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Title: MO-B-BRB-00: Three Dimensional Dosimetry

Abstract

Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already availablemore » in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT. Titania Juang: Special techniques in the clinic and research Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators Geoffrey S. Ibbott: 3D Dosimetry in end-to-end dosimetry QA Understand the potential for 3D dosimetry for end-to-end radiation therapy process validation in the in-house and external credentialing setting. Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835.« less

Publication Date:
OSTI Identifier:
22649511
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; 61 RADIATION PROTECTION AND DOSIMETRY; BIOMEDICAL RADIOGRAPHY; COMPUTERIZED TOMOGRAPHY; DOSEMETERS; DOSES; DOSIMETRY; NMR IMAGING; POTENTIALS; QUALITY ASSURANCE; READOUT SYSTEMS; THREE-DIMENSIONAL CALCULATIONS; TITANIUM OXIDES

Citation Formats

NONE. MO-B-BRB-00: Three Dimensional Dosimetry. United States: N. p., 2016. Web. doi:10.1118/1.4957182.
NONE. MO-B-BRB-00: Three Dimensional Dosimetry. United States. doi:10.1118/1.4957182.
NONE. 2016. "MO-B-BRB-00: Three Dimensional Dosimetry". United States. doi:10.1118/1.4957182.
@article{osti_22649511,
title = {MO-B-BRB-00: Three Dimensional Dosimetry},
author = {NONE},
abstractNote = {Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an irradiated volume can help understand interplay effects during TomoTherapy or VMAT. Titania Juang: Special techniques in the clinic and research Understand the potential for 3D dosimetry in validating dose accumulation in deformable systems, and Observe the benefits of high resolution measurements for precision therapy in SRS and in MicroSBRT for small animal irradiators Geoffrey S. Ibbott: 3D Dosimetry in end-to-end dosimetry QA Understand the potential for 3D dosimetry for end-to-end radiation therapy process validation in the in-house and external credentialing setting. Canadian Institutes of Health Research; L. Schreiner, Modus QA, London, ON, Canada; T. Juang, NIH R01CA100835.},
doi = {10.1118/1.4957182},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • To understand tumor response and normal organ toxicity following internal emitter therapy a succinct yet adequate representation of the spatial dose distribution within the target is necessary. Using 3D-ID, a software package that implements a patient-specific, three-dimensional approach to dosimetry, we obtain the mean and a dose-volume histogram of the spatial dose distribution to a target volume. Registered CT/MR and SPECT/PET images (generated using Pelizzari/Chen registration software) are used to define the radioactivity distribution relative to patient anatomy. Target contours are drawn on side-by-side enlarged SPECT/PET and CT/MR image slices that are selected from a scrollable image display. Contours drawnmore » in one modality simultaneously appear in the other. The user may switch between modalities by positioning the cursor in the appropriate window. This provides for the simultaneous use of both imaging modalities to define tumor (e.g. using SPECT) and normal organ (using CT/MR) contours. The dose to all voxels within the target volume is obtained by convolving the activity distribution with a point kernel table of absorbed dose versus distance. Patient-specific S-factors may be calculated by defining source organ contours and assigning unit activity to all voxels within each source. The {open_quotes}dose{close_quotes} to a given target is thus the patient-specific S-factor In the first patient examined using 3D-ID, approximately 16% of the tumor volume received a dose that was 25% less than the mean dose. The liver to spleen S-factor for this patient differed from the standard man value by approximately 48%; when the value was adjusted for the patient`s (enlarged) spleen volume the difference was approximately 21%. Dose histograms and patient-specific organ and tumor S-factors generated using 3D-ID may provide useful information in understanding tumor response and organ toxicity in radioimmunotherapy.« less
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