TY - JOUR
T1 - Random Positional Variation Among the Skull, Mandible, and Cervical Spine With Treatment Progression During Head-and-Neck Radiotherapy
AU - Ahn, Peter H.
AU - Ahn, Andrew I.
AU - Lee, C. Joe
AU - Shen, Jin
AU - Miller, Ekeni
AU - Lukaj, Alex
AU - Milan, Elissa
AU - Yaparpalvi, Ravindra
AU - Kalnicki, Shalom
AU - Garg, Madhur K.
N1 - Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/2/1
Y1 - 2009/2/1
N2 - Purpose: With 54° of freedom from the skull to mandible to C7, ensuring adequate immobilization for head-and-neck radiotherapy (RT) is complex. We quantify variations in skull, mandible, and cervical spine movement between RT sessions. Methods and Materials: Twenty-three sequential head-and-neck RT patients underwent serial computed tomography. Patients underwent planned rescanning at 11, 22, and 33 fractions for a total of 93 scans. Coordinates of multiple bony elements of the skull, mandible, and cervical spine were used to calculate rotational and translational changes of bony anatomy compared with the original planning scan. Results: Mean translational and rotational variations on rescanning were negligible, but showed a wide range. Changes in scoliosis and lordosis of the cervical spine between fractions showed similar variability. There was no correlation between positional variation and fraction number and no strong correlation with weight loss or skin separation. Semi-independent rotational and translation movement of the skull in relation to the lower cervical spine was shown. Positioning variability measured by means of vector displacement was largest in the mandible and lower cervical spine. Conclusions: Although only small overall variations in position between head-and-neck RT sessions exist on average, there is significant random variation in patient positioning of the skull, mandible, and cervical spine elements. Such variation is accentuated in the mandible and lower cervical spine. These random semirigid variations in positioning of the skull and spine point to a need for improved immobilization and/or confirmation of patient positioning in RT of the head and neck.
AB - Purpose: With 54° of freedom from the skull to mandible to C7, ensuring adequate immobilization for head-and-neck radiotherapy (RT) is complex. We quantify variations in skull, mandible, and cervical spine movement between RT sessions. Methods and Materials: Twenty-three sequential head-and-neck RT patients underwent serial computed tomography. Patients underwent planned rescanning at 11, 22, and 33 fractions for a total of 93 scans. Coordinates of multiple bony elements of the skull, mandible, and cervical spine were used to calculate rotational and translational changes of bony anatomy compared with the original planning scan. Results: Mean translational and rotational variations on rescanning were negligible, but showed a wide range. Changes in scoliosis and lordosis of the cervical spine between fractions showed similar variability. There was no correlation between positional variation and fraction number and no strong correlation with weight loss or skin separation. Semi-independent rotational and translation movement of the skull in relation to the lower cervical spine was shown. Positioning variability measured by means of vector displacement was largest in the mandible and lower cervical spine. Conclusions: Although only small overall variations in position between head-and-neck RT sessions exist on average, there is significant random variation in patient positioning of the skull, mandible, and cervical spine elements. Such variation is accentuated in the mandible and lower cervical spine. These random semirigid variations in positioning of the skull and spine point to a need for improved immobilization and/or confirmation of patient positioning in RT of the head and neck.
KW - Head-and-neck tumor
KW - Immobilization
KW - Radiotherapy
KW - Repositioning accuracy
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U2 - 10.1016/j.ijrobp.2008.10.007
DO - 10.1016/j.ijrobp.2008.10.007
M3 - Article
C2 - 19147027
AN - SCOPUS:58149326848
SN - 0360-3016
VL - 73
SP - 626
EP - 633
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 2
ER -