Here is the design of a clinical trial:

Official Title: Prevention of Radiotherapy Induced Enteropathy by Probiotics (PREP Trial): a Prospective, Randomized Controlled, Double Blinded, Single Center, Superiority Study

Included conditions:
- Radiotherapy
- Toxicity
- Diarrhea
- Probiotics

Study Armgroups:
- {'label': 'Probiotics', 'type': 'EXPERIMENTAL', 'description': 'Two weeks prior to the start of radiation therapy, the probiotics is administered three times daily until the end of radiation therapy.', 'interventionNames': ['Drug: Bacillus Licheniformis']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Two weeks prior to the start of radiation therapy, the placebo is administered three times daily until the end of radiation therapy.', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'Bacillus Licheniformis', 'description': 'Two weeks prior to the start of radiation therapy, the probiotics is administered three times daily until the end of radiation therapy.', 'armGroupLabels': ['Probiotics'], 'otherNames': ['Biscanen cap.']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'Two weeks prior to the start of radiation therapy, the placebo is administered three times daily until the end of radiation therapy.', 'armGroupLabels': ['Placebo'], 'otherNames': ['Placebo oral tablet']}

Primary Outcomes:
- {'measure': 'Number of participants with grade 2 or more acute intestinal toxicities', 'description': 'Evaluation using CTCAE version 4.0', 'timeFrame': 'Adverse effect evaluated at 3 months after radiation therapy'}

Please estimate the sample size based on the assumption: 
Alpha value of 0.05, beta of 0.2, and a 5% dropout rate.
Sample size and statistical analysis
        Two proportion test in Power Analysis and Sample Size Software 2018 (NCSS, LLC. Kaysville, Utah, USA) was utilized to estimate the sample size. Based on the assumption that 30% of the patients in the placebo group and 15% of the patients in the probiotics group will experience gradeââ¥â2 acute toxicities, 118 patients per group will be required to show a significant effect based on an alpha value of 0.05 and a beta of 0.2. Assuming a 5% dropout rate, 124 patients per group will be required (total, 248 patients).
        Acute toxicities will be analyzed in the intention to treat population, with categorical variables in the two groups compared by the Chi-Square or Fisherâs exact test. To find the other confounding factors for RIE, univariate and multivariate logistic regression for acute toxicity will be performed. The times from the start of radiotherapy to acute gradeââ¥â2 toxicities and to any chronic toxicities will be calculated using the Kaplan-Meier method and compared in the two groups using the log-rank test to compare survival curves between two groups. In the whole population, multivariate analysis, Cox proportional hazard model will be utilized to find the significant factor for the incidence of RIE in addition to the use of probiotics. Factors with pââ¤â0.2 in log-rank test will be entered in multivariate analysis. Descriptive statistics of all analyzed parameters will be provided, whenever appropriate.