Balcom B J, Lees T J, Sharp A R, Kulkarni N S, Wagner G S
Physics Department, University of New Brunswick, Fredericton, Canada.
Phys Med Biol. 1995 Oct;40(10):1665-76. doi: 10.1088/0031-9155/40/10/008.
We analyse the diffusion problem in the traditional Fe(II/III) agarose gel system employed in MRI studies of radiation dosimetry. The diffusion coefficient is measured using an inversion recovery null-point imaging method in a model gel/water phantom. The diffusion coefficient of Fe(III) in 1% agarose gel at pH 1.1 is D = 2.7 +/- 0.3 x 10(-6) cm2 s-1. The diffusion coefficient of Fe(II) is D = 3.3 +/- 0.5 x 10(-6) cm2 s-1. Measurement of the diffusion coefficients permits simulation of the MRI signal intensity from phantoms with model radiation dose distributions. We allow for diffusion of both Fe(II) and Fe(III) in our simulations as well as the effect of both relaxation agents on the local spin-lattice relaxation time T1. We also analyse the effects of the physical penumbra on the diffusion problem.
我们分析了传统的Fe(II/III)琼脂糖凝胶系统在辐射剂量学MRI研究中的扩散问题。在模型凝胶/水体模中，使用反转恢复零点成像方法测量扩散系数。在pH值为1.1的1%琼脂糖凝胶中，Fe(III)的扩散系数为D = 2.7 +/- 0.3 x 10(-6) cm2 s-1。Fe(II)的扩散系数为D = 3.3 +/- 0.5 x 10(-6) cm2 s-1。扩散系数的测量使得能够模拟具有模型辐射剂量分布的体模的MRI信号强度。在我们的模拟中，考虑了Fe(II)和Fe(III)的扩散以及两种弛豫剂对局部自旋晶格弛豫时间T1的影响。我们还分析了物理半影对扩散问题的影响。
