**1. Introduction**

The widespread sources in afterloading devices operated in high-dose-rate brachytherapy (HDR) are 60Co and 192Ir. This work aimed to investigate the dosimetric parameters for both HDR sources manufactured by BEBIG (Eckert & Ziegler BEBIG GmbH, Germany), 60Co model: Co0.A86 and 192Ir model: GI192M11, used in HDR

brachytherapy. According to the TG-43 U1 and HEBD Working Group Report, recommendations for high-energy photons emitting brachytherapy sources [1] were provided. The dosimetric parameters were calculated; The air-kerma strength, dose rate constant, radial dose function, and the 2D along & away dose rate table in Cartesian coordinates are calculated for both new BEBIG sources, except the 2D anisotropy function.

Several studies were made for the HDR brachytherapy sources with different geometries and nuclides; we have cited some of them in this work. Varieties of Monte Carlo codes have been used to investigate the HDR brachytherapy sources. The BEBIG Co0.A86 was investigated using Geant4 by Granero et al., (2007) [2], PENELOPE used by Guerrero et al., (2014) [3], a study was made by Anwarul et al., (2012) using the Monte Carlo code EGSnrc [4], and H. Badry et al., (2018) used EGS5 for simulation of the same source model [5].

For the 192Ir model: GI192M11, a study was made by Perez-Calatayud et al., (2012) using the Geant3 Monte Carlo code [1], Geant4 was used by Granero et al., (2005) for the same source model [6]. The comparison was also made in the case of radial dose function with the results obtained for the source model BEBIG Ir2.A852 simulated by Granero et al., (2008) [7] and Belousov et al., (2014) [8]. The obtained results in this study were in good coherence with the published data. Monte Carlo simulations were provided following the records cited in the report of the research committee Task Group 268 from AAPM [9]. MCNPX code was already used in some previous studies we cited the use of the version: 2.4 by Alizadeh et al., (2015) for the HDR 192Ir source Flexisource model [10]. Also, we have investigated the dosimetric parameters of the same 60Co source in our previous study Elboukhari et al., (2020) using the version 2.7 of the code Monte Carlo N-Particles eXtended (MCNPX) [11], this new version of the code operates the new updated tables of cross sections from ENDF/B-VII.1 data. MCNPX is a general-purpose three-dimensional simulation tool providing the transports of 37 different particle types for criticality, dosimetry, shielding, detector response, and many other applications. On the contrary of previous MCNPX Monte Carlo codes, the version used in this work of MCNPX provided a high precision, and the uncertainties depending on cross section tables are considered negligible.

To evaluate the difference between the two sources simulated in this study within a clinical use, we have generated the 2D along & away tables for complementing the commissioning of these sources within a clinical treatment planning system. A minor difference was observed in the generated along & away dose rates for the range of distances considered in this work. These results could help in the choice of the appropriate nuclide to use in the treatment regarding operation costs and frequency for source change, especially for developing countries such as in North Africa. Also, different studies were performed concerning the clinic practice. A study of M. Andrassy et al., (2012) concerned the behavior in the treated volume [12]. In addition, the studies of Venselaar et al., (1996) and Candela et al., (2013) mentioned that the behavior of the two nuclides at shorter distances from the treated volume is different from that at larger distances [13, 14]. This result is also mentioned in the study of Strohmaier and Zwierzchowski in 2011 [15].

### **2. Materials and methods**

In this study, Monte Carlo simulation for HDR brachytherapy sources was performed following the recommendations of the American Association of Physicists *Comparative Dosimetric Study between 60Co and 192Ir BEBIG High Dose… DOI: http://dx.doi.org/10.5772/intechopen.102435*

in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) in the HEBD working group report [1]. The formula proposed for 2D dose rates is:

$$\dot{D}(\mathbf{r},\theta) = \mathbf{S}\_{\mathbf{k}}\Lambda \frac{G(r,\theta)}{G(r\mathbf{0},\theta\mathbf{0})} \mathbf{g}\_{\mathbf{L}}(\mathbf{r})\mathbf{F}(\mathbf{r},\theta) \tag{1}$$

Where:


### **3. Sources descriptions and geometries**
