diff --git a/monai/data/ultrasound_confidence_map.py b/monai/data/ultrasound_confidence_map.py
index 5c716b62be..8c7c5326a3 100644
--- a/monai/data/ultrasound_confidence_map.py
+++ b/monai/data/ultrasound_confidence_map.py
@@ -285,7 +285,7 @@ def _solve_linear_system(self, lap, rhs):
             lap_sparse = lap.tocsr()
             ml = ruge_stuben_solver(lap_sparse, coarse_solver="pinv")
             m = ml.aspreconditioner(cycle="V")
-            x, _ = cg(lap, rhs, tol=self.cg_tol, maxiter=self.cg_maxiter, M=m)
+            x, _ = cg(lap, rhs, rtol=self.cg_tol, maxiter=self.cg_maxiter, M=m)
         else:
             x = spsolve(lap, rhs)