Search results for "RADIOTHERAPY"
showing 10 items of 473 documents
Robustness of radiation beam profile measurements
2023
In this master’s thesis, profile measurements of PTW Semiflex 3D and PTW Semiflex ionisation chambers in addition to IBA MatriXX matrix detector were compared to each other using different measurement set-ups. The ionisation chamber measure- ments were done in a water phantom in horizontal and vertical orientations. Using two different set-ups in the horizontal orientation. The first horizontal set-up used the current clinical quality assurance program in Tampere University Hospital with the wire of the chamber lying deep in the water phantom. The second horizontal measurements were done with more of the wire in the radiation field by having the wire closer to the surface of the water. Meas…
Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde
2017
This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear…
Tumour oxygenation during fractionated radiotherapy--comparison with size-matched controls.
1999
The effect of fractionated irradiation on the oxygenation status of experimental tumours was investigated using polarographic assessment of the pO2 distribution. Since an improvement in tumour oxygenation could simply be the result of tumour shrinkage, a comparison of pO2 readings of untreated size-matched control tumours was performed. Irradiation was carried out using 6 fractions of 6 Gy applied within 11 days. A comparison of polarographic pO2 data with size-matched untreated tumours revealed a significant improvement in oxygenation after the irradiation. The median pO2 was 0.9+/-0.1 mm Hg for unirradiated tumours at a volume of 180 mm3, while the corresponding data for irradiated tumour…
Combined TL and 10B-alanine ESR dosimetry for BNCT
2004
The dosimetric technique described in this paper is based on electron spin resonance (ESR) detectors using an alanine-boric compound acid enriched with 1 0 B, and beryllium oxide thermoluminescent (TL) detectors; with this combined dosimetry, it is possible to discriminate the doses due to thermal neutrons and gamma radiation in a mixed field. Irradiations were carried out inside the thermal column of a TRIGA MARK II water-pool-type research nuclear reactor, also used for Boron Neutron Capture therapy (BNCT) applications, with thermal neutron fluence from 10 9 to 10 1 4 n t h cm - 2 . The ESR dosemeters using the alanine-boron compound indicated ESR signals about 30-fold stronger than those…
Dose calculation in biological samples in a mixed neutron-gamma field at the TRIGA reactor of the University of Mainz
2010
To establish Boron Neutron Capture Therapy (BNCT) for non-resectable liver metastases and for in vitro experiments at the TRIGA Mark II reactor at the University of Mainz, Germany, it is necessary to have a reliable dose monitoring system. The in vitro experiments are used to determine the relative biological effectiveness (RBE) of liver and cancer cells in our mixed neutron and gamma fi eld. We work with alanine detectors in combination with Monte Carlo simulations, where we can measure and characterize the dose. To verify our calculations we perform neutron fl ux measurements using gold foil activation and pin-diodes . Material and methods . When L- α -alanine is irradiated with ionizing …
Braquiterapia en el cáncer de labio
2006
El cáncer de labio es de los más prevalentes entre los tumores cutáneos de cabeza y cuello. Las características del tumor, por su crecimiento exofítico en una zona de fácil acceso visual, permite un diagnóstico en estadios incipientes y, por tanto, un mejor pronóstico con los actuales tratamientos. En estadios iniciales se puede realizar tratamiento con cirugía o braquiterapia, siendo los resultados similares en cuanto al control local; sin embargo la braquiterapia ofrece mejores resultados estéticos y funcionales. Presentamos un trabajo de revisión bibliográfica al respecto de de las indicaciones, técnicas y resultados de la braquiterapia en el cáncer de labio. Lip cancer is one of the mos…
Cell and molecular response to IORT treatment
2014
Ionizing radiations (IRs) generated by intraoperative radiotherapy (IORT) treatment activates both pro- and antiproliferative signal pathways producing an imbalance in cell fate decision regulated by several genes and factors involved in cell cycle progression, survival and/or cell death, DNA repair and inflammation. This paper describes the latest advances on cellular and molecular response to IR, highlighting the most relevant research data from cell biology, gene expression profiling and epigenetic studies on different tumor cell types. Understanding the cell molecular strategies to choose between death and survival, after an irradiation-induced damage, opens new avenues for the selectio…
Transoral Robotic Surgery for Early-T Stage Glottic Cancer Involving the Anterior Commissure—News and Update
2022
BackgroundAbout 20% of all glottic carcinomas involve the anterior commissure (AC), and AC involvement was deemed to be a risk factor of local recurrence and poor prognosis. Transoral robotic surgery (TORS) has been developed for a panoramic view of the AC and en-bloc resection of the tumor by multidirectional dissection with endo-wristed instruments. With satisfactory preliminary results, we would like to update the data with a bigger cohort and present the news on using TORS for salvage treatment of recurrence from irradiation failure.MethodsFrom July 2010 to December 2019, 22 patients with early T1 and 2 stage primary (n = 11) or recurrent (n = 11) glottic cancer with AC involvement rece…
An automatic method for metabolic evaluation of gamma knife treatments
2015
Lesion volume delineation of Positron Emission Tomography images is challenging because of the low spatial resolution and high noise level. Aim of this work is the development of an operator independent segmentation method of metabolic images. For this purpose, an algorithm for the biological tumor volume delineation based on random walks on graphs has been used. Twenty-four cerebral tumors are segmented to evaluate the functional follow-up after Gamma Knife radiotherapy treatment. Experimental results show that the segmentation algorithm is accurate and has real-time performance. In addition, it can reflect metabolic changes useful to evaluate radiotherapy response in treated patients.
Impact of the Tiloop Bra mesh in CT images and dose delivery in breast radiotherapy
2012
A new titanized breast mesh, TiLOOP Bra, is currently available for implantation in patients who require radiotherapy. The purpose of this work is to study the dosimetric effect of the presence of a TiLOOP Bra mesh on breast radiation treatment and radiographic imaging. The dosimetric effects have been measured for three X‐ray energies: 1.25 MeV, 6 MV and 18 MV, using radiochromic films placed at three different depths. These depths are representative of mesh location in breast during the radiotherapy treatment and hence, are of interest in this study. In order to assess the disturbance in a radiographic image, different computed tomographic (CT) studies of the mesh have been performed. The…