Carrying RMB for medical treatment in China

Hi,
Please help me know that what are the documents that are needed if I declare cash(RMB) above 20,000 per person. I want to take 52000 RMB and the number of people traveling are 2. I have a treatment cost break-up shared by the Dr. at the hospital. I will also take the bill receipt from the money changer here in India. Is there anything else that would be required by the customs'?
The breakup is sent as an image file. Should that be on a letter signed and stamped like the invitation letter?