Ultrasound Imaging Capability for - PowerPoint Presentation

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Slide1

Ultrasound Imaging Capability for Otologic Surgical Drills

Julianna IanniMeher JuttukondaDavid MorrisAdvisor: Dr. Jadrien Young, M.D.Slide2

What is Otologic Surgery?

Surgery of the earMastoidectomyMastoidair-filled spaces behind the earUsesto remove cells from the mastoidto treat anti-biotic resistant infections in the regionto insert a cochlear implant30,000 to 60,000 performed annually in the U.S. [1]Slide3

Anatomy of the EarSlide4

Mastoidectomy ClipSlide5

ObjectivesTo find and attach an ultrasound transducer to an

otologic surgical drill. To calculate the thickness of the mastoid bone using USTo shut off the drill when the mastoid bone has been drilled or provide the surgeon with enough information to stop at the correct distance. Slide6

Why Ultrasound?

CategoryCT - MethodUltrasoundSafetyIonizing RadiationNo Ionizing Radiation

Real-time Data

Time

Drilling

Platform

Not necessary

Invasiveness

Invasive

Non-invasiveSlide7

Past Work

Studied ultrasound equipment in order to determine the most effective way to produce accurate imagesResearched the best transducer frequency for imaging that region of the skullDeveloped the websiteObserved use of otologic drills & identify design constraintsIdentified potential design obstaclesGenerated design ideas concerning mechanism of attachment

Restructured design goals focusing more on finding an ultrasound transducer compatible with an

otologic

drill.

Performed some proof of concept tests for ultrasound depth measurements through bone. Slide8

Solidworks Prototype

Side ViewTop ViewBottom ViewSlide9

The PrototypeThe ultrasound transducer is placed so that it allows for the surgeon to quickly move the transducer into place to perform quick ultrasound scans.

When not in use the transducer can be moved back out of the way and will allow the surgeon to quickly return to work. This set up allows for the surgeon to work quickly and prevents them from wasting a lot of time during surgery while also adding a safer means of cutting through the bones. Slide10

Model of MastoidBone -> Acrylic

Speed of Sound = 2750 m/s [4]Soft Tissue -> GelSpeed of Sound ~ 1540 m/sSlide11

Analysis of SimulationSlide12

Results of simulation(gradient plots matched well w/ built-in edge detection)

Worked really well with 1 layer of acrylic:Actual thickness= 2.03mmMeasured thickness= 2.23mm w/o tissue & 2.35mm w/tissueFor 4MHz: 2.13mm & 2.23mm respectivelyWant accuracy w/in 1mm Slide13

Multiple layers of acrylic?Harder to read

Multiple peaks (including ones at the correct thickness)Not as distinct from noiseAble to discern correct peaks knowing thickness, but can’t back them out just from dataMost likely due to small air-pockets between layers of acrylic caused more echoes & attenuation @ ea. intersectionSlide14

Multiple layers

Depth(cm)y-gradient amplitude

Example with 2 layers of acrylic

(total thickness= 4.06mm)

w/tissue layer

8.89MHzSlide15

Statistics

No.Layers

f (MHz)

Tissue

Thickness(cm)

Thickness(cm)

error(mm)

error(mm)

% Error

% Error

Layer 1

Layer 2

Layer 1

Layer 2

Layer 1

Layer 2

1

1

8.89

N

0.2275

0.243

11.96

2

1

8.89

Y

0.2398

0.366

18.01

3

1

4

N

0.2164

0.132

6.50

4

1

4

Y

0.2272

0.24

11.81

5

2

8.89

N

0.2023

0.4298

-0.009

0.234

-0.44

5.76

6

2

8.89

Y

0.2398

0.4543

0.366

0.479

18.01

11.79

7

2

4

N

0.2023

0.4298

-0.009

0.234

-0.44

5.76

8

2

4

Y

0.2394

0.4283

0.362

0.219

17.81

5.39

Actual

1st Layer

0.2032

cm

Thickness

2nd Layer

0.4064

cm

Tissue

0.2

cmSlide16

Future Work

Getting transducers in & testing (high frequency and low frequency)building prototype & attachment for drillcalibrating/signal processing and analysisSlide17

References1. French, LC et al. “An estimate of the number of

mastoidectomy procedures performed annually in the United States”. Ear Nose Throat J. 2008 May; 87(5): 267-70.2. Ear Anatomy: http://www.umm.edu/imagepages/1092.htm3. Clement, GT et. Al. “Correlation of Ultrasound Phase with Physical Skull Properties”. Ultrasound in Medicine & Biology. 2002 May; 28(5): 617-624.4. http://www.signal-processing.com/tech/us_data_plastic.htm