Motion monitoring during a course of lung radiotherapy with anchored electromagnetic transponders : Quantification of inter- and intrafraction motion and variability of relative transponder positions.
MetadataShow full item record
PURPOSE: Anchored electromagnetic transponders for tumor motion monitoring during lung radiotherapy were clinically evaluated. First, intrafractional motion patterns were analyzed as well as their interfractional variations. Second, intra- and interfractional changes of the geometric transponder positions were investigated. MATERIALS AND METHODS: Intrafractional motion data from 7 patients with an upper or middle lobe tumor and three implanted transponders each was used to calculate breathing amplitudes, overall motion amount and motion midlines in three mutual perpendicular directions and three-dimensionally (3D) for 162 fractions. For 6 patients intra- and interfractional variations in transponder distances and in the size of the triangle defined by the transponder locations over the treatment course were determined. RESULTS: Mean 3D values of all fractions were up to 4.0, 4.6 and 3.4 mm per patient for amplitude, overall motion amount and midline deviation, respectively. Intrafractional transponder distances varied with standard deviations up to 3.2 mm, while a maximal triangle shrinkage of 36.5% over 39 days was observed. CONCLUSIONS: Electromagnetic real-time motion monitoring was feasible for all patients. Detected respiratory motion was on average modest in this small cohort without lower lobe tumors, but changes in motion midline were of the same size as the amplitudes and greater midline motion can be observed in some fractions. Intra- and interfractional variations of the geometric transponder positions can be large, so for reliable motion management correlation between transponder and tumor motion needs to be evaluated per patient.
Version of record
Stability of marker positions
Equipment Failure Analysis
Reproducibility of Results
Sensitivity and Specificity
Radiotherapy Physics Modelling
License start date
Strahlenther Onkol, 2017, 193 (10), pp. 840 - 847
Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by/4.0/
Showing items related by title, author, creator and subject.
Incorporating dynamic collimator motion in Monte Carlo simulations: an application in modelling a dynamic wedge Verhaegen, F; Liu, HH (IOP PUBLISHING LTD, 2001-02)In radiation therapy, new treatment modalities employing dynamic collimation and intensity modulation increase the complexity of dose calculation because a new dimension, time, has to be incorporated into the traditional ...
Worst case optimization for interfractional motion mitigation in carbon ion therapy of pancreatic cancer. Steitz, J; Naumann, P; Ulrich, S; Haefner, MF; Sterzing, F; Oelfke, U; Bangert, M (2016-10-07)The efficacy of radiation therapy treatments for pancreatic cancer is compromised by abdominal motion which limits the spatial accuracy for dose delivery - especially for particles. In this work we investigate the potential ...
Magnitude of observer error using cone beam CT for prostate interfraction motion estimation: effect of reducing scan length or increasing exposure. McNair, HA; Harris, EJ; Hansen, VN; Thomas, K; South, C; Hafeez, S; Huddart, R; Dearnaley, DP (2015-10)Cone beam CT (CBCT) enables soft-tissue registration to planning CT for position verification in radiotherapy. The aim of this study was to determine the interobserver error (IOE) in prostate position verification using a ...