Document Detail

Adaptive radiation therapy for postprostatectomy patients using real-time electromagnetic target motion tracking during external beam radiation therapy.
MedLine Citation:
PMID:  23021439     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Using real-time electromagnetic (EM) transponder tracking data recorded by the Calypso 4D Localization System, we report inter- and intrafractional target motion of the prostate bed, describe a strategy to evaluate treatment adequacy in postprostatectomy patients receiving intensity modulated radiation therapy (IMRT), and propose an adaptive workflow.
METHODS AND MATERIALS: Tracking data recorded by Calypso EM transponders was analyzed for postprostatectomy patients that underwent step-and-shoot IMRT. Rigid target motion parameters during beam delivery were calculated from recorded transponder positions in 16 patients with rigid transponder geometry. The delivered doses to the clinical target volume (CTV) were estimated from the planned dose matrix and the target motion for the first 3, 5, 10, and all fractions. Treatment adequacy was determined by comparing the delivered minimum dose (Dmin) with the planned Dmin to the CTV. Treatments were considered adequate if the delivered CTV Dmin is at least 95% of the planned CTV Dmin.
RESULTS: Translational target motion was minimal for all 16 patients (mean: 0.02 cm; range: -0.12 cm to 0.07 cm). Rotational motion was patient-specific, and maximum pitch, yaw, and roll were 12.2, 4.1, and 10.5°, respectively. We observed inadequate treatments in 5 patients. In these treatments, we observed greater target rotations along with large distances between the CTV centroid and transponder centroid. The treatment adequacy from the initial 10 fractions successfully predicted the overall adequacy in 4 of 5 inadequate treatments and 10 of 11 adequate treatments.
CONCLUSION: Target rotational motion could cause underdosage to partial volume of the postprostatectomy targets. Our adaptive treatment strategy is applicable to post-prostatectomy patients receiving IMRT to evaluate and improve radiation therapy delivery.
Mingyao Zhu; Shyam Bharat; Jeff M Michalski; Hiram A Gay; Wei-Hsien Hou; Parag J Parikh
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-09-25
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  85     ISSN:  1879-355X     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-03-04     Completed Date:  2013-04-22     Revised Date:  2014-03-27    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1038-44     Citation Subset:  IM    
Copyright Information:
Copyright © 2013 Elsevier Inc. All rights reserved.
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MeSH Terms
Electromagnetic Fields*
Fiducial Markers*
Middle Aged
Postoperative Care
Prostatic Neoplasms / pathology,  radiotherapy*,  surgery
Radiotherapy Dosage
Radiotherapy, Adjuvant
Radiotherapy, Intensity-Modulated / methods*
Salvage Therapy
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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