A research team at the Korea Institute of Science and Technology (KIST) said that they have discovered the principle of using ultra-powered ultrasound to destroy cancer cells and tumors without surgery.

KIST Professor Park Ki-joo’s team has discovered the principle of using ultra-powered ultrasound to destroy cancer cells and tumors without surgery. (KIST)
KIST Professor Park Ki-joo’s team has discovered the principle of using ultra-powered ultrasound to destroy cancer cells and tumors without surgery. (KIST)

“When ultrasound energy is collected at a desired target location in the body to generate high heat, tissue can be burned and necrotized without surgical intervention,” KIST said. “Currently, the method is widely used for destroying tumors in uterine fibroids, prostatic hyperplasia, prostate cancer, and metastatic bone tumors, in the clinical field.”

Since the method uses high heat to burn cancer tissues, however, it can also burn normal tissues around the tumor, the hospital added.

To resolve this issue, the researchers, led by Professor Park Ki-joo, confirmed in 2019 that using ultrasound with an acoustic pressure intensity of tens of megapascals (MPa), 10 times more powerful than conventional ultrasound technology.

They could cleanly destroy tumors as if they were cut with a knife without damaging the body by heat.

The technology, which physically destroys tissues without using heat, generates water vapor bubbles at the target point, receiving a strong ultrasound. The target tumor tissue can be physically destroyed by the kinetic energy of the generated primary bubbles.

However, as the ultrasound can generate unwanted micro-bubbles around the same area and destroy nearby cells simultaneously, it was necessary to identify the cause of their creation and accurately predict the occurrence's location.

The researchers conducted a follow-up study by developing a mathematical model to elucidate the principle of the generation of secondary micro-bubbles that spawns when removing tumor tissue using focused ultrasound. Afterward, the team studied the effect of primary water vapor bubbles generated by ultrasound on the ultrasound's progression.

As a result, the team confirmed that the cause was the interference due to the ultrasonic waves spreading in all directions caused by water vapor bubbles and the continuous focused ultrasonic waves. Also, the team found that secondary vapor bubbles were generated in the interfering range.

Compared with the photographed results using a high-speed camera, the team saw the range of the ultrasonic interference and the location where the secondary microbubbles are the same.

“The result of this study not only explains the principle of how the secondary microbubbles are generated but also suggests the possibility to precisely remove only the target tissue more safely by predicting the range,” the team said.

“This study has found out that the ultrasonic scattering effect sequentially generates microbubbles after water vapor bubbles are generated at the ultrasound focus,” Professor Park said. “Using the developed mathematical model, the location of the bubbles and the extent of the tumor tissue to be destroyed can be predicted in advance.”

The team expects the study to develop an ultra-precise focused ultrasound surgery technology capable of physically crushing only tumor tissue without surgical operation, Park added.

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