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Image guided position verification for intensity modulated radiotherapy of prostate cancer (in English)
Author(s) -
Nederveen Aart J.
Publication year - 2003
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1563666
Subject(s) - prostate cancer , prostate , standard deviation , position (finance) , nuclear medicine , medicine , radiation therapy , dosimetry , computer science , medical imaging , intensity (physics) , radiology , mathematics , cancer , physics , statistics , optics , finance , economics
The aim of this thesis is to provide a practical framework for dose escalation in the prostate using intensity modulated radiotherapy (IMRT) and to find out if marker based on‐line position verification is clinically feasible and effective. We present a class solution for dose escalation in the prostate in which the issue of dose escalation is dealt with separately from the choice of margins and nominal rectum dose. We study verification and correction of the prostate position during treatment based on implanted gold markers. To perform such position verification in an automated way several requirements should be met. Thanks to the use of an a‐Si flat‐panel imager and a dedicated software algorithm, markers of 1 mm diameter and 5 mm length can be detected automatically (success rate >90%), fast (within 1 s) and accurate (better than 0.3 mm). Marker migration appears to be present, but remains very small (standard deviation 0.5 mm). The effect of prostate volume alteration during treatment appears to be smaller than the inaccuracy that is present due to volume delineation. For 10 patients that were treated in a feasibility study no major toxicity related to marker implantation was noticed. In a group of 23 patients off‐line marker based position verification was proved to reduce the standard deviations of the systematic error to below 1 mm. Intratreatment prostate motions could be visualized as well and appeared to be very small on average (standard deviation <1 mm). We conclude that marker based position verification provides a reliable method for decreasing the geometrical deviations during prostate irradiation .