Utilization of a multilayer polyacrylamide phantom for evaluation of hyperthermia applicators

Abstract

A muscle-stimulating material made of polyacrylamide gel (PAG) for testing various kinds of hyperthermia applicators was investigated. The permittivity and conductivity dispersion of PAG, as well as an internal wavelength and penetration depth, were in good agreement with those of actual muscle at frequencies between 500 MHz and 3 GHz. A single formula for PAG covering three ISM bands, most commonly used for hyperthermia, 433, 915 and 2450 MHz, is presented. The physical properties of the PAG phantom allow any desired form or shape to be moulded, including shapes conforming to the actual geometry of an interstitial or intracavitary applicator. Utilization of a multilayer phantom makes possible the generation of experimental three-dimensional specific absorption rate (SAR) distributions composed from several two-dimensional SAR images at different depths or radial distances from the applicator. Spatial resolution of 1 mm can be achieved. The two-dimensional SAR distributions at different depth values for commercial superficial applicator, an interstitial antenna and a new oesophageal applicator are presented.

Measurement of the thermal conductivity of polyacrylamide tissue-equivalent material

“…The recipe provided by Surowiec et al 1 has been used by this group 4,26 and by others 5 to investigate various aspects of microwave heating in tissue. The Surowiec et al phantom was designed to mimic the electrical and thermal properties of human muscle tissue at 378C.…”

“…The composition of polyacrylamide-based materials, in particular, can be adjusted to mimic the electrical and thermal properties of various types of human tissue [1][2][3] . As a result, these materials have been used extensively to evaluate radiofrequency (RF) and microwave applicators for hyperthermia and thermal therapy [4][5][6][7][8][9][10][11][12][13][14][15][16] , to validate numerical simulations of RF and microwave-based hyperthermia treatments 13,[17][18][19] and to evaluate the use of various thermometry techniques in RF and microwave hyperthermia [20][21][22][23][24][25][26] .…”

Preparation of a skin equivalent phantom with interior micron-scale vessel structures for optical imaging experiments

“…Other engraving methods could mostly disturb the optical properties of the turbiding matrix material [17]. Although the nature of the mutilayers of skin cutis can not be simulated, like described in [2,10,14], the diameter of the generated vessels, that we pursued, is more close to that of a real vascular compared to the results from Refs. [12][13][14][15].…”

“…In view of skin equivalent phantoms, many researches have been conducted onto the concept of multilayers that imitate the layers of the cutis: epidermis, dermis. Multilayer structure favors to assess some imaging modalities and their associated algorithms [9][10][11][12]. It is even practical to emboss vessel structures in multilayer phantoms to include biological / artificial solution [8,13].…”

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and dielectric liquid filled rectangular and a cylindrical phantom at 1.8 GHz

“…Many researchers have worked on the development of tissue-like phantoms for high and low water content human tissues at different frequencies. Early work exists in [9] and more recently, the authors of [10,11] and [12] have been involved in the fabrication of phantoms for this purpose.…”