## 4 Human Body Models
### Type of the Human Body Models
#### 4.1.2 Voxel Phantoms  
Voxel phantoms represent more realistic shapes and arrangements of biological tissues. Various medical imaging systems have been used to provide such realistic human-body \begin{table}
\begin{tabular}{c c c c} \hline
**References** & **Models** & **Body Parts** & **Frequency (MHz)** \\ \hline
[228; 229] & Adult, adult & Head & 900 \\ \hline
[230] & Pregnant woman/fetus in the uterus & Torso/whole body & 900, 2100, 2450, 2600 \\ \hline
[231] & Adult & Whole body & 98 to 2450 \\ \hline
[232] & Adult & Head/torso & 850, 900, 2100, 2600, 5100 \\ \hline
[233] & Adult phantom & Brain/eye/skin & 2300 to 2400 \\ \hline
[234] & Adult/SAM & Head/brain/muscle & 900, 2500, 3500 \\ \hline
[235] & Adult & Brain/skin/fat/bone & 900 \\ \hline
[236] & Adult & Head/skin/bone & 900, 1800 \\ \hline
[237] & Adult, child & Whole body/head/torso & 20 to 2400 \\ \hline
[238] & Adult (male), child (Boy, girl) & Head/brain/eye & 900, 1800 \\ \hline
[239] & Adult (male, female), child & Head/brain & 900, 1800, 2100, 2400 \\ \hline
[240] & Adult, child & Head/fat/skin/bone/brain/eye & 900, 800, 1800, 2100 \\ \hline \end{tabular}
\end{table} 
Table 4: A summary of SAR values calculations in the literature. \begin{table}
\begin{tabular}{c c c c c} \hline
**Standard** & **Cube Mass (W/kg)** & **Whole-Body Average** & **Head and Trunk** & **Limb** \\ \hline
**ICNIRP** & 10 g & 0.08 & 2 & 4 \\ \hline
**IEEE** & 1 g & 2 & 1.6 & 4 \\ \hline \end{tabular}
\end{table} 
Table 5: SAR limits for healthcare applications (W/Kg) [217; 219]. phantoms. One of these models is named \"Hugo\", which was based on the visible human project in 1994, and it was the first accessible voxel human model, as seen in Figure 18a [253]. Later, several human body models were created that included more high-resolution representations of the entire body. The Japanese male and female models [254] and the virtual family models [255] are illustrated in Figure 18b. Due to the complexity of the model that requires computational resources, whenever possible, it is common practice to restrict the body model to cut a specific section of the voxel model. This is especially possible when the device is small and is utilised outside of the body, such as mobile phones, microwave hyperthermia devices, or microwave imaging setups, as well as small wearable sensors [256]. These phantom models offer tissue data about the desired parts needed for applications. For the SAR computation of mobile phones, specific anthropomorphic mannequin (SAM) phantoms are used [257]. A volume shaped like a human head filled with material resembling the head tissues' average dielectric characteristics is used to model SAM phantoms. Realistic voxel breast models were employed in [258] for modelling microwave hyperthermia breast cancer treatment, as seen in Figure 18c. Various types of breasts, based on the American College of Radiology categorisation, were considered. The breast models may also be utilised for microwave breast cancer imaging [253]. Recently, there has been some interest in improving personalised treatment by creating patient-specific body phantom models. Furthermore, commercial electromagnetic solvers offer integrated modules that reconstruct 3D human models from magnetic resonance imaging (MRI) or computed tomography (CT) scan data. For instance, Sim4 Life-based supports the integration of the medical image segmentation (MIS) tool Set (iSEG), as well as the ALBA 3D Seg-based module, as shown in Figure 18d [11; 12; 13; 14; 30; 259; 260; 261], which was developed to integrate into the CST microwave studio software to design button antenna system [262]. The reconstruction of the 3D human models enhances the patient-specific simulations for real wearable applications. However, these computational human phantoms (CHPs) and their uses have achieved tremendous advancements in recent decades [262].