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Integrated Fluorescent Probe & Radiofrequency Ablator

Rachel Riti & Alex Walsh

Advisors: Bart Masters & Anita Mahadevan-Jansen

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Outline

• Background – RFA, Fluorescence• Motivation• Objective• Performance Criteria• Proposed Designs• Future Work

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Radiofrequency Ablation

• Ablation of tissue using high frequency radio waves

• Applied in lung, kidney, breast, bone and liver tumors

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Fluorescence

• Emission of light by a substance that has absorbed light of a different wavelength

• Property of biological tissue– Collagen, NADH, Elastin

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Motivation

• Determination of ablated area• Current Method

– Thermocouples• Alternative Methods

– Tissue Markers, Thermal Camera• Proposed Method

– Fluorescence

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Temperature Dependence of Fluorescence

400 500 600 7000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Enucleated Eye

Wavelength (nm)

Nor

mal

ized

Inte

nsity

400 500 600 7000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Rat Skin

Wavelength (nm)

Nor

mal

ized

Inte

nsity

400 500 600 7000

0.2

0.4

0.6

0.8

1

Excised Cornea

Wavelength (nm)N

orm

aliz

ed In

tens

ity

-10°C0°C

0°C

20°C

0°C 22°C

20°C

50°C

50°C50°C

60°C65°C

85°C

-10°C

Walsh A, Masters DB, Jansen ED, Welch AJ, Mahadevan-Jansen A, The Effect of Temperature on Fluorescence: An Animal Study, Lasers in Surgery and Medicine. Publishing Pending

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Objective

• Design a probe capable of both fluorescence and measurements of RFA

• Build the designed probe• Test the probe

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Performance Criteria

• Maintain RFA efficiency• Determine region of ablation• Accuracy

– Within 10% of originalfluorescence intensity– Determine margins ofablation within 5%

Brainstorming Ideas

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Prototype 1

RFA Probe

Laser

Fiber optic

15 cm

19 cm

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Validation

• RFA functionality not compromised• Fiber functional during RFA• Probe entry not affected• Observable significant difference between

ablated and normal tissue• Measurement of ablation area

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Prototype 2

Fiber enclosed

15 cm

2-5 cm

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Validation

• RFA functionality not compromised• Fiber functional during RFA• Probe entry not affected• Adjustable fiber length during procedure• Fluorescence measurements accurately

indicate ablation area

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Timeline

Timeline Process Description

November Research

Attempt to answer the following questions:

What is an RFA?

How is temperature measured during RF ablation?

How can fluorescence be used to measure temperature?

DecemberDevelop Preliminary

Design

Determine the best way to build a combined RFA and fiber optic so that both instruments are fully functional when integrated.

JanuaryReevaluate Design Review the previous design with supervision of mentors and make necessary changes.

Build Fiber Follow the necessary steps to create multiple fibers for collection.

February

Integrate RF Ablator and

FiberBuild the fibers into the prongs of the RFA.

Test Test the functionality of the RFA and the fibers as an integrated unit using bovine livers.

March

Design Critique Determine the functionality of the integrated unit and possible areas of redesign.

Possible Further Research

Expand research to include mechanical aspects of RFAs and fiber optics, as well as safer design techniques.

Begin Redesign Begin constructing a revised design for the probe.

AprilComplete

Redesign Complete revised design with supervision of mentors and make necessary changes.

Test Test the functionality of the redesigned probe on bovine livers.