Tuesday, July 26, 2005

Tissue-Equivalent Phantoms

Synthetic materials have been developed for invitro research of the effects of radiation on human tissue. These materials are known as tissue-equivalent phantoms and can be designed to mimic the dielectric properties of different tissues. The best studied phantom models that I have come across were first developed by Arthur Guy in 1971. In my case, I am looking into the effects of microwave radiation on the prostate from transurethral microwave theremotherapy (TUMT) devices.

Guy (1971) has developed tissue-equivalent phantom models specifically for preclinical studies of the effects of microwave radiation on human tissue. Based on Guy’s methods, Chou and coworkers (1984) published formulas for preparing tissue-equivalent phantom models with similar dielectric properties of muscle tissue at specific frequencies, including 915 MHz that commonly used in Transurethral Microwave Thermotherapy (TUMT) devices. This and similar methods have since been used by several groups including FDA Premarket Approval preclinical studies conducted by the device manufacturers in studying the heating profiles of TUMT devices.

In case this is useful to anyone, the references below are good resources for developing your own custom phantoms.

-Diego

1.      Guy AW, Analyses of Electromagnetic Fields Induced in Biological Tissues by Thermographic Studies on Equivalent Phantom Models. IEEE Transactions on Microwave Theory and Techniques. MTT-19 (2): 205-214, 1971

2.    Chou CK, Chen GW, Guy AW, Luk KH. Formulas for Preparing Phantom Muscle Tissue at Various Radiofrequencies. Bioelectromagnetics. 5: 435-441, 1984

3.      Land DV, Campbell AM. A quick accurate method for measuring the microwave dielectric properties of small tissue samples. Physics in Medicine and Biology. 37 (1): 183-192, 1992

4.      Dimofte A, Finlay JC, Zhu TC. A method for the determination of the absorption and scattering properties interstitially in turbid media. Physics in Medicine and Biology. 50: 2291-2311, 2005

5.      Gabriel C, Gabriel s. Compilation of the dielectric properties of body tissues at RF and microwave frequencies. Kings College, London. 1996. Accessed 7/26/05.

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