This is a prospective, multicenter randomized controlled trial designed to determine whether the use of computer-aided detection system could reduce the miss rates of adenomas, SSLs, and polyps in the proximal colon during tandem colonoscopy.

1. Study Centers 1) Nanfang Hospital, Southern Medical Univerisity, Guangzhou, China 2) The Fifth Affiliated Hospital of Zunyi Medical University, Zhuhai, China 3) Longgang District People's Hospital of Shenzhen, Shenzhen, China 4) Yangjiang People's Hospital, Yangjiang, China 5) Jiangmen Central Hospital, Jiangmen, China 6) Huizhou Third People's Hospital, Huizhou, China 7) Dongguan Shuixiang Central Hospital, Dongguang, China 8) Pingshan District People's Hospital of Shenzhen, Shenzhen, China

2. Study population 1) Inclusion criteria:

   1. Patients age 40-75 years old, regardless of gender
   2. Patients presenting for physical examination, colorectal cancer screening or diagnosis
   3. Patients voluntarily signs an informed consent form 2) Exclusion criteria:

   1. Unable to cooperate ot tolerate colonoscopy

   2. History of inflammatory bowel disease

   3. History of colorectal cancer

   4. Previous colorectal surgery

   5. History of recurrent constipation

   6. Taking anticoagulant and antiplatelet drugs berfore procedure

   7. High risk conditions such as severe cardiovascular and cerebrovascular diseases, severe anemia, or uncorrected infections

   8. Pregnant or lactating women Researchers concluded that patient was not suitable to participate in this trial.

      3) Post-randomization exclusion criteria:

   1. Cecum could not be intubated for various reasons
   2. Boston Bowel Preparation Scale (BBPS) score of the proximal colon is <2

3. Study design This is a prospective , multicenter randomized controlled trial comparing the miss rates of proximal colonic lesions (including adenomas, SSLs, and polyps) by computer-aided detection-assisted colonoscopy or conventional colonoscopy. The study will be conducted in the Endoscopy Centre of the participating hospitals.

4. Randomization 1) Eligible patients at each center will be randomized (1:1) to computer-aided detection-assisted colonoscopy first or conventional white light colonoscopy first, followed immediately by the other procedure in tandem fashion by the same endoscopist. The proximal colon is defined as the colonic segment proximal to the hepatic flexure.

2) Randomization will be performed using computer-generated random sequences in blocks of 6, with stratification by academic level of participation center, experience of endoscopists, and indications of colonoscopy. Patients will be blinded to their group assignment.

Inclusion Criteria:

1. Patients age 40-75 years old, regardless of gender
2. Patients presenting for physical examination, colorectal cancer screening or diagnosis
3. Patients voluntarily signs an informed consent form

Exclusion Criteria:

1. Unable to cooperate ot tolerate colonoscopy
2. History of inflammatory bowel disease
3. History of colorectal cancer
4. Previous colorectal surgery
5. History of recurrent constipation
6. Taking anticoagulant and antiplatelet drugs berfore procedure
7. High risk conditions such as severe cardiovascular and cerebrovascular diseases, severe anemia, or uncorrected infections
8. Pregnant or lactating women Researchers concluded that patient was not suitable to participate in this trial.