PURPOSE: To assess the impact of intrafraction intervention on margins for prostate radiotherapy. METHODS AND MATERIALS: Eleven supine prostate patients with three implanted transponders were studied. The relative transponder positions were monitored for 8 min and combined with previously measured data on prostate position relative to skin marks. Margins were determined for situations of (1) skin-based positioning, and (2) pretreatment transponder positioning. Intratreatment intervention was simulated assuming conditions of (1) continuous tracking, and (2) a 3-mm threshold for position correction. RESULTS: For skin-based setup without and with inclusion of intrafraction motion, prostate treatments would have required average margins of 8.0, 7.3, and 10.0 mm and 8.2, 10.2, and 12.5 mm, about the left-right, anterior-posterior, and cranial-caudal directions, respectively. Positioning by prostate markers at the start of the treatment fraction reduced these values to 1.8, 5.8, and 7.1 mm, respectively. Interbeam adjustment further reduced margins to an average of 1.4, 2.3, and 1.8 mm. Intrabeam adjustment yielded margins of 1.3, 1.5, and 1.5 mm, respectively. CONCLUSION: Significant reductions in margins might be achieved by repositioning the patient before each beam, either radiographically or electromagnetically. However, 2 of the 11 patients would have benefited from continuous target tracking and threshold-based intervention.
PURPOSE: To assess the impact of intrafraction intervention on margins for prostate radiotherapy. METHODS AND MATERIALS: Eleven supine prostate patients with three implanted transponders were studied. The relative transponder positions were monitored for 8 min and combined with previously measured data on prostate position relative to skin marks. Margins were determined for situations of (1) skin-based positioning, and (2) pretreatment transponder positioning. Intratreatment intervention was simulated assuming conditions of (1) continuous tracking, and (2) a 3-mm threshold for position correction. RESULTS: For skin-based setup without and with inclusion of intrafraction motion, prostate treatments would have required average margins of 8.0, 7.3, and 10.0 mm and 8.2, 10.2, and 12.5 mm, about the left-right, anterior-posterior, and cranial-caudal directions, respectively. Positioning by prostate markers at the start of the treatment fraction reduced these values to 1.8, 5.8, and 7.1 mm, respectively. Interbeam adjustment further reduced margins to an average of 1.4, 2.3, and 1.8 mm. Intrabeam adjustment yielded margins of 1.3, 1.5, and 1.5 mm, respectively. CONCLUSION: Significant reductions in margins might be achieved by repositioning the patient before each beam, either radiographically or electromagnetically. However, 2 of the 11 patients would have benefited from continuous target tracking and threshold-based intervention.
Authors: X J Juan-Senabre; J López-Tarjuelo; A Conde-Moreno; A Santos-Serra; A L Sánchez-Iglesias; J D Quirós-Higueras; N de Marco Blancas; S Calzada-Feliu; C Ferrer-Albiach Journal: Clin Transl Oncol Date: 2011-11 Impact factor: 3.405
Authors: Bongile Mzenda; Mir Hosseini-Ashrafi; Antony Palmer; Honghai Liu; David J Brown Journal: Med Biol Eng Comput Date: 2010-04-23 Impact factor: 2.602
Authors: Charles W Scarantino; Bradley R Prestidge; Mitchel S Anscher; Carolyn R Ferree; William T Kearns; Robert D Black; Natasha G Bolick; Gloria P Beyer Journal: Int J Radiat Oncol Biol Phys Date: 2008-10-01 Impact factor: 7.038
Authors: Tobias Pommer; Marianne Falk; Per R Poulsen; Paul J Keall; Ricky T O'Brien; Peter Meidahl Petersen; Per Munck af Rosenschöld Journal: Phys Med Biol Date: 2013-03-14 Impact factor: 3.609