Search results for "Radiation treatment planning"
showing 10 items of 75 documents
Gamma Knife treatment planning: MR brain tumor segmentation and volume measurement based on unsupervised Fuzzy C-Means clustering
2015
Nowadays, radiation treatment is beginning to intensively use MRI thanks to its greater ability to discriminate healthy and diseased soft-tissues. Leksell Gamma Knife® is a radio-surgical device, used to treat different brain lesions, which are often inaccessible for conventional surgery, such as benign or malignant tumors. Currently, the target to be treated with radiation therapy is contoured with slice-by-slice manual segmentation on MR datasets. This approach makes the segmentation procedure time consuming and operator-dependent. The repeatability of the tumor boundary delineation may be ensured only by using automatic or semiautomatic methods, supporting clinicians in the treatment pla…
A smart and operator independent system to delineate tumours in Positron Emission Tomography scans
2018
Abstract Positron Emission Tomography (PET) imaging has an enormous potential to improve radiation therapy treatment planning offering complementary functional information with respect to other anatomical imaging approaches. The aim of this study is to develop an operator independent, reliable, and clinically feasible system for biological tumour volume delineation from PET images. Under this design hypothesis, we combine several known approaches in an original way to deploy a system with a high level of automation. The proposed system automatically identifies the optimal region of interest around the tumour and performs a slice-by-slice marching local active contour segmentation. It automa…
A simple analytical method for heterogeneity corrections in low dose rate prostate brachytherapy
2015
In low energy brachytherapy, the presence of tissue heterogeneities contributes significantly to the discrepancies observed between treatment plan and delivered dose. In this work, we present a simplified analytical dose calculation algorithm for heterogeneous tissue. We compare it with Monte Carlo computations and assess its suitability for integration in clinical treatment planning systems. The algorithm, named as RayStretch, is based on the classic equivalent path length method and TG-43 reference data. Analytical and Monte Carlo dose calculations using Penelope2008 are compared for a benchmark case: a prostate patient with calcifications. The results show a remarkable agreement between …
Brachytherapy organ dose estimation using Monte Carlo simulations of realistic patient models
2018
Radiation Therapy Planning Systems (RTPS) currently used in hospitals contain algorithms based on deterministic simplifications that do not properly consider electrons lateral transport in the areas where there are changes of density, and as a result, erroneous dose predictions could be produced. According to this, the present work proposes the use of Monte Carlo method in brachytherapy planning systems, which could affect positively on the radiotherapy treatment planning, since it provides results that are more accurate and takes into account the in homogeneities density variations. This paper presents a Monte Carlo (MC) simulation of a brachytherapy prostate treatment with I-125 seeds, us…
Impact of 18F-Choline PET/CT in the Decision-Making Strategy of Treatment Volumes in Definitive Prostate Cancer Volumetric Modulated Radiation Therapy
2015
INTRODUCTION Aim of the study is to evaluate the impact of Cho-PET/CT in decision-making strategy of patients with localized prostate cancer (PC) eligible to definitive radiotherapy (RT). MATERIALS AND METHODS Sixty patients Cho-PET/CT before RT were prospectively enrolled. All patients were treated with volumetric modulated arc therapy with simultaneous integrated boost in 28 fractions. Androgen deprivation therapy was prescribed according to National Comprehensive Cancer Network (NCCN) risk classification. Therapeutic strategy based on the Cho-PET/CT evaluation was compared with the strategy that would have been proposed in case of PET not available and/or not strictly indicated, accordin…
Radiolucent Carbon Fiber–Reinforced Pedicle Screws for Treatment of Spinal Tumors: Advantages for Radiation Planning and Follow-Up Imaging
2016
Objective Surgical treatment of spinal tumors regularly includes spinal instrumentation with pedicle screws. Most modern pedicle screws are made of titanium alloy, which is associated with artifacts on postoperative imaging such as computed tomography and/or magnetic resonance imaging. These artifacts hamper radiation treatment planning and execution and follow-up imaging. Recently, carbon fiber–reinforced polyetheretherketone (CFRP) implants became available for posterior instrumentation with the aim to reduce imaging artifacts by implants. Methods Patients harboring spinal tumors underwent posterior stabilization using CFRP pedicle screws. Postoperative imaging was evaluated for implant a…
Preoperative imaging findings in patients undergoing transcranial magnetic resonance imaging-guided focused ultrasound thalamotomy
2021
AbstractThe prevalence and impact of imaging findings detected during screening procedures in patients undergoing transcranial MR-guided Focused Ultrasound (tcMRgFUS) thalamotomy for functional neurological disorders has not been assessed yet. This study included 90 patients who fully completed clinical and neuroradiological screenings for tcMRgFUS in a single-center. The presence and location of preoperative imaging findings that could impact the treatment were recorded and classified in three different groups according to their relevance for the eligibility and treatment planning. Furthermore, tcMRgFUS treatments were reviewed to evaluate the number of transducer elements turned off after…
Calculation of bone graft volume using 3D reconstruction system.
2010
Objectives: To obtain bone ?bioreplicas? for determining precisely the amount of biomaterial required for bone regeneration procedure. Study design: A case-control comparison with a total sample size of 20 cases, 10 control and 10 test samples. ?Bioreplicas? were generated from helical CAT scans with 0.5 mm slices, without 3D reconstruction or image filters. Bone defects in premolar and molar areas were treated with titanium mesh and xenograft (MP3) combined with resorbable carriers. Time taken to carry out procedures with and without the use of ?bioreplicas? (in minutes), discrepancies between the grafts performed with and without ?bioreplicas? and bone defects (mm), and postoperative comp…
Skillful management of exodontia complication to prevent dreadful sequelae
2011
Successful surgical treatments depend upon accurate diagnosis, judicious treatment planning, selection and execution of an appropriate surgical technique, and on a well monitored post-operative period. However, despite these precautions, extraction of teeth (particularly third molar) is exposed to the accidents and complications common to all buccomaxillary and facial interventions. A maxillary third molar may be displaced in maxillary sinus, nearby soft tissue, or may migrate in a superioposterior direction towards paraphyrangeal space, or infratemporal fossa. Dislocating the maxillary third molar in infratemporal fossa is one of the worst nightmare as this area has complex anatomy consist…
Boron determination in liver tissue by combining quantitative neutron capture radiography (QNCR) and histological analysis for BNCT treatment plannin…
2011
The typical primary malignancies of the liver are hepatocellular carcinoma and cholangiocarcinoma, whereas colorectal liver metastases are the most frequently occurring secondary tumors. In many cases, only palliative treatment is possible. Boron neutron capture therapy (BNCT) represents a technique that potentially destroys tumor tissue selectively by use of externally induced, locally confined secondary particle irradiation. In 2001 and 2003, BNCT was applied to two patients with colorectal liver metastases in Pavia, Italy. To scrutinize the rationale of BNCT, a clinical pilot study on patients with colorectal liver metastases was carried out at the University of Mainz. The distribution o…