ACC	adenoid cystic carcinoma
AJCC	American Joint Committee on Cancer
CIRT	carbon ion radiotherapy
CR	complete remission
CRT	chemoradiotherapy
CT	computed tomography
CTCAE	Common Terminology Criteria for Adverse Events
C12	carbon ions
DPFS	distant progression-free survival
EQD2	equivalent dose in 2 Gy fractions
HIT	Heidelberg Ion-Beam Therapy Center
LPFS	local progression-free survival
LC	local control
IMRT	intensity-modulated radiotherapy
MRI	magnetic resonance imaging
NPC	nasopharyngeal carcinoma
OS	overall survival
PR	partial remission
RECIST	Response Evaluation Criteria in Solid Tumors
RT	radiotherapy
SD	stable disease
TNM	tumor, node, metastasis
UICC	International Union Against Cancer
WHO	World Health Organization