Using the staggered grid full domain 3D modeling schemes of various accuracies have been developed. This study focuses on the second order finite difference method with the 13-point rule for meshes extending into the air. Tests with Krylov space iterative solvers indicate that the restarted Bi-CG Stablised method offers the best convergence for our problems. Because the air and the conductive earth have distinctive physical properties which greatly broaden the spectra of the whole matrix system, the whole mesh with both domains in one system either converges very slowly or fails to converge completely. However, the matrix systems for each domain have much smaller condition numbers. To overcome instability caused by the inclusion of the air in the mesh a domain decomposition method are experimented. Tests show that the adaptive iteration amongst the subdomains converges exponentially, which implies that large models can be solved by using the domain decomposition method.

抄録全体を表示

Twenty two cases with primary hepatocellular carcinoma, 6 cases with cholangiocellular carcinoma and 12 cases with metastatic liver cancer were examined by scintiphotography using scintillation camera with ^99mTc radio colloid (^99mTc-sulfur colloid, ^99mTc-staneous colloid or ^99mTc-phytate) and ⁶⁷Ga-citrate or ⁶⁷Ga-malate. In addition to the conventional analysis of hepatic scintiphotography, the data were also fed into computer system and stored in the memory (64×64 memory). Application of Fourier transforms and the interative according to Iinuma's method to the data were performed to restore true information of hepatic image. The subtraction scintigram was obtained by subtracting ^99mTc activity from ⁶⁷Ga activity in each matrix data treated with computer focusing.
Twenty of 22 cases of patients with hepatocellular carcinoma were diagnosed by liver by liver scintiphotography with ^99mTc radio colloid, but one of 2 cases undetectable on conventional scintigram. In the remaining one case, diagnosis was accomplished by continuous increase of serum α-fetoprotein. One case of metastatic liver cancer invisible on conventional scintiphotography were diagnosed by means of computer scintigraphy and subtraction scintigraphy. This is indicated that more cases of hepatic carcinoma can be deagnosed by the application of serial determination of serum α-fetoprotein, computer scintigraphy and subtraction scintigraphy simultaneously.

抄録全体を表示