## 2 Materials and Methods
#### 2.4.1 Effective Dose Estimation in Occupational Exposure: Algorithm by [PERSON] et al.  
Various methods have been developed using personal dosimeters to estimate the effective dose or effective dose equivalent. Two algorithms are commonly used to convert radiation dose measurements from personal monitors into an effective dose estimate [23]. In a study by [PERSON] et al., the Niklason algorithm showed closer agreement with experimental data [24; 25]. Consequently, the effective dose was calculated using the Niklason algorithm, which relies on readings from two dosimeters [26]. One dosimeter measures the dose beneath the lead apron, while the other measures the dose above the apron or at the thyroid shield.  
When the reading beneath the apron was unavailable, a modified version of the Niklason approach was applied. This version estimates the effective dose from a single dosimeter reading [27].  
The algorithm recommends the use of two dosimeters: one worn over the apron at neck level and another positioned beneath the apron at waist level. However, the algorithm remains applicable when only a single dosimeter is used at neck level, provided the apron attenuation is approximately 98-99%. Additionally, it incorporates provisions for the use of a thyroid collar shield.  
In cases where two dosimeters are employed without a thyroid shield, the effective dose (\(E\)) is determined by the following equation:  
\[E=0.06(H_{os}-H_{u})+H_{u} \tag{6}\]  
where \(H_{os}\) represents the shallow dose recorded by the dosimeter at neck level, denoted as Hp(0.07) and measured over the protective shield at the thyroid level. \(H_{u}\) represents the Hp(10) measured beneath the lead apron at waist level. Typically, \(H_{u}\ \approx 0.01\ H_{os}\), so when a single dosimeter is worn at the collar, the effective dose can be approximated as:  
\[E=0.07H_{os} \tag{7}\]  
when a thyroid shield is worn, the effective dose is calculated using the following equation:  
\[E=0.02(H_{os}-H_{u})+H_{u} \tag{8}\]  
Additionally, assuming that \(H_{u}\ \approx 0.01H_{os}\), the effective dose with a single dosimeter at neck level can be approximated as  
\[E=0.03H_{os} \tag{9}\]  
The estimation of the effective dose is notably influenced by the use of a thyroid shield, as this device provides protection not only to the thyroid gland but also to adjacent regions, including the skin, esophagus, vertebrae, and bone marrow. According to the Niklason algorithm, the absence of a thyroid shield can result in a two-fold increase in the estimated effective dose [28; 29].  
In this analysis, the effective dose was calculated based on the assumption that a thyroid shield was employed (Equation (8)). Although thyroid shield use is not universal, this assumption was grounded in a review of 62 studies, 30 of which discussed thyroid shield usage. Among these, 28 studies reported regular use of the shield, while only two indicated it was not used [30]. In cases where measurements over the thyroid shield were unavailable, alternative dose measurements--such as those recorded over the eye, trunk, or hand on personal protective equipment--were utilized in that order. This substitution was justified due to the minimal variation in radiation exposure across these anatomical sites during the same procedure.