# Posture-Transformed Monkey Phantoms Developed from a Visible Monkey
## 4 Discussion  
Monkey phantoms are beneficial for research on the safety of EMR from ordinary electronic and medical devices because the effect of EMR on humans can be deduced based on the results of monkey phantoms [7; 10; 11; 12]. In addition, the monkey phantoms of daily postures are necessary to accurately examine the EMR effect because the results of the EMR are sensitive to various phantom postures [19; 20]. However, strictly speaking, to examine the precise impact of EMR on living humans, living humans should be used in EMR tests; however, doing so is impossible. Therefore, human phantoms have been employed instead of actual humans [3; 4; 6; 34]. However, we still cannot help but consider the reliability of such human phantoms because they have never been compared to living humans in relation to EMR. To verify the reliability of human phantoms, we chose to use monkeys, which are commonly applied as human surrogates. Using a monkey, researchers can directly check the impact of EMR on both living monkeys and monkey phantoms. If the reliability of the monkey phantoms is verified through comparisons with living monkeys, we can deduce logically the relation between human phantoms and living humans without the EMR testing of actual humans. Because this study was the first step into monkey phantom research, we developed posture-transformed monkey phantoms (Figure 3b,d,f). To develop the posture-transformed monkey phantoms, three points must be considered. First, monkey phantoms with precise anatomy are required to obtain accurate results with regard to EMR. Although phantoms are easily created using CT and MRI scans, small structures cannot be identified in detail in such phantoms [35; 36; 37; 38]. By contrast, it is difficult  
Figure 4: Comparison of the mass proportion of each structure in the monkey phantom and the VK-phantom of female human [29]. The mass proportions of skin, muscle, and structures of alimentary system of the monkey phantom are larger than those of the VK-phantom. The monkey phantom has larger proportions of cerebral white matter, brainstem, and spinal cord than those of the human. (* Cerebral gray matter including thalamus, hypothalamus, and hippocampus; §Brainstem including midbrain, pons, and medulla oblongata). to create phantoms from the sectioned images owing to the need for a high resolution and true color [39; 40; 41; 42; 43]. Nevertheless, we have successfully created VK-phantoms for 583 male whole-body structures, 459 female whole-body structures, and 300 head structures from the sectioned images of humans [29; 44]. Using not only the image data of Visible Monkey but also the experience and software techniques employed for the VK-phantoms, precise phantoms of rhesus monkeys were produced in this study (Figure 3b,d,f) [22; 27]. Second, posture-transformed monkey phantoms are required to obtain simulation values in situations identical to real life. EMR simulations usually use phantoms in the anatomical position [3; 6; 45]. However, in the real world, living things assume different postures, and are thus exposed to EMR in different postures. Consequently, phantoms in various positions are needed for more precise measurements. Although posture-transformed phantoms of whole bodies have been employed in some EMR and SAR studies (the hands of the phantoms were even placed over their ears), these studies did not provide voxel phantoms for other researchers [7; 9; 10]. Most importantly, not only a monkey phantom but also posture-transformed phantoms with detailed structures were applied. Therefore, in this study, considering the most common postures in the daily routine of a monkey, we chose anatomical, quadrupedal, and sitting positions, and produced phantoms of these three positions (Figure 3 and Table 1 and Appendix A). For reference, monkeys usually walk quadrupedally, and sleep and relax on tree branches in a sitting position. Third, in the posture-transformed procedure, manual works are required to obtain phantoms with an anatomical correct shape.