Résumé
Background: New treatment modalities are developed with the aim of escalating tumor absorbed dose and simultaneously sparing the normal structures. The use of nanotechnology in cancer treatment offers some possibilities including destroying cancer tumors with minimal damage to healthy tissues. Zinc Oxide nanoparticles [ZnO NPs] are wide band gap semiconductors and seem to have a good effect on increasing the absorbed dose of target volume especially when doped with a high Z element. The aim of this study was to evaluate the effect of ZnO NPs doped with Gadolinium [Gd] on dose enhancement factor by 6MV photon beam irradiation. Materials and Methods: Various concentrations of ZnO NPs doped with 5% Gd were incorporated into PRESAGE composition, the 3D chemical dosimeter. Then by using a UV-Vis spectrophotometer optical density changes and also dose enhancement factor [DEF] were determined. Results: The results of this study showed that by incorporating 500, 1000, 3000 and 4000 micro g/ml ZnO NPs doped with Gd into PRESAGE structure the dose enhancement factor of about 1.57, 1.69, 1.78 and 1.82 in a 15 ×15 cm[2] field size could be found, respectively. Conclusion: The results of this study showed that ZnO NPs doped with Gd could be considered as new compound for increasing the absorbed dose
Résumé
Making use of the orthovoltage machines in Radiotherapy, is one of the routine methods for the treatment of the superficial lesions. In this study, an important determinant of X-ray quality, the HVL [Half Value Layer], has been evaluated. The HVLs of a orthovoltage X-ray machine in 120 and 180 kVp are measured, using an empirical method, in which the HVLs are derived from the absorption curves. The measured HVLs are compared with calculated [Monte Carlo simulation] HVLs. Using the BEAMDP code of simulation, the output spectra are obtained and employed for the measurement of the HVLs. Comparing the calculated and measured HVL values, the results show that the highest and lowest differences between the two are 4.96% and 2.27%, respectively, which are, in fairly good agreement with those obtained in the former studies. This study shows that the EGSnrc simulation code is capable of being used for the extraction of the quality indices for the superficial X-ray radiotherapy machines. It seems that, the mentioned code, with the mentioned experimental method, can be employed as a routine clinical test tool for every superficial radiotherapy department