Search results for "phantom"

WE-C-108-08: Organ Doses in a Male Phantom Undergoing High-Dose-Rate Brachytherapy Applied to the Prostate

2013

Purpose: The aim of this study was to obtain equivalent doses to radiosensitive organs when applying high‐dose‐rate (HDR) brachytherapy to the prostate using60 Co or 192 Ir sources, and in comparison to external‐beam radiotherapy (EBRT) modalities. Methods: Monte Carlo simulations in Geant4 were performed using a voxelized adult reference man described in Publication 110 by the International Commission on Radiological Protection (ICRP). Point sources of 60Co or 192Ir with photon energy spectra corresponding to those exiting their capsules were placed in the center of the prostate. Equivalent doses per therapeutic absorbed dose to the prostate were obtained in several radiosensitive organs. …

Monte Carlo dosimetric study of Best Industries and Alpha Omega Ir-192 brachytherapy seeds

2004

Ir-192 seeds are widely used in the USA for low dose rate interstitial brachytherapy. There are two commercially available models: those manufactured by Best Industries filtered with stainless steel, and those manufactured by Alpha-Omega seeds filtered with Pt. Newly developed 3D correction algorithms for brachytherapy are based on dosimetry data obtained on unbounded phantom size, allowing corrections for heterogeneities and actual tissue boundaries. Published dosimetric datasets for both seeds have been obtained under bounded conditions. The aim of the present study is to obtain dosimetric datasets for these seeds under full scatter conditions. The Monte Carlo GEANT4 code has been used to…

Combined Endo- and Exoscopic Semi-robotic Manipulator System for Image Guided Operations

2006

This paper describes the development of a robotic assistance system for image guided operations. To minimize operation time, a multimodal user interface enables freehand robotic manipulation of an extracorporeal stereoscopic digital camera (exoscope) and an endoscope. The surgeon thereby wears a head-mounted unit with a binocular display, a head tracker, a microphone and earphones. Different view positioning and adjustment modes can be selected by voice and controlled by head rotation while pressing a miniature confirmation button with a finger. Initial studies focused on the evaluation and optimization of the intuitiveness, comfort and precision of different modes of operation, including a…

Trans-cranial Magnetic Resonance-guided Focused UltraSound (tcMRgFUS) system integrated with a 1.5T: an SNR study on DQA phantoms

2018

Background: In recent years transcranial Magnetic Resonance-guided Focused Ultrasound Surgery (tcMRgFUS) treatments have been performed only using 3T units. Since following some internal analysis, planning images obtained using a 1.5T MRI’s body RF coil (as usually done with 3T systems) showed generally reasonable quality in terms of anatomy visualization and SNR but thermal images noise was above acceptable standard for treatments, a dedicated 2-channels head coil was developed (InSightec Ltd.) to ensure an adequate signal-to-noise ratio (SNR). Hence, we present the imaging protocol and the technological methods successfully used with the world-first installation of a certified tcMRgFUS sy…

Technical note : Simulation of lung counting applications using Geant4

2023

A Geant4 simulation package has been developed to investigate and test detector configurations for lung counting applications. The objective of this study was to measure radiation emitted from the human body and to make a qualitative comparison of the results of the simulation with an experiment. Experimental data were measured from a plastic phantom with a set of lungs containing 241Am activity. For comparison, simulations in which 241Am activity was uniformly distributed inside the lungs of the ICRP adult reference computational phantom were made. The attenuation of photons by the chest wall was simulated and from this photopeak ef-ficiency and photon transmission were calculated as a fun…

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…

Artefacts in CBCT: a review

2011

Artefacts are common in today's cone beam CT (CBCT). They are induced by discrepancies between the mathematical modelling and the actual physical imaging process. Since artefacts may interfere with the diagnostic process performed on CBCT data sets, every user should be aware of their presence. This article aims to discuss the most prominent artefacts identified in the scientific literature and review the existing knowledge on these artefacts. We also briefly review the basic three-dimensional (3D) reconstruction concept applied by today's CBCT scanners, as all artefacts are more or less directly related to it.

IC‐P‐050: The European diffusion tensor imaging study in dementia (EDSD): Physical phantom study and multimodal clinical study on the diagnosis of Al…

2012

Radiation exposure to the hands and the thyroid of the surgeon during intramedullary nailing.

1998

Abstract During 41 procedures of intramedullary nailing of femoral and tibial fractures, the primary surgeon and the first assistant wore ring dosimeters on their dominant index fingers. While the average fluoroscopy time per procedure was 4.6 min, the average dose of radiation to the dominant hand of the primary surgeon was 1.27 mSv and 1.19 mSv to the first assistant. The dose limit for the extremities is 500 mSv per year, as recommended by the International Commission on Radiological Protection. Extrapolation of the mean dose of the primary surgeon and first assistent per procedure of 1.23 mSv leads to the result that the recommended dose limit of 500 mSv would only be exceeded if more t…

Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

2017

Purpose: To describe the implementation of dosimetry equipment and phantoms into clinical practice of light ion beam therapy facilities. This work covers standard dosimetry equipment such as computerized water scanners, films, 2D-array, thimble and plane parallel ionization chambers, but also dosimetry equipment specifically devoted to the pencil beam scanning delivery technique such as water columns, scintillating screens or multi-layer ionization chambers. Method: Advanced acceptance testing procedures developed at MedAustron and complementary to the standard acceptance procedures proposed by the manufacturer are presented. Detailed commissioning plans have been implemented for each piece…