Posture-Transformed Monkey Phantoms Developed from a Visible Monkey

A monkey phantom is of significant value for electromagnetic radiation (EMR) dosimetry simulations. Furthermore, phantoms in various postures are needed because living beings are exposed to EMR in various postures during their daily routine. In this study, we attempted to produce monkey phantoms based on three daily postures of a rhesus monkey. From our Visible Monkey project, we selected surface models with 177 monkey structures. In the surface models, 52 virtual joints were created to allow for changes from the anatomical position to quadrupedal and sitting positions using commercial software. The surface models of the three positions were converted into monkey voxel phantoms. These phantoms were arranged in three positions, and the number of voxels and mass of each structure were analyzed. The phantoms in anatomical, quadrupedal, and sitting positions have a total of 5,054,022, 5,174,453, and 4,803,886 voxels, respectively. The mass of 177 structures in three positions were also calculated based on the number of voxels. By comparing the monkey phantom with the phantom of a female human, we confirmed thicker skin, less fat, heavier muscle, and a lighter skeleton in monkeys than those in humans. Through posture-transformed monkey phantoms, more precise EMR simulations could be possible. The ultimate purpose of this study is to determine the effects of EMR on humans. For this purpose, we will create posture-transformed human phantoms in a following study using the techniques employed herein and the human phantoms from our previous study.

Organ Dose Calculations Using ICRP Adult Voxel Phantoms and TRIPOLI-4 Monte Carlo Code

The ICRP 110 adult male and female voxel phantoms are the official computational models representing the ICRP (International Commission on Radiological Protection) Reference Male and Reference Female. In 2018, the Working Group 6 (WG6) of European Radiation Dosimetry Group (EURADOS) organized a study on the usage of the ICRP voxel reference phantoms. Organ dose calculation tasks with radiation transport codes were proposed in occupational, environmental, and medical dosimetry. The TRIPOLI-4 Monte Carlo radiation transport code has been widely used in radiation shielding, criticality safety, and reactor physics fields for supporting French nuclear energy research and industrial applications. To enhance the application fields of TRIPOLI-4, the 2018 EURADOS-WG6 tasks are being taken into account by using different features of the TRIPOLI-4 code. In this work, the ICRP reference voxel phantoms were first adapted into TRIPOLI-4. More than 14 × 106 voxels were represented in a mixed lattice geometry including 140 organs-tissues and 52 tissue media. Diverse exposure scenarios were then investigated by using 60Co and 241Am gamma-ray sources, 16N beta source, and 10 keV neutron source. The TRIPOLI-4 standard nuclear data library was utilized on these neutron, photon, electron, and positron-coupled transport calculations. Energy deposition estimators for electron, positron, neutron, and photon coupled with mesh tally options were used to calculate the organ absorbed dose DT and the effective dose E. TRIPOLI-4 calculation methods and primary results for the EURADOS-WG6 voxel phantom exercise on organ dose study tasks are reported here.

COMPRESSION OF HIGH-RESOLUTION VOXEL PHANTOMS BY MEANS OF B+ TREE

Data structures are chosen to save space and to grant fast access to data by it’s key for a particular structural representation. The data structures surveyed are linear lists, hierarchical structures, graph structures. B+ tree is an expansion of a B tree data structure which allows efficient insertions, deletions and search operations. It is used to store a large amount of data that cannot be stored in the main memory. B+ tree leaf nodes are connected together in the form of a singly linked list to make search queries more efficient and effective. The drawback of binary tree geometry is that the decrease in memory use comes at the expense of more frequent memory access, might slow down simulation in which frequent memory access constitutes a significant part of the execution time. Processing and compression of voxel phantoms without loss of quality. Voxels are often utilized in the visualization and analysis of medical and scientific (logical) information. Voxel phantoms which comprise a set of small volume components appeared towards the end of the 1980s and improved on the first scientific models. These are the models of the human body. These phantoms are an extremely exact representation. Fetching of records in the equal number of disk accesses and to reduce the access time by reducing the height of the tree and increasing the number of branches in the node.