Here is the design of a clinical trial:

Official Title: Improving the Efficacy of Exposure Therapy Using Projection-Based Augmented Reality for the Treatment of Cockroach Phobia: A Randomized Clinical Trial

Included conditions:
- Specific Phobia, Animal

Study Armgroups:
- {'label': 'Treatment with Multiple Stimuli', 'type': 'EXPERIMENTAL', 'description': 'Projection-based augmented reality therapy (P-ARET) with Multiple Stimuli (MS) (P-ARET MS). Intervention group that receives P-ARET treatment varying the stimuli available in the system (different cockroaches in colour, size, etc).', 'interventionNames': ['Behavioral: Projection-based augmented reality therapy (P-ARET)']}
- {'label': 'Treatment with Single Stimuli', 'type': 'EXPERIMENTAL', 'description': 'Projection-based augmented reality therapy (P-ARET) with Single Stimuli (SS) (P-ARET SS). Intervention group that receives P-ARET treatment using a single stimulus (one cockroach).', 'interventionNames': ['Behavioral: Projection-based augmented reality therapy (P-ARET)']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Projection-based augmented reality therapy (P-ARET)', 'description': 'The intervention will be based on exposure therapy to cockroaches using P-ARET. The treatment will follow the guidelines of the "one-session treatment" (OST). Main components: Psychoeducation, Exposure to the feared object (cockroach), modeling (the therapist will interact with the phobic stimulus first and if possible, the patient will follow the same steps), cognitive challenge, and reinforcement and relapse prevention.', 'armGroupLabels': ['Treatment with Multiple Stimuli', 'Treatment with Single Stimuli']}

Primary Outcomes:
- {'measure': "Change in Behavioral Avoidance Test (BAT; adapted from Öst, Salkovskis, & Hellström's, 1991).", 'description': 'Patients will be confronted to a real cockroach and they will be encouraged to get closer and interact with the stimulus as much as they can. The anxiety level (0-10), distance and level of interaction with the animal will be registered and evaluated in a scale ranging from 0 (the participant does not enter the room) to 12 (the participant interacts with the cockroach).', 'timeFrame': 'Baseline ( At the beginning of the intervention) and immediately after the intervention, and at 1, 6 and 12 months after the end of the treatment.'}

Please estimate the sample size based on the assumption: 
Power of 0.80, alpha set at 0.05, and an additional 20% for expected follow-up attrition
Sample size calculations
          Power calculations were carried out using the statistical software Epidat V.4.2. to estimate the necessary sample size to detect a moderate between-group standardised mean difference (Cohenâs d=0.70) with a power of 0.80 and an alpha set at 0.05, based on a similar study comparing MS and SS exposure.24 This size calculation is based on the main result, which is the âperformanceâ variable of the behavioural avoidance test (BAT) with a real cockroach.
          The minimum sample size for each group was identified as 33 (66 in all), but at least an additional 20% will be recruited to allow for expected follow-up attrition, with an estimated minimum total sample of 80 participants (40 per group).17