科研之友
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摘要
Purpose To determine planning target volume margins for prostate intensity-modulated radiotherapy based on Inter- and intrafraction motion using four daily localization techniques three point skin mark alignment, volumetric imaging with bony landmark registration, volumetric imaging with implanted fiducial marker registration, and Implanted electromagnetic transponders (beacons) detection Methods and Materials Fourteen patients who underwent definitive intensity-modulated radiotherapy for prostate cancer formed the basis of this study Each patient was Implanted with three electromagnetic transponders and underwent a course of 39 treatment fractions Daily localization was based on three point skin mark alignment followed by transponder detection and patient repositioning Transponder positioning was verified by volumetric imaging with cone beam computed tomography of the pelvis Relative motion between the prostate gland and bony anatomy was quantified by offline analyses of daily cone beam computed tomography lntratreatment organ motion was monitored continuously by the Calypso (R) System for quantification of intrafraction setup error Results As expected, setup error (that is, Inter plus intrafraction motion, unless otherwise stated) was largest with skin mark alignment, requiring margins of 7 5 mm, 11 4 mm, and 16 3 mm, in the lateral (LR), longitudinal (SI), and vertical (AP) directions, respectively Margin requirements accounting for intrafraction motion were smallest for transponder detection localization techniques, requiring margins of 1 4 mm (LR), 2 6 mm (SI), and 2 3 mm (AP) Bony anatomy alignment required 2 1 mm (LR), 9 4 mm (SI), and 10 5 mm (AP), whereas Image guided marker alignment required 2 8 mm (LR), 3 7 mm (SI), and 3 2 mm (AP) No marker migration was observed in the cohort Conclusion Clinically feasible, rapid, and reliable tools such as the electromagnetic transponder detection system for pretreatment tar
- 出版日期2010-12-1
