Dr Kristie TSANGDepartment of Anesthesia and Intensive CareThe Chinese University of Hong KongPrince of Wales HospitalShatinHong Kong

The Ultrasound PhantomA Teaching and Learning Tool

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What is an Ultrasound Phantom?

Any material that simulates body tissue in its interaction with ultrasound and which can be used to perform simulated interventions.

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Why Use a Phantom?

Helps develop Hand-Eye coordination necessary forultrasound guided intervention

Allows one to perform simulated interventions without having to do it for the first time in a patient

Helps develop confidence

Helps one to understand the factors that affect the visibility of a needle during ultrasound guided interventions

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Commercially Available Phantom

e.g. Blue phantomwww.bluephantom.com

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The Blue PhantomSonographic Appearence

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Home-made Ultrasound PhantomTissue Mimicking Material

Agar based(大菜)Gelatin based (魚膠)Mixture of agar and gelatinChicken breastPork meat with porcine tendon embedded1

TargetsLatex tubingFoley catheterWireCystPorcine tendon1

HousingsPVC lunch box

1: Xu D, et al. Ultrasound phantom for hands-on practice. Reg Anesth Pain Med. 2005 Nov-Dec;30(6):593-4.

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Recipe for a Home Made Ultrasound Phantom

1) 3 table spoons of corn flour added to 200 ml of tap water at room temperature. Gently stir until completely dissolved

2) Then, add 3 table spoons of Gelatin powder and an aditional 200 ml of near boiling water

3) Let the mixture cool down for 30 min before refrigerating at 4 degree Celsius

4) Mixture will be ready for use in 10-12 hours time

Corn flour and gelatin are available at most supermarkets

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Made of an agar based material with a latex rubber tubingembedded in it (to mimic a blood vessel)

Home-made Ultrasound Phantom

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A resident practicing ultrasound guided vascular puncture (hand-eye coordination) in the short axis using an agar based phantom

Agar Based Phantom

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Blue Phantom

Practicing vasular puncture in the long axis using a blue phantom

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Gelatin Based Phantom

A resident practicing interventional skills (visualizing the needle in long axis) using a home made Gelatin based phantom

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Gelatin Based Phantom

A resident practicing interventional skills (visualizing the needle in short axis) using a home made Gelatin based phantom

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Regional Anesthesia & Pain Medicine.2004; 29(6):544-8

10 inexperienced residents were asked to place a 22-gauge needle into the exact midpoint of an olive buried inside a turkey breast under ultrasound guidance.

The commonest error committed was the failure to accurately image the needle while advancing whichresulted in excessive depth of penetration and inadvertent transfixation of the olive.

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Reg Anesth Pain Med 2004;29:480-488

The shaft of the needle is better visible than the needle tip andthe visibility is better in the Long axis (LAX) than Short axis (SAX)

The Husted needle tip is subjectively better visibile thanthe Tuohy and pencil-point needles

Larger outer diameter needles are better visible

Insulated needles are slightly more visible than non-insulatedneedles

Stylet placement does not change needle tip visibility

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Reg Anesth Pain Med 2004;29:480-488

Needle tip and shaft visibility decreases gradually with steeperangles. Shaft visibility decreases more sharply than tip visibility

The Needle tip is better visible in LAX when inserted at an angle < 30 degrees

The Needle tip is better visible in SAX when inserted at an angle > 600

Air or water priming does not change needle visibility

Insertion of a guide wire enhances needle tip and shaft visibility

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Needle Visibility – Effect of Needle Size

Tuohy needle 22-G, B Braun Tuohy needle 16-G, Portex

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Needle Visibility – Effect of Needle Type

Tuohy needle, 16-G

Portex

Echo-Coat needle, 25-G

STS Biopolymer Inc

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Needle Visibility – Angle of InsertionTuohy needle 22G, B Braun

Needle inserted in LAX

Needle inserted prallel to the foot print

Needle inserted at 30 0

angle

Needle inserted at > 60 0

angle

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Orientation and Measurement Excercise

Perform a transverse scan of the phantom to obtain a cross- sectional view of the latex tubing (embedded in the phantom)

Now rotate the scan head to visualize the transition from cross-sectional to longitudinal view of the latex tubing

Use the electronic caliper to measure1. The distance from the surface to the tubing 2. The diameter of the tubing

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Orientation and Measurement Excercise

Cross section of the saline filled latex tubing

Internal diameter of the latex tubing

Transverse Scan of Latex Tubing

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Orientation and Measurement Exercise

Wall thickness 0.12 cm

Internal diameter

0.5 cm

Longitudinal view of latex tubing

Longitudinal Scan of Latex Tubing

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Needling and Target Exercise

Perform a transverse scan to obtain a cross-sectionalview of the latex tubing embedded in the phantom

Now pass a needle in the long axis of the ultrasound beam so as to position the tip of the needle at the 12O’clock and 6 O’clock position of the tubing

Note that it is essential to visualize the tip of the needleat all times and avoid passing through the tubing or overshooting the target.

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Needle tip at 12 o’clock position of the latex tubing

Needling and Target Exercise

Needle inserted in the Long Axis of the Ultrasound Beam

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Needling and Target Exercise

Needle inserted in the Long Axis of the Ultrasound Beam

Needle tip at 6 o’clock position of the latex tubing

The Ultrasound Phantom A Teaching and Learning Tool

Ultrasound Guided Regional Anesthesia WorkshopUltrasound Guided Regional Anesthesia WorkshopDepartment of Anesthesia and Intensive CareDepartment of Anesthesia and Intensive CareThe Chinese University of Hong KongThe Chinese University of Hong KongPrince of Wales HsopitalPrince of Wales HsopitalShatin, Hong KongShatin, Hong KongWeb link: Web link: http://www.aic.cuhk.edu.hk/Ultrasound Workshop/http://www.aic.cuhk.edu.hk/Ultrasound Workshop/Copyright: Department of Anesthesia and Intensive Care, CUHK

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