Table 1:

Detailed nodule characteristics labels in LIDC dataset.

Semantic Feature	Description	Ratings
Malignancy	Likelihood of malignancy	1. Highly unlikely 2. Moderately unlikely 3. Indeterminate 4. Moderately suspicious 5. Highly suspicious
Margin	How well defined the margins are	1. Poorly defined 2. 3. 4. 5. Sharp
Sphericity	Three dimensional shape in terms of roundness	1. Linear 2. 3. Ovoid 4. 5. Round
Subtlety	Difficulty of detection relative to surround	1. Extremely subtle 2. Moderately subtle 3. Fairly subtle 4. Moderately obvious 5. Obvious
Spiculation	Degree of exhibition of spicules	1. Marked 2. 3. 4. 5. None
Radiographic solidity (texture)	Internal texture (consistency) of nodule	1. Non-solid 2. 3. Part Solid 4. 5. Solid
Calcification	Presence and pattern of calcification	1. Popcorn 2. Laminated 3. Solid 4. Non-central 5. Central 6. Absent
Internal structure	Expected internal composition of the nodule	1. Soft tissue 2. Fluid 3. Fat 4. 5. Air
Lobulation	The presence and degree of lobulation of the nodule margin	1. Marked 2. 3. 4. 5. None