Nanodiamonds as a state-of-the-art material for enhancing the gamma radiation resistance properties of polymeric membranes.

We report, for the first time, the development of gamma radiation resistant polysulfone (Psf)-nanodiamond (ND) composite membranes with varying concentrations of NDs, ranging up to 2 wt% of Psf. Radiation stability of the synthesized membranes was tested up to a dose of 1000 kGy. To understand the structure-property correlationship of these membranes, multiple characterization techniques were used, including field-emission scanning electron microscopy, atomic force microscopy, drop shape analysis, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, gel permeation chromatography, positron annihilation spectroscopy, and small angle X-ray scattering. All the composite membranes exhibited enhanced radiation resistance properties, with 0.5% loading of NDs as the optimum. Compared to the radiation stability of Psf membranes up to a dose of 100 kGy, the optimum composite membranes are found to be stable up to a radiation dose of 500 kGy, owing to the unique surface chemistry of NDs and interfacial chemistry of Psf-ND composites. Experimental findings along with the Monte Carlo simulation studies confirmed a five times enhanced life-span of the composite membranes in an environment of the intermediate level radioactive waste, compared to the control Psf membrane.

Computed organ doses to an Indian reference adult during brachytherapy treatment of esophagus, breast, and neck cancers.

This study aims to generate the normalized mean organ dose factors (mGy min(-1) GBq(-1)) to healthy organs during brachytherapy treatment of esophagus, breast, and neck cancers specific to the patient population in India. This study is in continuation to the earlier published studies on the estimation of organ doses during uterus brachytherapy treatments. The results are obtained by Monte Carlo simulation of radiation transport through MIRD type anthropomorphic mathematical phantom representing reference Indian adult with (192)Ir and (60)Co high dose rate sources in the esophagus, breast, and neck of the phantom. The result of this study is compared with a published computational study using voxel-based phantom model. The variation in the organ dose of this study to the published values is within 50%.

Monte Carlo investigation of energy response of various detector materials in ¹²5I and ¹69Yb brachytherapy dosimetry.

Relative absorbed-dose energy response correction R for different detector materials in water, PMMA and polystyrene phantoms are calculated using Monte Carlo-based EGSnrc code system for ¹²5I and ¹69Yb brachytherapy sources. The values of R obtained for ¹²5I source are 1.41, 0.92, 3.97, 0.47, 8.32 and 1.10, respectively, for detector materials LiF, Li2B4O7 , A12O3, diamond, silicon diode and air. These values are insensitive to source-to-detector distance and phantom material. For ¹69Yb source, R is sensitive to source-to-detector distance for detector materials other than air and Li2B4O7. For silicon, R increases from 3 to 4.23 when depth in water is increased from 0.5 cm to 15 cm. For ¹69Yb source, the values of R obtained for air and Li2B4O7 in PMMA and polystyrene phantoms are comparable to that obtained in water. However, LiF, Si and A12O3 show enhanced response and diamond shows decreased response in PMMA and polystyrene phantoms than in water.