Visualization of HIFU-induced lesions with thermoacoustic tomography

High-intensity focused ultrasound (HIFU) has proved to be an effective minimally invasive surgical technology. In this study, we focus on the visualization of HIFU-induced lesions using microwave-induced thermoacoustic tomography (TAT). TAT has high spatial resolution, comparable with ultrasound imaging, and high contrast, which is induced by differences in the microwave absorption rates between tumor tissue and normal tissue. TAT can, in addition, differentiate tumors before and after treatment. A single, spherically focused transducer operating at a center frequency of approximately 4 MHZ was used to generate the focused field. The lesion was generated in porcine muscle. A local-tomography-type reconstruction algorithm was applied to reconstruct the TAT image of the lesions. The lesion shown by gross pathology confirms the corresponding region measured by TAT

Imaging of high-intensity focused ultrasound-induced lesions in soft biological tissue using thermoacoustic tomography

An imaging technology, thermoacoustic tomograpy (TAT), was applied to the visualization of high-intensity focused ultrasound (HIFU)-induced lesions. A single, spherically focused ultrasonic transducer, operating at a central frequency of approximately 4 MHz, was used to generate a HIFU field in fresh porcine muscle.Microwave pulses from a 3-GHz microwave generator were then employed to generate thermoacoustic sources in this tissue sample. The thermoacoustic signals were detected by an unfocused ultrasonic transducer that was scanned around the sample. To emphasize the boundaries between the lesion and its surrounding tissue, a local-tomography-type reconstruction method was applied to reconstruct the TAT images of the lesions. Good contrast was obtained between the lesion and the tissue surrounding it. Gross pathologic photographs of the tissue samples confirmed the TAT images.This work demonstrates that TAT may potentially be used to image HIFU-induced lesions in biological tissues

The cooling intensity dependent on landscape complexity of green infrastructure in the metropolitan area

The cooling effect of green infrastructure (GI) is becoming a hot topic on mitigating the urban heat island (UHI) effect. Alterations to the green space are a viable solution for reducing land surface temperature (LST), yet few studies provide specific guidance for landscape planning adapted to the different regions. This paper proposed and defined the landscape complexity and the threshold value of cooling effect (TVoE). Results find that: (1) GI provides a better cooling effect in the densely built-up area than the green belt; (2) GI with a simple form, aggregated configuration, and low patch density had a better cooling intensity; (3) In the densely built-up area, TVoE of the forest area is 4.5 ha, while in the green belt, TVoE of the forest and grassland area is 9 ha and 2.25 ha. These conclusions will help the planners to reduce LST effectively, and employ environmentally sustainable planning