# Sex Estimation from Computed Tomography of Os
## 2 Materials and Methods  
The sample consisted of computed tomography images of the pelvis taken from adult living individuals examined at the Department of Radiology, Emergency Municipal Clinical Hospital Timisoara. The clinical data were anonymized and collected following the Declaration of Helsinki. A total of 80 pelvic CT scans were included in this study, with an equal distribution of 40 males and 40 females. It is essential to consider age when selecting samples. Bones undergo significant changes throughout a person's lifetime, particularly during growth and development. The degree of sexual dimorphism is a complex phenomenon that varies with age. For example, certain skeletal features may fully differentiate between sexes in adulthood [28; 29]. Moreover, different populations may exhibit unique patterns of skeletal variation related to sex [30; 31]. These age-related factors could include changes in bone density, the rate of bone growth, or the timing of bone fusion, all of which can vary significantly with age and impact the accuracy of sex estimation techniques [28; 29]. Considering all of this, the sample is chosen to ensure the diversity and representativeness of the population. This is achieved by equally dividing the sample based on both sexes and various age groups in order to accurately represent the population of interest. This balanced representation aims to ensure sex parity in the analysis, with participants' ages ranging from 22 to 93 years and a mean age of 59.51 \(\pm\) 22.7 years. The age range of male individuals varied from 23 to 93 years, with a mean age of 60.13 \(\pm\) 22.80 years. The age range of female individuals varied between 22 and 92 years, with a mean age of 58.9 \(\pm\) 22.89 years (Figure 1). The selection criteria required all anatomical landmarks to be visible and the entire region of interest to be included. Scans with metal implants or fractures, which could potentially interfere with the accuracy of measurements, were excluded from this study. Also, we considered the practical and resource limitations, particularly with regards to pelvic CT scans, which can be demanding in terms of resources, necessitating both time and equipment. The examinations were conducted using a Siemens Somatom Definition Edge (Erlangen, Germany) at 120 kV with 250 mAs, 0.6 mm slice thickness, 1 mm slice increment, and a B30f reconstruction algorithm, following a standardized scan protocol. OsiriX software version 11.0 (Pixmeo SARL, Bernex, Switzerland) was utilized for generating the 3D VR's and conducting measurements, as it offers specific tools for accurate anatomical analysis. Diagnose Sexuelle Probabiliste (DSP) software (available at [[https://osteomics.com/DSP/](https://osteomics.com/DSP/)]([https://osteomics.com/DSP/](https://osteomics.com/DSP/)), accessed on 12 May 2024) was used to estimate the sex [32]. We select four measurements from the ten variables listed in [PERSON]'s original study, acquired as recommended in  
Figure 1: Age distribution of the sample. the original paper [16]. PUM, ISMM, and SCOX are suggested for sex estimation and likely showed strong correlations with biological sex in the original study by [PERSON] or in subsequent research. Selecting variables with a known association with sex estimation increases the likelihood of accurate predictions. The chosen variables are noted for their simplicity in measurement and reproducibility on CT (computed tomography) images. This implies that the variables are easy to measure and interpret consistently across different observers or imaging setups. Simplicity and reproducibility are essential in ensuring that the measurements can be reliably obtained and compared across different samples or studies. By applying these criteria, the researchers aim to select a subset of variables that are not only theoretically relevant for sex estimation but also practical in terms of measurement and reproducibility.