Mohsen Khosroabadi; Ebrahim Golmakani; Mehdi Bakhshabadi; Reza Ganji; MohammadAmin Yones Heravi; Hamid Kardani; Homa Rezaee Moghaddam; Mohammad Mehrpoyan
Volume 21, Issue 6 , January and February 2015, , Pages 1008-1018
Abstract
Background and purpose: Photon activation therapy is a radiation technique in which the energy deposition within a tumor can be increased by provoking the emission of Auger electrons emitted through photoelectric effect, through the addition of high Z elements. In this process the DNA molecules are ...
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Background and purpose: Photon activation therapy is a radiation technique in which the energy deposition within a tumor can be increased by provoking the emission of Auger electrons emitted through photoelectric effect, through the addition of high Z elements. In this process the DNA molecules are as targets for the Auger electrons which are emitted from high Z atoms. The aim of this study is to assess dose enhancement factor for 170Tm and 125I brachytherapy sources, in photon activation therapy in presence of various activation elements in tumor, using Monte Carlo method.
Materials and Method: In present study 125I source Iso Aid Advantage (model IA1-125A) and a hypothetical 170Tm source were simulated usingMonte Carlo code MCNPX. Calculating and verifying TG-43 parameters, dose enhancement factor on the transverse axis in presence of activation elements like Pt, Ag, gold and iodine inside tumor obtained with the concentration of 7, 18 and 30 mg/ml in photon activation therapy, individually.
Results: Dose rate constant and radial dose functions for the sources were in agreement with the previous studies. Maximum dose enhancement factor obtained 4.87 which belongs to 170Tm with the concentration of 30 mg/ml. DEF for 170Tm source was more than 125I in the presence of all activation elements.
Conclusion: In DEF point of view, using gold inside tumor can be more beneficial in photon activation therapy. Also 170Tm brachytherapy source is recommended in photon activation therapy.
Ebrahim Golmakani; Reza Ganji; Mohsen Abad; Homa Rezaee moghaddam; Mehdi Bakhshabadi; Mohammad Mehrpoyan; Mohsen Khosoabadi; Ramin Shahraeini
Volume 21, Issue 5 , September and October 2014, , Pages 808-818
Abstract
Background: The aim of this study is to assess of dose enhancement effect in tumour in presence of 10B, 157Gd, 10B nanoparticles and 157Gd nanoparticles in radiotherapy through neutron capture by Monte Carlo method.
Materials and Methods: A 252Cf brachytherapy source AT model was simulated by Monte ...
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Background: The aim of this study is to assess of dose enhancement effect in tumour in presence of 10B, 157Gd, 10B nanoparticles and 157Gd nanoparticles in radiotherapy through neutron capture by Monte Carlo method.
Materials and Methods: A 252Cf brachytherapy source AT model was simulated by Monte Carlo method code MCNPX and its TG-43 parameters were calculated and compared with previous corresponding data. This 252Cf brachytherapy source was used as a neutron source in neutron capture therapy. Dose enhancement factor was compared in tumour in presence of 10B, 157Gd, 10B nanoparticles and 157Gd nanoparticles for the concentrations of 100, 200 and 500 ppm of each capture agents in neutron capture. For this aim, around the 252Cf source, a spherical soft tissue phantom and a tumour containing each capture agents were considered.
Results: Calculated air kerma strength and dose rate constant for 252Cf source equals to 0.306 cGycm2/hµg and 5.782 cGy/Uh respectively. Among examined agents, maximum DEF belonged to 10B and 10B nanoparticles in concentration of 500 ppm. These values were reported as 1.06 and 1.08 respectively.
Conclusion: IN this study, air kerma strength and dose rate constant indicate difference of %7.27 and %1.10 with other corresponding values. In dose enhancement point of view, capture agents containing 10B are more useful in neutron capture therapy. In the same concentrations, dose enhancement factor for capture agents in nanoparticles form is higher than the presence of capture agents in atomic form. So, it is preferable to use of nanoparticle capture agent rather than atomic form. However, it should be noted that before clinical usage of this agents, other medical, chemical and physical criteria should be considered, for their comparison, in selection of capture agents in neutron capture therapy.