Abstract
The object of the study is to measure the photon mass attenuation coefficient of hydrophilic materials with the aim of investigating their suitability as tissue equivalent material. Two types of hydrophilic material were tested; the ED4C which has 72% water uptake by weight and the H-40 which has 40% water uptake by weight. Measurements were made for both types in dry and fully hydrated state. The measurements were obtained by using (a) narrow beam geometry and mono-energetic beams with a range of energies between 13.37 and 662 keV; (b) medical x-ray sources, used in diagnostic radiology such as mammography, radiology and CT scans; and (c) medical linear accelerator to generate high energy beams such as 6 and 18 MV beams. The measured mass attenuation coefficients were compared with the mass attenuation coefficient of various body tissues published by ICRU with the use of XCOM computer code. Magnetic Resonance Imaging (MRI) was used to measure T1 and T2 of the hydrophilic material to study the suitability of the material as tissue equivalent for MRI. The physical characteristics of the hydrophilic materials were studied by measuring the uptake rate (amount of water absorbed by the sample in a certain time) versus sample thickness, and generating uptake rate curves for each thickness for both types of material. Mathematical models to fit the uptake rate curves by applying diffusion equations were obtained. The uptake rate (hydration process) and dryness (dehydration process) were conducted at two different water and room temperatures of 23°C and 9°C.