Long term effects of gamma radiation on inflammatory and apoptotic biomarkers in nuclear medicine staff.

Background: Gamma radiation at low doses might have potential health effects in long-term exposure. The current study was aimed to search cell death pathway and inflammatory biomarkers in nuclear medicine workers with long-term exposure to gamma radiation.

Material And Methods: Fifty cases with a history of 10 years' exposure to gamma radiation and 30 normal individuals were included in the current study.

Monte Carlo Simulation for the Radixact™ Tomotherapy Linac Using EGSnrc.

Purpose: When exact information regarding the treatment head and initial electron beam is available, the Monte Carlo (MC) approach can properly simulate any linear accelerator. However, manufacturers seldom offer information such as the incident electron beam's energy, radial intensity (spot size), or angular spread. This research aims to forecast these features and verify an MC-simulated linear accelerator model using measurements.

Evaluation of the geometric and dosimetric accuracies of deformable image registration of targets and critical organs in prostate CBCT-guided adaptive radiotherapy.

Purpose: Kilovoltage cone beam computed tomography (kVCBCT)-guided adaptive radiation therapy (ART) uses daily deformed CT (dCT), which is generated automatically through deformable registration methods. These registration methods may perform poorly in reproducing volumes of the target organ, rectum, and bladder during treatment. We analyzed the registration errors between the daily kVCBCTs and corresponding dCTs for these organs using the default optical flow algorithm and two registration procedures.

The geometric and dosimetric accuracy of kilovoltage cone beam computed tomography images for adaptive treatment: a systematic review.

Objectives: To provide an overview and meta-analysis of different techniques adopted to accomplish kVCBCT for dose calculation and automated segmentation.

Methods: A systematic review and meta-analysis were performed on eligible studies demonstrating kVCBCT-based dose calculation and automated contouring of different tumor features. Meta-analysis of the performance was accomplished on the reported γ analysis and dice similarity coefficient (DSC) score of both collected results as three subgroups (head and neck, chest, and abdomen).

Evaluation of Anticancer and Cytotoxic Effects of Genistein on PC3 Prostate Cell Line under Three-Dimensional Culture Medium.

Background: Prostate cancer is a major cause of disease and mortality among men. Genistein (GNT) is an isoflavone found naturally in legumes. Isoflavones, a subset of phytoestrogens, are structurally similar to mammalian estrogens.

Neutron contamination in radiotherapy processes: a review study.

Using high-energy photon beams is one of the most practical methods in radiotherapy treatment of cases in deep site located tumors. In such treatments, neutron contamination induced through photoneutron interaction of high energy photons (>8 MeV) with high Z materials of LINAC structures is the most crucial issue which should be considered. Generated neutrons will affect shielding calculations and cause extra doses to the patient and the probability of increase induced secondary cancer risks.

Synthesis and evaluation of thermoluminescence properties of ZrO:Mg for radiotherapy dosimetry.

This study aimed to investigate the thermoluminescent properties of ZrO:Mg irradiated with a 6 MV X-ray beam and its potential application in radiotherapy dosimetry. ZrO powder was synthesized using the sol-gel method and Mg was used as a dopant. Irradiations were performed with ZrO:Mg chips located at the center of a 10 × 10 cm radiation field at a source surface distance of 100 cm, below a stack of solid water slabs, at the depth of maximum absorbed dose.

Evaluating the effects of metal artifacts on dose distribution of the pelvic region.

Aim Of The Study: Some cancerous patients have hip prosthesis of metal elements when they undergo radiation therapy. Metal implants are a cause of metal artifacts in computed tomography (CT) images due to their higher density compared to normal tissues. The aim of this study is to evaluate the quantitative effects of metal artifacts on dose distribution of the pelvic region.

The effect of magnetic field on Linac based Stereotactic Radiosurgery dosimetric parameters.

: MR-linac machines are being developed for image-guided radiation therapy but the magnetic field of such machines could affect dose distributions. The purpose of this work was to evaluate the effect of a magnetic field on linac beam dosimetric parameters including penumbra for circular cones used in radiosurgery.: Monte Carlo simulation was conducted for a linac machine with circular cones at 6 MV beam.

Enhanced dose measurement of zinc oxide nanoparticles by radiochromic polymer dosimeter and Monte Carlo simulation.

Aim: The aim of this study is to evaluate the effects of Zinc Oxide nanoparticles on dose enhancement factor using PRESAGE dosimeter and Monte Carlo simulation.

Background: High Z materials absorb X-ray remarkably. Among Nano-science, Zinc Oxide nanoparticles are interesting semiconductors, producing reactive oxygen species when irradiated by photons.

Dosimetric evaluation of electron total skin irradiation using gafchromic film and thermoluminescent dosimetry.

Aim Of Study: The aim of this study is to evaluate some dosimetry parameters such as uniformity, surface dose, and max depth dose with thermoluminescent dosimetry (TLD) and EBT3 film in total skin electron beam therapy (TSEBT).

Methods: Stationary and rotary methods were set on Varian linear accelerator, Clinac 2100C. To create a radiation field large enough (168 cm × 60 cm) and uniform, the source skin distance was set 400 cm.

Determination of the dose enhancement exclusively in tumor tissue due to the presence of GNPs.

Purpose: The purpose of this study is to investigate the differences between obtained percentage dose enhancements in areas around nanoparticles in GNPs (gold nanoparticles) enriched medium and percentage dose enhancements in the entire GNPs enriched medium including nanoparticles region.

Methods And Materials: To verify the accuracy of Ir-192 source simulation, the obtained values of air kerma strength, dose rate constants, and radial dose functions were compared against previously published results. Then a 1 cm × 1 cm× 1 cm tumor volume loaded with different diameters of GNPs were considered at a source to the tumor center of 1 cm.

Determination of geometric accuracy of radiotherapy fields by port film and DRR using Matlab graphical user interface.

The purpose of this study is to determine and verify the exact location of radiation therapy fields by using port-film and digital reconstruction radiograph (DRR) as a low-cost tool. Initially, an appropriate algorithm was written for the application of port film in the megavoltage beam irradiation. Detectable contrast was created for the image and then by using appropriate markers and developed written program by MATLAB as DRrPortRegistartion.

Comparison of penumbra regions produced by ancient Gamma knife model C and Gamma ART 6000 using Monte Carlo MCNP6 simulation.

The accuracy of penumbral measurements in radiotherapy is pivotal because dose planning computers require accurate data to adequately modeling the beams, which in turn are used to calculate patient dose distributions. Gamma knife is a non-invasive intracranial technique based on principles of the Leksell stereotactic system for open deep brain surgeries, invented and developed by Professor Lars Leksell. The aim of this study is to compare the penumbra widths of Leksell Gamma Knife model C and Gamma ART 6000.

Dosimetric properties of new formulation of PRESAGE with tin organometal catalyst: Development of sensitivity and stability to megavoltage energy.

Aim: Tin-base catalyst is one of the widely used organometallic catalysts in polyurethane technology. The purpose of this study was to evaluate the effect of tin organometallic catalyst in the radiation response and radiological properties of a new formula of PRESAGE.

Materials And Methods: In the study, two types of PRESAGE were fabricated.

Comparison of full width at half maximum and penumbra of different Gamma Knife models.

As a radiosurgical tool, Gamma Knife has the best and widespread name recognition. Gamma Knife is a noninvasive intracranial technique invented and developed by Swedish neurosurgeon Lars Leksell. The first commercial Leksell Gamma Knife entered the therapeutic armamentarium at the University of Pittsburgh in the United States on August 1987.

Monte Carlo calculation of photo-neutron dose produced by circular cones at 18 MV photon beams.

Aim: The aim of this study is to calculate neutron contamination at the presence of circular cones irradiating by 18 MV photons using Monte Carlo code.

Background: Small photon fields are one of the most useful methods in radiotherapy. One of the techniques for shaping small photon beams is applying circular cones made of lead.

Optical computed tomography in PRESAGE three-dimensional dosimetry: Challenges and prospective.

With the advent of new complex but precise radiotherapy techniques, the demands for an accurate, feasible three-dimensional (3D) dosimetry system have been increased. A 3D dosimeter system generally should not only have accurate and precise results but should also feasible, inexpensive, and time consuming. Recently, one of the new candidates for 3D dosimetry is optical computed tomography (CT) with a radiochromic dosimeter such as PRESAGE®.

Measurement of neutron dose in the compensator IMRT treatment.

A radiation treatment delivery technique, intensity modulated radiation therapy (IMRT), has found widespread use in the treatment of cancers. One of IMRT implementing methods is IMRT compensator based, which the modulation are done by high Z materials. When photons with energies higher than 8MV interact with high Z material in path, Photoneutrons are produced.

Neutron dose measurements of Varian and Elekta linacs by TLD600 and TLD700 dosimeters and comparison with MCNP calculations.

High-energy linacs produce secondary particles such as neutrons (photoneutron production). The neutrons have the important role during treatment with high energy photons in terms of protection and dose escalation. In this work, neutron dose equivalents of 18 MV Varian and Elekta accelerators are measured by thermoluminescent dosimeter (TLD) 600 and TLD700 detectors and compared with the Monte Carlo calculations.