Bubble Dynamics with the Progress of Histotripsy

Bubble Dynamics with the Progress of Histotripsy

Yufeng Zhou and Xiaobin Wilson Gao

School of Mechanical & Aerospace Engineering

Nanyang Technological University

IntroductionUltrasound therapy is an emerging

modality in clinics;High-intensity low-duration ultrasound

pulse can be implemented in drug delivery, thrombolysis, etc.

Histotripsy can be used to erode soft tissue noninvasively;

Bubble dynamics plays an important role in such application.

Experiment Setup

Lesion GrowthN = 1 N = 2 N = 5 N = 10

N = 50 N = 100

3.3 MHz, 30 ms burst, 1 Hz pulse repetition rate, 150 W

N = 20 N = 70

Passive Cavitation Detection

Number of pulses0 10 20 30 40 50 60 70 80 90 100

Peak

-to-

peak

PC

D si

gnal

(V

)

0.0

0.1

0.1

0.2

0.2

0.3

0.3

PCD

Lig

ht T

rans

mis

sion

(V

)

0.3

0.4

0.4

0.4

0.5

0.5

0.6

Light transmission

0 2 4 6 8 10 12 14 16 18 200

0.02

0.04

0.06

0.08

0.1

0.12

Time (ms)

PC

D (

V)

0 2 4 6 8 10 12 14 16 18 200

0.02

0.04

0.06

0.08

0.1

0.12

Time (ms)

PC

D (

V)

1st pulse

100th pulse

3.3 MHz, 30 ms burst, 1 Hz pulse repetition rate, 150 W output

Number of pulses0 10 20 30 40 50 60 70 80 90 100

Peak

-to-

Peak

PC

D si

gnal

(V

)

0.00

0.05

0.10

0.15

0.20

0.25

0.3010ms 20ms 30ms

Effect of Pulse Duration

3.3 MHz, 1 Hz pulse repetition rate, 150 W

Lesion Growth

1.1 MHz, 100 ms burst, 1 Hz pulse repetition rate, 150 W

N = 1 N = 2 N = 5 N = 10

N = 20 N = 50 N = 70 N = 100

Effect of Frequency

Number of pulses0 10 20 30 40 50 60 70 80 90 100

Peak

-to-

peak

PC

D si

gnal

(V

)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

60 ms 80 ms 100 ms 120 ms

1.1 MHz, 1 Hz pulse repetition rate, 150 W

Ex Vivo Results

3.3 MHz, 1 Hz pulse repetition rate, 150 W

Ex Vivo PCD

Number of pulses0 10 20 30 40 50 60 70 80 90 100

Peak

-to-

peak

PC

D si

gnal

(V

)

0.0

0.1

0.2

0.3

0.4

20ms 30ms

3.3 MHz, 1 Hz pulse repetition rate, 150 W output

B-Mode Sonography

3.3 MHz, 30 ms burst, 1 Hz pulse repetition rate, 150 W output

N = 1 N = 5

N = 50 N = 100

ConclusionsCharacteristics of bubble dynamics vary

with the progress of the ultrasound therapy;

Ultrasound parameters (i.e., burst duration, frequency, target type) have great influence on the bubble dynamics, thermal effects, and consequent lesion formation;

Appropriate combination of mechanical and thermal effect would broaden the application;

Monitoring bubble dynamics could control the ultrasound therapy effectively and efficiently.