# Dose Estimation by Geant4-Based Simulations for Cone-Beam CT Applications: A Systematic Review
## 3 Results and Discussion  
Finally, we found 34 studies that satisfied the inclusion criteria coming from 14 different sources between 2008 and 2021. An overview of this information is shown in Table 2, which displays the main information about the selected papers, and Table 3, which presents the selected publications regarding author, application, and year of publication. Below, the studies from this selection will be discussed individually, addressing the aforementioned research questions. \begin{table}
\begin{tabular}{c c} \hline \hline
**Results** & \\ \hline Timespan & 2008–2021 \\ Sources (journals, books, etc.) & 14 \\ Documents & 34 \\ Average years from publication & 4.97 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main information about selected articles. Figure 1: Flowchart consistent with preferred reporting items for systematic reviews (PRISMA) statement. \begin{table}
\begin{tabular}{c c} \hline \hline
**Reference** & **Applications** & **Year** \\ \hline [PERSON] et al. [90] & Cone-Beam Breast CT & 2021 \\ [PERSON] et al. [91] & Novel method to improve quality of CBCT images & 2020 \\ [PERSON] et al. [92] & Comparison between LBTE methods against Geant4 benchmark & 2020 \\ [PERSON] et al. [93] & GPU-based for proton simulation & 2020 \\ [PERSON] et al. [94] & Deep Learning-based scatter correction method & 2019 \\ [PERSON] et al. [95] & Dental and maxillofacial CBCT & 2019 \\ [PERSON] et al. [96] & Comparison between Acuros CTD against Geant4 & 2019 \\ [PERSON] et al. [97] & Proton Gantry-Mounted CBCT & 2018 \\ [PERSON] et al. [98] & Proton Gantry-Mounted CBCT & 2018 \\ [PERSON] et al. [99] & Stereotactic Radiosurgery with small radiation fields & 2018 \\ [PERSON] et al. [100] & Comparison between Acuros CTD against Geant4 & 2018 \\ [PERSON] et al.[101] & Image-Guided RadioTherapy & 2018 \\ [PERSON] et al. [102] & Image-Guided RadioTherapy & 2018 \\ [PERSON] et al. [103] & Adaptive Radiotherapy & 2017 \\ [PERSON] et al. [104] & Simulated Mega-Voltage CBCT & 2017 \\ [PERSON] et al. [105] & Optimization of a Multilayer Imager Mega-Voltage CBCT & 2017 \\ [PERSON] et al. [106] & Dual-Energy Computed Tomography & 2017 \\ [PERSON] et al. [107] & Image-Guided RadioTherapy & 2017 \\ [PERSON] et al. [108] & Radiotherapy & 2017 \\ [PERSON] et al. [109] & Cone-Beam Breast CT & 2017 \\ [PERSON] et al. [110] & Cone-Beam Breast CT & 2016 \\ [PERSON] et al. [111] & TLE method for low-energy X-ray irradiations & 2015 \\ [PERSON] et al. [112] & New dose point measurement method validated by Geant4 & 2015 \\ [PERSON] et al. [113] & Radiotherapy & 2014 \\ [PERSON] et al. [114] & Perfusion and Interventional CBCT & 2014 \\ [PERSON] et al. [115] & Proton Computed Tomography & 2014 \\ [PERSON] et al. [116] & Image-Guided RadioTherapy & 2014 \\ [PERSON] et al. [117] & Image-Guided RadioTherapy & 2013 \\ [PERSON] et al. [118] & Cone-Beam Breast CT & 2013 \\ [PERSON] et al. [119] & Volumetric Modulated Arc Therapy & 2013 \\ [PERSON] et al. [120] & Cone-Beam Breast CT & 2012 \\ [PERSON] et al. [121] & Cone-Beam Breast CT & 2010 \\ [PERSON] et al. [122] & Cone-Beam Breast CT & 2009 \\ [PERSON] et al. [123] & Cone-Beam Breast CT & 2008 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c} \hline \hline
**Results** & \\ \hline Average citations per documents & 9.56 \\ Average citations per year per doc & 1.27 \\ References & 839 \\ Articles & 32 \\ Conference papers & 1 \\ Meeting abstracts & 1 \\ Keywords plus & 132 \\ Author’s keywords & 107 \\ Authors & 150 \\ Authors of single-authored documents & 0 \\ Authors of multi-authored documents & 150 \\ Documents per author & 0.23 \\ Authors per document & 4.41 \\ Co-Authors per documents & 5.62 \\ Collaboration index & 4.41 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Overview of extracted data from papers regarding reference named by first author, applications, and year of publication. RQ1: What Are the Most Significant Current Publications Estimating Radiation Dose Using Geant4 in CBCT Applications?