Search results for "DOSIMETRY"

Novel dosimetric gels for three-dimensional dose mapping in radiotherapy

2016

One of the most recent and promising developments for radiotherapy (RT) dosimetry was the introduction of 3D radiation- sensitive gels. The gels are tissue equivalent, so they also serve as a phantom, and their response is largely independent of rad iation quality and dose rate. Some gels are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels) . These gels suffer from spontaneous-oxidation and diffusion of ferric ions after irradiation; the latter is significantly reduced by chelating agents such as xylenol orange (XO) (Fricke-XO gels) [2]. Other formulations consist of dispersed monomers, and rely on radiation-induced cross-…

Dosimetry comparison between TG-43 and Monte Carlo calculations using the Freiburg flap for skin high-dose-rate brachytherapy

2012

Abstract Purpose The purpose of this work was to evaluate whether the delivered dose to the skin surface and at the prescription depth when using a Freiburg flap applicator is in agreement with the one predicted by the treatment planning system (TPS) using the TG-43 dose-calculation formalism. Methods and Materials Monte Carlo (MC) simulations and radiochromic film measurements have been performed to obtain dose distributions with the source located at the center of one of the spheres and between two spheres. Primary and scatter dose contributions were evaluated to understand the role played by the scatter component. A standard treatment plan was generated using MC- and TG-43-based TPS appl…

Is dust a suitable material for retrospective personal dosimetry?

2010

This work investigates the feasibility of using silicates contained in dust for retrospective individual dosimetry in case of a radiation accident or a radiological attack involving people not wearing physical dosimeters. It is well known that minerals (silicates) can be used for dosimetry and dust already plays an important role in the field of food irradiation detection using luminescence techniques as described in the European Standards (EN 13751 and EN 1788). This paper explores the feasibility of conducting retrospective personal dosimetry on the basis of thermoluminescence analysis of silicates extracted from dust on objects that people usually wear (e.g. jewelry, watches, keys and co…

On the use of the absorbed depth-dose measurements in the beam calibration of a surface electronic high-dose-rate brachytherapy unit, a Monte Carlo-b…

2019

PURPOSE To evaluate the use of the absorbed depth-dose as a surrogate of the half-value layer in the calibration of a high-dose-rate electronic brachytherapy (eBT) equipment. The effect of the manufacturing tolerances and the absorbed depth-dose measurement uncertainties in the calibration process are also addressed. METHODS The eBT system Esteya® (Elekta Brachytherapy, Veenendaal, The Netherlands) has been chosen as a proof-of-concept to illustrate the feasibility of the proposed method, using its 10 mm diameter applicator. Two calibration protocols recommended by the AAPM (TG-61) and the IAEA (TRS-398) for low-energy photon beams were evaluated. The required Monte Carlo (MC) simulations w…

EPR DOSIMETRY WITH ALANINE FOR TOTAL BODY IRRADIATION USING AN ANTHROPOMORPHIC PHANTOM

2016

The Total Body Irradiation (TBI) is a radiation therapy technique widely used in clinical hemato-oncological treatment of patients that underwent bone marrow transplantation or peripheral stem cell transplantation. Typically, the administration of TBI treatment provides irradiations in 3 consecu-tive days with a double daily fractionation, although other dose fractionation modes have been widely adopted in the clinic procedures. Although this tech-nique allows to irradiate the whole body from head to toes, it has some limitations such as the lack of homogeneity of the dose distribution (which can show varia-tions of 20% in the different areas), irradiation of critical organs such as lungs, …

Determination of consensus kQ values for megavoltage photon beams for the update of IAEA TRS-398

2020

The IAEA is currently coordinating a multi-year project to update the TRS-398 Code of Practice for the dosimetry of external beam radiotherapy based on standards of absorbed dose to water. One major aspect of the project is the determination of new beam quality correction factors, kQ, for megavoltage photon beams consistent with developments in radiotherapy dosimetry and technology since the publication of TRS-398 in 2000. Specifically, all values must be based on, or consistent with, the key data of ICRU Report 90. Data sets obtained from Monte Carlo (MC) calculations by advanced users and measurements at primary standards laboratories have been compiled for 23 cylindrical ionization chamb…

A dosimetric study on the Ir-192 high dose rate Flexisource

2006

In this work, the dose rate distribution of a new Ir-192 high dose rate source (Flexisource used in the afterloading Flexitron system, Isodose Control, Veenendaal, The Netherlands) is studied by means of Monte Carlo techniques using the GEANT4 code. The dosimetric parameters of the Task Group No. 43 Report (TG43) formalism and two-dimensional rectangular look-up tables have been obtained.

Monte Carlo calculation of the TG-43 dosimetric parameters of a new BEBIG Ir-192 HDR source

2005

Background and purpose: High dose rate (HDR) brachytherapy is a highly extended practice in clinical brachytherapy today. Quality dose rate distribution datasets of the HDR sources used in a clinical treatment are required. Because of the different source designs, a specific dosimetry dataset is required for each source model. In the recently published BRAPHYQS-ESTRO Report, an overview of available dosimetric data for all HDR Ir-192 sources is given, pointing out the lack of data for one of the sources that is used by the BEBIG MultiSource afterloading system (BEBIG GmbH, Germany). The purpose of this study is to obtain detailed dose rate distributions in liquid water media around this sou…

TL dose reconstruction in watch glasses exposed to photon, electron and proton beams

2010

The response behaviour of LiF:Mg,Cu,P thermoluminescence dosimeters to high-energy electron beams used in radiotherapy

1995

To ensure the effectiveness of radiation-therapy treatments, both in-phantom and in-patient reliable dose measurements are required. Thermoluminescence dosimeters are used commonly for both applications. Among the various available materials, the relatively new LiF:Mg,Cu,P phosphor is a suitable candidate for quality control of in vivo dosimetry in electron-beam therapy. The response behaviour of LiF:Mg,Cu,P chips to 6-21 MeV electron beams used in radiotherapy was studied. Batch homogeneity, dose linearity, sensitivity change after use, dose and dose-rate response, energy dependence and fading characteristics were investigated. The contribution from each factor to the overall uncertainty i…