Please assess the completion status of the following clinical trial:

Trial Title: The Efficacy of N-acetylcysteine on Alleviating Symptom Caused by Lugol Chromoendoscopy

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: DIAGNOSTIC
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: None
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Patients at risk of esophageal squamous cell cancer including those over 50 years old, or over 45 years old with family history of esophageal squamous cell cancer;~* Patients with suspected esophageal lesions by screening endoscopy;~* Patients requiring surveillance after endoscopic resection or radiotherapy for esophageal squamous cell cancer one year later。~Exclusion Criteria:~* Patients allergic to iodine or with hyperthyroidism;~* Patients with advanced esophageal cancer, esophageal varices, esophageal ulcer or other conditions inadvisable for Lugol chromoendoscopy;~* Patients with severe gastroesophageal reflux disease or reflux symptoms which may interfered with the outcome measures of current study;~* Patients with postoperative esophageal stenosis affecting endoscopic observation;~* Patients with serious comorbidities that cannot tolerate un-sedated gastroscopy;~* Patients who could not cooperate with the observation including patients with mental disorders, severe neurosis or dysgnosia;~* Patients undergoing sedation or general anesthesia during endoscopy.~* Patients who do not agree to sign informed consent forms or follow the trial requirement.

- Gender: ALL
- Minimum Age: 18 Years
- Maximum Age: 80 Years
- Healthy Volunteers: t

Study Arms:
- sodium thiosulfate solution arm (Type: ACTIVE_COMPARATOR): 20ml of 5% sodium thiosulfate solution were prepared with 1g sodium thiosulfate crystal dissolved in normal saline in a 20 ml syringe
- N-acetylcysteine solution arm (Type: EXPERIMENTAL): 20ml of 3% N-acetylcysteine solution were prepared with one piece of N-acetylcysteine effervescent tablet （ net weight 0.6g ）dissolved in normal saline in a 20 ml syringe

Based on this trial design, predict the completion outcome and termination type (if applicable).