Search results for "Radiation treatment"

Monte Carlo study of the dose rate distributions for the Ir2.A85-2 and Ir2.A85-1 Ir-192 afterloading sources

2008

The two most commonly used modalities of cancer treatment in clinical brachytherapy practice today are high dose rate (HDR) and pulsed dose rate (PDR) brachytherapy. In a clinical treatment, quality dose rate distribution data sets of the brachytherapy sources are required for each source model. The purpose of this study is to obtain detailed dose rate distributions around the new BEBIG HDR and PDR Ir-192 brachytherapy sources. These distributions will then be used as input data in the treatment planning systems dedicated to brachytherapy and its calculations can be verified. The Monte Carlo method was used to obtain the dose rate distributions around the sources studied, taking into accoun…

A practical MRI-based reconstruction method for a new endocavitary and interstitial gynaecological template

2015

Purpose: There are perineal templates for interstitial implants such as MUPIT and Syed applicators. Their limitations are the intracavitary component deficit and the necessity to use computed tomography (CT) for treatment planning since both applicators are non-magnetic resonance imaging (MRI) compatibles. To overcome these problems, a new template named Template Benidorm (TB) has been recently developed. Titanium needles are usually reconstructed based on their own artifacts, mainly in T1-weighted sequence, using the void on the tip as the needle tip position. Nevertheless, patient tissues surrounding the needles present heterogeneities that complicate the accurate identification of these …

SU-FF-T-329: Monte Carlo Dosimetric Study of the Flexisource Ir-192 HDR Source

2006

Purpose:Brachytherapy with high dose rate (HDR) sources of 192 Ir is a usual practice in clinical brachytherapy today. The TG43 U1 update report recommends that accurate dose distribution data of the brachytherapysource in use should be obtained experimentally or by Monte Carlo (MC), to be used as input in the HDR Treatment Planning System (TPS). The purpose of this study is to obtain the dose rate distribution in liquid water media for the Flexisource HDR 192 Ir source (Isodose Control GmbH, Germany) using the Monte Carlo method to obtain the TG43 U1 parameters and the 2‐D rectangular dose rate table. Material and methods: The MC code GEANT4 (7.1 version) was used to estimate dose rate in …

WE-C-141-01: Research and Relevance of Brachytherapy Dose Calculation Advancements

2013

Research and Relevance of Brachytherapy Dose Calculation Advancements Organizer: Mark J. Rivard Moderator: Geoffrey S. Ibbott Speakers: Facundo Ballester, Asa Carlsson Tedgren, Firas Mourtada Brachytherapy dosimetry is undergoing a renaissance with the scrutiny of the AAPM TG‐43 dose calculation formalism and comparisons with alternate approaches such as the Monte Carlo method, the grid‐based Boltzmann solvers, and the collapsed‐cone technique. Treatment planning systems (TPS) using these more advanced, model‐based dose calculation algorithms (MBDCAs) are now available for clinical use. However, their accuracy and the preferred method for their use have not been established. Thus, it is imp…

Exclusive MRI-based tandem and colpostats reconstruction in gynaecological brachytherapy treatment planning

2008

Purpose: According to the GYN GEC-ESTRO Recommendations, MRI is needed with the modality of T2 weighted. CT-MR compatible tandem Plus colpostats (T/C) (Nucletron) is widely used in cervical brachytherapy. The major challenge of MRI is the lack of dummy catheters. Therefore, an additional imaging modality is usually required. One disadvantage of sliced-based reconstruction is that resolution in longitudinal directions can be affected by the slice thickness. The aim of this study is to present a modified T/C applicator in which the catheter visibility is significantly improved. Methods and materials: A modification to the existing T/C applicator has been made available, increasing the cathete…

Brachytherapy treatment planning for complex applicators based on the AAPM TG-43 dosimetry algorithm: Case studies and clinical impact

2009

MRI based treatment planning in gynaecological brachytherapy

2008

NeXt for neuro-radiosurgery: A fully automatic approach for necrosis extraction in brain tumor MRI using an unsupervised machine learning technique

2017

Stereotactic neuro-radiosurgery is a well-established therapy for intracranial diseases, especially brain metastases and highly invasive cancers that are difficult to treat with conventional surgery or radiotherapy. Nowadays, magnetic resonance imaging (MRI) is the most used modality in radiation therapy for soft-tissue anatomical districts, allowing for an accurate gross tumor volume (GTV) segmentation. Investigating also necrotic material within the whole tumor has significant clinical value in treatment planning and cancer progression assessment. These pathological necrotic regions are generally characterized by hypoxia, which is implicated in several aspects of tumor development and gro…

Jaw in a day: Osseointegration of the implants in the patient’s leg before reconstructive surgery of a maxilla with ameloblastoma. A 4-year follow-up…

2021

Background To describe a clinical case of a cancer patient who underwent ablative tumor surgery, including treatment planning, surgical resection and subsequent implant rehabilitation. Case report A 61-year-old patient with a diagnosis of multicystic follicular ameloblastoma in the maxilla, in which it was necessary a multidisciplinary approach and two surgical steps. In the first surgical intervention osseointegrated implants (OII) were placed in the fibula, until their osseointegration period of 8 weeks was complete. Afterwards, in the second surgery, the micro-vascularized free fibular flap bearing the implants was transplanted into the oral cavity, in order to perform simultaneous recon…

Rapid prototyping modelling in oral and maxillofacial surgery: a two year retrospective study

2015

Background The use of rapid prototyping (RP) models in medicine to construct bony models is increasing. Material and Methods The aim of the study was to evaluate retrospectively the indication for the use of RP models in oral and maxillofacial surgery at Helsinki University Central Hospital during 2009-2010. Also, the used computed tomography (CT) examination – multislice CT (MSCT) or cone beam CT (CBCT) - method was evaluated. Results In total 114 RP models were fabricated for 102 patients. The mean age of the patients at the time of the production of the model was 50.4 years. The indications for the modelling included malignant lesions (29%), secondary reconstruction (25%), prosthodontic …