Helical tomotherapy setup variations in canine nasal tumor patients immobilized with a bite block.
The purpose of our study was to compare setup variation in four degrees of freedom (vertical, longitudinal, lateral, and roll) between canine nasal tumor patients immobilized with a mattress and bite block, versus a mattress alone. Our secondary aim was to define a clinical target volume (CTV) to planning target volume (PTV) expansion margin based on our mean systematic error values associated with nasal tumor patients immobilized by a mattress and bite block. We evaluated six parameters for setup corrections: systematic error, random error, patient-patient variation in systematic errors, the magnitude of patient-specific random errors (root mean square [RMS]), distance error, and the variation of setup corrections from zero shift. The variations in all parameters were statistically smaller in the group immobilized by a mattress and bite block. The mean setup corrections in the mattress and bite block group ranged from 0.91 mm to 1.59 mm for the translational errors and 0.5°. Although most veterinary radiation facilities do not have access to Image-guided radiotherapy (IGRT), we identified a need for more rigid fixation, established the value of adding IGRT to veterinary radiation therapy, and define the CTV-PTV setup error margin for canine nasal tumor patients immobilized in a mattress and bite block.
Department of Surgical Sciences, University of Wisconsin, WI, USA. lbunting@svm.vetmed.wisc.edu
Lyndsay N
LN
Kubicek
Songwon
S
Seo
Richard J
RJ
Chappell
Robert
R
Jeraj
Lisa J
LJ
Forrest
D000818:Animals; D004283:Dog Diseases / Q000532:radiotherapy*; D004285:Dogs; D007103:Immobilization / Q000662:veterinary*; D009669:Nose Neoplasms / Q000532:radiotherapy / Q000662:veterinary*; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*