TITLE:
Measuring Radiotherapy Setup Errors in IMRT Treated Head and Neck Cancer Patients Requiring Bilateral Neck Irradiation, NCI-Egypt Experience
AUTHORS:
May G. Ashour, Tarek H. Shouman, Ashraf H. Hassouna, Reem M. Emad El Din, Maha H. Mokhtar, Mohamed A. Khalil
KEYWORDS:
IMRT, CBCT, Setup Errors, Head and Neck
JOURNAL NAME:
Journal of Cancer Therapy,
Vol.8 No.13,
December
13,
2017
ABSTRACT: Objective: We aim to quantify the magnitude of setup errors in
intensity-modulated radiotherapy (IMRT) treated Head and Neck cancer patients
and recommend appropriate PTV margin. Methods: 60 patients with head and
neck cancer required bilateral neck irradiation were planned and treated by
simultaneous integrated boost IMRT technique either treated radically or
postoperative. Patients undergoing image-guided radiotherapy (IGRT) each with
once weekly scheduled cone beam computed tomography (CBCT). The 3D
displacements, systematic and random errors were calculated. The appropriate
PTV expansion was determined using Van Herk’s formula. Results: Mean 3D
displacement was 0.16 cm in the vertical direction, 0.14 cm in the horizontal
direction and 0.16 cm in the longitudinal direction. Conclusion: Use of
weekly CBCT allows the planning target volume (PTV) expansion to be reduced
according to our setup. The appropriate clinical target volume (CTV)-PTV margin for our institute is 0.30 cm, 0.38 cm,
and 0.33 cm in the horizontal, vertical, and longitudinal directions,
respectively.