Evaluation of correlation between chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation

Currently several therapeutic applications of ultrasound in cancer treatment are under progress which uses cavitation phenomena to deliver their effects. There are several methods to evaluate cavitation activity such as chemical dosimetry and measurement of subharmonic signals. In this study, the cavitation activity induced by the ultrasound irradiation on exposure parameters has been measured by terephthalic acid chemical dosimetry and subharmonic analysis. Experiments were performed in the near 1 MHz fields in the progressive wave mode and effect of duty cycles changes with 2 W/cm2 intensity (ISATA) and acoustic intensity changes in continuous mode on both fluorescence intensity and subharmonic intensity were measured. The dependence between fluorescence intensity of terephthalic acid chemical dosimetry and subharmonic intensity analysis were analyzed by Pearson correlation (p-value < 0.05). It has been shown that the subharmonic intensity and the fluorescence intensity for continuous mode is higher than for pulsing mode (p-value < 0.05). Also results show that there is a significant difference between the subharmonic intensity and the fluorescence intensity with sonication intensity (p-value < 0.05). A significant correlation between the fluorescence intensity and subharmonic intensity at different duty cycles (R = 0.997, p-value < 0.05) and different intensities (R = 0.985, p-value < 0.05) were shown. The subharmonic intensity (μW/cm2) significantly correlated with the fluorescence intensity (count) (R = 0.901; p < 0.05) and the fluorescence intensity due to chemical dosimetry could be estimated with subharmonic intensity due to subharmonic spectrum analysis. It is concluded that there is dependence between terephthalic acid chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation activity.