Radiat Oncol J.  2013 Mar;31(1):12-17. 10.3857/roj.2013.31.1.12.

Parotid gland sparing effect by computed tomography-based modified lower field margin in whole brain radiotherapy

• Cho O
• Chun M
• Park SH
• Oh YT
• Kim MH
• Park HJ
• Nam SS
• Heo J
• Noh OK

• KMID: 1842027
• DOI: http://doi.org/10.3857/roj.2013.31.1.12

Abstract

PURPOSE
Parotid gland can be considered as a risk organ in whole brain radiotherapy (WBRT). The purpose of this study is to evaluate the parotid gland sparing effect of computed tomography (CT)-based WBRT compared to 2-dimensional plan with conventional field margin.
MATERIALS AND METHODS
From January 2008 to April 2011, 53 patients underwent WBRT using CT-based simulation. Bilateral two-field arrangement was used and the prescribed dose was 30 Gy in 10 fractions. We compared the parotid dose between 2 radiotherapy plans using different lower field margins: conventional field to the lower level of the atlas (CF) and modified field fitted to the brain tissue (MF).
RESULTS
Averages of mean parotid dose of the 2 protocols with CF and MF were 17.4 Gy and 8.7 Gy, respectively (p < 0.001). Mean parotid dose of both glands > or =20 Gy were observed in 15 (28.3%) for CF and in 0 (0.0%) for MF. The whole brain percentage volumes receiving >98% of prescribed dose were 99.7% for CF and 99.5% for MF.
CONCLUSION
Compared to WBRT with CF, CT-based lower field margin modification is a simple and effective technique for sparing the parotid gland, while providing similar dose coverage of the whole brain.

Keyword

Whole brain radiotherapy; Parotid gland sparing; Xerostomia; Normal tissue complication probability

MeSH Terms

Brain
Humans
Parotid Gland
Xerostomia