No abstract

No abstract

The computerized treatment planning system plays a major role in radiation therapy in delivering correct radiation dose to the patients within ±5% as recommended by the ICRU. To evaluate the dosimetric performance of the Treatment Planning system (TPS) with three-dimensional dose calculation algorithm using the basic beam data measured for 6 MV X-rays. Eleven numbers of test cases were created according to the Technical Report Series-430 (TRS 430) and are used to evaluate the TPS in a homogeneous water phantom. These cases involve simple field arrangements as well as the presence of a low-density material in the beam to resemble an air in-homogeneity. Absolute dose measurements were performed for the each case with the MU calculation given by the TPS, and the measured dose is compared with the corresponding TPS calculated dose values. The result yields a percentage difference maximum of 2.38% for all simple test cases. For complex test cases in the presence of in-homogeneity, beam modifiers or beam modifiers with asymmetric fields a maximum percentage difference of 5.94% was observed. This study ensures that the dosimetric calculations performed by the TPS are within the accuracy of ±5% which is very much warranted in patient dose delivery. The test procedures are simple, not only during the installation of TPS, but also repeated at periodic intervals.

In the present study, we evaluated the radioprotective effect of carvacrol (CVC) against X-radiation-induced cellular damage in cultured human blood lymphocytes. By MTT assay, the LD50 doses of CVC and X-radiation to lymphocytes were determined to be 100 μg/ml and 4 Gy, respectively. To explore the radioprotective effect of CVC, the cultured lymphocytes were treated with 100 μg/mL of CVC 30 min prior to 4 Gy irradiation. Subsequently, the radiation-induced damage was screened by micronuclei (MN) and dicentric chromosome (DC) frequencies and comet assay. The percentage of cell death was evaluated by acridine orange/ethidium bromide (AO/EB) staining. The radiation-induced oxidative stress was estimated by assessing the changes in the levels of enzymatic antioxidants and lipid peroxidation markers. Compared with the sham control, we observed increases in MN and DC frequencies, comet attributes, % cell death, and lipid peroxidation with a concomitant decrease in the antioxidant status of the lymphocytes treated with radiation alone. Pre-treatment of lymphocytes with CVC (100 μg/mL) altered those changes mediated by radiation. These results clearly indicate that CVC may be an effective radioprotector against X-radiation. It has the ability to scavenge the free radicals produced and to protect cells from radiation-induced cell damage.

A columnar mini phantom is designed as recommended by ESTRO to measure the Head Scatter Factor (S C ) for 6 MV beam of two linear accelerators. The measurement of S C at different orientations of the chamber, parallel and perpendicular at 1.5 cm depth predicts the deviation of 2.05% and 1.9% for Elekta and Siemens linear accelerators respectively. The measurement of S C at 1.5 cm is higher compared to 10 cm depth for both the linear accelerators suggesting the electron contamination at 1.5 cm depth. The effect of wedges on S C yields a significant contribution of 3.5% and 5% for Siemens and Elekta linear accelerators respectively. The collimator exchange effect reveals the opening of upper jaw increases the S C irrespective of the linear accelerator. The result emphasizes the need of S C measurement at 10 cm. The presence of wedge influences the S C value and the SSD has no influence on S C . The measured S C values are in good agreement with the published data.