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Cohen RJ , Paskalev K , Litwin S , Price RA Jr , Feigenberg SJ , Konski AA
Esophageal motion during radiotherapy: quantification and margin implications
Dis Esophagus. 2010 Aug;23(6) :473-9
PMID: 20095993    PMCID: PMC2933373   
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Abstract
The purpose was to evaluate interfraction and intrafraction esophageal motion in the right-left (RL) and anterior-posterior (AP) directions using computed tomography (CT) in esophageal cancer patients. Eight patients underwent CT simulation and CT-on-rails imaging before and after radiotherapy. Interfraction displacement was defined as differences between pretreatment and simulation images. Intrafraction displacement was defined as differences between pretreatment and posttreatment images. Images were fused using bone registries, adjusted to the carina. The mean, average of the absolute, and range of esophageal motion were calculated in the RL and AP directions, above and below the carina. Thirty-one CT image sets were obtained. The incidence of esophageal interfraction motion > or =5 mm was 24% and > or =10 mm was 3%; intrafraction motion > or =5 mm was 13% and > or =10 mm was 4%. The average RL motion was 1.8 +/- 5.1 mm, favoring leftward movement, and the average AP motion was 0.6 +/- 4.8 mm, favoring posterior movement. Average absolute motion was 4.2 mm or less in the RL and AP directions. Motion was greatest in the RL direction above the carina. Coverage of 95% of esophageal mobility requires 12 mm left, 8 mm right, 10 mm posterior, and 9 mm anterior margins. In all directions, the average of the absolute interfraction and intrafraction displacement was 4.2 mm or less. These results support a 12 mm left, 8 mm right, 10 mm posterior, and 9 mm anterior margin for internal target volume (ITV) and can guide margins for future intensity modulated radiation therapy (IMRT) trials to account for organ motion and set up error in three-dimensional planning.
Notes
Cohen, R J Paskalev, K Litwin, S Price, R A Jr Feigenberg, S J Konski, A A P30 CA006927-449005/CA/NCI NIH HHS/United States Clinical Trial Australia Diseases of the esophagus : official journal of the International Society for Diseases of the Esophagus / I.S.D.E Dis Esophagus. 2010 Aug;23(6):473-9. Epub 2010 Jan 15.