Comparison and estimation of photoneutron dose produce between 10 MV flattened and unflattened beam in Elekta Versa HD™ medical linac.

BACKGROUND: In a high-energy medical linear accelerator (linac), if the interaction of photon energy is higher than the neutron binding energy of high atomic material, it emits a neutron field through photonuclear (γ, n) reaction. AIM: The current study, evaluates the photoneutron dose equivalent (PNDE) produced between the 10 MV flattened and unflattened beams as a function of field sizes in the Elekta Versa HD™ linac. MATERIALS AND METHODS: The PNDE produced from Versa linac was recorded along the patient plane using the bubble detector personal neutron dosimeter and from the measured PNDE values, the theoretical PNDE values were simulated for various field sizes using nonlinear least-squares curve-fitting as a function of a polynomial. The percentage of deviation (PoD) and Chi-square (χ2) tests were performed between the measured and simulated PNDE values to study the reliability and validity. RESULTS: The results show that the mean PoD between the measured and simulated PNDE values for respective positions of a field size of FF beam was found to be -1.99% for 0.3×0.3, -4.39% for 5×5, -3.868% for 10×10, 0.590% for 15×15, 9.18% for 20×20, -4.133% for 25×25, and 0.467% for 30×30 cm2. Similarly, the mean PoD between the measured and simulated PNDE values for flattening filter-free (FFF) beam was found to be 1.36% for 0.3×0.3, -1.39% for 5×5, -5.38% for 10×10, 4.41% for 15×15, 3.84% for 20×20, 5.69% for 25×25, and -1.75% for 30×30 cm2. The maximum deviation between the measured and simulated PNDE values lies within the range ± 5%. CONCLUSIONS: From the study, it is observed that the FFF beam produces lesser neutron contamination than the FF beam.

Evaluation of photoneutron dose equivalent in 10 MV and 15 MV beams for wedge and open fields in the Elekta Versa HD linac.

In a high-energy medical linear accelerator (linac), if the interaction of photon energy is higher than the neutron binding energy of high atomic material, it emits a neutron field through a photonuclear reaction. The objective of this current study is to measure the photoneutron dose equivalent produces in a motorized wedge field and open field of 10 MV and 15 MV photon beams in Elekta Versa HD™ linac. The PNDE values were recorded at various positions along the patient plane using the Bubble Detector-Personal Neutron Dosimeter (BD-PND). The results revealed that the PNDE values are higher in 20 × 20 cm2 than 10 × 10 cm2 field sizes for both the 60° wedge and open fields of 10 MV and 15 MV beams. In addition, the 60° wedge fields generate higher photoneutron contamination when compared with the 45°, 30° wedge fields and open field sizes. Hence, on average PNDE values produced by the 15 MV beam were higher by a factor of 1.98 and 2.11 times for open and 60° wedge fields than the 10 MV beam, respectively.

Synthesis and Characterization of Gd3+ Doped HfO2 Nanoparticles for Radiotherapy Applications.

Synthesis of pure Hafnium Oxide (HfO2), and HfO2 doped with Gadolinium (1, 3, 5 and 7 mol%) nanoparticles (NPs) had been carried out by Precipitation and co-precipitation method using the precursor solution of Hafnium (IV) chloride (HfCl4) and Gadolinium(III) chloride hexahydrate (GdCl3·6H2O) with Sodium hydroxide (NaOH) which was dissolved in deionized water. The synthesized compound was characterized and analyzed by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDX), UV-visible spectrophotometer, Photoluminescence (PL), Fourier Transform infrared spectroscopy (FTIR) and Raman spectroscopy. The result from X-ray diffraction showed that the Gd3+ concentration for 7 mol% had attended directly crystalline phase of Cubic HfO2 structure. Morphology and element analysis of the samples were analyzed using FESEM and EDX, which indicated cluster formation, fluffy and voids with highly agglomerated particles and EDX exhibited no extra peaks with other than constituent elements present in extrinsic HfO2. From UV Spectra it was observed that the optical band gap of both Intrinsic and extrinsic of HfO2 NPs were found to be 5.74 eV, 3.62 eV, 3.69 eV, 3.78 eV and 4.19 eV. The Photoluminescence Spectra showed the 313 nm emission line which might be due to 6P7/2→8S7/2 transition and the Raman Spectra clearly represented the monoclinic structure by showing the presence of Ag and Bg Modes and cubic structure because of the presence of F2g mode.