Toward correcting drift in target position during radiotherapy via computer-controlled couch adjustments on a programmable Linac Journal Article
| Authors: | Mcnamara, J. E.; Regmi, R.; Michael Lovelock, D.; Yorke, E. D.; Goodman, K. A.; Rimner, A.; Mostafavi, H.; Mageras, G. S. |
| Article Title: | Toward correcting drift in target position during radiotherapy via computer-controlled couch adjustments on a programmable Linac |
| Abstract: | Purpose: Real-time tracking of respiratory target motion during radiation therapy is technically challenging, owing to rapid and possibly irregular breathing variations. The authors report on a method to predict and correct respiration-averaged drift in target position by means of couch adjustments on an accelerator equipped with such capability. Methods: Dose delivery is broken up into a sequence of 10 s field segments, each followed by a couch adjustment based on analysis of breathing motion from an external monitor as a surrogate of internal target motion. Signal averaging over three respiratory cycles yields a baseline representing target drift. A Kalman filter predicts the baseline position 5 s in advance, for determination of the couch correction. The methods feasibility is tested with a motion phantom programmed according to previously recorded patient signals. Computed couch corrections are preprogrammed into a research mode of an accelerator capable of computer-controlled couch translations synchronized with the motion phantom. The methods performance is evaluated with five cases recorded during hypofractionated treatment and five from respiration-correlated CT simulation, using a root-mean-squared deviation (RMSD) of the baseline from the treatment planned position. Results: RMSD is reduced in all 10 cases, from a mean of 4.9 mm (range 2.7-9.4 mm) before correction to 1.7 mm (range 0.7-2.3 mm) after correction. Treatment time is increased ∼5 relative to that for no corrections. Conclusions: This work illustrates the potential for reduction in baseline respiratory drift with periodic adjustments in couch position during treatment. Future treatment machine capabilities will enable the use of on-the-fly couch adjustments during treatment. © 2013 American Association of Physicists in Medicine. |
| Keywords: | controlled study; radiotherapy; prediction; feasibility study; motion; motion analysis system; linear accelerator; breathing pattern; velocity; tracking; breathing; camera; respiratory motion; oscillation; noise; adaptive radiotherapy; mean-position estimation; eye tracking; computer controlled couch adjustment; computer controlled linac; radiology phantom |
| Journal Title: | Medical Physics |
| Volume: | 40 |
| Issue: | 5 |
| ISSN: | 0094-2405 |
| Publisher: | American Association of Physicists in Medicine |
| Date Published: | 2013-05-01 |
| Start Page: | 051719 |
| Language: | English |
| DOI: | 10.1118/1.4802736 |
| PROVIDER: | scopus |
| PMCID: | PMC3656942 |
| PUBMED: | 23635267 |
| DOI/URL: | |
| Notes: | --- - "Export Date: 3 June 2013" - "CODEN: MPHYA" - "Source: Scopus" |
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