ABSTRACT
In nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. Monte Carlo simulation and phantoms have been used in many works before. The shape, size and volume in organs are varied, and this variation will produce error in dose calculation if no correction is applied. A computational framework for constructing individual phantom for dosimetry was performed on five liver CT scan data sets of Japanese normal individuals. The Zubal phantom was used as an original phantom to be adjusted by each individual data set. This registration was done by Spherical Harmonics [SH] and Thin-Plate Spline methods. Hausdorff distance was calculated for each case. Result of Hausdorff distance for five individual phantoms showed that before registration ranged from 140.9 to 192.1, and after registration it changed to 52.5 to 76.7. This was caused by index similarity ranged from%56.4 to%70.3. A new and automatic three-dimensional [3D] phantom construction approach was suggested for individual internal dosimetry simulation via Spherical Harmonics [SH] and Thin-Plate Spline methods. The results showed that the individual comparable phantom can be calculated with acceptable accuracy using geometric registration. This method could be used for race-specific statistical phantom modeling with major application in nuclear medicine for absorbed dose calculation
Subject(s)
Humans , Monte Carlo Method , Liver , Tomography, X-Ray Computed , Nuclear Medicine , Phantoms, ImagingABSTRACT
A comparison of the sequences in an internally transcribed spacer [ITS] 1 region of rDNA between clonally regenerated A. vera and the same species in Japan, USA and Egypt revealed the presence of two types of nucleotide sequences, 252 and 254 bps. Based on the findings in the ITS 1 region, A.vera having 252 and 254 bps clearly showed a stable sequence similarity, suggesting high conservation of the base peak sequence in the ITS 1 region. However, frequent base substitutions in the 252 bps sample leaves that came from callus tissue and micropropagated plants were observed around the regions of nucleotide positions 66, 99 and 199-201.The minor deviation in clonally regenerated A.vera may be due to the stage of regeneration and cell specification in cases of the callus tissue. In the present study, the base peak sequence of the ITS 1 region of rDNA was adopted as a molecular marker for differentiating A.vera plants from geographically distributed and clonally regenerated A.vera plants, and it was suggested that the base peak substitutions in the ITS 1 region may arise from the different nutritional and environmental factors in cultivation and plant growth stages