title: Tracking errors in a prototype real-time tumour tracking system.
abstract: In motion-compensated radiation therapy, radio-opaque markers can be implanted in or near a tumour and tracked in real-time using fluoroscopic imaging. Tracking these implanted markers gives highly accurate position information, except when tracking fails due to poor or ambiguous imaging conditions. This study investigates methods for automatic detection of tracking errors, and assesses the frequency and impact of tracking errors on treatments using the prototype real-time tumour tracking system. We investigated four indicators for automatic detection of tracking errors, and found that the distance between corresponding rays was most effective. We also found that tracking errors cause a loss of gating efficiency of between 7.6 and 10.2%. The incidence of treatment beam delivery during tracking errors was estimated at between 0.8% and 1.25%.
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA 02114, USA. gcsharp@partners.org
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Sharp
authors.forename: Steve B
authors.initials: SB
authors.lastname: Jiang
authors.forename: Shinichi
authors.initials: S
authors.lastname: Shimizu
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
mesh_terms: D000465:Algorithms; D000818:Animals; D003199:Computer Systems; D019544:Equipment Failure Analysis; D005471:Fluoroscopy; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000532:radiotherapy*; D010363:Pattern Recognition, Automated; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors