Retinoblastoma is a malignant tumor in children. A new method for the treatment of cancerous tumors is hyperthermia using ultrasonic waves. Treatment with focused ultrasound waves is a non-invasive method. In the hyperthermia temperature range (42-46°C), tumor cells can be degraded depending on the temperature and duration of the hyperthermia. In this study, the effect of hyperthermia by ultrasonic waves on the percentage of viability of human retinoblastoma cells (Y79) was investigated using MTT assay after 48 hours.

Initially, hyperthermia on the cell requires temperature control using a digital thermometer. The cell culture plate was subjected to 3MHz ultrasonic exposure and intensity of 1W/cm2. Initially, to reach the hyperthermia temperature, it was under continuous mode and then switched to a pulse mode with a duty factor of 40% to stay stable at hyperthermia temperature. It was found that to achieve hyperthermia temperature, the duration time of continuous mode should be 2 minutes. Retinoblastoma cells cultured in RPMI1640 medium with 10% FBS and 1% antibiotic at 37°C. Cells with ultrasonic waves of 3MHz and intensity of 1W/cm2 and duty factor of 40% treated with different exposure times of hyperthermia (0.5,1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7,8,9,10 and 11minutes) was irradiated. The percentage of viable cells in each treatment group compared to control group (without irradiation) was evaluated by MTT method after 48 hours. Data were analyzed using SPSS 22 software.

Based on the findings, the percentage of cell viability in treatment groups with a duration of hyperthermia more than 4 minutes was significantly different compared to the control group after 48hours but treatment groups with a duration of hyperthermia less than 4 minutes was not significantly different compared to the control group. Also, in the treatment group with a duration of hyperthermia of 9 minutes, nearly 50% of cells died and in the treatment group with a hyperthermia duration of 11 minutes, nearly 69% of cells died.

Due to the proven 3MHz ultrasound effect on cancer cell lines in this study, this method can be used in the treatment of retinoblastoma.