Asghar Mesbahi

[ 1 ] - Dose calculations accuracy of TiGRT treatment planning system for small IMRT beamlets in heterogeneous lung phantom

Background: Accurate dose calculations in small beamlets and lung material have been a great challenge for most of treatment planning systems (TPS).  In the current study, the dose calculation accuracy of TiGRT TPS was evaluated for small beamlets in water and lung phantom by comparison to Monte Carlo (MC) calculations. Materials and Methods: The head of Siemens Oncor-impression linac...

[ 2 ] - Monte Carlo calculation of shielded colpostat effect on rectum received dose in high dose rate brachytherapy with Cobalt-60 sources

Background: In the current study the effect of shielded colpostat on rectum received dose was calculated in cervical brachytherapy using Monte Carlo (MC) method. Materials and Methods: Two 60Co sources of GZP6 brachytherapy unit used for intracavitary treatments were simulated using MCNPX Monte Carlo code. Also the two types of colpostats including shielded and unshielded were simulated inside ...

[ 3 ] - Patient doses from X-ray computed tomography examinations by a single-array detector unit: Axial versus spiral mode

Background: X-ray computed tomography (CT) examinations deliver a significant amount of radiation doses to patients comparing to conventional radiography examinations. The objective of the current study was to analyze and investigate the average patient received dose from axial and spiral CT exams in a medical imaging center. Material and Methods: In this study, the patient imaging tec...

[ 4 ] - Monte Carlo characterization of photoneutrons in the radiation therapy with high energy photons: a Comparison between simplified and full Monte Carlo models

Background: The characteristics of secondary neutrons in a high energy radiation therapy room were studied using the MCNPX Monte Carlo (MC) code. Materials and Methods: Two MC models including a model with full description of head components and a simplified model used in previous studies were implemented for MC simulations. Results: Results showed 4-53% difference between full and wit...

[ 5 ] - Multifunctional GQDs-Coated Fe/Bi Nanohybrids for CT/MR Dual Imaging and in vitro Photothermal Therapy

Introduction: The multipurpose nanocomposites have gained growing biomedical attention as promising nanotheranostics to improve The effectiveness of cancer treatment, which concurrently combine advantages of the therapeutic and diagnostic techniques into one nanosystem. The “all-in on” probes not only help to ablate cancerous tumors, but also allow to optimize and monitoring of...

[ 6 ] - Comparison of Radiobiological Models for Radiation Therapy Plans of Prostate Cancer: Three-dimensional Conformal versus Intensity Modulated Radiation Therapy

Purpose: In the current study, using different radiobiological models, tumor control probability (TCP) and normal tissue complication probability (NTCP) of radiotherapy plans were calculated for three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) of prostate cancer.Methods and Materials: 10 prostate plans were randomly selected among patients ...

[ 7 ] - A New Potential Contrast Agent for Magnetic Resonance Imaging: Iron Oxide-4A Nanocomposite

Background: Magnetic resonance imaging (MRI) contrast agents have an important role to differentiate healthy and diseased tissues. Access and design new contrast agents for the optimal use of MRI are necessary. This study aims to evaluate iron oxideâ€“4A nanocomposite ability to act as a magnetic resonance imaging contrast agent.Materials and Methods: Iron oxideâ€“4A nanocomposite (F4A) was syn...

[ 8 ] - Dosimetry of Critical Organs in Maxillofacial Imaging with Cone-beam Computed Tomography

Background: While the benefits of cone-beam computed tomography (CBCT) are well known in maxillofacial imaging, the use of this modality is not risk-free.Objective: The aim of this study was to evaluate the exposure doses received by patients during maxillofacial imaging with CBCT.Methods: Entrance surface dose (ESD) was measured by using thermoluminescent dosimeters (TLDs) attached to the eyes...

[ 9 ] - A review on neutron shielding performance of nano-composite materials

Neutron sources employed in different applications in both medicine and industry. Due to the harmful effects of neutron particles on living organisms, radiation shields have played a vital role in radiation protection against neutrons. In recent decade, numerous investigations conducted on the design and fabrication of nanocomposites as more efficient shielding materials against fast and therma...