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Title: Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators

Abstract

Purpose: The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. Methods: In order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. Results: The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator andmore » detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. Conclusions: The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate distribution, which then can be used as input for a refined clinical treatment planning system. The improved dose rate measurements will facilitate a clinical study, which could correlate the therapeutic outcome of a brachytherapy treatment with an applicator and its individual dose rate distribution.« less

Authors:
; ;  [1];  [2];  [2]
  1. Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund (Germany)
  2. (Germany)
Publication Date:
OSTI Identifier:
22102113
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 36; Journal Issue: 10; Other Information: (c) 2009 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; 61 RADIATION PROTECTION AND DOSIMETRY; ACCURACY; BRACHYTHERAPY; DISTRIBUTION; DOSE RATES; DOSIMETRY; NEOPLASMS; PLANNING; QUALITY ASSURANCE; RADIATION DOSES; SCINTILLATION COUNTERS; SPATIAL RESOLUTION; SURFACES; SURGERY

Citation Formats

Eichmann, Marion, Fluehs, Dirk, Spaan, Bernhard, Klinische Strahlenphysik, Universitaetsklinikum Essen, D 45122 Essen, and Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund. Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators. United States: N. p., 2009. Web. doi:10.1118/1.3218762.
Eichmann, Marion, Fluehs, Dirk, Spaan, Bernhard, Klinische Strahlenphysik, Universitaetsklinikum Essen, D 45122 Essen, & Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund. Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators. United States. doi:10.1118/1.3218762.
Eichmann, Marion, Fluehs, Dirk, Spaan, Bernhard, Klinische Strahlenphysik, Universitaetsklinikum Essen, D 45122 Essen, and Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund. Thu . "Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators". United States. doi:10.1118/1.3218762.
@article{osti_22102113,
title = {Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators},
author = {Eichmann, Marion and Fluehs, Dirk and Spaan, Bernhard and Klinische Strahlenphysik, Universitaetsklinikum Essen, D 45122 Essen and Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund},
abstractNote = {Purpose: The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. Methods: In order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. Results: The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator and detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. Conclusions: The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate distribution, which then can be used as input for a refined clinical treatment planning system. The improved dose rate measurements will facilitate a clinical study, which could correlate the therapeutic outcome of a brachytherapy treatment with an applicator and its individual dose rate distribution.},
doi = {10.1118/1.3218762},
journal = {Medical Physics},
number = 10,
volume = 36,
place = {United States},
year = {Thu Oct 15 00:00:00 EDT 2009},
month = {Thu Oct 15 00:00:00 EDT 2009}
}