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Title: SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry

Abstract

Purpose: The purpose of this study was to observe the effect of an electromagnetic array used for patient localization and tumor tracking on optically-stimulated luminescent in-vivo dosimetry. Methods: A linear accelerator equipped with four photon energies was used to irradiate optically stimulated luminescent dosimeters (OSLDs) at the respective dmax depths and in the buildup region, with and without the presence of an electromagnetic array used for tumor tracking and patient localization. The OSLDs were placed on solid water slabs under 5 mm bolus and on each face of an octagonal phantom, and irradiated using both static beam and arc geometry, with and without the electromagnetic array under our setup. The electromagnetic array was placed 6 cm above the phantom to coincide with similar distances used during patient treatment. Ionization chamber measurements in a water phantom were also taken initially for comparison with the simple geometry OSLD measurements and published data. Results: Under simple geometry, a negligible change was observed at dmax for all energies when the electromagnetic array was placed over the setup. When measuring at five millimeter depth, increases of 1.3/3.1/16/18% were observed for energies 4X/6X/10X/15X respectively when the electromagnetic array was in place. Measurements using the octagonal phantommore » yielded scattered results for the lateral and posterior oblique fields, and showed increases in dose to the OSLDs placed on the anterior and lateral anterior faces of the phantom. Conclusion: Placing the electromagnetic array very close to the patient’s surface acts as a beam spoiler in the buildup region (at 5 mm depth), which in turn causes an increase in the measured dose reading of the OSLD. This increase in dose is more pronounced when the OSLD is placed directly underneath the electromagnetic array than off to one side or the other.« less

Authors:
; ; ; ;  [1]
  1. Northwell Health, Center for Advanced Medicine, Department of Radiation Medicine, Lake Success, NY (United States)
Publication Date:
OSTI Identifier:
22648927
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 43 PARTICLE ACCELERATORS; DOSIMETRY; GEOMETRY; IN VIVO; IONIZATION CHAMBERS; LINEAR ACCELERATORS; NEOPLASMS; PATIENTS; PHANTOMS

Citation Formats

Rea, A, Kuruvilla, A, Gill, G, Riegel, A, and Klein, E. SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry. United States: N. p., 2016. Web. doi:10.1118/1.4956506.
Rea, A, Kuruvilla, A, Gill, G, Riegel, A, & Klein, E. SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry. United States. doi:10.1118/1.4956506.
Rea, A, Kuruvilla, A, Gill, G, Riegel, A, and Klein, E. 2016. "SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry". United States. doi:10.1118/1.4956506.
@article{osti_22648927,
title = {SU-F-T-321: The Effect of an Electromagnetic Array Used for Patient Localization and Tumor Tracking On OSLD in Vivo Dosimetry},
author = {Rea, A and Kuruvilla, A and Gill, G and Riegel, A and Klein, E},
abstractNote = {Purpose: The purpose of this study was to observe the effect of an electromagnetic array used for patient localization and tumor tracking on optically-stimulated luminescent in-vivo dosimetry. Methods: A linear accelerator equipped with four photon energies was used to irradiate optically stimulated luminescent dosimeters (OSLDs) at the respective dmax depths and in the buildup region, with and without the presence of an electromagnetic array used for tumor tracking and patient localization. The OSLDs were placed on solid water slabs under 5 mm bolus and on each face of an octagonal phantom, and irradiated using both static beam and arc geometry, with and without the electromagnetic array under our setup. The electromagnetic array was placed 6 cm above the phantom to coincide with similar distances used during patient treatment. Ionization chamber measurements in a water phantom were also taken initially for comparison with the simple geometry OSLD measurements and published data. Results: Under simple geometry, a negligible change was observed at dmax for all energies when the electromagnetic array was placed over the setup. When measuring at five millimeter depth, increases of 1.3/3.1/16/18% were observed for energies 4X/6X/10X/15X respectively when the electromagnetic array was in place. Measurements using the octagonal phantom yielded scattered results for the lateral and posterior oblique fields, and showed increases in dose to the OSLDs placed on the anterior and lateral anterior faces of the phantom. Conclusion: Placing the electromagnetic array very close to the patient’s surface acts as a beam spoiler in the buildup region (at 5 mm depth), which in turn causes an increase in the measured dose reading of the OSLD. This increase in dose is more pronounced when the OSLD is placed directly underneath the electromagnetic array than off to one side or the other.},
doi = {10.1118/1.4956506},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • Purpose: To determine the relative positional stability of implanted glass-encapsulated circuits (transponders) used in continuous electromagnetic localization and tracking of target volumes during radiation therapy. Ideally, the distances between transponders remains constant over the course of treament. In this work, we evaluate the accuracy of these conditions. Methods and Materials: Three transponders were implanted in each of 20 patients. Images (CT scan or X-ray pair) were acquired at 13 time points. These images occurred from the day of implant (2 weeks before simulation) to 4 weeks posttreatment. The distance between transponders was determined from each dataset. The average and standardmore » deviation of each distance were determined, and changes were evaluated over several time periods, including pretreatment and during therapy. Results: Of 60 transponders implanted, 58 showed no significant migration from their intended positions. Of the two transponders that did migrate, one appears to have been implanted in the venous plexus, and the other in the urethra, with no clinical consequences to the patients. An analysis that included the planning CT scan and all subsequent distance measurements showed that the standard deviation of intertransponder distances was {<=}1.2 mm for up to 1 month after the completion of therapy. Conclusions: Implanted transponders demonstrate the same long-term stability characteristics as implanted gold markers, within statistical uncertainties. As with gold markers, and using the same implant procedure, basic guidelines for the placement of transponders within the prostate help ensure minimal migration.« less
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