Design and characterization of a spatially distributed multibeam field emission x‐ray source for stationary digital breast tomosynthesis

Abstract

Digital breast tomosynthesis ͑DBT͒ is a limited angle computed tomography technique that can distinguish tumors from its overlying breast tissues and has potentials for detection of cancers at a smaller size and earlier stage. Current prototype DBT scanners are based on the regular full-field digital mammography systems and require partial isocentric motion of an x-ray tube over certain angular range to record the projection views. This prolongs the scanning time and, in turn, degrades the imaging quality due to motion blur. To mitigate the above limitations, the concept of a stationary DBT ͑s-DBT͒ scanner has been recently proposed based on the newly developed spatially distributed multibeam field emission x-ray ͑MBFEX͒ source technique using the carbon nanotube. The purpose of this article is to evaluate the performance of the 25-beam MBFEX source array that has been designed and fabricated for the s-DBT system. The s-DBT system records all the projection images by electronically activating the multiple x-ray beams from different viewing angles without any mechanical motion. The configuration of the MBFEX source is close to the published values from the Siemens Mammomat system. The key issues including the x-ray flux, focal spot size, spatial resolution, scanning time, beam-to-beam consistency, and reliability are evaluated using the standard procedures. In this article, the authors describe the design and performance of a distributed x-ray source array specifically designed for the s-DBT system. They evaluate the emission current, current variation, lifetime, and focal spot sizes of the source array. An emission current of up to 18 mA was obtained at 0.5ϫ 0.3 mm effective focal spot size. The experimentally measured focal spot sizes are comparable to that of a typical commercial mammography tube without motion blurring. Trade-off between the system spatial resolution, x-ray flux, and scanning time are also discussed. Projection images of a breast phantom were collected using the x-ray source array from 25 different viewing angles without motion. These preliminary results demonstrate the feasibility of the proposed s-DBT scanner. The technology has the potential to increase the resolution and reduce the imaging time for DBT. experimentally the feasibility of achieving 11 s scanning time at full detector resolution with 0.5 ϫ 0.3 mm source resolution without motion blur. The flexibility in configuration of the x-ray source array will also allow system designers to consider imaging geometries that are difficult to achieve with the conventional single-source rotating approach.

High resolution stationary digital breast tomosynthesis using distributed carbon nanotube x‐ray source array

“…The x-ray beams can be programed individually in any time sequence to allow various imaging configurations. The possible sequences include 15 views over 14 coverage, 31 views over 30 coverage, and 15 views over 28 coverage at the source-object-distance (SOD) of 650 mm. The x-ray anode is tilted 16 and the entire x-ray tube is rotated 6 as illustrated in Fig.…”

“…12 To address the limitations of the current DBT technology, we recently demonstrated the concept of stationary digital breast tomosynthesis (s-DBT) in a bench top system using a vacuum chamber based CNT x-ray source array. 28 Instead of mechanically moving a single x-ray tube to the multiple viewing angles, s-DBT employs a stationary x-ray source array, which generates x-ray beams from different viewing angles by electronically activating the individual sources (beams) prepositioned at the corresponding viewing angles without mechanical moving the x-ray tube, therefore eliminating the focal spot motion blurring. 29,30 The scanning speed is determined only by the x-ray tube flux (which determines the exposure time per view) and the detector readout time and is independent of angular coverage.…”

A tetrahedron beam computed tomography benchtop system with a multiple pixel field emission x-ray tube

“…MPFEX has been used in a few imaging applications. [11][12][13] We have developed a TBCT benchtop system using an MPFEX tube. In this note, we report our initial experience and results from the MPFEX tube and TBCT system.…”

Statistical iterative reconstruction to improve image quality for digital breast tomosynthesis

“…We acquired data on the stationary DBT prototype system 7,8 to assess the performance of the proposed method. In this system, a flat-panel detector is used for image acquisition.…”

“…7,8 Instead of mechanically moving a single x-ray tube, s-DBT applies a stationary x-ray source array, which generates x-ray beams from different view angles by electronically activating the individual source prepositioned at the corresponding view angle, thereby eliminating the focal spot motion blurring. The scanning speed is thus determined only by the detector readout time and the number of sources, regardless of the angular coverage spans.…”