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.

Investigation of TG-43 Dosimetric Parameters for Ir Brachytherapy Source Using GATE Monte Carlo Code.

Purpose: According to the revised Task Group number 43 recommendations, a brachytherapy source must be validated against a similar or identical source before its clinical application. The purpose of this investigation is to verify the dosimetric data of the high dose rate (HDR) BEBIG Ir source (Ir2.A85-2).

Bystander Response Following High-Dose X-irradiation; Time-dependent Nature of GammaH2AX Foci and Cell Death Consequences.

Background: The paradigm shifts in target theory could be defined as the radiation-triggered bystander response in which the radiation deleterious effects occurred in the adjacent cells.

Objective: This study aims to assess bystander response in terms of DNA damage and their possible cell death consequences following high-dose radiotherapy. Temporal characteristics of gH2AX foci as a manifestation of DNA damage were also evaluated.

Intensity-modulated brachytherapy for vaginal cancer.

This study aimed to evaluate the dose modulation potential of static and dynamic steel-shielded applicators using the Geant4 Application for Emission Tomography (GATE) Monte Carlo code for the treatment of vaginal cancer. The GATE TOOLKIT (version 9.0) was used to simulate vaginal cancer intensity-modulated brachytherapy (IMBT) in a pelvic water-equivalent phantom.

Evaluation of Capability and Relationship of Different Radiobiological Endpoints for Radiosensitivity Prediction in Human Tumor Cell Lines Compared with Clonogenic Survival.

Background: Establishing a predictive assay of radiosensitivity (as an appropriate, practical and cost-effective method) has been challenging.

Objective: The purpose of this study is to evaluate the capability and relationship of various endpoints, including GammaH2AX, micronuclei; and apoptosis in determining the human tumor cell lines radiosensitivities compared with clonogenic survival.

Material And Methods: In an experimental in-vitro study, the response of carcinoma cell lines of HN5 and HeLa to 2 Gy of 6 MV photon beam was investigated via various assays.

BEBIG Co HDR brachytherapy source dosimetric parameters validation using GATE Geant4-based simulation code.

Purpose: This study aims to validate the dosimetric characteristics of High Dose Rate (HDR) Co source (Co0.A86 model) using GATE Geant4-based Monte Carlo code. According to the recommendation of the American Association of Physicists in Medicine (AAPM) task group report number 43, the dosimetric parameters of a new brachytherapy source should be verified either experimentally or by Monte Carlo calculation before clinical applications.

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.

Ipsilateral lung normal tissue complication probability parameters for different dose calculation algorithms in radiotherapy of breast cancer.

Purpose: Different dose calculation algorithms (DCAs) predict different dose distributions for the same treatment. Awareness of optimal model parameters is vital for estimating normal tissue complication probability (NTCP) for different algorithms. The aim is to determine the NTCP parameter values for different DCAs in left-sided breast radiotherapy, using the Lyman-Kutcher-Burman (LKB) model.

Normal lung tissue complication probability in MR-Linac and conventional radiotherapy.

Purpose: To study normal lung tissue (NLT) complications in magnetic resonance (MR) image based linac and conventional radiotherapy (RT) techniques.

Materials And Methods: The Geant4 toolkit was used to simulate a 6 MV photon beam. A homogenous magnetic field of 1.

Enhanced response of radioresistant carcinoma cell line to heterogeneous dose distribution of grid; the role of high-dose bystander effect.

Purpose: The classical dogma that restricted the radiation effect to the directly irradiated cells has been challenged by the bystander effect. This off-target phenomenon which was manifested in adjacent cells via signaling of fully exposed cells might be involved in high-dose Grid therapy as well. Here, an in-vitro study was performed to examine the possible extent of carcinoma cells response to the inhomogeneous dose distribution of Grid irradiation in the context of the bystander effect.

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.

Grid Block Design Based on Monte Carlo Simulated Dosimetry, the Linear Quadratic and Hug-Kellerer Radiobiological Models.

Purpose: The clinical efficacy of Grid therapy has been examined by several investigators. In this project, the hole diameter and hole spacing in Grid blocks were examined to determine the optimum parameters that give a therapeutic advantage.

Methods: The evaluations were performed using Monte Carlo (MC) simulation and commonly used radiobiological models.

Application of Geant4 Monte Carlo simulation in dose calculations for small radiosurgical fields.

The Geant4 toolkit was used to develop a Monte Carlo (MC)-based engine for accurate dose calculations in small radiation field sizes. The Geant4 toolkit (version 10.1.

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.

Assessment and Comparison of Homogeneity and Conformity Indexes in Step-and-Shoot and Compensator-Based Intensity Modulated Radiation Therapy (IMRT) and Three-Dimensional Conformal Radiation Therapy (3D CRT) in Prostate Cancer.

Intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D CRT) are two treatment modalities in prostate cancer, which provide acceptable dose distribution in tumor region with sparing the surrounding normal tissues. IMRT is based on inverse planning optimization; in which, intensity of beams is modified by using multileaf collimators and also compensators with optimum shapes in step and shoot (SAS) and compensator-based method, respectively. In the recent study, some important parameters were compared in two IMRT and 3D CRT methods.

Evaluation of the effect of temperature variation on response of PRESAGE® dosimeter.

Introduction: Many factors, such as PRESAGE ® composition, dose rate, energy, and type of radiation, temperature, etc., may effect on PRESAGE ® dosimeter response. The aim of this study was investigating the effect of temperature variation on response of PRESAGE ® solid dosimeter.

Dose distribution verification for GYN brachytherapy using EBT Gafchromic film and TG-43 calculation.

Aim: Verification of dose distributions for gynecological (GYN) brachytherapy implants using EBT Gafchromic film.

Background: One major challenge in brachytherapy is to verify the accuracy of dose distributions calculated by a treatment planning system.

Materials And Methods: A new phantom was designed and fabricated using 90 slabs of 18 cm × 16 cm × 0.

Is grid therapy useful for all tumors and every grid block design?

Grid therapy is a treatment technique that has been introduced for patients with advanced bulky tumors. The purpose of this study is to investigate the effect of the radiation sensitivity of the tumors and the design of the grid blocks on the clinical response of grid therapy. The Monte Carlo simulation technique is used to determine the dose distribution through a grid block that was used for a Varian 2100C linear accelerator.