Calculation of Organ Dose Distribution (in-field and Out-of-field) in Breast Cancer Radiotherapy on RANDO Phantom Using GEANT4 Application for Tomographic Emission (Gate) Monte Carlo Simulation.

Introduction: Organ dose distribution calculation in radiotherapy and knowledge about its side effects in cancer etiology is the most concern for medical physicists. Calculation of organ dose distribution for breast cancer treatment plans with Monte Carlo (MC) simulation is the main goal of this study.

Materials And Methods: Elekta Precise linear accelerator (LINAC) photon mode was simulated and verified using the GEANT4 application for tomographic emission.

Patients' Experiences of Life Challenges After Liver Transplantation: A Qualitative Study.

Patients experience a new life with different challenges after liver transplantation (LT). Identifying these challenges can facilitate the improvement of their quality of life. This study aimed to explore patients' experiences of post-LT life challenges.

Regulation of XPA could play a role in inhibition of radiation-induced bystander effects in QU-DB cells at high doses.

Introduction: Radiation-induced bystander effects (RIBE) is the radiobiological effects detected in nonirradiated cells that have received signals from neighboring irradiated cells. In some studies, there are observations that RIBE unexpectedly reduces at high doses. In this study, the expression of two selected apoptotic and repair genes and their possible role in the formation of this unexpected reduction is examined.

THERMAL AND FAST NEUTRON DOSE EQUIVALENT DISTRIBUTION MEASUREMENT OF 15-MV LINEAR ACCELERATOR USING A CR-39 NUCLEAR TRACK DETECTORS.

The main purpose of this study is to measure the contribution of the thermal and fast neutron dose along the central axis of the 15 MV Elekta Precise linac in a tissue equivalent phantom. In order to achieve this purpose, different points were selected in three field sizes of 5 × 5 cm2, 10 × 10 cm2 and 15 × 15 cm2. Fast and thermal neutrons were measured using CR-39 nuclear track detectors with and without thermal neutron converter of 10B, respectively.

Evaluation of electron dose calculations accuracy of a treatment planning system in radiotherapy of breast cancer with photon-electron technique.

Aim: The aim of this study was to assess the accuracy of electron dose calculations of Prowess Panther treatment planning system (TPS) for abutting photon-electron (PE) technique. In this work, we have assessed the accuracy of electron dose calculations in a simulated internal mammary field because this field is irradiated with electron in PE technique.

Materials And Methods: In this study, regions of in-field, under electron shield, and outside the internal mammary field were evaluated.

expression ratio in prediction of response to breast cancer radiotherapy.

Objectives: Radiotherapy is one of the most effective modalities of cancer therapy, but clinical responses of individual patients varies considerably. To enhance treatment efficiency it is essential to implement an individual-based treatment. The aim of present study was to identify the mechanism of intrinsic apoptosis pathway on radiosensitivity and normal tissue complications caused by the radiotherapy.

The effect of glucose-coated gold nanoparticles on radiation bystander effect induced in MCF-7 and QUDB cell lines.

Due to biocompatibility and relative non-toxic nature, gold nanoparticles (GNPs) have been studied widely to be employed in radiotherapy as radio-sensitizer. On the other hand, they may enhance radiation-induced bystander effect (RIBE), which causes radiation adverse effects in non-irradiated normal cells. The present study was planned to investigate the possibility of augmenting the RIBE consequence of applying glucose-coated gold nanoparticles (Glu-GNPs) to target cells.

Comparison of the hypothetical (57)Co brachytherapy source with the (192)Ir source.

Aim Of The Study: The (57)Co radioisotope has recently been proposed as a hypothetical brachytherapy source due to its high specific activity, appropriate half-life (272 days) and medium energy photons (114.17 keV on average). In this study, Task Group No.

A comparison of the doses received by normal cranial tissues during different simple model conventional radiotherapeutic approaches to pituitary tumours.

This aim of this study was to compare the doses received by critical cranial organs when three different radiation techniques were used to treat pituitary tumours. Cranial computed tomography scans of a RANDO phantom and 30 patients were used for pituitary macroadenoma radiotherapy treatment planning. For each slice, target volumes and other critical organs were contoured and three techniques were applied: (A) two parallel-opposed lateral fields, (B) two oblique fields (45°) in coronal plane and (C) two parallel-opposed lateral and anterior fields while the head was tilted 45° in the sagittal plane.

Preliminary results of an attempt to predict over apron occupational exposure of cardiologists from cardiac fluoroscopy procedures based on DAP (dose area product) values.

This study is an effort to propose a mathematical relation between the occupational exposure measured by a dosimeter worn on a lead apron in the chest region of a cardiologist and the dose area product (DAP) recorded by a meter attached to the X-ray tube. We aimed to determine factors by which DAP values attributed to patient exposure could be converted to the over-apron entrance surface air kerma incurred by cardiologists during an angiographic procedure. A Rando phantom representing a patient was exposed by an X-ray tube from 77 pre-defined directions.

Design and fabrication of the control part of a prototype multileaf collimator system.

Multileaf collimator (MLC) is among the radiation field shaping systems used for conformal radiotherapy and intensity modulation radiation therapy techniques. The MLC system that has been designed and fabricated in this study includes 52 leaves, 52 stepper motors, 2 DC motors, 16 programmable logic controllers (PLCs) and one human machine interface (HMI). This system can be mounted on conventional linear accelerators (linac) as an add-on accessory.

MRC5 and QU-DB bystander cells can produce bystander factors and induce radiation bystander effect.

Radiation damages initiated by radiation-induced bystander effect (RIBE) are not limited to the first or immediate neighbors of the irradiated cells, but the effects have been observed in the cells far from the irradiation site. It has been postulated that bystander cells, by producing bystander factors, are actively involved in the propagation of bystander effect in the regions beyond the initial irradiated site. Current study was planned to test the hypothesis.

Assessment of skin dose modification caused by application of immobilizing cast in head and neck radiotherapy.

Skin dose assessment for radiotherapy patients is important to ensure that the dose received by skin is not excessive and does not cause skin reactions. Immobilizing casts may have a buildup effect, and can enhance the skin dose. This study has quantified changes to the surface dose as a result of head and neck immobilizing casts.

Investigation of the bystander effect in MRC5 cells after acute and fractionated irradiation in vitro.

Radiation-induced bystander effect (RIBE) has been defined as radiation responses observed in nonirradiated cells. It has been the focus of investigators worldwide due to the deleterious effects it induces in nonirradiated cells. The present study was performed to investigate whether acute or fractionated irradiation will evoke a differential bystander response in MRC5 cells.

An effective hair removal algorithm for dermoscopy images.

Background/purpose: Dermoscopy is one of the major imaging modalities used in the diagnosis of pigmented skin lesions. Due to the difficulty and subjectivity of human interpretation, computerized image analysis techniques have become important tools in this research area. Hair removal from skin lesion images is one of the key problems for the precise segmentation and analysis of the skin lesions.

Application of a color scanner for (60)Co high dose rate brachytherapy dosimetry with EBT radiochromic film.

Unlabelled: BACKGROUND.: The aim of this study is to evaluate the performance of a color scanner as a radiochromic film reader in two dimensional dosimetry around a high dose rate brachytherapy source.

Materials And Methods: A Microtek ScanMaker 1000XL film scanner was utilized for the measurement of dose distribution around a high dose rate GZP6 (60)Co brachytherapy source with GafChromic® EBT radiochromic films.

Monte carlo study of the effect of collimator thickness on T-99m source response in single photon emission computed tomography.

In single photon emission computed tomography (SPECT), the collimator is a crucial element of the imaging chain and controls the noise resolution tradeoff of the collected data. The current study is an evaluation of the effects of different thicknesses of a low-energy high-resolution (LEHR) collimator on tomographic spatial resolution in SPECT. In the present study, the SIMIND Monte Carlo program was used to simulate a SPECT equipped with an LEHR collimator.

Monte Carlo dose calculation of GZP6 (60)Co stepping source based on a matrix shift technique.

Background: As a routine method for stepping source simulation, a Monte Carlo program is run according to the number of steps and then the summation of dose from each run is taken to obtain total dose distribution. This method is time consuming.

Aim: As an alternative method, a matrix shift based technique was applied to simulate a stepping source for brachytherapy.

Air kerma strength characterization of a GZP6 Cobalt-60 brachytherapy source.

Background: Task group number 40 (TG-40) of the American Association of Physicists in Medicine (AAPM) has recommended calibration of any brachytherapy source before its clinical use. GZP6 afterloading brachytherapy unit is a (60)Co high dose rate (HDR) system recently being used in some of the Iranian radiotherapy centers.

Aim: In this study air kerma strength (AKS) of (60)Co source number three of this unit was estimated by Monte Carlo simulation and in air measurements.