Bijan Hashemi
I Work as an associate professor in the field of Medical Physics at Tarbiat Modares University in Tehran, Iran.
My teaching and research interests are focused mainly on the Physics of Radiology and Radiotherapy namely on the development of radiological and radiotheraputical practices based on their underlying principles of physics such as Radiation Dosimetry, Monte Carlo and Finite Element Simulation, ... .
My teaching and research interests are focused mainly on the Physics of Radiology and Radiotherapy namely on the development of radiological and radiotheraputical practices based on their underlying principles of physics such as Radiation Dosimetry, Monte Carlo and Finite Element Simulation, ... .
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Method and Materials: In this experimental study, we used the MCF7 breast cancer cell line to investigate the effect of 13.56 MHz hyperthermia (at a temperature of 43°C for a period of 20 min) on their cell cycle arrest. We performed the flowcytometry assay to assess the changes in the mitotic phases of the cell population at different time intervals (1, 6, 24, and 48 h) after hyperthermia.
Results: Our flowcytometry results indicated the 24-h time interval has the most significant effect on the cell population at S and G2/M phases. Therefore, the 24-h time interval can be proposed as the most appropriate time after hyperthermia for carrying out combinational radiotherapy procedure.
Conclusion: Among various investigated time intervals examined in our research, the 24-h time interval can be proposed as the most appropriate time between hyperthermia and radiotherapy for combinational therapy of breast cancer cells.
Kerwords: Radiotherapy, Hyperthermia, Gold Nanoparticles, MCF‑7 cancer cells
Jeywoeds: MTT assay, Clonogenic Aassay, Dose Response, Survival Curve
Ketwords: Radiation Therpay, Radiation sentisizers, Targeted Radiotherapy, Gold Nanoparticles (GNPSs), Cervical Cancer
Materials and methods: An anthropomorphic pelvis phantom was used in two modes representing a homogeneous and heterogeneous phantom. Three dimensional (3D) CRT planning composed of five fields were performed on the CT images of the phantoms using the CorPLAN treatment planning system (TPS) of a 2100C/D Varian linac. Delivery of 3DCRT was also simulated by EGSnrc Monte Carlo code for the same conditions used in the CorPLAN TPS. The dose distributions resulted from the MC simulations were compared with those of the CorPLAN TPS for both of the phantoms based on the "dose difference (DD) percentages" and "distance to agreement (DTA)" parameters.
Results: Findings indicated that the heterogeneity leads to an overdose estimation at the target location up to 2.8% and 4.4% for the 6 and 18 MV energies, respectively by the CorPLAN TPS compared with the MC simulation data. The average DD and DTA for the homogeneous phantom were 2.7%-3.4mm and 1.6%-2.3 mm while for the inhomogeneous phantom they were 5.5%-3.7 mm and 6.0%-2.5 mm at the 6 and 18 MV energies, respectively.
Conclusion: Our results indicates that the accuracy of the dosimetry parameters estimated by the CorPLAN TPS at 18 MV is more than that of 6 MV energy. But, the heterogeneity deteriorates more the accuracy level of such dosimetry parameters estimated by this commercial TPS at 18 MV energy.
Keywords: prostate cancer, conformal radiation therapy, Monte Carlo, treatment planning system
Method and Materials: In this experimental study, we used the MCF7 breast cancer cell line to investigate the effect of 13.56 MHz hyperthermia (at a temperature of 43°C for a period of 20 min) on their cell cycle arrest. We performed the flowcytometry assay to assess the changes in the mitotic phases of the cell population at different time intervals (1, 6, 24, and 48 h) after hyperthermia.
Results: Our flowcytometry results indicated the 24-h time interval has the most significant effect on the cell population at S and G2/M phases. Therefore, the 24-h time interval can be proposed as the most appropriate time after hyperthermia for carrying out combinational radiotherapy procedure.
Conclusion: Among various investigated time intervals examined in our research, the 24-h time interval can be proposed as the most appropriate time between hyperthermia and radiotherapy for combinational therapy of breast cancer cells.
Kerwords: Radiotherapy, Hyperthermia, Gold Nanoparticles, MCF‑7 cancer cells
Jeywoeds: MTT assay, Clonogenic Aassay, Dose Response, Survival Curve
Ketwords: Radiation Therpay, Radiation sentisizers, Targeted Radiotherapy, Gold Nanoparticles (GNPSs), Cervical Cancer
Materials and methods: An anthropomorphic pelvis phantom was used in two modes representing a homogeneous and heterogeneous phantom. Three dimensional (3D) CRT planning composed of five fields were performed on the CT images of the phantoms using the CorPLAN treatment planning system (TPS) of a 2100C/D Varian linac. Delivery of 3DCRT was also simulated by EGSnrc Monte Carlo code for the same conditions used in the CorPLAN TPS. The dose distributions resulted from the MC simulations were compared with those of the CorPLAN TPS for both of the phantoms based on the "dose difference (DD) percentages" and "distance to agreement (DTA)" parameters.
Results: Findings indicated that the heterogeneity leads to an overdose estimation at the target location up to 2.8% and 4.4% for the 6 and 18 MV energies, respectively by the CorPLAN TPS compared with the MC simulation data. The average DD and DTA for the homogeneous phantom were 2.7%-3.4mm and 1.6%-2.3 mm while for the inhomogeneous phantom they were 5.5%-3.7 mm and 6.0%-2.5 mm at the 6 and 18 MV energies, respectively.
Conclusion: Our results indicates that the accuracy of the dosimetry parameters estimated by the CorPLAN TPS at 18 MV is more than that of 6 MV energy. But, the heterogeneity deteriorates more the accuracy level of such dosimetry parameters estimated by this commercial TPS at 18 MV energy.
Keywords: prostate cancer, conformal radiation therapy, Monte Carlo, treatment planning system