The study of virtual source position with the geometric convergent ratio errors prevention management method of spot scanning beam in carbon ion therapy.

"Competing interests There are no actual or potential competing interests in this study. This manuscript has not been published nor concurrently submitted for publication elsewhere."

"Funding Central government Guided Local fund projects of the Science and Technology Department of Gansu Province, China. (The Precise therapy platform of clinical and research for radiation oncology in carbon ion therapy 22ZY1QH001). Overseas high professional experts introduced projects of the Science and Technology Department, Gansu Province, China. (The clinical application of carbon ion beams in radiation oncology 22JR10KA029). Special project for popular science of Gansu Province, China (The most significant equipment in the field of radiotherapy—The fundamental principle, facility and radiobiology in all aspects of carbon ion in radiation oncology 22JR10KA030)."