35 and above, solid nodule, single nodule, <6mm, unknown risk, <12 months.

ACR Fleischner Society recommendations (MacMahon, et al. Radiology 2017; 284(1): 228-43) suggest the following:

For patients with low risk of lung cancer, no need for follow-up.

For patients with high risk of lung cancer, generally no need for follow-up. An optional chest CT at 12 months could be performed if there is high index of suspicion.