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Showing 2 results for Ghahremani
H. Pourbeigi, H. Ghafourian, A.s. Meigooni, M. Taghizadeh-Asl, A.r. Ghahremani,
Volume 2, Issue 2 (9-2004)
Abstract
Background: Recent pre-clinical and clinical studies indicate that irradiation in the dose range of 15 to 30 Gy can reduce rate of restenosis in patients who have undergone an angioplasty. The use of filled balloon with radioactive solution was proposed as one of the possible intravascular irradiation techniques. Materials and Methods: The Monte Carlo N-particle Transport Code (MCNP4b) was used to calculate the dose rate distribution in the tissue equivalent material around the 188Re and 186Re liquid sources. Schematic of Medical Internal Radiation Dose (MIRD) for homogeneous distribution of radio-nuclide in a lesion was used for mean organ absorbed dose calculation due to the internal distribution. Results: Results indicate that 188Re liquid with 100 mCi/ml and 186Re liquid with 250 mCi/ml can deliver desired dose in the vessel wall to reduce restenosis. The dose ratio in depth of 0.5 mm to surface of vessel wall for 188Re and 186Re were 40% and 18%, respectively. Therefore in case of 186Re, there is a little non-uniformity with respect to the 188Re case. The delivery of form 186Re dose to normal tissue around target tissue is less than 188Re. Conclusion: Use of the Monte Carlo simulation with 188Re-DTPA and 186Re-DTPA for
intra-vascular brachytherapy is a feasible method of delivering a desired dose to the vessel walls. Although188Re-DTPA delivers the desired dose to the target tissue with lower radioactive concentration (mCi/ml), but with the use of 186Re-DTPA, the delivery dose to normal tissue around the target tissue is less. Iran . J. Radiat. Res., 2004 2 (2): 89-95
Ph.d., M. Zabihzadeh, Z. Ghahremani, S.m. Hoseini, H. Shahbazian, M. Hoseini Ghahfarokhi,
Volume 18, Issue 3 (7-2020)
Abstract
Background: Presence of inhomogeneities such as lung tissue with low density can perturbs the dose distribution in the path of therapeutic photon beam and causes undesired cold or hot spots. The aim of this study was to investigate the effect of lung tissue inhomogeneities on dose distribution in thorax irradiation. Materials and Methods: The Monte Carlo simulation (MC) code of EGSnrc-based BEAMnrc was used to calculate dose distribution for 6 MV- Siemens Primus linear accelerator (Linac) in a homogenous phantom. Dose perturbation and inhomogeneity corrected factors (ICFs) were calculated due to implementation of lung tissue depended to the lung density and field size. Results: The maximum increased dose in lung tissue with lung density of 0.5 and 0.25gr/cm3 was 15.9%, 16.2%, 15.6%, 23.8 %, 24.8% and 25.0% for 6 × 6, 10 × 10 and 20 × 20 cm2 field sizes, respectively. The maximum ICF for these field sizes was 1.16 and 1.25 for lung density of 0.5 and 0.25gr/cm3, respectively. The maximum dose reduction in lung tissue with density of 0.25 and 0.5gr/cm3 was 19.5% and 4.2 %, and the related ICF was estimated 0.84 and 0.95, respectively. Conclusion: Involvement of lung tissue in the path of irradiation perturbs the dose distribution which is dependent to the lung density and field size. The ICFs resulted from our MC model could be useful to accurately calculate the dose distribution in radiotherapy of lung abnormalities.
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