Type:
Educational Exhibit
Keywords:
Patterns of Care, Diagnostic procedure, Digital radiography, Conventional radiography, Radiation physics
Authors:
S. PHILLIPS1, K. Schmiedehausen2, S. Wells2; 1Cardiff/UK, 2Oxford/UK
DOI:
10.26044/ecr2019/C-2547
Background
Digital Tomosynthesis (DT) has been adopted as a valuable clinical tool,
ranging from mammography to musculoskeletal and thoracic imaging (Fig 2). Conventional DT systems work by physically moving an X-ray tube through a range of positions in order to capture multiple ultra-low dose projection images from a variety of different angles and then reconstruct slices through a 3D volume [1,2]. Early concepts in the 1970s were largely abandoned in favour of CT,
but the increasing availability of dynamic digital detectors in the last two decades have made DT a viable proposition again [1,2]. Many clinical studies have shown the superior performance of DT compared to 2D X-ray in mammography [3],
orthopaedic imaging [4] and chest imaging [5,6]. For this reason,
DT has become the gold standard in breast imaging but its adoption and utilisation for other clinical applications has been less rapid (Fig 3), potentially because of the bulky imaging equipment and its cost.
In contrast to CT,
the range of angles used in DT is much less than 360˚,
which substantially reduces the radiation exposure of the patient. The cost of the system and the cost and time per procedure are also much less than CT [7].
There are no current mobile/portable DT systems,
hence no potential for point-of-care diagnostics. These systems are still rather large and expensive which limits their deployment outside of a hospital setting in primary care,
requiring a dedicated three-phase power supply and ceiling mounting system; making installation costly and time-consuming. Due to the physical motion of the heavy X-ray tube and longer acquisition time,
blurred images can be a concern associated with DT [8].
Conventional X-ray tubes operate with a single thermionic cathode but recent technical developments have enabled the development of so-called "cold cathode" emitters.
These generate electrons without using heat,
are more compact than conventional solutions and several emitters can be arranged in different geometric constellations [9] (Fig 4).
Electronically switching between sources allows a faster acquisition than when physically moving a single source,
avoiding the risk of motion blur (Fig 5).