Quang-Huy Tran, Sharma Bhisham, Theu Luong Thi, Tran Duc-Tan, Chowdhury Subrata, Karthik Chandran, Gurusamy Saravanakumar
Faculty of Physics, Hanoi Pedagogical University 2, Xuan Hoa Ward, Phuc Yen City, Vinh Phuc Province, Vietnam.
Centre of Research Impact and Outcome, Chitkara University, Rajpura, Punjab, 140401, India.
Sci Rep. 2024 Jul 5;14(1):15483. doi: 10.1038/s41598-024-66138-2.
The distorted Born iterative (DBI) method is considered to obtain images with high-contrast and resolution. Besides satisfying the Born approximation condition, the frequency-hopping (FH) technique is necessary to gradually update the sound contrast from the first iteration and progress to the actual sound contrast of the imaged object in subsequent iterations. Inspired by the fact that the higher the frequency, the higher the resolution. Because low-frequency allows for low-resolution object imaging, hence for high-resolution imaging requirements, using low-frequency to possess a high-resolution image from the first iteration will be less efficient. For an effective reconstruction, the object's resolution at low frequencies should be small. And similarly, with high frequencies, the object resolution should be larger. Therefore, in this paper, the FH, and the resolution-turning (RT) technique are proposed to obtain object images with high-contrast and -resolution. The convergence speed in the initial iterations is rapidly achieved by utilizing low frequency in the frequency-turning technique and low image resolution in the resolution-turning technique. It is crucial to ensure accurate object reconstruction for subsequent iterations. The desired spatial resolution is attained by employing high frequency and large image resolution. The resolution-turning distorted Born iterative (RT-DBI) and frequency-hopping distorted Born iterative (FH-DBI) solutions are thoroughly investigated to exploit their best performance. This makes sense because if it is not good to choose the number of iterations for the frequency f in FH-DBI and for the resolution of N × N in RT-DBI, then these solutions give even worse quality than traditional DBI. After that, the RT-FH-DBI integration was investigated in two sub-solutions. We found that the lower frequency f used both before and after the RT would get the best performance. Consequently, compared to the traditional DBI approaches, the normalized error and total runtime for the reconstruction process were dramatically decreased, at 83.6% and 18.6%, respectively. Besides fast and quality imaging, the proposed solution RT-FH-DBI is promised to produce high-contrast and high-resolution object images, aiming at object reconstruction at the biological tissue. The development of 3D imaging and experimental verification will be studied further.
扭曲玻恩迭代（DBI）方法被认为可用于获取具有高对比度和分辨率的图像。除了满足玻恩近似条件外，跳频（FH）技术对于从第一次迭代开始逐步更新声对比度，并在后续迭代中逐渐逼近成像对象的实际声对比度是必要的。受频率越高分辨率越高这一事实的启发，由于低频适用于低分辨率对象成像，因此对于高分辨率成像需求，从第一次迭代就使用低频来获取高分辨率图像效率会较低。为了实现有效的重建，低频下对象的分辨率应较小。同样，在高频下，对象分辨率应较大。因此，本文提出了跳频（FH）和分辨率转换（RT）技术来获取具有高对比度和分辨率的对象图像。通过在频率转换技术中利用低频以及在分辨率转换技术中使用低图像分辨率，可在初始迭代中快速实现收敛速度。确保后续迭代中对象的准确重建至关重要。通过采用高频和大图像分辨率来实现所需的空间分辨率。对分辨率转换扭曲玻恩迭代（RT-DBI）和跳频扭曲玻恩迭代（FH-DBI）解决方案进行了深入研究，以充分发挥它们的最佳性能。这是有道理的，因为如果在FH-DBI中为频率f选择的迭代次数以及在RT-DBI中为N×N分辨率选择的迭代次数不合适，那么这些解决方案给出的质量甚至会比传统DBI更差。之后，在两个子解决方案中研究了RT-FH-DBI集成。我们发现，在分辨率转换前后都使用较低频率f会获得最佳性能。因此，与传统DBI方法相比，重建过程的归一化误差和总运行时间分别大幅降低，分别为83.6%和18.6%。除了快速且高质量的成像外，所提出的RT-FH-DBI解决方案有望生成高对比度和高分辨率的对象图像，旨在对生物组织进行对象重建。3D成像的发展和实验验证将进一步研究。
