# Skin Absorbed Dose Coefficients for Human Legs from Beta Radiation as a Function of Height
## 2 Materials and Methods
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Material** & **H** & **C** & **N** & **O** & **Na** & **Al** & **Si** & **P** & **S** & **Cl** & **K** & **Ca** & **Fe** & **Ar** & **Density** (g/cm\({}^{3}\)) \\ \hline Tissue & 10 & 20.4 & 4.2 & 64.5 & 0.2 & 0 & 0 & 0.1 & 0.2 & 0.3 & 0.1 & 0 & 0 & 0 & 1.09 \\ Leather & 9.08 & 19.14 & 4.8 & 67 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1.15 \\ Soil & 2.1 & 1.6 & 0 & 57.7 & 0 & 5 & 27.1 & 0 & 0 & 0 & 1.3 & 4.1 & 1.1 & 0 & 1.60 \\ Air & 0.064 & 0.014 & 75.4 & 23.2 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1.3 & 0.0012 \\ \hline \end{tabular}
\end{table} 
Table 1: Table of Materials. The elemental composition by weight for each material and the density of each material used in the simulation are detailed. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Energy (MeV)** & **CSDA Range (cm)** & **Energy (MeV)** & **CSDA Range (cm)** \\ \hline
0.1 & 13.5 & 1.5 & 660 \\
0.2 & 42 & 2.0 & 910 \\
0.4 & 121 & 2.5 & 1150 \\
0.8 & 310 & 3.0 & 1380 \\
1.0 & 410 & 4.0 & 1840 \\ \hline \end{tabular}
\end{table} 
Table 2: Source energies and corresponding CSDA ranges. The cylindrical source was placed at 1 \(\upmu\)m depth in the soil, and its radius was set equal to the CSDA range of each electron's energy, as shown in Table 2. These CSDA ranges for electrons in the air are equal to those from the ESTAR program [43]. If the CSDA range for a given energy source was less than about 155 cm, which is slightly higher than the length of the leg, the radius of the cylindrical source was set to the CSDA range to save on simulation time because the electrons out of this range would not reach the leg. For energies equal to or higher than 0.8 MeV, the source radius and the simulation universe's radius were set to the corresponding CSDA range. The target, the human leg skin, consists of different layers: the outermost layer of the skin is the Epidermis, the Dermis layer is placed underneath it, and the innermost layer of the skin is the Hypodermis. Each of these layers has different depths, which might vary based on the classification. Under the Hypodermis are the muscle layers [44]. The Epidermis layer is placed at the skin's surface, and there are no blood vessels in this layer, it is most crucial in body protection since it separates the body from the outside environment and protects it from external exposures, including low-energy beta particles [45]. The epidermis layer consists of five different layers, which function together to keep the skin surface healthy and repair it constantly. The innermost layer of the Epidermis is the Basal layer. It is placed right above the dermis layer; the basal layer is an active layer of skin that helps repair the outer sublayers of the Epidermis by constantly producing skin cells and replacing the damaged or older skin cells with new ones [46]. The basal cells are considered at the highest radiogenic risk when exposed to radiation due to their important role in repairing the skin. Therefore, in radiation protection, it is vital to calculate the absorbed dose to the basal layer of the Epidermis. The absorbed dose to the basal layer has been the main research topic of several studies due to radioactive or non-radioactive exposures to the skin [47; 48]. [PERSON] et al. studied the effects of ultra-violate radiation due to sunburns on the basal layer of the skin [49]. [PERSON] et al. studied the delivered dose to the basal layer of skin under alpha radiation exposure. Moreover, basal cell carcinoma is the most common type of skin cancer in the U.S.; ionizing radiation exposure to the skin's basal cells can significantly increase the risk of basal cell carcinoma. [PERSON] et al. showed that exposure of the basal cell layer to more than 1 Gy increased the risk of cancer [50]. Consequently, studying exposure to the basal layer is very important for radiation protection. The thickness of the epidermis layer varies in different parts of the body. Moreover, the basal layer has an undulating nature, and the thickness is not the same in all parts.