The effect of HIFU exposure time on the treatment of hepatocellular carcinoma

Today, hepatocellular carcinoma is one of the most common and dangerous types of liver cancer. In most treating methods of liver cancer such as using microwaves, radio frequency radiation, etc., the electrode enters the patient's body, so these methods are ineffective in the case of metastatic cancer. High-intensity focused ultrasound (HIFU) therapy is an appropriate non-invasive treatment method which no external elements enter the patient's body and can be used frequently. However, the success of the treatment depends on treatment parameters such as exposure time. Therefore, in this paper HIFU heat therapy is simulated for the treatment of hepatocellular carcinoma as a non-invasive method. For this purpose, Model-JC HIFU System, tissue and tumor, and water are included in the simulations. The tumor is considered as a symmetrical sphere with a radius of 0.4 cm. Then Helmholtz and bioheat equations are solved by finite element method (FEM) with considering the boundary and initial conditions. The frequency and power of ultrasonic waves are 1 MHz and 150 W, respectively. Investigation of the temperature distribution and fraction of necrotic tissue declare that the exposure time of HIFU is an important parameter. If the treatment is performed in 100 seconds with this HIFU system, the oval area with large diameter and small diameter of 21.1 and 9.95 mm is completely destroyed. Also, complete tumor destruction is available in HIFU exposure time of 72 seconds. Furthermore, the results also show that this method is suitable for deep and oval tumors.