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Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels
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10.1121/1.4812878
/content/asa/journal/jasa/134/2/10.1121/1.4812878
http://aip.metastore.ingenta.com/content/asa/journal/jasa/134/2/10.1121/1.4812878
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

IR system for visualization of ultrasound fields.

Image of FIG. 2.
FIG. 2.

A diagram of the experimental arrangement used for hydrophone measurements.

Image of FIG. 3.
FIG. 3.

(Color online) Ultrasound radiators used in experiments: (a) Flat physiotherapy transducer ENRAF,  = 1.022 MHz; (b) HIFU transducer ICR,  = 1.07 MHz; (c) HIFU transducer Sonic Concepts H101,  = 1.1 MHz.

Image of FIG. 4.
FIG. 4.

Axial pressure distribution of the flat physiotherapy transducer measured with the hydrophone (1) and calculated for a piston source (2). Dashed vertical lines correspond to the planes of IR measurement  = 10, 25, 30, 50, 70, 81, and 90 mm. Bold gray vertical lines correspond to the planes of hydrophone scanning  = 25 and 81 mm.

Image of FIG. 5.
FIG. 5.

Spatial distributions of intensity in the field of the flat physiotherapy transducer, measured at the plane  = 81 mm (top row) and  = 25 mm (bottom row) with the hydrophone [(a) and (d)] and IR camera [(b) and (e)]. Contour lines are given with increments of 2 W/cm [(a) and (b)] and 1 W/cm [(d) and (e)]. Intensity distributions measured along the axis ( = 0) in the same planes with the hydrophone ( ) and IR camera (—) [(c) and (f)].

Image of FIG. 6.
FIG. 6.

Spatial distributions of intensity in the field of the flat physiotherapy transducer, measured with the IR camera at the planes: (a)  = 10 mm; (b) 30 mm; (c) 50 mm; (d) 70 mm; and (e) 90 mm. The distributions are normalized to the maximum value in each plot. Contour lines are given with the step of 0.2 .

Image of FIG. 7.
FIG. 7.

Axial pressure distribution of the focused ICR transducer measured with the hydrophone (1) and calculated for the focused piston source model (2). Dashed vertical lines correspond to the planes of the IR measurement  = 50, 70, 80, 90, 110, 120, 130 mm. Bold gray vertical lines correspond to the planes of the hydrophone scanning  = 80 and 120 mm.

Image of FIG. 8.
FIG. 8.

Spatial distributions of intensity in the field of the ICR transducer, measured at the focal plane  = 120 mm (top row) and at the distance  = 80 mm (bottom row) with the hydrophone [(a) and (d)] and IR camera [(b) and (e)]. Contour lines are given with the step 10 W/cm [(a) and (b)] and 0.25 W/cm [(d) and (e)]. Intensity distributions measured along the axis ( = 0) in the same planes with the hydrophone ( ) and IR camera (—) [(c) and (f)].

Image of FIG. 9.
FIG. 9.

Spatial distributions of the intensity in the field of the ICR transducer, measured at the planes: (a)  = 50 mm; (b) 70 mm; (c) 90 mm; (d) 110 mm; (e) 130 mm with the IR camera. The distributions are normalized to their maximum value . Contour lines are given with the step of 0.2 .

Image of FIG. 10.
FIG. 10.

Axial pressure distributions for the focused transducer Sonic Concepts H101, measured with the hydrophone (1) and calculated for the uniform piston source model (2). Dashed vertical lines correspond to the planes of IR measurement  = 42, 50, 54, 62, and 82 mm. Bold gray vertical lines correspond to the planes of hydrophone scanning  = 50, 54, and 62 mm.

Image of FIG. 11.
FIG. 11.

Intensity distributions of the Sonic Concepts H101 transducer, measured at the focal plane  = 62 mm (a), at the plane of the first prefocal minimum  = 54 mm (b), and at the plane of the first prefocal maximum  = 50 mm (c), obtained from the hydrophone ( ) and IR camera (—) measurements.

Image of FIG. 12.
FIG. 12.

2D intensity distribution of the Sonic Concepts H101 transducer, measured with the IR camera at the planes: (a)  = 42 mm; (b) 50 mm: focal plane; (c) 54 mm: Plane of the first prefocal minimum; (d) 62 mm: Plane of the first prefocal maximum; and (e) 82 mm. The distributions are normalized to their maximum values in each plot. Contour lines are given with the step of 0.2 .

Image of FIG. 13.
FIG. 13.

Temperature distributions measured for the ICR transducer in planes at intervals of 40 m along the axis of the beam: CW insonation (on the left) and tone burst insonation (on the right).

Image of FIG. 14.
FIG. 14.

Illustration of the systematic reduction in time-average intensity when using tone burst mode of insonation and reducing the burst duration. (a) Pressure amplitude distribution from the hydrophone signal; (b) pressure amplitude squared distribution i.e., relative energy distribution; (c) relative time-average intensity distribution.

Image of FIG. 15.
FIG. 15.

IR signal in binary levels time measured at the focal plane of the ICR transducer [Fig. 8(c) ] on the axis ( = 0, solid curve) and at 0.27 mm (dashed) and −0.27 mm (short dashed) off axis. Analytic solution of Myers (Ref. ) with parameters χ = 1.92·10 m/s (temperature conductivity) and  = 4186 m (wave number) that correspond to our experiment is plotted in gray color. The solution is scaled so that the temperature slope after 0.2 s is approximately the same as in the experiment at  = 0.

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/content/asa/journal/jasa/134/2/10.1121/1.4812878
2013-08-01
2014-04-24
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels
http://aip.metastore.ingenta.com/content/asa/journal/jasa/134/2/10.1121/1.4812878
10.1121/1.4812878
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