A thermoacoustic imaging system with variable curvature and multi-dimensional detection adapted to breast tumor screening

Abstract

Microwave-induced thermoacoustic (TA) imaging is efficient in detecting anomalous absorption areas, especially breast tumors. The operation of previous imaging systems has generally suffered from complexity, and early-stage tumors could be missed because of signal loss. In this paper, we report a variable-curvature and multi-dimensional screening method realized by combining a redesigned adaptive algorithm and an integrated TA breast screening system (ITBCS) comprising a flexible detector and a traction device designed for multi-axis rotation. In contrast to conventional TA imaging systems, the proposed system improves the ability to identify early-stage breast tumors, with a simplified system and operational process. Variable curvature is achieved by the flexible characteristics of the detector, which achieves good shape adaptation between the tissue and the detector. Moreover, multi-dimensional scanning is achieved by the multi-axis traction device and meets the requirements for angle transformation and dynamic imaging. The experimental results indicate that ITBCS exhibits a good performance in detecting breast tumors. Faster screening makes inspection more efficient, thereby improving clinical applicability and providing a convenient facility for large-scale physical examination.

Technical Note: Anti‐phase microwave illumination‐based thermoacoustic tomography of in vivo human finger joints

“…TAT combines the advantages of high microwave absorption contrast and high ultrasound resolution. To date, TAT has been used for breast cancer detection, foreign body detection, brain imaging, molecular imaging and blood imaging . TAT can directly recover the distribution of absorbed microwave energy density .…”

Technical Note: Design of a handheld dipole antenna for a compact thermoacoustic imaging system

“…One potential caveat of this proposal is that in vivo tissue has heterogeneous distributions of permittivity and conductivity than that of the targets used in the present study, making it harder to compensate the electric field attenuation accurately. However, breast tissue is adipose‐dominated, and the conductivity contrast between malignant and normal breast tissues is up to sixfold at microwave frequencies . Thus, microwaves can easily penetrate several centimeters through normal breast tissue to reach deep tumors with acceptable distortions.…”

“…However, breast tissue is adipose-dominated, and the conductivity contrast between malignant and normal breast tissues is up to sixfold at microwave frequencies. 16 Thus, microwaves can easily penetrate several centimeters through normal breast tissue to reach deep tumors with acceptable distortions. Further evaluation of our compact handheld antenna utilizing both breast tumor-bearing animals and excised breast cancer specimens is under way in our laboratory, and the results from these studies will be reported in the near future.…”

“…To simplify the variables in comparison of the handheld dipole antenna with the open‐ended waveguide and pyramidal horn antenna, only transmission‐mode (TM) TAI was used in this study (application of the handheld dipole antenna to reflection‐mode TAI can easily extended). Note that while a shorter pulse width (e.g., 2~3 ns) and lower center frequency (e.g., ~420 MHz) can achieve higher spatial resolution and deeper penetration, no such microwave source was available in our laboratory at present . Thus, in this system, pulsed microwaves with a center frequency of 3.0 GHz and a peak power of 70 kW radiated from a custom‐designed magnetron generator were coupled to the antenna via a semirigid coaxial cable (1.5 m long with 1.2 dB insertion loss) to excite thermoacoustic (TA) waves .…”

“…Note that while a shorter pulse width (e.g., 2~3 ns) and lower center frequency (e.g.,~420 MHz) can achieve higher spatial resolution and deeper penetration, no such microwave source was available in our laboratory at present. 16 Thus, in this system, pulsed microwaves with a center frequency of 3.0 GHz and a peak power of 70 kW radiated from a custom-designed magnetron generator were coupled to the antenna via a semirigid coaxial cable (1.5 m long with 1.2 dB insertion loss) to excite thermoacoustic (TA) waves. 17 The microwave pulse duration and repetition rates were 0.75 ls and 10 Hz, respectively.…”