JOURNAL ARTICLE

Setup variations in radiotherapy of esophageal cancer: evaluation by daily megavoltage computed tomographic localization

Yi-Jen Chen, Chunhui Han, An Liu, Timothy E Schultheiss, Kemp H Kernstine, Stephen Shibata, Nayana L Vora, Richard D Pezner, Jeffrey Y C Wong
International Journal of Radiation Oncology, Biology, Physics 2007 August 1, 68 (5): 1537-45
17531399

PURPOSE: To use pretreatment megavoltage computed tomography (MVCT) scans to evaluate setup variations in anterior-posterior (AP), lateral, and superior-inferior (SI) directions and rotational variations, including pitch, roll, and yaw, for esophageal cancer patients treated with helical tomotherapy.

METHODS AND MATERIALS: Ten patients with locally advanced esophageal cancer treated by combined chemoradiation using helical tomotherapy were selected. After patients were positioned using their skin tattoos/marks, MVCT scans were performed before every treatment and automatically registered to planning kilovoltage CT scans according to bony landmarks. Image registration data were used to adjust patient setups before treatment. A total of 250 MVCT scans were analyzed. Correlations between setup variations and body habitus, including height, weight, relative weight change, body surface area, and patient age, were evaluated.

RESULTS: The standard deviations for systematic setup corrections in AP, lateral, and SI directions and pitch, roll, and yaw rotations were 1.5, 3.7, and 4.8 mm and 0.5 degrees, 1.2 degrees, and 0.8 degrees, respectively. The appropriate averages of random setup variations in AP, lateral, and SI directions and pitch, roll, and yaw rotations were 2.9, 5.2, and 4.4 mm, and 1.0 degrees, 1.2 degrees, and 1.1 degrees, respectively. Setup variations were stable throughout the entire course of radiotherapy in all three translational and three rotational displacements, with little change in magnitude. No significant correlations were found between setup variations and body habitus variables.

CONCLUSIONS: Daily MVCT scans before each treatment can effectively detect setup errors and thereby reduce planning target volume (PTV) margins. This will reduce radiation dose to critical organs and may translate into lower treatment-related toxicities.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
17531399
×

Save your favorite articles in one place with a free QxMD account.

×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"