High-Intensity Focused Ultrasound Therapy Array

May1005

Alex ApelStephen RashidJustin Robinson

Need and Problem StatementNeed

A research tool to provide data on phase error correction in high-intensity ultrasound arrays

ProblemTo provide a PC based interface for a user to

control the phase and duration of a four channel array of ultrasound transducers

Existing solutions

System Architecture

PCSoftware

Microcontroller Circuit

Serial

Control Logic

Analog Hardware

Control Logic

Analog Hardware

Control Logic

Analog Hardware

Control Logic

Analog Hardware

Users and Operating EnvironmentResearchers

Advancement of ultrasound therapy technology

To be used in a laboratory with a controlled environment

User InterfaceInputs

Phase control per channelPulse lengthStart and Stop

Available OutputRelative phase from feedback loop

RequirementsPhase Control

Set phase of each channel360º of control

Duty Cycle Control20 ms cycle timeVariable between 0.01% and 1%

ScalabilityPotential to expand system

DeliverablesComputer Software

A CD installer. Needs Microsoft .NET Framework (Win2000 SP4 or newer).

Application provides UI with Microcontroller BoardDriver Board

Driver board controls multiple transducer control circuits.Driver board is manipulated via a RS232 connection to the user

PC.Transducer Card

(4x) Controls the Analog Power Circuits. Allows for concurrent processes.

Analog Power Circuits (4x) Amplify the waveform and provide power to Transducer.

End User GuideReference on how each element of the system works. Guide to

using the software.

Work BreakdownDesign and Documentation Process

Group influence and final decision makingDiversity of knowledge allows for specialties in decision

makingComputer Software

Primary focus area of Justin RobinsonDigital Circuit and Microcontroller Software

Primary focus of Alex ApelAnalog Power Circuits

Primary Focus of Stephan RashidEnd User Guide

Sum of group knowledge of the device and its functionalityGroup Contribution

Task Hours Cost

Problem Definition 84 $1680

Technology/Implementation Considerations/Selection 79 $1580

System Design 77 $1540

System Implementation 104 $2080

System Tesing 82 $1640

System Documentation 55 $1100

System Demonstration 12 $240

Project Reporting 185 $3700

Totals 678 $13,560

Item Cost

Microcontroller Dev Board $159

H Bridge Amplifier $100 - $660

Supporting Discrete Parts $100

Total $359 - $919

RisksLoss of Team Member

Reduce knowledge baseLose time commitmentMitigated by effective communication and system scope

scalabilityLoss of Transducer

Needed to display resultsIrreplaceable, costEmulation circuit for testing

Lack of Expertise Risk posed by time restrictionsMay lead to poor decision makingEffective use of external resources and knowledge bases

System RequirementsPower

500W per Channel0.01% to 0.1%, Max 1% Duty Cycle20 ms Cycle Period

ScalabilityFuture system may control 500 elements

Operating FrequencyMaximum amplitude at 1.1 MHz Wish of 3.3 MHz

Phase Control360º of phase correction 8 bit resolution = 1.4º Allows for a 1.2 nm3 focal point

Functional DecompositionInput

Relative Phase ControlSignal PeriodSignal Duty Cycle

GenerationPower: 500WFeedback Generation

ProcessingFrequency 1.1 – 3.3

MHzAdjustable Duty Cycle20 ms Cycle PeriodPhase CorrectionWaveform Generation

PCSoftware

Microcontroller Circuit

Serial

Control Logic

Analog Hardware

Control Logic

Analog Hardware

Control Logic

Analog Hardware

Control Logic

Analog Hardware

GUI

Input•Relative Transducer Phase•Transducer Amplitude•Signal Period•Signal Duty Cycle•Start/Stop GenerationOutput•Phase

Micro

Transducer

Output•Mechanical Wave

RS-232

Transducer

Output•Mechanical Wave

TransducerControl Logic

TransducerAnalog Hardware

Phas

e Co

rrec

tion

User PC SoftwareGUI

Transducer Input [1..n]•ID•Relative Phase•Amplitude

Global Input•Signal Period•Signal Duty Cycle•Start/Stop Generation

Misc.•Save Input Data•Load Input Data

Transducer•ID : int•Relative Phase : int•Amplitude : int

•AdjPhase() : int•AdjAmplitude() : int

File Storage

Comm.Out

InSerial

Lab PC

Microcontroller CircuitSerial Interface to PCMicrocontrollerStorage and Correction

of Waveforms

System of addressing multiple transducers

Assertion and Control of global time frame

Transducer Control CircuitFeedback Collection Waveform AssertionConcurrent Access

Analog Hardware Design

H Bridge Controller

H Bridg

e

Power Supply

Transducer

Hi/Lo

On/Off

To Digital Phase Correction

Test PlanUnit Tests

Comm. Test

Integration Tests

Comm. Test

System TestComm. Test

PC PCRS-232

PC MicroRS-232

PC MicroRS-232 Hydro

phone

Transducer

Simulation & ModelingIdentifying Needs of Generated Waveform

Transducers Operate at Odd HarmonicsFourier Analysis of Proposed Waveforms

P-Spice Modeling of CircuitryH-Bridge Amplifier BehaviorFrequency Characteristics

AcknowledgmentsDr. Timothy Bigelow

Dr. Randy Geiger

Texas Instruments