BACKGROUND: COMPUTED TOMOGRAPHY (CT) BASED LUNG CANCER SCREENING INCREASES THE NUMBER OF LUNG NODULES REQUIRING DIAGNOSIS AND TREATMENT. BRONCHOSCOPIC PERIPHERAL LUNG BIOPSY HAS EMERGED AS A FIRST LINE, SAFE, MINIMALLY INVASIVE DIAGNOSTIC AND STAGING MODALITY, BUT CURRENTLY LACKS SAFE ABLATIVE CATHETERS. SURGERY AND STEREOTACTIC BODY RADIOTHERAPY (SBRT) ARE MOST WIDELY USED CURATIVE THERAPIES FOR PATIENTS WITH EARLY STAGE LUNG CANCER. BOTH APPROACHES HAVE LIMITATIONS IN RISK PROFILES, LOCAL RECURRENCE RATES, AND COST. PERCUTANEOUS AND BRONCHOSCOPIC RADIOFREQUENCY (RF) AND MICROWAVE (MW) ABLATION TECHNOLOGIES EXIST AND OFFER OUTCOMES RIVALLING SBRT TREATMENTS HOWEVER, ARE ALSO ASSOCIATED WITH SIGNIFICANT COMPLICATION RATES. EXTERNAL HIGH INTENSITY FOCUSED ULTRASOUND (HIFU) IS CAPABLE OF FOCUSING AND DIRECTING HIGH ACOUSTIC POWER ULTRASOUND (US) WAVES, RESULTING IN THERMAL TISSUE ABLATION WITH MINIMAL DAMAGE TO SURROUNDING STRUCTURES, MAKING US SAFER THAN THE AFOREMENTIONED MODALITIES. AS US WAVES DO NOT PROPAGATE THROUGH AIR, SURFACE HIFU IN LUNG TUMORS IS EXTREMELY LIMITED. A MINIATURIZED US TRANSDUCER DIRECTED INTO THE TUMOR TARGET FROM AN INTERNAL APPROACH VIA MINIMALLY INVASIVE BRONCHOSCOPY WOULD MITIGATE THESE ISSUES. WE HAVE SUCCESSFULLY MODELED, DESIGNED, AND BUILT A MINIATURIZED MULTIDIRECTIONAL HIFU TRANSDUCER CAPABLE OF DELIVERING HIGH ACOUSTIC INTENSITY. LCRP AREA OF EMPHASIS: IDENTIFY INNOVATIVE STRATEGIES FOR THE TREATMENT OF LUNG CANCER. OBJECTIVE/HYPOTHESIS: WE PROPOSE TO OPTIMIZE A PROTOTYPE MINIATURIZED MULTIDIRECTIONAL ULTRASOUND