Here is the design of a clinical trial:

Official Title: A Prospective, Multicenter, Randomized, Controlled Clinical Trial to Validate the Safety and Efficacy of Microwave Versus Laser Ablation of the Great Saphenous Vein in Patients With Varicose Veins

Included conditions:
- Varicose Veins of Lower Limb

Study Armgroups:
- {'label': 'treatment group', 'type': 'EXPERIMENTAL', 'description': 'Microwave Ablation Therapeutic Apparatus. Patients with primary lower extremity varicose veins were treated with endovenous microwave therapy using Microwave Ablation Therapy Apparatus. Ultrasound examination and questionnaire survey（AVVQ and VCSS) were performed at 1 week, 3 months, 6 months,12 months after treatment,drug use and adverse events were recorded to assess complications and target lesion closure rate.', 'interventionNames': ['Device: Microwave Ablation Therapeutic Apparatus']}
- {'label': 'control group', 'type': 'EXPERIMENTAL', 'description': 'Semiconductor Laser Treatment Apparatus. Patients with primary lower extremity varicose veins were treated with endovenous laser treatment using Semiconductor Laser Treatment Apparatus. Ultrasound examination and questionnaire survey（AVVQ and VCSS) were performed at 1 week, 3 months, 6 months, 12 months after treatment,drug use and adverse events were recorded to assess complications and target lesion closure rate.', 'interventionNames': ['Device: Microwave Ablation Therapeutic Apparatus']}

Interventions:
- {'type': 'DEVICE', 'name': 'Microwave Ablation Therapeutic Apparatus', 'description': 'The selected and qualified subjects with primary lower extremity varicose veins were randomly treated with microwave ablation equipment or laser treatment equipment. Subjects in the two groups were returned to the hospital for follow-up at 7 days, 3 months, 6 months, 12 months after surgery, respectively, for ultrasound examination and questionnaire evaluation, medication status and adverse events were recorded, and target lesion closure rate and subject satisfaction were evaluated.', 'armGroupLabels': ['control group', 'treatment group'], 'otherNames': ['Semiconductor Laser Treatment Apparatus']}

Primary Outcomes:
- {'measure': 'the complete closure rate of great saphenous vein at 6 months after surgery', 'description': 'Complete closure: Doppler ultrasonography showed that the target vein segment of the entire treatment is closed, with no discontinuous unclosed segment more than 5 cm.\n\nCalculation method: Complete closure rate = number of subjects with complete closure of target vein in the group/total number of subjects in the same group × 100%.\n\nThe B-ultrasound check is performed on subjects 6 months after the surgery for whether the target vein is completely closed, the result is recorded. After the trial is completed, the number of subjects whose target vein is completely closed is counted, and the complete closure rate of great saphenous vein is calculated.', 'timeFrame': '6 months after surgery'}

Please estimate the sample size based on the assumption: 
The significance level (α) is 0.025, the power is 80%, and the maximum dropout rate is 20%.
Sample size calculation
        The sample size will be calculated based on the occlusion rate of GSV at 6 months after the treatment. According to the data reported in relevant literature, the effective rate ranges from 92% to 98%.15 16 After comprehensive consideration, the effective rate in this trial is preset as 95%. The non-inferiority cut-off value recognised by clinical experts is â10%. The Î± is 0.025, and the power is taken as 80%. The calculation formula for the sample size of the qualitative index non-inferiority design in the Guidelines for Clinical Trial Design of Medical Devices17 is adopted:
        

nT=nC=(Z1-Î±/2+Z1-Î²)2[(PC1-PC+PT1-PT](D-â)2


        PT and PC are the expected occlusion rates of GSV in the EMA group and the EVLA group, respectively, and Î refers to the non-inferiority test cut-off value (negative here). Based on this calculation formula, 75 patients are needed in each group. Considering a possible maximum dropout rate of 20% in each group during the trial, the planned number of patients in each group is increased to 90. As a result, the total number of patients enrolled in the two groups is 180.