Our facility provides carbon ion radiotherapy as a treatment option for some cancers.7, 8 Radiography technologists manually perform patient positioning using orthogonal (vertical and horizontal) radiographic images. Manual positioning requires skill and experience because individual differences in positioning can increase the exposure dose with repeated x‐ray images. Additionally, inexperience can result in longer time necessary for positioning. It takes approximately 10–15 min for patient positioning, with 30–60 s for each single matching. Therefore, a high‐precision and high‐speed automatic positioning system is needed to realize safer treatments and increase treatment throughput.