[A single center experience with a lithotripsy machine "Modulith SLX-F2" : evaluation of dual focus system and clinical results].

We evaluated the usefulness of a new shock-wave lithotripsy machine with a dual focus system (large focus : 9x50 mm, standard focus : 6x28 mm), "Modulith SLX-F2" on 361 patients. In the first period, 210 patients, were treated with the large focus, and in the second period, 151 patients were treated with the standard focus. Complications, efficacy and subsequent auxiliary procedures were compared between the first and second periods. The efficacy was evaluated with efficiency quotient (EQ). Administered total energy was displayed with stortz medical lithotripsy index (SMLI). After treatment, we performed ultrasonography to evaluate renal hematoma in all cases. Average size of renal stones and ureteral stones was 14.25 and 11.0 mm, respectivery, in the first period, and 13.80 and 8.97 mm, respectivery, in the second period. EQ of renal and ureteral stones was 0.565 and 0.626, respectivery, in the first stage, and 0.553 and 0.798, respectivery, in the second period. The total EQ was 0.646. This value was good and particularly the result obtained on ureteral stones in the second period was thought to be excellent compared with other reports. In this series, 6 renal hematomas were confirmed. A statistically significant risk factor was SMLI, but the severity of hematoma was not correlated with SMLI. In hematoma patients, 2 patients had no notable risk factor, but they were thin or were small. Dual focus has a potential to improve ESWL results on ureteral stones. Excessive SMLI may be a risk factor of renal hematoma in thin or small patients.