1.5 T	1.5 tesla (MRI field strength)
ADASYN	Adaptive synthetic sampling
ADC	Apparent diffusion coefficient
ADCb0-1000	Apparent diffusion coefficient calculated using b = 0 and b = 1000 s/mm2 (ADC b0–1000)
ADCmean	Mean apparent diffusion coefficient
AI	Artificial intelligence
AJCC	American Joint Committee on Cancer
AJCC-8	AJCC 8th edition staging system
ANCOVA	Analysis of covariance
AUC	Area under the (ROC) curve
AUC-CSH	Area under the curve of the cumulative SUV–volume histogram (AUC-CSH)
AUROC	Area under the receiver operating characteristic curve
C-index	Concordance index
C3D	C3D (3D convolutional neural network architecture)
CAM	Class activation mapping
CCRT	Concurrent chemoradiotherapy
CE	Contrast-enhanced
CE-T1	Contrast-enhanced T1-weighted imaging
CE-T1/T2	Contrast-enhanced T1-weighted imaging/T2-weighted (MRI sequence)
CI	Confidence interval
CNN	Convolutional neural network
CoLlAGe	Co-occurrence of Local Anisotropic Gradient Orientations (radiomic feature family)
ComBat	ComBat harmonisation method
CRT	Chemoradiotherapy
CT	Computed tomography
CT/MRI	Computed tomography/magnetic resonance imaging
DFS	Disease-free survival
DFS/OS	Disease-free survival/overall survival
DL	Deep learning
DM	Distant metastasis
DW-MRI	Diffusion-weighted magnetic resonance imaging
DWI	Diffusion-weighted imaging
DWI/ADC	Diffusion-weighted imaging/apparent diffusion coefficient
E3311	ECOG-ACRIN E3311 trial (OPSCC de-escalation trial)
ECOG-ACRIN	ECOG-ACRIN Cancer Research Group (Eastern Cooperative Oncology Group + ACRIN)
EFS	Event-free survival
EIBALL/EORTC	EIBALL/EORTC (joint guidance)
ENE	Extranodal extension
EPI	Echo-planar imaging
FDG	(18F-)fluorodeoxyglucose
FDG-PET	(18F-)fluorodeoxyglucose positron emission tomography
FDG-PET/CT	(18F-)fluorodeoxyglucose PET/CT
FDR	False discovery rate
GLCM	Grey-level co-occurrence matrix
GLRLM	Grey-level run-length matrix
GLRLM/GLSZM/NGTDM	Grey-level run-length matrix/grey-level size zone matrix/neighbourhood grey-tone difference matrix
GLSZM	Grey-level size zone matrix
Grad-CAM	Gradient-weighted class activation mapping
GTV	Gross tumour volume
GTV-N	Gross tumour volume—nodal
GTV-P	Gross tumour volume—primary
GTVn	Gross tumour volume—nodal
GTVp	Gross tumour volume—primary
H&N	Head and neck
HECKTOR	Head and neck tumour segmentation and outcome prediction (challenge)
HNSCC	Head and neck squamous cell carcinoma
HPV	Human papillomavirus
HPV-POSITIVE	Human papillomavirus—positive
HR	Hazard ratio
IBEX	Imaging Biomarker Explorer
IBSI	Image Biomarker Standardisation Initiative
IDEAL	IDEAL Framework (Idea, Development, Exploration, Assessment, Long-Term Study)
ImageNet	ImageNet dataset
IMRT	Intensity-modulated radiotherapy
IMRT/CRT	Intensity-modulated radiotherapy/Chemoradiotherapy
Inception-V3	Inception v3 (CNN architecture)
KM	Kaplan–Meier
LR	Local recurrence
LR/RF	Logistic regression/random forest
LRC	Locoregional control
MATLAB	MATLAB (MathWorks numerical computing environment)
MICCAI	Medical Image Computing and Computer Assisted Intervention
MITK	Medical Imaging Interaction Toolkit
MR	Magnetic resonance
MRgRT	Magnetic resonance-guided radiotherapy
MRI	Magnetic resonance imaging
MRMR	Minimum redundancy maximum relevance
MTV	Metabolic tumour volume
MTV/TLG	Metabolic tumour volume/total lesion glycolysis
NAC	Neoadjuvant chemotherapy
NGTDM	Neighbourhood grey-tone difference matrix
NPC	Nasopharyngeal carcinoma
NPV	Negative predictive value
OAR	Organ at risk
OPC	Oropharyngeal cancer
OPSCC	Oropharyngeal squamous cell carcinoma
OPSCC-HPV	HPV-associated OPSCC
OS	Overall survival
OS/DFS	Overall survival/disease-free survival
OS/PFS	Overall survival/progression-free survival
PERCIST	PET Response Criteria in Solid Tumours
PET	Positron emission tomography
PET-CT	Positron emission tomography/computed tomography
PET-NECK	PET-NECK trial (PET-guided surveillance vs. neck dissection after CRT)
PET/CT	Positron emission tomography/computed tomography
PET/DWI	Positron emission tomography/diffusion-weighted imaging
PET/MRI	Positron emission tomography/magnetic resonance imaging
PET/MRI/CT	Positron emission tomography/MRI/CT
PFS	Progression-free survival
PFS/DFS	Progression-free survival/disease-free survival
PFS/DSS	Progression-free survival/disease-specific survival
PFS/DSS/OS	Progression-free survival/disease-specific survival/overall survival
PFS/OS	Progression-free survival/overall survival
PPV	Positive predictive value
QI	Quality improvement
QIBA	Quantitative Imaging Biomarkers Alliance
R-IDEAL	R-IDEAL framework for radiotherapy innovation evaluation
RCT	Randomised controlled trial
RFS	Recurrence-free survival
ROC	Receiver operating characteristic
ROC/AUC	Receiver operating characteristic/area under the (ROC) curve
ROI	Region of interest
RRS	Radiomics risk score
RT	Radiotherapy
SCC	Squamous cell carcinoma
SD	Standard deviation
SMOTE	Synthetic Minority Over-Sampling Technique
SPM12	Statistical Parametric Mapping (version 12)
SPSS	Statistical Package for the Social Sciences
SULpeak	Peak standardised uptake value (lean body mass-normalised)
SUV	Standardised uptake value
SUVmax	Maximum standardised uptake value
SUVmean	Mean standardised uptake value
SUVpeak	Peak standardised uptake value
SVM	Support vector machine
T1	T1-weighted (MRI sequence)
T1WI	T1-weighted imaging
T2	T2-weighted (MRI sequence)
T2WI	T2-weighted imaging
TCIA	The Cancer Imaging Archive
TLG	Total lesion glycolysis
UK	United Kingdom
VOI	Volume of interest
XGBoost	eXtreme Gradient Boosting
ΔADC	Change in apparent diffusion coefficient