Focused ultrasound to displace renal calculi: threshold for tissue injury

Table 1 Exposures used for renal parenchyma treatment

Threshold intensity at normal duty cycle		Threshold intensity if on continuously		Sensitivity to duty cycle at maximum prototype intensity
3.3% Duty cycle		100%Duty cycle		I_SPPA.3 = 9,320 W/cm²
I_SPPA.3(W/cm²)	Samples	I_SPPA.3(W/cm²)	Samples	Duty cycle(%)	Samples
0	29	0	13	0	13
930	12	470	3	2	7
2,530	14	930	6	6	5
4,090	10	2,530	7	10	8
6,030	10	4,090	8	25	3
9,320	12	6,030	5	50	5
12,230	11	9,320	4	100	4
16,620	14
21,000	11
26,130	10

Exposures were based on the expected clinical exposure parameters (3.3% duty cycle), maximum duty cycle (100%) of clinical device, and for a range of duty cycles at an intensity with similar peak positive and negative pressures as the clinical device. The samples represent the number of tissue samples evaluated for injury at each condition.

ISSN: 2050-5736