There are two biological actions produced in the patient’s body – thermal effect and non-thermal effect. Thermal Effect When ultrasound is applied to cancer cells at a temperature of over 60 °C (140 °F) for a few seconds, the cancer tissue coagulates and is destroyed. Non-Thermal Effect Ultrasound also generates a non-thermal effect which is called cavitation. Cavitation is the phenomenon by which air bubbles are generated when ultrasound is spotted. The shock wave generated by air bubbles or a micro jet stream is also considered to kill cancer cells.
Radiation Exposure The energy level of HIFU is about 1000 times that of an ultrasound device for imaging yet when compared to a proton beam, X-ray or a CT, it is extremely low and thus is fairly safe. And there is no worry about radiation exposure. Skin Burn The targeted area by a single irradiation is limited to 3 mm x 3 mm x 10 mm. When there are cancer cells in an internal organ near the skin, it will cause skin burn due to the higher skin temperature. The FEP?BY02 HIFU has a transducer with a large diameter whereby safety is enhanced by increasing the angle of incidence by 80 degrees.
In general, it takes about 1 hour and 30 minutes for a single treatment which is performed 1 or 2 times. Anaesthetics are not usually administered. This treatment uses ultrasound energy so there is no limitation as with radiation. HIFU treatment can be used repeatedly because there is no risk of radiation exposure. Depending on the size and location of the cancer, various treatments will be looked at. Generally, hospitalization is not required. Treatment contents, dose and the need for hospitalization, however, vary depending on the patient’s medical condition.
HIFU Treatment Indications
- Uterine fibroids (Myoma)
- Liver cancer
- Metastatic liver tumor
- Breast cancer
- Kidney cancer
- Pancreatic cancer
- Prostate cancer
- Soft-tissue sarcoma
- Bone tumors
- Other indications
Significance of HIFU Treatment for Hepatocellular Carcinoma (HCC)
The use of Gd-EOB-DAPT MRI makes it possible to detect hepatocellular carcinoma (HCC), the most common type of liver cancer and difficult to detect with dynamic CT at an early stage. Thus, prompt treatment measures are required. In the circumstances, HIFU has made it possible to treat a patient with liver cancer sized 1-2 cm for approximately one hour without hospitalization. HIFU is considered one of the leading treatments for HCC in Japan.
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