hamideh naderi

some cardio-pulmonary complications, such as lung pneumonia in the radiotherapy treatment of breast cancer are associated with several factors including the amount of irradiated lung volume. Therefore in this study, the determining factors in irradiated lung volume have been investigated.
In this study, 48 patients with early breast cancer treated with 3D CRT radiation, were chosen. All ORS and PTV were contoured based on the RTOG atlas. CLD, MLD and GPD parameters were measured and their relationship with irradiated lung volume percentage was studied by DVH curves.
The correlation between CLD and GPD with a percentage of irradiated lung volume in the tangential fields was linear. For example, CLD of right lung CLD equal to 15, 25 and 35 mm accounted for 10%, 17% and 24% of lung volume in Tangential fields, respectively.
The correlation between CLD and lung volume in tangential fields for the left and right lung was significant. With an increase of one unit in the CLD, on average we expect that left and right lungs volume is increased 2% and 3.2%, respectively.

Recently, electron beams are widely used for superficial and skin lesions treatment. Since the accelerator devices, create electron beams with finite energies, the treatment area is limited to a specified depth. The objective of this study was to assess the effect of combination of electron beams with different energies and different contribution in order to produce PDD curve with a more uniform central dose distribution for the shallow superficial lesions treatment (up to cm 3). The results were compared with using a single electron beam energy. Subjects and at First, percentage depth dose (PDD) was measured by using a Varian accelerator devices for energies 4, 6, 9, 12 Mev of electron beams and field size 20 × 20 cm2. Then, PDD curve was converted to dose curve. 4 Gaussian function was fit to dose curve using MATLAB software and the best combination was selected by combining different proportions of each of this functions. percentage of the build up dose increased to about %90-%95 maximum dose and also percentage of the surface dose increases to about %90 maximum dose by combination of electron beams with different energies and different contribution. low energy electron beams Combination cause optimization of the dose distribution PDD curve. Furthermore, we can produce electron beam with arbitrary energy by this method.