An institutional experience of quality assurance of a treatment planning system on photon beam

Aim

The purpose of the present study is to show the application of the IAEA TRS-430 QA procedures of Eclipse™v7.5 TPS for photon energies. In addition, the trends of the deviations found in the conducted tests were determined.

Background

In the past, the lack of complete TPS QA procedures led to some serious accidents. So, QA in the radiotherapy treatment planning process is essential for determination of accuracy in the radiotherapy process and avoidance of treatment errors.

Materials and methods

The calculations of TPS and measurements of irradiations of the treatment device were compared in the study. As a result, the local dose deviation values (δ₁: central beam axis, δ₂: penumbra and build up region, δ₃: inside field, δ₄: outside beam edges, δ_50–90: beam fringe, RW₅₀: radiological width) and their confidence limit values (including systematic and random errors) were obtained.

Results

The confidence limit values of δ₄ were detected to increase with expanding field size. The values of δ₁ and δ₃ of hard wedge were larger than open fields. The values of δ₂ and δ_50–90 of the inhomogeneity effect test were larger, especially than other tests of this study. The average deviation was showed to increase with the rise of the wedge angle. The values of δ₃ and δ₄ of lung irradiation were outside tolerance.

Conclusions

The QA of TPS was done and it was found that there were no reservations in its use in patient treatment. The trend of the deviations is shown.     

Caffeic Acid Phenethyl Ester Modulates Gentamicin-Induced Oxidative Nephrotoxicity in Kidney of Rats

In this study, the modulator effect of caffeic acid phenethyl ester (CAPE) on the oxidative nephrotoxicity of gentamicin in the kidneys of rats was investigated by determining indices of lipid peroxidation and the activities of antioxidant enzymes as well as by histological analyses. Forty female Wistar albino rats were randomly divided into four groups, namely control, gentamicin, CAPE, and gentamicin plus CAPE. On the 12th day of the study, all rats were sacrificed and then blood samples and kidneys were taken. Lipid peroxidation and nitric oxide levels, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) enzyme activities, and histological evaluation were measured in kidneys of rats. Levels of blood urea nitrogen and creatinine were studied in serum. CAPE with gentamicin caused decreases in lipid peroxidation, nitric oxide, urea nitrogen, and creatinine levels, although it caused increases in CAT, GSH-Px, and SOD activities when compared with gentamicin alone. In addition, on histological evaluation, the renal damage caused by gentamicin alone appeared much higher than that caused by CAPE plus gentamicin. It is concluded that oxidative stress plays a critical role in causing gentamicin nephrotoxicity and that this nephrotoxicity may be significantly reduced by CAPE.     

Strategy for Restoration of Brine-Disturbed Land

Brine-affected land at oil exploration sites is a prime source of pollution to soil, plant, and aquatic communities. The two primary effects of brine on soil are (1) degradation of soil structure and (2) alteration of the osmotic gradient between plant roots and the soil. Runoff from the damaged land also degrades the quality of receiving streams. The objective of this study was to assess the extent of damage caused by brine on a productive land and two adjacent streams. Data on soil quality revealed that over time the combined effects of brine and erosion had left the land devoid of vegetation. Detailed soil analyses showed elevated levels of soluble salt, moderate pH (7.5), high clay content (>38%), electrical conductivity values that ranged from 7 to 62?dSm^?1, and very high exchangeable sodium percentage (70%). The water quality of the two receiving streams was severely impacted by high salt and sediment loading. Based on soil and water quality data from the disturbed site, a strategy was developed to rehabilitate the land by a combination of engineering and agronomic practices. Six months after the rehabilitation, approximately 90% of the land had been restored with full establishment of seeded Bermuda grass (Cynodon dactylon).     

Biochemical alterations in neonatal hypoxic ischaemic brain damage

Asphyxiated (n = 39) and control (n = 23) were elected for the study. Free radical-mediated lipid peroxidation, prostaglandin E₂ and vitamin E levels were studied and the degree of hypoxic ischaemic encephalopathy was determined in each case. In the hypoxic group the concentration of prostaglandin E₂ activity (P < 0.05) and malondialdehyde levels (P < 0.01) were significantly higher when compared to that of controls. The high vitamin E concentrations in the asphyxiated infants supports the role of oxygen free radicals in hypoxic ischaemic encephalopathy of newborns.