Document Detail

Clinical application of a repositioning scheme, using gold markers and electronic portal imaging.
MedLine Citation:
PMID:  16581149     Owner:  NLM     Status:  MEDLINE    
BACKGROUND AND PURPOSE: To implement an on-line correction scheme based on implanted markers to reduce treatment margins in external beam radiation therapy (EBRT) of carcinoma of the prostate. In turn reduction in treatment margins reduces irradiated volumes and offers the possibility of reduced normal tissue complications or escalated target dose. PATIENTS AND METHODS: Five or six gold markers were implanted in 10 patients treated for prostate carcinoma using EBRT. All patients were enlisted in an IRB-approved protocol. Before each fraction two portal images were obtained using a low dose (2MU). Positions of the markers were calculated from these images using an in-house developed program. Corrections were applied with a threshold of 2mm displacement. After correction the procedure was repeated. RESULTS: Overall systematic errors were reduced from 7.45, 1.29, and 5.12 mm to 0.65, 0.11, and 0.46 mm in, respectively, the antero-posterior, lateral, and cranio-caudal directions. Likewise, the overall SD were reduced from 5.99, 5.34, and 4.44 mm to 2.82, 2.64, and 2.22 mm, respectively. All reductions were highly significant (P < 0.01) using a t-test for systematic and an F-test for random errors. On an individual level all but three patients showed significant improvements in all directions for the random errors. All patients improved in at least one direction. Systematic errors were significantly lower in all patients. Simulated correction schemes using this data suggest that margin reduction using off-line reduction does not benefit substantially from on-line corrections in the first few fractions. CONCLUSIONS: Use of marker-based correction improves the patient position. Factors influencing the accuracy were: (1) number of seeds usable for correction, (2) distribution of markers throughout the volume of interest, and (3) objective instructions for patient realignment.
Frank Van den Heuvel; James Fugazzi; Ed Seppi; Jeffrey D Forman
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-04-03
Journal Detail:
Title:  Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology     Volume:  79     ISSN:  0167-8140     ISO Abbreviation:  Radiother Oncol     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-05-08     Completed Date:  2006-10-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8407192     Medline TA:  Radiother Oncol     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  94-100     Citation Subset:  IM    
Department of Oncology and Experimental Radiation Oncology, University of Leuven, Belgium.
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MeSH Terms
Carcinoma / radiotherapy*
Pelvic Bones / radiation effects
Prostate / radiation effects
Prostatic Neoplasms / radiotherapy*
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Intensity-Modulated / methods*
Reg. No./Substance:

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

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