Ultrasonic Attenuation of an Agar, Silicon Dioxide, and Evaporated Milk Gel Phantom

Abstract

Background: It has been demonstrated that agar-based gel phantoms can emulate the acoustic parameters of real tissues and are the most commonly used tissue-mimicking materials for high-intensity focused ultrasound applications. The following study presents ultrasonic attenuation measurements of agar-based phantoms with different concentrations of additives (percent of agar, silicon dioxide and evaporated milk) in an effort of matching the material's acoustic property as close as possible to human tissues. Methods: Nine different agar-based phantoms with various amounts of agar, silicon dioxide, and evaporated milk were prepared. Attenuation measurements of the samples were conducted using the through-transmission immersion techniques. Results: The ultrasonic attenuation coefficient of the agar-based phantoms varied in the range of 0.30–1.49 dB/cm-MHz. The attenuation was found to increase in proportion to the concentration of agar and evaporated milk. Silicon dioxide was found to significantly contribute to the attenuation coefficient up to 4% weight to volume (w/v) concentration. Conclusion: The acoustic attenuation coefficient of agar-based phantoms can be adjusted according to the tissue of interest in the range of animal and human tissues by the proper selection of agar, silicon dioxide, and evaporated milk.

Preclinical robotic device for magnetic resonance imaging guided focussed ultrasound

“… 39 Additionally, this phantom has similar acoustical properties as human tissue. 39 , 40 The phantom was specially designed to securely fit the acoustic opening of the device so that vibrations during ultrasonic heating are minimised.…”

Robotic system for magnetic resonance imaging‐guided focused ultrasound treatment of thyroid nodules

“…The phantom was developed with 6% weight per volume (w/v) agar (10164, Merck KGaA) and 2% w/v silicon dioxide (S5631, Sigma-Aldrich) following a preparation procedure mentioned in the literature. 68 The specific phantom was employed since it has previously been shown to exhibit homogeneity in MR images and similar MRI signal with certain human tissues. 69 The SNR was calculated for each image by measuring the average signal intensity in a region of interest (ROI) set within the agar-based phantom and in a ROI set in the background, and substituting in the following equation:…”

“…Initially, sonications were performed with the robotic system on the After the development of all three moulds, the thyroid phantom was developed using a 6% w/v agar (10164, Merck KGaA) and 4% w/ v silicon dioxide (S5631, Sigma-Aldrich) mixture that was prepared according to the method in the literature 68 and was poured in the thyroid mould to solidify. Upon solidification, the 6% w/v agar and 4% w/v silicon dioxide thyroid phantom was placed around the sealed ABS air-filled trachea phantom, and both parts were accommodated in the rectangular mould that was filled with an agar-based mixture consisting of 6% w/v agar (10164, Merck KGaA) which was prepared according to the previously described procedure.…”

“…Upon solidification, the 6% w/v agar and 4% w/v silicon dioxide thyroid phantom was placed around the sealed ABS air-filled trachea phantom, and both parts were accommodated in the rectangular mould that was filled with an agar-based mixture consisting of 6% w/v agar (10164, Merck KGaA) which was prepared according to the previously described procedure. 68…”

Focused ultrasound for the remote modulation of nitric oxide release from injectable PEG-fibrinogen hydrogels for tendon repair

“…However, the acoustic simulation did not account for the presence of microparticles or any effects of varying concentration of microparticles on acoustic attenuation of the composite hydrogels. Existing literature suggests that microparticle presence and increasing concentrations in the composite hydrogel would increase acoustic attenuation (Drakos et al, 2021). Another limitation of the acoustic simulation when compared to experimental FUS treatments of the hydrogels was the absence of the potential effects of the hydrogel sample well holders on acoustic attenuation.…”