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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:53 |
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Conference: Bucharest University Faculty of Physics 2014 Meeting
Section: Biophysics; Medical Physics
Title:
Dosimetric evaluations due to minimal displacements in high dose rate brachytherapy
Authors:
N. DUMITRU(1), M. HYVARINEN(2), Samanthia LONG(2), Silvia PELLA(2,3), R. HERRERA(4), Casey CURLEY(2), Theodora LEVENTOURI(2)
Affiliation:
(1)Faculty of Physics, University of Bucharest, Romania
(2)Department of Physics, Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, FL, USA
(3)South Florida Radiation Oncology, Boca Raton, FL, USA
(4)Louis Stokes VA Medical Center, Cleveland, USA
E-mail
puiudumitru@yahoo.com
Keywords:
High dose rate brachytherapy, dosimetry, dose distribution, cervix cancer, immobilization, localization
Abstract:
Introduction: High dose rate (HDR) brachytherapy is a technique in which an applicator is placed near or within a site on a patient, whether it be on a surface, interstitial or intracavitary, after which radioactive isotope is passed through the catheters in the applicator in such a way as to create a dose distribution which is desirable for a radiation therapy treatment for the patient. The purpose of this study is to establish a need to revise most of the HDR types of treatments with their applicators and their localization challenges.
Materials and Methods: This dosimetric study was carried out using the Oncentra treatment planning system (TPS) by Nucletron. The study analyzed 55 patient plans using gynecological vaginal cylinders, including Nucletron multicatheter cylinders, the Miami cylinder and a few others. For each of the 55 plans, the point on the rectum receiving the maximal amount of radiation first was identified and then the hypothetical displacements of each of the three types were modeled, and measurements of the dose variation were taken.Results: The dose variation calculated by Oncentra due to a hypothetical motion of 1 mm in the medial lateral direction at the spot on the rectum receiving maximum dose, ranges from 0.14 % to 22.19 % among all patients; and due to a hypothetical rotational motion of 5 degrees about the central axis of the applicator, ranges from 0.06 % to 11.97 % among all patients. Conclusions: These data indicates that an improvement of the immobilization devices for HDR is absolutely necessary. Better applicator fixation devices are required as well. Developing new immobilization devices for all applicators is recommended. HDR suites with on board imaging (OBI) capabilities should use a cone beam computed tomography (CBCT) before each treatment.
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