ORIGINAL ARTICLE Year : 2019  Volume : 15  Issue : 8  Page : 4246 Effect of Au197 nanoparticles along with Sm153 radiopharmaceutical in prostate cancer from simulation method Akbar Abbasi^{1}, Fahreddin Sadikoglu^{2}, Mostafa Hassanzadeh^{3}, ^{1} Faculty of Engineering, University of Kyrenia, Girne, Turkey; Reactor Research School, Nuclear Science and Technology Institute (NSTRI), Tehran, Iran ^{2} Department of Electrical and Electronic Engineering, Near East University, Nicosia, North Cyprus, Mersin 10, Turkey ^{3} Reactor Research School, Nuclear Science and Technology Institute (NSTRI), Tehran, Iran Correspondence Address: Aims: Based on recent studies, it was indicated that gold (Au197) nanoparticles could be safely prescribed and used to enhance the absorbed dose during radiation therapy. Subjects and Methods: We evaluated the samarium153 (Sm153) radiopharmaceutical and Au197 and Sm153 radiopharmaceutical absorbed dose rate by means of the Monte Carlo technique in prostate cancer. Results: The results show that absorbed dose rate in entire prostate volume due to 20 mCi of Sm153 radiopharmaceutical is 27.339 μGy/s, 48.837 μGy/s, and 76.176 μGy/s for γinteraction, β¯ particle interaction, and γ+β¯ interaction, respectively. The results in the exterior of the prostate for β¯ interaction, β¯ particle interaction, and γ+β¯ interaction were 20.971 μGy/s, 1.110 μGy/s, and 22.081 μGy/s, respectively. Conclusions: The calculation results for Au197 and Sm153 radiopharmaceutical show that the absorbed dose rate in entire prostate volume 3% was increased and undesirable dose value in exterior of prostate 7% was decreased.
Introduction Prostate cancer is the third most common cancer worldwide among males and the fourth in terms of incidence worldwide.[1] Conventional methods of cancer treatment such as normal radiotherapy, surgery, or chemotherapy due to damage healthy cells surrounding cancer cells and leave cancer cells, are not safe and deterministic methods. Protecting healthy cells in the beam path or in the vicinity of cancer cells in tumors during treatment is very important. The study in the United States shows that one in six men or 230,000 new cases of prostate cancer are diagnosed every year, with an estimated 27,000 deaths every year.[2] However, increasing radiation dose in a tumor can improve cell kill, but the effects of radiation often restrict its practical use in patients. Despite all the advances in threedimensional diagnosis, intensity modulated of external radiation, radiotherapy toxicities in the rectum and bladder remaining is a major concern. Thus, it is important to develop novel approaches for enhancing radiation effectiveness in prostate cancer.[3],[4] Nanoparticles such as Au197 nanoparticles are solid colloidal particles ranging in size from 10 nm to 200 nm that are 102–104 times smaller than human cells.[5] Nanoparticles between 10 nm and 50 nm are able to pass through cell membranes, and the particles with 20 NM size can pass through blood vessel endothelial.[2] Samarium153 (Sm153) is a beta and gamma emitter synthetic radioisotope with halflife of 46.7 h. The therapeutic effect of Sm153 arises from the emission of radioisotopes short halflife and desirable particle emission. Sm153 emits three common beta particles including Emax= 704 keV (49.4%), Emax= 634 keV (31.3%), and Emax= 807 keV (18.4%) that are suitable for killing malignant cells. It also emits two gamma photons at Eγ=103 keV (29.2%) and Eγ=70 keV (4.7%) energy [Figure 1]. Hence, this low energy releasing photon, allow physicians to be aware from distribution and amount of the radionuclide. In addition, the short halflife of Sm153 makes its suitable radionuclide to rapid clearance from the body.{Figure 1} The application of the Monte Carlo simulation technique in brachytherapy and external beam radiation therapy has been demonstrated in some research reports.[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18] The application of the Monte Carlo simulation technique in dosimetry applications can be developed by the availability's of Monte Carlo codes such as MCNP4C code a[19] along with the advancement of biological and physical investigations for more accurate dose and intensity calculations for patient treatment. The purpose of this research is applying the MCNP4C Monte Carlo code for investigation of the effect of Sm153 radiopharmaceutical composed with Au197 nanoparticles in prostate cancer treatment. Furthermore, a comparison is made between the Au197 nanoparticles effects in prostatesimulated dose contributions. Subjects and Methods Monte Carlo method A Monte Carlo Nparticle Transport Code (MCNP4C, version 4C) was used to calculate the doses in the prostate. This code calculates the phenomena of Photoelectric, Compton, and Pairproduction interactions with matter. In the MCNP4C code, there are several tally types available to dose calculation. In this paper, the frequency modulation (FM) (tally multiplier) card was used to calculation of the doses rate. A tally is a specification of what should be included in the problem output. For example, the FM card can modify any flux or current tally or dose rate through the Eq. (1). Thus, to calculation of the dose rate we used the following equation: [INLINE:1] Where ϕ (E) is the energydependent fluence (particles/cm2) and R (E) is an operator of additive and/or multiplicative response functions from the MCNP4C code crosssection libraries or specially designated quantities. That the crosssection library used in this code is ENDF/BIV library. The constant C is any arbitrary scalar quantity that can be used for normalization. The material number m must appear on a Mm card but not need to use in a geometrical cell of the problem. Sm153 sources The Sm153 source is a beta and gamma emitter source that emits the gamma photon energy in 103 Kiev and 70 keV. The beta particles emit at Emax= 704 keV, Emax= 634 keV, and Emax= 807 keV energy. In this state, the absorbed dose rate has been simulated in the prostate model (4 cm × 3 cm × 2 cm), with 20 mCi value of Sm153 radiopharmaceutical that uniformly distributed in prostate tissue [Figure 2]a.{Figure 2} Au197 and Sm153 sources The Au197 nanoparticle and Sm153 sources is a mixed solution that contains 20 mCi of Sm153 and 10 ml of Au197 nanoparticles. The Sm153 radionuclide interaction with prostate tissue will be by direct gamma photon interaction and beta particles. The application of Au197 nanoparticles in the treatment of cancer was reported in some articles.[20],[21],[22],[23] The interaction between gold atoms and beta particles occurs by the bremsstrahlung phenomena. Those interactions are shown in [Figure 2]b and [Figure 3].{Figure 3} Dose rate calculation The “F4” tally gives a quantity in unit of particles/cm2 per source particle. For dose calculation, we need the “FM” (tally multiplier) card to convert this unit to units of dose. Two basic approaches are useful for converting from flounce quantities to units of dose. One choice is to use a heating number method. The other choice is to fold in one or more flounce to dose conversion function. Both approaches are valid for photon dose calculation, but the use of conversion functions is recommended for electron dose equivalent and effective dose. Thus, we select the heating number method. In the heating number method, MCNP4C calculates absorbed dose on the basis of the KERMA approximation, which assumes that kinetic energy transferred to charge particles is locally deposited.[24] Using the KERMA approximation, the dose can be represented using the following equation: [INLINE:2] The parameter C is calculated by: [INLINE:3] Where Nα is Avogadro's number (6.022 × 1023 mol −1); η, number of atoms per molecule; M, molar mass in grams; ϕ, flufluency ore in particles/cm2; σT, total atomic cross section at energy of scoring track in barns; H, heating number in MeV per collision; T, number of scoring source particle tracks, and N, number of source particles. Results The absorbed dose rates per se cond Ḋ (μGy/s) due to 20 mCi activity concentration of the Sm153 radiopharmaceutical in entire prostate volume and its exterior were calculated by MCNP4C code and are shown in [Table 1]. This calculation is results of interaction between the main gamma photon energy in 103 Kev and 70 keV, and three beta particles at Emax= 704 keV, Emax= 634 keV, and Emax= 807 keV energy, that emitted by Sm153 in prostate tissue. The accuracy of the code input data to calculate the absorbed dose rates at all cases are considered the number of particles history 2.5 × 106 with relative error of 0.9%. The simulated results of photons and particle tracks in prostate and outside of prostate tissue are shown in [Figure 4].{Table 1}{Figure 4} As shown in the results of the absorbed dose rate due to β¯ particles and γ photon in entire prostate volume are higher than in the exterior of the prostate. The total absorbed dose rate in entire prostate volume and in exterior of the prostate is 76.176 ± 0.032 μGy/s and 22.081 ± 0.028 μGy/s, respectively. Furthermore, the absorbed dose rate per se cond of 20 mCi activity concentration of Sm153 radiopharmaceutical along with Au197 nanoparticle has been estimated by MCNP4C code, and the obtained results are shown in [Table 2].{Table 2} The calculation results show that Au197 nanoparticles along with Sm153 can increase the absorbed dose rates in entire prostate volume and decrease the absorbed dose rate in the exterior of the prostate. The calculated values for photon interaction in entire prostate volume and in exterior of prostate are 27.387 ± 0.021 μGy/s and 18.627 ± 0.012 μGy/s, respectively. Furthermore, the absorbed dose rate magnitude due to β¯ particle interaction in entire and exterior of prostate are 51.241 ± 0.032 μGy/s and 1.890 ± 0.058 μGy/s, respectively. As well as the total absorbed dose rates in entire prostate volume are 78.627 ± 0.024 μGy/s, and this parameter in the exterior of the prostate is 20.517 ± 0.079 μGy/s. Finally, this increased absorbed dose rate due to bremsstrahlung phenomena of β particles with Au197 atoms. [Figure 5] shows a comparison between the Sm153 radiopharmaceutical intake and the Sm153 along with Au197 nanoparticle usage for dose calculation by Monte Carlo MCNP4C code. These results show that the effect of Au197 nanoparticle along with Sm153 is in beta interaction more than gamma interaction.{Figure 5} Discussion The Au197 nanoparticle treatment for a sample prostate model was successfully performed using the Monte Carlo MCNP4C code. In these calculations, it was found that the Au197 and Sm153 sources can be optimizing the absorbed dose rate in prostate tumor treatment. The increasing dose value in the entire prostate volume is about 3% and decreasing undesirable dose value in exterior of the prostate is 7%. Therefore, using the Au197 nanoparticle in prostate cancer treatment has an effective role. A comparison between the results shows that the effect of Au197 nanoparticle along with Sm153 is in beta interaction more than gamma interaction. This difference is about 8%–0.2%. In summary, the results of this investigation is support the Monte Carlo simulation technique with the data presented by Cho;[18] as reported in this research, the effect of Au197 nanoparticles in absorbed dose due to 192Ir gamma rays is 2% on average. Conclusion In conclusion, the results of this investigation shown that Au197 has Effective role in cancer therapy from theoretical view. Au197 and Sm153 mixed radiopharmaceutical indicated that the absorbed dose rate in entire prostate volume 3% was increased and undesirable dose value in exterior of prostate 7% was decreased. Acknowledgement This work was carried out between Science and Technology Research Institute (STRI) and University of Kyrenia. Therefore, the authors are very grateful to the cooperation and support of management and staff of STRI. Financial support and sponsorship This study was financially supported by University of Kyrenia, Kyrenia, North Cyprus, Mersin 10, Turkey. Conflicts of interest There are no conflicts of interest. References


