Microwave Imaging - University of...

University of ManitobaDepartment of Electrical & Computer Engineering

ECE 4600 Group Design Project

Progress Report

Microwave Imaging

byGroup 12

Steven Brown Bryce O’DonnelTrevor Ingelbeen Steve Demedash

Brett Trombo Devon Hudson

Academic Supervisor(s)

Dr. Joe LoVetri

Industry Supervisors

Ian Jeffrey – 151 Industries

Colin Gilmore – 151 Industries

Paul Card – 151 Industries

Date of Submission

January 12, 2015Copyright © 2015 Steven Brown, Bryce O’Donnel, Trevor Ingelbeen, Steve Demedash,

Brett Trombo, Devon Hudson

Microwave Imaging Methods for Breast Cancer Research TABLE OF CONTENTS

Table of Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Project Progress and Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.1 Field Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.2 Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Appendix A Updated Gantt Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Appendix B Updated Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Appendix C System Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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Microwave Imaging Methods for Breast Cancer Research 1 Introduction

1 Introduction

The Electromagnetic Imaging Lab (EIL) at the University of Manitoba is researching breast imaging

systems for the purpose of non-invasive breast cancer detection. The imaging systems researched

in the EIL use microwave imaging (MWI) technology to detect breast cancer as an alternative to

MRI and mammogram technology.

The first MWI system contains a field coil capable of producing 0.2 Tesla magnetic field and

Group 12 is designing the hardware for this project. The material costs of this project have driven

a scope change therefore this project is no longer progressing according to the original plan.

The second MWI system requires a dual polarized antenna array to produce a 3D image

of the healthy and cancerous tissue within a patient’s breast. During the design phase of the

dual polarized antenna, Group 12 encountered significant project scope change and is no longer

progressing according to the original plan.

Lastly, the EIL requires control and monitoring software for its devices. Group 12 is developing

new software for the devices mentioned above as well as improving existing software within the EIL.

The software project is progressing as originally planned.

2 Project Progress and Future Work

The progress for group 12 from the past four months and planned future work is described below

for each of the three project components, with our new tasks outlined in Appendix A. To view a

system block diagram refer to Appendix C.

2.1 Field Coil

In the past four months, Group 12 has divided the magnetic field coil design into three sections:

field coil, cooling system and power supply. Bryce and Trevor simulated the magnetic field with

Matlab to design the coil size and electric current required to produce the magnetic field. The

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Microwave Imaging Methods for Breast Cancer Research 2 Project Progress and Future Work

simulation determined that a magnetic field of 0.2T could be achieved by feeding 500 Amps of DC

current though a field coil. Bryce, Joe LoVetri and Dan Card determined that from an economic

standpoint, using copper refrigeration tubing was the best material for the copper conductor and

cooling system. Refrigeration copper is malleable, readily available, and can be manually coiled

without outsourcing to a manufacturer. The cost of the copper conductor required for this project

created a scope change for project. Group 12 and its supervisor removed the manufacturing of the

entire field coil from the project scope. Instead Group 12 will now produce a 1/16th scaled proof

of concept test and if time and money permits, the remainder 15/16th of the project will be built.

The cooling system design was completed in parallel with the field coil design by Bryce and

Trevor. Originally the cooling system was proposed to be completed after the coil design but due

to the high importance of the cooling system it was incorporated into the field coil design. The

high amperage required to produce the specified magnetic field will generate a large amount of

heat. The heat will affect the resistivity of the coil and potentially damage the coils insulation.

The cooling system maintains a safe operating temperature by circulating a coolant through the

hollow interior of the field coil conductor.

The power supply will provide the field coil with 500A which will produce the magnetic field.

Trevor designed the power source using lithium batteries because Group 12 had access to these

batteries. Trevor and Bryce designed the power source to have a freewheeling diode to allow a

gradual current decay across the inductive coil when the device is turned off. A properly rated

controllable switch was also used in the power supply so that the GUI control software can turn

the source on or off.

In the next two months, Trevor and Bryce will assemble the individual components required to

build and test the entire field coil, power supply and cooling system. A complete list of parts and

their expected delivery date is located in the budget section of Appendix B. The first component

that Trevor and Bryce will assemble is the power supply. Jumper cables, capable of withstanding

500A DC are required to connect the field coil, freewheeling diode and switch to the batteries.

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Custom jumper cables will be built by Trevor and Bryce because they are less expensive than pur-

chasing them from a supplier. Next, the batteries, freewheeling diode and switch will be installed,

completing the assembly of the power supply. Prior to installing the switch, the interface between

the GUI and switch will be assembled and tested by Trevor, Devon and Bryce. The GUI will control

the on/off status of the magnetic field. During the assembly of the power supply, quality control

measures will be implemented to determine the circuit properties and verify the functionality of

the control switch.

The next component that Trevor and Bryce will build is the interface between the power supply

and field coil. The preferred method to electrically connect the field coil and power supply will

require a soldered connection arm between the field coil and the cables from the power supply.

If the soldered connection arm fails, a ground clamp will be used to connect the field coil to the

power supply cable cables. Next, the cooling system will be assembled by Trevor and Bryce. The

plumbing from the pump outlet to field coil will be assembled and tested to verify the flow rate of

the cooling system.

Finally, Trevor and Bryce will assemble the entire field coil system which consists of the field

coil, power supply, and cooling system as shown in our updated Gantt Chart in Appendix A. All

electrical connections will be terminated and the entire system will be tested to verify that the

system is operating as intended. If required, troubleshooting will occur at this point.

2.2 Antennas

The antenna portion of the project can be separated into three areas, the cavity resonator, the

printed circuit board (PCB), and the control system. Thus far Group 12 has researched and

preformed various simulations of time electric (TE10) mode resonating cavities. From these sim-

ulations, Brett and Steven Brown were able to create the polarization of an antenna in both

orientations. The number of slots are not increasing in the antenna cavity as proposed due to

the orthogonal orientation of the cavities. Brett and Steven Brown explored higher order modes

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of waveguides, which does increase the physical size and complexity of the feed arrangement. Al-

though more challenging, we have determined that a waveguide using higher order modes is better

as it allowed both polarizations of antenna slots to be on one resonating waveguide cavity.

Brett and Steven Brown have designed multiple resonating waveguide cavities using high fre-

quency simulation software (HFSS). The HFSS simulations show a simulated TE11 resonating

cavity with the reflection coefficient or return loss. The1 HFSS simulations have calculated the

gain loss coefficient to -11.31dB, which exceeds our project specifications. Brett and Steven Brown

are currently optimizing the antenna design by adjusting the input feed position and slot length

with a method called optometrics. This is a process in which the model is simulated in the HFSS

CAD Tool and the position of various variables are adjusted. The position and length of the coax-

ial feed that satisfies the most requirements are saved for the user. Brett and Steven Brown have

decided to minimize the return loss of the resonating cavity to ensure that the maximum radiation

would propagate from the resonating cavity as well as, maximize the surface current density on the

PCB ground plane.

Brett and Steven Brown are actively working on slot schemes (positioning of slots in the PCB)

that cut the surface current density to maximize the radiation in the desired polarization. By

selecting to cut the slots on one resonating cavity as opposed to making two, saves space in the

antenna chamber because the resonating cavities with one polarization take up horizontal and ver-

tical space. The TE11 resonating cavity occupies mainly one orientation which we can select. A

singular resonating cavity also enables us to modify the existing slot selection system by simply

running through all combinations of receiver and transmitter in one orientation followed by the

other orientation. For the remainder of the course, Group 12 will concentrate on three antenna

system components: the cavity resonator, PCB, and control system. The TE11 mode resonating

cavity must adapt the design to the specific application. Manufacturing, mounting, and mechanical

limitations must now be balanced with the best theoretical design. After final mechanical dimen-

sions are selected the appropriate slot schemes will be selected and simulated to verify the new

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dimensions. The best slot scheme from the simulations will be used for manufacturing.

There three major system components that still have to be manufactured as seen on the updated

Gantt Chart in Appendix A. After the resonating cavity design is finalized, the PCB design can

be sized to meet physical constraints of the antenna chamber. Once the PCB size is determined

it will be manufactured by an external vendor. The cavity resonator is purchased at the required

dimensions and the one side is removed then replaced with the PCB at the University of Manitoba.

The existing control system in the EIL is retrofitted to work with the new design.

Next testing will be conducted on the input impedance, radiated power, and slot control of

the antenna. Input impedance will be measured using a network analyzer and verified with the

expected design results. If time permits the antenna will be tested in an antenna lab to determine

radiation pattern and radiated power. The fall-back method will be to test the antennas in the

prototype application system and results measured by the control system. Integration with the

software control system will be the last testing procedure after the main components have been

tested individually.

2.3 Software

In the past four months, Group 12 has worked on the integration of the existing data acquisition and

control software currently used by the EIL into a single software package. Individual VNA and LIA

devices within the EIL are controlled by multiple versions of the control software. By consolidating

these versions, a single version will exist that is capable of running a variety of different devices,

allowing the user to select which device is to be used.

To begin, Devon and Steve Demedash modified the existing versions of the separate software

by removing extraneous comments and lines of code from the existing code. Devon and Steve

Demedash removed large blocks of code that constituted individual sub-processes from the main

loop, and created separate functions which increased the modularity and readability of the software.

When consolidating multiple versions of the algorithm Devon and Steve Demedash maintained

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functionality without reducing algorithm speed. However, consolidating the software versions added

more decision-making steps to the main process, introducing significant lag. To maintain algorithm

speed, and further reduce the code size, Devon and Steve Demedash designed a Finite State Machine

for quick branching when device specific portions of code were encountered.

In the next two months, Devon and Steve Demedash will follow the tasks outlined in the Gantt

Chart located in Appendix A. They will test the software to ensure it is operating as intended.

There are multiple hardware setups to be tested, this testing phase may be quick and present

positive results from the outset. Alternatively it could last much longer than anticipated, and may

take until the end of the semester to complete.

After the testing phase, they will either need to reevaluate the completed software updates, or

proceed with graphical user interface updates, and algorithm optimization. We introduced these

as an optional task, to be completed if time permits.

To update the graphical user interface, Devon and Steve Demedash will propose a new layout

that does not take away any functionality that already exists. The majority of the user interface

involves the selection of devices through which the user may configure the system for the devices

used, and type of scan to be done. This layout is cumbersome, so moving the device selection panel

over to a temporary tab or window would create a cleaner, more straight-forward interface. The

method by which the antennas are selected also needs to be re-examined. Currently, this portion

of the interface is small, and as such, it is difficult to select the desired antenna positioning.

Optimizing the imaging algorithm involves two things. First, the time it takes to measure

the data between antennas is the longest running time of the program, so they have the most to

gain by focusing our attention on this area of the code. Secondly, the software currently sends out

data to an excel file that is then loaded into Matlab where graphs and plots are generated. This

transfer over to Matlab takes time and it would be nice to have this in the same program that

performs the measurements. To do this Devon and Steve Demedash will need to get familiar with

the preexisting Matlab code and create graphical elements in the imaging software that allow the

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Microwave Imaging Methods for Breast Cancer Research 3 Conclusions

program to display the relevant graphs after taking the measurements has been completed.

3 Conclusions

Overall Group 12 has made significant progress in all areas of the project. Numerous setbacks in

specific project areas has led to a change in scope for both the field coil and antenna portion of the

project. Due to the sensitive nature of electromagnet devices more time was allotted to the design

stages of the product to ensure of functionality of the final product. The field coil section will

complete 1/16th of the original scope of the project due to expensive manufacturing and material

cost. The antenna portion is now designing a TE11 resonating cavity to meet all of the project

specification, while software is completing proposed tasks on schedule. With these new changes we

intend on completing tasks as assigned in our revised project schedule found on our updated Gantt

chart.

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Microwave Imaging Methods for Breast Cancer Research

Appendix A

Updated Gantt Chart

Fig. A.1: Revised Gantt Chart for Microwave Imaging Project (1 of 2)

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Fig. A.2: Revised Gantt Chart for Microwave Imaging Project (2 of 2)

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Appendix B

Updated Budget

The budget for the our Microwave imaging project is $1346.48 and is covered but the Dept. of

Electrical and Computer Engineering with the remainder of the fund provided EIL.

Fig. B.1: Up to Date Budget of the Project

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Appendix C

System Diagram

Fig. C.1: System Overview

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