Table 2.

Ultrasonic exposure parameters and threshold results. MI is the estimated equivalent on-screen Mechanical Index. The sources include laboratory transducers (LAB), and diagnostic ultrasound probes from the GE Vingmed system (FPA) and from the Toshiba system (PVN) (see text).

	Frequency	Exposure Duration	Position Spacing	Threshold	Threshold	Threshold
Source	MHz	min	mm	MPa	MI	MPa/MHz
LAB 1.0	1.0	1	-	0.67	0.67	0.67
LAB 1.5	1.5	2	2.6	0.95	0.78	0.63
FPA 2.5	1.5	1	-	0.76	0.62	0.51
LAB 2.25	2.3	3	1.8	1.3	0.87	0.58
PVN-375AT	2.5	1	-	1.22	0.76	0.48
FPA 2.5	3.2	1	-	1.71	0.96	0.53
LAB 3.5	3.5	4	1.1	2.34	1.25	0.67
FPA 10	5.0	1	-	-	-	-
LAB 5.0	5.0	6	0.8	2.78	1.24	0.56
FPA 10	7.4	1	-	-	-	-
LAB 7.5	7.5	9	0.5	5.93	2.16	0.79