Simple carotid-sparing intensity-modulated radiotherapy technique and preliminary experience for T1-2 glottic cancer.
OBJECTIVE
To investigate the dosimetry and feasibility of carotid-sparing intensity-modulated radiotherapy (IMRT) for early glottic cancer and to report preliminary clinical experience.


METHODS
Digital Imaging and Communications in Medicine radiotherapy (DICOM-RT) datasets from 6 T1-2 conventionally treated glottic cancer patients were used to create both conventional IMRT plans. We developed a simplified IMRT planning algorithm with three fields and limited segments. Conventional and IMRT plans were compared using generalized equivalent uniform dose and dose-volume parameters for in-field carotid arteries, target volumes, and organs at risk. We have treated 11 patients with this simplified IMRT technique.


RESULTS
Intensity-modulated radiotherapy consistently reduced radiation dose to the carotid arteries (p < 0.05) while maintaining the clinical target volume coverage. With conventional planning, median carotid V35, V50, and V63 were 100%, 100%, and 69.0%, respectively. With IMRT planning these decreased to 2%, 0%, and 0%, respectively (p < 0.01). Radiation planning and treatment times were similar for conventional radiotherapy and IMRT. Treatment results have been excellent thus far.


CONCLUSIONS
Intensity-modulated radiotherapy significantly reduced unnecessary radiation dose to the carotid arteries compared with conventional lateral fields while maintaining clinical target volume coverage. Further experience and longer follow-up will be required to demonstrate outcomes for cancer control and carotid artery effects.
Rosenthal
David I
DI
Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. dirosenthal@mdanderson.org
Fuller
Clifton D
CD
Barker
Jerry L
JL
Mason
Bryan
B
Garcia
John A
JA
Lewin
Jan S
JS
Holsinger
F Christopher
FC
Stasney
C Richard
CR
Frank
Steven J
SJ
Schwartz
David L
DL
Morrison
William H
WH
Garden
Adam S
AS
Ang
K Kian
KK
D000465:Algorithms; D002339:Carotid Arteries / Q000528:radiation effects*; D005240:Feasibility Studies; D005931:Glottis; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D047368:Tumor Burden
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