Table 2. Overview of deep iterative registration studies.

Study	Learning	Transform	Modality	ROI	Public dataset for training/validation	Evaluation metrics
(76)	Metric	Deformable	MRI-MRI	Brain	LONI LPBA40	DSC
(77)	Metric	Deformable	MRI-MRI	Brain	IXI, ALBERTs	DSC
(78)	Metric	Deformable	MRI-MRI	Brain	IXI	FRE, DSC
(79)	Metric	Rigid	MRI-US	Prostate	PROMISE12, Prostate-3T	TRE
(80)	Metric	Deformable	MRI-MRI	Brain	OASIS, ABIDE	DSC
(81)	Metric	Rigid & Deformable	MRI-MRI	Brain	Simulated brain	DSC
(82)	Metric	Deformable	MRI-MRI	Brain	LPBA40, CUMC12, MGH10, IBSR18	DSC, Jaco. Det.
(83)	RL agent	Rigid	CT-CBCT	Spine and heart	N/A	TRE
(84)	RL agent	Deformable	CT-CT	Thorax, abdomen, and pelvis	N/A	Euclidean distance
(85)	RL agent	Deformable	MRI-MRI	Prostate	PROMISE12, Prostate-3T	DSC, HD
(86)	RL agent	Affine	MR-CT	Brain	N/A	TRE

CBCT, cone-beam computed tomography; CT, computed tomography; DSC, Dice coefficient; FRE, fiducial registration error; HD, Hausdorff distance; MRI, magnetic resonance imaging; RL, reinforcement learning; ROI, region of interest; TRE, target registration error.