PURPOSE The impact of multileaf collimator (MLC) design and IMRT technique on plan quality and delivery improvements for head-and-neck and meningioma patients is compared in a planning study. MATERIAL AND METHODS Ten previously treated patients (5 head-and-neck, 5 meningioma) were re-planned for step-and-shoot IMRT (ssIMRT), sliding window IMRT (dMLC) and VMAT using the MLCi2 without (-) and ...

PURPOSE The purpose of this paper is to characterize EBT3 using two types of scanner, analyzing the factors of influence of each dosimetry system. METHODS The film used in this study was GAFCHROMIC EBT3, the films were exposed at a dose range between 0Gy a 9Gy in a solid water phantom, SSD=100cm, 5cm depth and perpendicularly to the 6MV photon beam generated by a Novalis TX linear accelerator...

To measure and compare the contrast to noise ratio (CNR) as a function of dose for the CBCTs produced by the mega-voltage (MV) imaging beam line (IBL) and the treatment beam line (TBL), and to compare the dose to target and various critical structures of pediatric patients for the IBL CBCT versus standard TBL orthogonal port films. Two Siemens Oncor linear accelerators were modified at our inst...

Background: This Study Evaluate two state of Art techniques, Rapid Arc and large-field sliding window IMRT in terms of dosimetric end points and delivery time for head and neck cancer. Materials and Methods: 22 patients with head and neck cancer were selected for a planning comparative study. All patients went to CT-simulation in supine position. PTVs were delineated for two dose level of presc...

MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitati...

Introduction: Recently Cerium oxide nanoparticles (CONPs) are being checked as interventional treatments in biological systems. The scavenging of free radicals by nanoparticles performance is the inhibition of Reactive Oxygen Species (ROS). Ionizing radiations can prevent the proliferation and differentiation of cells and even cause apoptosis. CONPs, as radioprotection, can pro...

background: monte carlo method (mc) has played an important role in design and optimization of medical linacs head and beam modeling. the purpose of this study was to compare photon beam features of two commercial linacs, varian 21ex and elekta sl-25 using mcnp4c mc code. materials and methods: the 6mv photon beams of varian 21ex and elekta sl-25 linacs were simulated based on manufacturers pro...

The liver is the most common site for metastasis in colorectal cancer patients (CCR), occurring less frequently when spreads from breast, lung or a melanoma. Surgery has shown rise overall survival (OS) of selected patients. However, only 10%-20% metastases are resectable. Local treatments, including radiofrequency ablation and SBRT, may be considered not eligible surgery. Conventional radiothe...

Background: Monte Carlo method (MC) has played an important role in design and optimization of medical linacs head and beam modeling. The purpose of this study was to compare photon beam features of two commercial linacs, Varian 21EX and Elekta SL-25 using MCNP4C MC code. Materials and Methods: The 6MV photon beams of Varian 21EX and Elekta Sl-25 linacs were simulated based on manufacturers pro...