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

<p>Abstract</p> <p>Background</p> <p>The optimum protocol for expander volume adjustment with respect to the timing and application of radiotherapy remains controversial.</p> <p>Methods</p> <p>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. Group I underwent radiotherapy with full expanders while in Group II, expanders were partially deflated immediately prior to radiotherapy. Control group did not receive radiotherapy.</p> <p>The changes in blood flow at different volume adjustments were investigated in Group II by laser Doppler flowmetry. Variations in the histopathologic properties of the irradiated tissues including the skin, capsule and the pocket floor, were compared in the biopsy specimens taken from different locations in each group.</p> <p>Results</p> <p>A significant increase in skin blood flow was detected in Group II with partial expander deflation. Overall, histopathologic exam revealed aggravated findings of chronic radiodermatitis (epidermal atrophy, dermal inflammation and fibrosis, neovascularisation and vascular changes as well as increased capsule thickness) especially around the lower expander pole, in Group II.</p> <p>Conclusions</p> <p>Expander deflation immediately prior to radiotherapy, may augment the adverse effects, especially in the lower expander pole, possibly via enhanced radiosensitization due to a relative increase in the blood flow and tissue oxygenation.</p

History of Brachytherapy

The origin of brachytherapy is directly related to the discovery of radioactivity by Becquerel in 1896, which led to Marie and Pierre Curie discovering radium in 1898. The first successful radium brachytherapy was the skin irradiation of two patients with basal cell carcinoma in St. Petersburg in 1903. The surface mold and plaque treatments were followed by intracavitary techniques for cervical and endometrial cancer. A few years later, an interstitial radium brachytherapy technique was developed, and most body areas were treated with radium brachytherapy. In the 1950s, radium was replaced by artificial cobalt-60 and cesium-137. In the 1960s, iridium-192 was the most commonly used source of brachytherapy. During this time period, remote after-loading devices were developed, and improvements in imaging techniques and computer technology were adapted to brachytherapy. The evolution of brachytherapy has continued over the years, but many of the techniques have remained unchanged. The limited use of brachytherapy compared to conformal external radiotherapy may be due to its invasive approach, operative risk, technical difficulty, and long learning curve. Today with the development of imaging techniques and dose planning, individual treatment planning has become possible. The success of brachytherapy has increased with extensive technological advances, accurate three-dimensional dose distributions in the patient, and optimization of treatment planning. In this article, the history of brachytherapy will be briefly reviewed

Dosimetric Accuracy of an HDR Brachytherapy Treatment Planning System for Different Irradiation Lengths with Monte Carlo Simulation

OBJECTIV

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 2.7 (range: 2.4, 22.6) and 1.7 (range: 12.2, 10.8), respectively. The corresponding differences between the MC calculations and the ion chamber measurements were 2.2 (range: 2.4, 24.7) and 1.8 (range: 17, 15.2) for all field sizes and depths, respectively. Whereas the PDs increased with field sizes, the variations with depth were negligible at large distances. The TPS calculations usually yielded higher PDs than ion chamber measurements at distances close to the field edge. In contrast, at the farther distances, the TPS results indicated lower doses than both the ion chamber and the MC data. TPS data are not sufficient for use in calculating the out-of-field doses. These results can be used to estimate non-target organ doses to patients

Verification of CyberKnife dose distributions with gafchromic EBT2 film

OBJECTIV

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

Is stereotactic body radiotherapy a treatment option for pelvic recurrences?

OBJECTIVE

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

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. Rats with CD exposed to hyperthermia exhibited seizures with mean Racine's scores of 3.92 +/- 1.2. Among the rats with CD pretreated with TPM, 21 of 24 rats showed no sign of seizure activity upon exposure to hyperthermia (p<0.01). The immunoreactivity of occludin, a tight junction protein, remained essentially unaltered in capillaries of hippocampus in all groups. In animals with CD exposed to hyperthermia, the significantly increased p-glycoprotein immunoreactivity in hippocampus (p<0.01) was slightly decreased by TPM pretreatment. Hyperthermic seizures increased BBB permeability to EB in animals with CD, but TPM pretreatment decreased the penetration of the tracer into the brain in these animals (p<0.01). Ultrastructurally frequent vesicles containing HRP reaction products were observed in capillary endothelial cells in cerebral cortex and hippocampus of rats with CD subjected to hyperthermia-induced seizures, and TPM pretreatment prevented the development of HRP reaction products in these animals. The results of this study suggest that TPM inhibits seizure activity and maintains BBB integrity in the course of febrile seizures in the setting of CD. (C) 2012 Elsevier B.V. All rights reserved