Your browser does not support JavaScript!

Home    Search  

Results - Details

Search command : Author="Εφροσύνη"  And Author="Παπαδάκη"

Current Record: 1 of 6

Back to Results Previous page
Next page
Add to Basket
[Add to Basket]
Identifier 000454335
Title Διαμόρφωση συστήματος πλοήγησης με δεδομένα από εγκάρσιες απεικονιστικές μεθόδους για την ακριβή τοποθέτηση ραδιενεργού πλάκας σε ασθενείς που υποβάλλονται σε βραχυθεραπεία
Alternative Title Navigation protocol configuration based on data from transverse imaging methods for the precise placement of radioactive source in patients undergoing brachytherapy
Author Λιακόπουλος, Δημήτριος Α.
Thesis advisor Δετοράκης, Ευστάθιος
Reviewer Παπαδάκη, Εφροσύνη
Περυσινάκης, Κωνσταντίνος
Κυμιωνής, Γεώργιος
Παλλήκαρης, Ιωάννης
Χλουβεράκης, Γρηγόριος
Κουβιδάκης, Αλέξανδρος
Abstract Purpose: To estimate dosimetric plan accuracy of Ophthalmic brachytherapy with ruthenium-106 (106Ru) plaque based on individualized parameter of ocular geometry. Moreover, to investigate the possibility of creating fusion images from magnetic tomography (in the preoperative period) and special protocol of dual energy computed tomography (DECT) (in the postoperative period with plaque placed on the scleral surface) as a tool for confirming the anatomic accuracy of plaque placement. Additionally, to determine a protocol of dual energy computed tomography that will suppress metal artifacts and accurately depict the placed plaque. Materials and Methods: Thirty patients with intraocular lesions undergone brachytherapy using plaque 106Ru of inner radius of 12mm. Imaging with magnetic tomography used to determine the external sclera radius at the tumor site and the tumor margins. Mathematical algorithm was used to calculate the distance between the external sclera and the internal surface of the plaque. The differences between the typical ocular parameters (sclera radius of 12 mm) and individualized parameters in the applied radiation dose to the tumor apex, the sclera and the tumor margins were calculated with Plaque SimulatorTM software (Eye Physics LLC, Los Alamitos, CA). On the second part of the study, six patients with intraocular lesions were included. Fusion images of preoperative magnetic resonance imaging and postoperative DECT imaging were constructed in the ImFusion software (ImFusion GmbH, Munchen, Germany). Clearance margins between the tumor and plaque edge in sagittal, coronal and transverse planes and also elevation of the posterior edge of the plaque from the sclera were recorded and correlated with tumor location. Finally, an anthropomorphic phantom simulating an adult head was used for implementation of nine protocols of DECT imaging of the orbits after plaque placement. Monochromatic 140keV were obtained using iterative reconstruction and metal artifact reduction algorithm. The DECT imaging protocol providing accurate orientation of plaque using minimum radiation exposure was identified. Results: Taking into account the individualized ocular and tumor geometry the calculated applied dose was found to be overestimated at the points of interest namely the tumor apex, tumor margins and sclera compared to the calculated applied dose using the typical ocular parameters. The clearance margins were found greater in all planes (sagittal, coronal and transverse) for lesions which are located anteriorly (anterior to the ocular equator) compared to the posteriorly located lesions. The posterior elevation of the plaque edge from the sclera was higher for the anteriorly located lesions compared to the posterior ones. All DECT protocols were found to facilitate accurate plaque demarcation in spite of some moderate artifacts. The suggested DECT protocol was found to have a radiation dose exposure to the ocular lens at the lowest limit of the range that is observed with single energy computed tomography. Conclusions: The suggested approach of individualized brachytherapy 106Ru includes a preliminary study encompassing geometrical parameters of the eye and the tumor from magnetic resonance imaging in order to improve precision of dosimetric calculation. The individualized dosimetry brachytherapy plan can prevent insufficient treatment of intraocular tumors especially for eyes with axial length that refrains from mean values. Additionally, fusion images from DECT and magnetic resonance imaging can be used as a tool to confirm the accuracy of plaque 106Ru placement in accordance with the intraocular tumor. The appropriate protocol for orbital DECT imaging after plaque 106Ru placement was determined and allowed for the plaque demarcation with minimal artifacts and low radiation exposure for the patient also providing the possibility for verification of accurate plaque placement.
Language Greek, English
Subject Ophthalmic imaging
Ophthalmic oncology
Plaque
Radiotherapy plate
Ακτινοθεραπεία
Οφθαλμική απεικόνιση
Οφθαλμική ογκολογία
Οφθαλμολογία
Ραδεινεργός πλάκα
Issue date 2023-04-05
Collection   School/Department--School of Medicine--Department of Medicine--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/c/3/f/metadata-dlib-1683709406-372168-17218.tkl Bookmark and Share
Views 631

Digital Documents
No preview available

No permission to view document.
It won't be available until: 2024-04-05