Tissue-equivalent

Sv - Sievert radiation health effects (IJ/kg tissue) equivalent to ICX) REM. system - A collection of components to perform a purpose. 

Personal monitors are irradiated to a known value of dose equivalent while mounted on a 30 cm X 30 cm X 15 cm slab of polymethylmethacrylate (PMMA). PMMA is an inexpensive and widely available material, but has a somewhat different density and yields somewhat different amounts of backscatter than a tissue equivalent material (Selbach et al., 1989). 

Xu (1994) explored three photon energies (i.e., 80 keV, 300 keV and 1 MeV) and a number of irradiation geometries, including geometries with a large range of non-normal incidence. In particular, Xu (1994) provided (estimate) values for a variety of point sources at various locations and distances from the body. Xu (1994) computed the/fpdO) values in tissue-equivalent spheres located on the relevant surface of the anthropomorphic phantom. 

GROSSWENDT, B. (1991). The angular dependence and irradiation geometry factor for the dose equivalent for photons in slab phantoms of tissue-equivalent material and PMMA, Radiat. Prot. Dosim. 35, 221-235. 

Armstrong WA, Facey RA, Grant DW, Flumphreys WG (1963) A tissue-equivalent chemical dosimeter sensitive to 1 rad. Can J Chem 41 1575-1577... 

A representative microscopic network is introduced within each finite element allowing macroscopic strain to be transferred to the network boundaries. The representative network is designed to capture the essential features of the collagen mesh in a tissue equivalent - interconnectivity and fiber nonlinearity. The network within each finite element is chosen so as to be the smallest representative unit of the microstructure within the material space of the element. The fibers in each element are assumed to be independent of those in other elements. The macroscopic spatial variations are captured by the element-to-element variations in the network. The representative network is generated randomly and has these features ... 

We have presented a multi-scale method to simulate a fibrillar structure such as a collagen tissue equivalent. The method is able to predict macroscopic behavior based on microscopic properties, and it also demonstrates the microscopic restructuring that can occur during deformation. Although the method is computationally demanding, the potential for parallelization is high, and three-dimensional problems should not be out of reach. 

Agoram, B., and Barocas, V.F1. (2001) Coupled macroscopic and microscopic scale modeling of fibrillar tissues and tissue equivalents. Journal of Biomechanical Engineering 123, 362-369... 

Note that the radiation weighting factor for alpha particles is 20 times that of gamma rays and f3 particles. With the above information, we can calculate the tissue equivalent dose Hr using ... 

Optional parameters of hypothalamic-pituitary function to be determined are the hypothalamic content of CRH, and the anterior pituitary content of ACTH (group means and standard deviation). Final data may be calculated as hormone content per mg or gram of organ tissue (pituitary hormone contents), or as hormone content per tissue equivalent (hypothalamic fragments). 

In vivo counting systems are calibrated using tissue-equivalent phantoms. These phantoms have shapes similar to the human torso and are made of polystyrene or other tissue equivalent material. Standard uranium sources of known activity are inserted into the phantom at locations where uranium would be expected to accumulate in a human body (DOE 1988). Relationships are determined between the uranium activity measured by the detection system and the known activity in the phantom (DOE 1988 HPS 1996). 

A summation of the tissue equivalent doses, each multiplied by the appropriate tissue-weighting factor ... 

Peripheral Tissue Equivalent (PTE) module a three-dimensional construct that recapitulates the innate arm of the immune system... 

Lymphoid Tissue Equivalent (LTE) module an artificial lymph node, where generated antigen-presenting cells (APCs) efficiently interact with T and B lymphocytes to initiate antigen-specific immune responses... 

Figure 19-4 Reactogenicity of commercial vaccines in the PTE module and by monocytes alone. Vaccines hepatitis B virus (FIBV 1 200), influenza virus vaccine (Fluzone 1 400), and tetanus toxoid vaccine (DTaP 1 200) were used in the study. PTE is the peripheral tissue equivalent module containing CD33+ positively selected cells (left). CD33+ monocytes alone do not produce any appreciable cytokines nor chemokines when stimulated with the vaccines (right).

Testskin human tissue equivalents (human kerationcytes on collagen or collagen - glycosaminoglycan matrix with human fibroblasts) forming an epidermis for examining Dye penetration (Neutral Red)... 

Fig. 3 Reversed-phase HPLC of the shoot and seed extracts of P. vulgaris as monitored by rice-lamina inclination test [(A) stem (C) seed] and RIA with anti-CS antiserum [(B) stem (D) seed]. Dosages in fresh-weight tissue equivalents 150 g in A 2 g in B 30 g in C and 0.5 g in D. TeS teasterone TyS typhas-terol.

An important parameter, CT dose index (CTDI, defined as the cumulative dose along the patient s axis for a single tomographic image), should be evaluated at least semiannually at different values of kVp and mA. It is measured by using an ionization chamber or a thermoluminescent dosimeters placed in a tissue-equivalent acrylic phantom simulating head or body. ACR (2007) recommends maximum doses CTDI) of 6 rad (60 mGy) for brain, 3.5 rad (35 mGy) for adult abdomen and 2.5 rad (25 mGy) for pediatric (5-year-old) abdomen. The details of these measurements are available in standard CT physics books. 

Although the limitations of the method and sophisticated equipment required are likely to restrict the use of the e aq dosimeter to places equipped for pulse radiolysis, the system has some advantage in that its low atomic number makes the dosimeter tissue equivalent. LiF, however, is not exactly tissue equivalent for x-rays of energy below about 100 Kev. its response becomes 20 to 30% too high below 50 Kev. (3). 

F.E.W. Schmidt, J.C. Hebden, E.M.C. Hillman, M.E. Fry, M. Schweiger, H. Dehghani, D.T. Delpy, S.R. Arridge, Multiple-slice imaging of a tissue-equivalent phantom by use of time-resolved optical tomography, Appl. Opt. 39, 3380-3387 (2000)... 

Tissue equivalent proportional counter (TEPC) is the instrument for measuring the dis-... 

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