Dosimetry characteristics of polycarbonate/bismuth oxide nanocomposite for real-time application in the field of gamma-rays.

BACKGROUND

Polymer-carbon nanostructures have previously been introduced for dosimetry of gamma rays with potential application in radiotherapy. In this research work, bismuth oxide (BiO) nanoparticles were added into the amorphous polycarbonate (PC) matrix to enhance the probability of the photoelectric effect and dosimetry response in parallel.

MATERIALS AND METHODS

PC/BiO nanocomposites at concentrations of 0, 5, 20, 40, and 50 BiO wt% were fabricated via a solution method. Afterward, the samples were irradiated by gamma rays of cobalt-60 (Co) related to Picker V-9, and Therarton-780 machines at 30-254 mGy/min. Dosimetric characteristics were carried out including linearity, angular dependency, energy, bias-polarity, field size, and repeatability.

RESULTS

Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses exhibited an appropriate dispersion state. The dosimeter response was linear at 30-254 mGy/min for the all samples. The 50 wt% sample exhibited the highest sensitivity at 4.61 nC/mGy. A maximum angular variation of approximately 15% was recorded in normal beam incidence. The energy dependence at two energies of 662 and 1250 keV was obtained as 0.7%. Bias-polarity for the 40, and 50 wt% samples at 400 V were measured as 15.9% and 9.0%, respectively. The dosimetry response was significantly dependent on the radiation field size. Also, the repeatability of the dosimeter response was measured as 0.4%.

CONCLUSIONS

Considering the dosimetry characteristics of PC-BiO nanocomposites, and appropriate correction factors, this material can be used as a real-time dosimeter for the photon fields at therapy level.