Acoustic cavitation plays an important role in sonochemical processes and the rate of sonochemical reaction is influenced by sonication parameters. There are several methods to evaluate cavitation activity such as chemical dosimetry. In this study, to comparison between iodide dosimetry and terephthalic acid dosimetry, efficacy of sonication parameters in reactive radical production has been considered by iodide and terephthalic acid dosimetries. For this purpose, efficacy of different exposure parameters on cavitations production by 1 MHz ultrasound has been studied. The absorbance of KI dosimeter was measured by spectrophotometer and the fluorescence of terephthalic acid dosimeter was measured using spectrofluorometer after sonication. The result of experiments related to sonication time and intensity showed that with increasing time of sonication or intensity, the absorbance is increased. It has been shown that the absorbance for continuous mode is remarkably higher than for pulsing mode (p-value < 0.05). Also results show that with increasing the duty cycles of pulsed field, the inertial cavitation activity is increased. With compensation of sonication time or intensity in different duty cycles, no significant absorbance difference were observed unless 20% duty cycle. A significant correlation between the absorbance and fluorescence intensities (count) at different intensity (R = 0.971), different sonication time (R = 0.999) and different duty cycle (R = 0.967) were observed (p-value < 0.05). It is concluded that the sonication parameters having important influences on reactive radical production. These results suggest that there is a correlation between iodide dosimetry and terephthalic acid dosimetry to examine the acoustic cavitation activity in ultrasound field.

The inertial cavitation activity depends on the sonication parameters. The purpose of this work is development of dual frequency inertial cavitation meter for therapeutic applications of ultrasound waves. In this study, the chemical effects of sonication parameters in dual frequency sonication (40 kHz and 1 MHz) were investigated in the progressive wave mode using iodide dosimetry. For this purpose, efficacy of different exposure parameters such as intensity, sonication duration, sonication mode, duty factor and net ultrasound energy on the inertial cavitation activity have been studied. To quantify cavitational effects, the KI dosimeter solution was sonicated and its absorbance at a wavelength of 350 nm was measured. The absorbance values in continuous sonication mode was significantly higher than the absorbance corresponding to the pulsed mode having duty factors of 20-80% (p<0.05). Among different combination modes (1 MHz 100%+40 kHz 100%, 1 MHz 100%+40 kHz 80%, 1 MHz 80%+40 kHz 100%, 1 MHz 80%+40 kHz 80%), the continuous mode for dual frequency sonication is more effective than other combinations (p<0.05). The absorbance for this combined dual frequency mode was about 1.8 times higher than that obtained from the algebraic summation of single frequency sonications. It is believed that the optimization of dual frequency sonication parameters at low-level intensity (<3 W/cm(2)) by optically assisted cavitation event sensor can be useful for ultrasonic treatments.

This study was designed to evaluate the effect of the radiological technologists’ training on optimising the eye lens dose in brain computed tomography (CT) examinations. The lens dose of 50 adult patients was measured using thermoluminescent dosimeters before and after technologists’ training. Dose values of lenses, dose length product (DLP), volumetric CT dose index (CTDIvol) as well as image quality in terms of quantitative (contrast to noise ratio and signal to noise ratio) and subjective (artefact) parameters were compared before and after training. Lens dose values were 31.57 ± 9.84 mGy and 5.36 ± 1.53 mGy before and after training, respectively, which was reduced by ~83% (p &lt; 0.05). The values of DLP, CTDIvol and image quality parameters were not significantly different (p &gt; 0.05) and all images were diagnostically acceptable. Excluding the orbits from the scanning range is an efficient approach to optimize the lens dose; the training of the technologists has also a pivotal role in dose reducing.

In this study, a technique to overcome the limitation of systemic administration of Methylene (MB), encapsulation of methylene blue in polymeric liposomes and drug release after dual frequency sonication has been investigated. After loading methylene blue into liposomes of the mice, the drug encapsulation efficiency and stability is measured by fluorometrically and its biodistribution of drug is studied. The level of drug release in vitro is checked using single and dual frequency sonication (1MHz+40kHz) with intensity through fluorometrically. The dynamic light scattering (DLS) studies showed that the synthesized liposomes had an average size of 66±5 nm. The results indicate that a 5 min applying the dual frequency sonication causes a MB release of about 79% nanoparticles. The biodistribution study revealed that, the drug content in the group that received liposomal drugs in the tumor tissue was significantly higher than in the group receiving methylene blue in its free form (p<0.05). Also, for the group that received liposomal MB, the ultrasound measurement showed significantly higher drug content in the tumor tissue than other groups (p<0.05). It is concluded that the sonication with a dual frequency system causes the drug to release from the liposome and increases drug uptake ability.

This study was designed to investigate the effect of the different topograms (AP and dual AP/Lateral) on patient dose indices and image quality in thorax and abdomen-pelvis CT. Size-specific dose estimation (SSDE), volumetric CT dose index (CTDIvol), milliampere seconds (mAs), effective dose, as well as signal to noise ratio (SNR) and contrast to noise ratio (CNR) of 60 thorax and 60 abdomen-pelvis CT scans were analyzed. In thorax CT, SSDE, mAs, CTDIvol and effective dose were significantly reduced by using dual topograms (p < 0.05) but not significantly reduced in abdominal-pelvic scans (p > 0.05). There was no significant difference between CNR parameter in the two groups for thorax CT (p > 0.05) and SNR parameter in abdomen-pelvic CT (p < 0.05) and all images were diagnostically acceptable. The use of two topograms in thorax CT is an efficient approach to reduce dose indices without decreasing the image quality.