Table 1 Data description and source for spatial accessibility calculation

Supply data

Spatial distribution of CT scanners, including CT model, purchase date, quantity purchased in the same batch, and owner institution information including name, type, and address.

The equipment registration platform of the Sichuan Provincial Health Commission’s Information Center.

Demand data

Spatial distribution of high-risk population for lung cancer. For more accurate assessment, township level aggerated high-risk population was further allocated to 1 km*1km population grids.

Age and gender-specific population data at the township level from the Sichuan Provincial Health Commission.

Population density at 1 km*1km grid scale from WorldPop.

Spatial cost data

Travel time along the road network from demand location to institution providing LDCT was utilized as spatial cost.

National transportation network data at a 1:100 scale published by the National Geomatics Center of China.