Medicion De Ultrasonido

Abstract— Ultrasound power measurement system is widely

used in health care institutions especially to measure the power

generated by ultrasound therapeutic machines. The existing

ultrasound power meter, however is high cost, heavy and only for

specific machine. Besides, most of them have limitation of resolution,

are not considering temperature disturbance and no graphical

interface for further analysis. Since piezoelectric polyvinylidene

fluoride (PVDF) has been explored to be a potential candidate for

ultrasound sensor, this work has observed this polymer film behavior

in medical ultrasound power measurement application. Effects of

distance, frequency, voltage and temperature on the received signal

(voltage) were analyzed. In order to enable PVDF sensor for low cost

ultrasound power meter, a robust low-cost casing has been built. The

casing has been designed to enable optimum capturing ultrasound

power from therapeutic and diagnostic ultrasound machine, minimize

interference effect and noise as well as stabilize mechanical

construction of sensor. Test result shows acceptable correlation

between ultrasound intensity and sensor’s generated voltage. For

signal processing unit, a Field-Programmable Gate Array (FPGA)

based ultrasound processing platform has been proposed. This

platform is able to process data from two PVDF sensors and a

temperature sensor with high precision. It was prepared to measure

ultrasound frequency from 500 kHz to 10 MHz with temperature

range from 10 °C to 50 °C and power range from 1 mW/cm

2

up to 10

W/cm

2

(with resolution 0.87 mW/cm

2

). In addition, a graphical user

interface (GUI) has been utilized for further analysis. Test result

shows that the platform is able to process 10 µs ultrasound data with

20 ns time-domain resolution and 0.12 mV magnitude resolutions

then display these waveform and calculation result in the GUI.

Keywords—Ultrasound power, low cost, precision, PVDF,

temperature effect, robust casing, FPGA, GUI.

Manuscript received August 31, 2011. This work was supported in part by

the Ministry of Higher Education (MOHE), Malaysia under Fundamental

Research Grant Scheme (FRGS) vot 78696.

I. Muttakin is with Faculty of Health Science and Biomedical Engineering,

Universiti Teknologi Malaysia (e-mail: [e-mail]).

S.-Y. Yeap was with Faculty of Electrical Engineering, Universiti

Teknologi Malaysia.

M. M. Mansor was with Faculty of Electrical Engineering, Universiti

Teknologi Malaysia.

M. H. M. Fathil was with Faculty of Electrical Engineering, Universiti

Teknologi Malaysia.

I. Ibrahim is with Faculty of Electrical Engineering, Universiti Teknologi

Malaysia.

I. Ariffin is with Faculty of Electrical Engineering, Universiti Teknologi

Malaysia.

C. Omar is with Faculty of Electrical Engineering, Universiti Teknologi

Malaysia.

E. Supriyanto is with Department of Clinical Science and Engineering,

Faculty of Health Science and Biomedical Engineering, Universiti Teknologi

Malaysia, UTM Skudai, 81310 Johor, Malaysia (phone: [phone]; fax:

[phone]; e-mail: [e-mail]).

I. INTRODUCTION

LTRASOUNDis one of the most popular and productive

non-invasive therapeutic and diagnostic modality. The

major frequencies used for the diagnostic and therapeutic

purposes are about 1-10 MHz. Higher frequency of the

ultrasound will give good resolution of image. However, high

frequency and high power ultrasound may cause harmful

impacts to human soft tissues [1].

Ultrasound power meter measures and calibrates output

power and intensity of the ultrasound machine. It is useful to

ensure the ultrasound wave is under safety condition

according to International Electrotechnical Commission (IEC).

Currently, there are several ultrasound power meters in market

but high in cost, big and heavy (less portability). Using

radiation force balance method [2-3] and another method with

single polymer sensor [4], they are also do not concern about

temperature changing at the medium which was used. Most of

them have power resolution between 10 and 100 mW/cm

2

.