An investigation on thermal Effects of therapeutic ultrasound on silicone tissue mimicking phantoms

Silicone is one of the key ingredients of most of implant used in human body. because of similar properties like elasticity to human soft tissue, silicone is a reliable material for medical implants and its being used as tissue mimicking phantoms in different medical studies or as a educational phantom for example in training students for breast core needle biopsy. With an accurate design It’s possible to build low-cost, accessible Silicone rubber with properties like elasticity and acoustic impedance similar to human soft tissue or properties similar to expensive silicone implants that are used inside human body. implants that are used in human body are expensive because all of ingredients are compatible inside body and these products have food and drug administration (FDA) approval. By building low-cost silicone rubber with elasticity and acoustical impedance in the range of human soft tissue and FDA approved expensive medical implants we can investigate thermal effects of therapeutic ultrasound on soft tissue and implants. Because of similar elasticity Silicone rubber can be used as core needle biopsy training phantom for students. In this study we built a type of silicone rubber known as Room-Temperature-Vulcanizing silicone or silicone RTV with mechanical properties close to soft tissue and breast implants. Non-ionazing ultrasound waves are one of the most important methods in physical therapy for patients with silicone breast implant who suffer from capsular contractures which is a common complication after breast implant surgery. recently therapeutic ultrasound was suggested by many researchers to treat capsular contractures. For issues like this, Precise knowledge about effects of ultrasound on silicone is necessary. One of issues with using therapeutic ultrasound in patients is choosing ultrasound mechanical wave parameters for therapy and evolving current clinical guidelines especially for patients with prosthesis and breast implants. The most common type of implant used in human body are silicone implants. The aim of this study is to determine change in temperature in silicone phantoms due to ultrasound.With medical phantoms it is possible to investigate all parameters like different ultrasound powers and comparing countinous waves radiation with pulse waves with certain ratios. By controlling the system in a way that only one parameter changes at a time with a phantom that holds its properties after each experiment this task is achievable. performing experiment in 25 °C room temprature with silicone rubber phantom with 0.4 watt and 0.8 watt on same phantom in 10 minutes showed 6.8 °C & 9.3 °C increase in temprature respectively. Experiment on the same silicone rubber phantom with continuous waves and pulse waves with 1 to 2 , 1 to 4 and 1 to 8 were measured for 10 minutes and increase in temprature was 9.3 °C which was more than pulse waves. Temprature increase for all pulse ratios were close to eachother due to heat exchange between phantom and environement. Knowledge about effect of mechanical ultrasound waves on silicone rubber has engeeniring applications. since we measured temprature in the center of the silicone phantom with dimensions close to breast implants, these experiments might be usefull when using therapeutic ultrasound near silicone implants. for patients with silicone breast implant even considering the heat exchange between body and implant the temprature increase in the center or core of implant which has limited heat exchange might be dangerous. Medical conclusion of these results is using caution and necessity of new protocols in clinics when therapeutic ultrasound is used for pain alleviation or physical therapy in regions of body near silicone implants due to high temprature increase in implant and possible rupture or damage to implant or sorrunding tissue.

کلیدواژه ها:

Silicone implant ، Therapeutic Ultrasound ، Tissue Mimicking Phantom ، Temperature Profile