Absolute dose verification of static intensity modulated radiation therapy (IMRT) with ion chambers of various volumes and TLD detectors.

Aim: This study aims at examining absolute dose verification of step-and-shoot intensity modulated radiation treatment (IMRT) of prostate and brain patients by use of ion chambers of two different volumes and thermoluminescent detectors (TLD).

Background: The volume of the ion chamber (IC) is very important for absolute dose verification of IMRT plans since the IC has a volume average effect. With TLD detectors absolute dose verification can be done measuring the dose of multiple points simultaneously.

Patient-specific quality assurance for intracranial cases in robotic radiosurgery system.

Purpose: The purpose of this study was to perform pretreatment patient-specific quality assurance (QA) for intracranial irradiation using CyberKnife with an ion chamber.

Methods: Twenty-five intracranial plans created using the ray-tracing algorithm were used for this study. Computed tomography (CT) images of the water-equivalent RW3 slab phantom with PinPoint ionization chamber were acquired with 1-mm slice thickness and transferred to the MultiPlan treatment planning system (TPS).

A comparative study of the peripheral doses from a linear accelerator with a multileaf collimator system.

This study presents a comparison of peripheral doses (PDs) measured using an ionisation chamber with treatment planning system (TPS) data and a Monte Carlo (MC) simulation of a 6-MV photon beam. The ion chamber measurements and MC simulation produced similar results for all out-of-field distances and field sizes considered in this study. For the 0° and 90° collimation angles, the average local per cent dose differences between the MC and TPS calculations were 2.

Vagus nerve stimulation inhibits seizure activity and protects blood-brain barrier integrity in kindled rats with cortical dysplasia.

Aims: This study investigates the effects of vagus nerve stimulation (VNS) on seizure severity and blood-brain barrier (BBB) integrity in kindled rats with cortical dysplasia (CD).

Main Methods: Pregnant rats were exposed to 145 cGy of gamma-irradiation on day 17 of pregnancy. In offsprings, kindling was induced by giving subconvulsive doses of pentylenetetrazole.

Evaluation of material heterogeneity dosimetric effects using radiochromic film for COMS eye plaques loaded with (125)I seeds (model I25.S16).

Purpose: (1) To measure absolute dose distributions in eye phantom for COMS eye plaques with (125)I seeds (model I25.S16) using radiochromic EBT film dosimetry. (2) To determine the dose correction function for calculations involving the TG-43 formalism to account for the presence of the COMS eye plaque using Monte Carlo (MC) method specific to this seed model.

Topiramate reduces blood-brain barrier disruption and inhibits seizure activity in hyperthermia-induced seizures in rats with cortical dysplasia.

We investigated the effects of topiramate (TPM), a novel broad spectrum anticonvulsant, on seizure severity, survival rate and blood-brain barrier (BBB) integrity during hyperthermic seizures in rats with cortical dysplasia (CD). Offsprings of irradiated mothers were used in this study. To show the functional and morphological alterations in BBB integrity, quantitative analysis of Evans blue (EB) extravasation, immunohistochemistry and electron microscopic assessment of horseradish peroxidase (HRP) permeability were performed.

Dosimetric investigation of LDR brachytherapy ¹⁹²Ir wires by Monte Carlo and TPS calculations.

Purpose: The aim of this study was to investigate the dose rate distribution around (192)Ir wires used as radioactive sources in low-dose-rate brachytherapy applications.

Materials And Methods: Monte Carlo modeling of a 0.3-mm diameter source and its surrounding water medium was performed for five different wire lengths (1-5 cm) using the MCNP software package.

Does partial expander deflation exacerbate the adverse effects of radiotherapy in two-stage breast reconstruction?

Background: The optimum protocol for expander volume adjustment with respect to the timing and application of radiotherapy remains controversial.

Methods: Eighteen New Zealand rabbits were divided into three groups. Metallic port integrated anatomic breast expanders of 250 cc were implanted on the back of each animal and controlled expansion was performed.

Does hyperbaric oxygen administration before or after irradiation decrease side effects of irradiation on implant sites?

Background: One of the main limitations of implant-based breast reconstruction is the high rate of complications such as capsular contracture and poor aesthetic outcome, due to adjuvant radiotherapy. Hyperbaric oxygen treatment (HBOT) has been used to assist wound healing in the prevention and treatment of the side effects of irradiation. We aimed to investigate this effect of HBOT on the capsule reaction and skin, applied before and after irradiation, following the placement of an implant under the dorsal skin of the rat.

Effects of levetiracetam on blood-brain barrier disturbances following hyperthermia-induced seizures in rats with cortical dysplasia.

Aims: The mechanisms underlying the changes in blood-brain barrier (BBB) integrity and the generation of seizures in childhood associated with preexisting brain lesions like cortical dysplasia (CD) are poorly understood. We investigated the effects of levetiracetam (LEV) on BBB integrity and the survival during hyperthermic seizures in rats with CD.

Main Methods: Pregnant rats were exposed to 145 cGy of gamma-irradiation on embryonic day 17.

Levetiracetam decreases the seizure activity and blood-brain barrier permeability in pentylenetetrazole-kindled rats with cortical dysplasia.

This study investigates the effects of levetiracetam (LEV) on the functional and structural properties of blood-brain barrier (BBB) in pentylenetetrazole (PTZ)-kindled rats with cortical dysplasia (CD). Pregnant rats were exposed to 145 cGy of gamma-irradiation on embryonic day 17. In offsprings, kindling was induced by giving subconvulsive doses of PTZ three times per week for 45 days.

Effect of a carbon fiber tabletop on the surface dose and attenuation for high-energy photon beams.

Purpose: The dose changes in the buildup region and beam attenuation by a carbon fiber tabletop were investigated for 6-and 18-MV photon beams.

Materials And Methods: Measurements were performed for 2 x 2 cm to 40 x 40 cm field sizes. The surface dose and percentage depth doses (PDD) were measured by a Markus parallel plate chamber.

Morphological and functional changes of blood-brain barrier in kindled rats with cortical dysplasia.

Cortical dysplasia (CD) is one of the major causes contributing to epileptogenesis associated with blood-brain-barrier (BBB) disturbances. The current study investigated the functional and ultrastructural changes of BBB in pentylenetetrazole (PTZ)-kindled rats with CD. Pregnant rats on E17 were exposed to 145 cGy of gamma-irradiation and offspring were used for experiments.

Effects of lipopolysaccharide on the radiation-induced changes in the blood-brain barrier and the astrocytes.

The use of radiation to improve the efficacy of chemotherapy on malignant brain tumors is also known to cause side effects on vascular endothelial cells and astrocytes in normal parts of the brain. We investigated the effects of lipopolysaccharide (LPS) on the functional and structural properties of blood-brain barrier (BBB) and the activity of astrocytes during whole-brain irradiation in rats. The permeability of the BBB to Evans blue (EB) dye significantly increased in the cerebral cortex, diencephalon and cerebellum regions of rats exposed to irradiation (P<0.

Determination of surface dose and the effect of bolus to surface dose in electron beams.

When treating tumors from surface to a certain depth (<5 cm), electron beams are preferred in radiotherapy. To increase the surface doses of lower electron beams, tissue-equivalent bolus materials are often used. We observed that the surface doses increased with increasing field sizes and electron energies.