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Title: PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants

Abstract

The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. Itmore » also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of the detector itself. In addition to PET alone, PET/CT imaging provides accurate information on the position of the imaged object and may assess possible anatomical changes during fractionated radiotherapy in clinical applications.« less

Authors:
; ; ; ; ; ; ;  [1];  [2];  [2];  [2]
  1. Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20951035
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 2; Other Information: DOI: 10.1118/1.2401042; (c) 2007 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; ACCURACY; ALGORITHMS; BRAGG CURVE; CLINICAL TRIALS; HOSPITALS; IMAGE SCANNERS; IMPLANTS; IRRADIATION; LUNGS; MASSACHUSETTS; MONTE CARLO METHOD; PHANTOMS; PLASTICS; PMMA; POSITRON COMPUTED TOMOGRAPHY; PROTON BEAMS; RADIOTHERAPY; SKELETON; SPATIAL DISTRIBUTION; VERIFICATION

Citation Formats

Parodi, Katia, Paganetti, Harald, Cascio, Ethan, Flanz, Jacob B., Bonab, Ali A., Alpert, Nathaniel M., Lohmann, Kevin, Bortfeld, Thomas, Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114, Siemens Medical Solutions USA, Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932-2571, and Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114. PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants. United States: N. p., 2007. Web. doi:10.1118/1.2401042.
Parodi, Katia, Paganetti, Harald, Cascio, Ethan, Flanz, Jacob B., Bonab, Ali A., Alpert, Nathaniel M., Lohmann, Kevin, Bortfeld, Thomas, Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114, Siemens Medical Solutions USA, Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932-2571, & Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114. PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants. United States. doi:10.1118/1.2401042.
Parodi, Katia, Paganetti, Harald, Cascio, Ethan, Flanz, Jacob B., Bonab, Ali A., Alpert, Nathaniel M., Lohmann, Kevin, Bortfeld, Thomas, Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114, Siemens Medical Solutions USA, Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932-2571, and Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114. Thu . "PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants". United States. doi:10.1118/1.2401042.
@article{osti_20951035,
title = {PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants},
author = {Parodi, Katia and Paganetti, Harald and Cascio, Ethan and Flanz, Jacob B. and Bonab, Ali A. and Alpert, Nathaniel M. and Lohmann, Kevin and Bortfeld, Thomas and Massachusetts General Hospital, Department of Radiology, 55 Fruit Street, Boston, Massachusetts 02114 and Siemens Medical Solutions USA, Molecular Imaging, 810 Innovation Drive, Knoxville, Tennessee 37932-2571 and Massachusetts General Hospital, Department of Radiation Oncology, 30 Fruit Street, Boston, Massachusetts 02114},
abstractNote = {The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of the detector itself. In addition to PET alone, PET/CT imaging provides accurate information on the position of the imaged object and may assess possible anatomical changes during fractionated radiotherapy in clinical applications.},
doi = {10.1118/1.2401042},
journal = {Medical Physics},
number = 2,
volume = 34,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}