Doppler ultrasound uses high frequency sound waves to visualize blood vessels. It is a non-invasive technique to test for conditions like deep vein thrombosis. The document discusses the Doppler effect, which is a change in observed frequency of a wave caused by relative motion between the source and observer. It defines key terms like frequency and wavelength. It also describes different Doppler ultrasound techniques like continuous wave and color Doppler, and discusses applications in assessing blood flow velocity and direction in vessels.

1. DOPPLER EFFECT ON
ULTRASOUND
COURSE: ULTRASONIC
MUKA KEHINDE PAUL
M.Sc MEDICAL PHYSICS PROGRAMME,
COLLEGE OF MEDICINE, UNIVERSITY
OF LAGOS, 2018.

2. OUTLINE
 Introduction of Doppler effect
 Doppler effect- key terms
 Doppler ultrasound
 Physics of Doppler effect
 Derivation of Doppler effect
 Applications
 Hemodynamic
 Conclusion
2

3. INTRODUCTION
The Doppler effect describes the change in the observed
frequency of a wave when there is relative motion between the
wave source and the observer. It was first proposed in 1842 by
Austrian mathematician and physicist Christian Johann Doppler.
To explain why the Doppler effect occurs, we need to start with a
few basic features of wave motion. Waves come in a variety of
forms: ripples on the surface of a pond, sounds (as with the siren),
light, and earthquake tremors all exhibit periodic wave motion.
3

4. DOPPLER EFFECT-KEY TERMS
 FREQUENCY : This is the number of cycles that occurs in one second.
 PERIOD: This is the amount of time required to complete one full cycle.
Period is mathematically related to frequency, wavelength, and wave
speed.
 WAVELENGTH(λ) :The distance between a crest and the adjacent crest, or
the trough and an adjacent trough, of a wave. It is vector quantity. It is
measured in meter/seconds.
4

5. DOPPLER ULTRASOUND
 Doppler ultrasound is a non invasive technique by which high
frequency sound waves are use to visualise blood vessels of the
body. Colour Doppler It is one of the main way to test for deep vein
thrombosis.
 Deep Vein Thrombosis (DVT) is a condition where blood clots form
in veins deep in the body, usually in the leg. DVT can lead to more
serious problems, such as clot in the lungs. It can be life threatening.
5

6. DEEP VEIN THROMBOSIS 6

7. TYPES OF DOPPLER ULTRASOND
 Continuous waves
 Duplex
 Colour Doppler ultrasound
 A continuous wave Doppler is a device that allows to
examine blood flow by implementing the Doppler effect. A
continuous wave Doppler is portable, easy to use and
cheap.
7

8. ADVANTAGES OF CONTINUOUS WAVE
DOPPLER
 principles can be learned in a matter of minutes. Portable –
Continuous wave Doppler probes are often handheld. They basically
contain two piezoelectric crystals. One is for emitting a wave and the
other for receiving a reflected wave. There is also a speaker and/or a
small screen for signal interpretation.
 Simple to use – A continuous Doppler is very simple to use.
8

9. DISADVANTAGES OF CONTINUOUS WAVE DOPPLER
 No extra information – A continuous wave Doppler only offers
information about the blood flow. There is no anatomic information
available.
 Sensitivity to operator mistakes – Because continuous wave Doppler
is qualitative an operator may not be aware of mistakes. For example,
a wrong or incorrect positioning
9

10. CONTINUOUS WAVE TRANSDUCER
 The simplest Doppler systems use
continuous wave Doppler and are
usually small hand-held devices.
 A continuous wave transducer of
two adjacent piezoelectric elements
angled slightly towards one
another. The transducer emits a
continuous sinusoidal wave in form
of (cos wt) and the receiver detects
echoes returning.
 From the region of the overlap
between transmitter and receiver
10

11. DOPPLER SHIFT
(1) If blood if moving towards the
transducer then received
frequency will be greater than
the initial frequency.
(2) If blood is moving away from
the transducer then the received
frequency will be lower than the
initial frequency
The lower the Doppler angle, the
higher the Doppler shift.
11

12. DOPPLER FREQUENCY SHIFT EQUATION
ΔF=
𝑉2𝐹𝑂
𝐶
COSθ
ΔF is the Doppler frequency shift
F0 is the initial Doppler frequency
V is the velocity of moving blood
C is the speed of sound in tissue
Cosθ is the angle between the ultrasound beam and the flow
direction.
12

13. COLOUR DOPPLER ULTRASOUND
 Colour Doppler ultrasound uses high frequency sound
waves to visualize the blood vessels and coloured images
of the blood vessels are obtained.
 If there is a doubt of claudication, deep veins thrombosis,
to check the condition of blood supply to the foetus, colour
Doppler can be used.
13

14. CLAUDICATION 14

15. VARICOSE VEIN
15

16. HOW IS THIS TEST DONE?
 A patient lies on a supine position, a sonographer applies
gel on the area of the body that is needed to be visualized.
This helps sound waves travel and give better results.
 The sonographer will press the a transducer against the
area of interest.
16

17. COLOUR DUPLEX DOPPLER
 Color duplex ultrasound is use to diagnosis vein problem
i.e. varicose vein.
 We allow the sound wave to enter the leg where the picture
of the vein and blood flow is build up. We are looking at
where the superficial vein join the deep vein in the groin.
17

18. COLOR DUPLEX ULTRASOUND
SUPERFICIAL VIEN VS DEEP VEIN COLOR DUPLEX IMAGING
18

19. SUPERFICIAL VEIN REFLUX
Reflux due to floppy valves appears red Blood flow up the leg appears blue
19

20. 20

21. DOPPLER EFFECT EQUATIONS
V=Fλ--------------(1) V is the speed of sound in tissue
λ=
𝑉
𝐹
-----------------------(2) F is the frequency of sound in
air
F=
𝑉
λ
-----------------(3) λ is the wavelength of sound
21

22. DOPPLER EFFECT 22

23. DOPPLER EFFECT
23

24. DOPPLER EFFECT EQUATIONS
FOUR SCENAIRIOS OF DOPPLER EFFECT EQUATION
Scenario 1:when object moves towards the stationary source
of sound.
Vrel =vs+vo Fo=
𝑽 𝒔
+𝑽𝑶
𝑽 𝑺
*F
Fo =
𝑽 𝒔
+𝑽𝒐
λ
----------------(4)
Fo=
𝑽 𝑺
+𝑽𝑶
𝑽 𝑺/𝑭
24

25. DOPPLER EFFECT EQUATIONS
Scenario 2: When the observer moves away from the
stationary source of sound
Relative Velocity VREL=VS-VO
FO=
𝑽 𝑺−𝑽𝑶
λ
FO=
𝑽 𝑺
−𝑽𝑶
𝑽 𝑺
/𝑭
/
FO=
𝑽 𝑺
−𝑽𝑶
𝑽 𝑺
*F
25

26. DOPPLER EFFECT EQUATIONS
Scenario 3 : When source moving towards observer who is at
rest
Δλ=
𝑉 𝑆
𝑓
Δλ=VST since λ=
𝑣
𝑓
the observe frequency ϝ’
The wavelength observe is thus;
λ′=λ-Δλ λ′=λ-
𝑉 𝑆
𝐹
Since 𝐹′=
𝑉
λ′
, =
𝑉
λ−Δλ
=
𝑉
λ−(
𝑣
𝑓
)
=
𝑣
𝑣
𝑓
−(
𝑣 𝑠
𝑓
)
F’=
𝑉
𝑉−𝑉𝑆
∗ F
26

27. HEMODYNAMICS
The study of blood flow is called hemodynamics.
GENERAL PRINCIPLE OF CARDIOVASCULAR
SYSTEM
Velocity is the speed of movement with respect to time.
Flow is the volume of fluid with respect to time. Flow means how
much fluid flow through a pipe
Vcm/s =
𝑄 𝑚𝑙
/
𝑚
𝐴𝑐𝑚2 =
𝑓𝑙𝑜𝑤
𝑐𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑟𝑒𝑎
1meter = 39.37 inches
1millimeter = 1 cubic centimeter
1ml = 1cm3
27

28. HEMODYNAMICS (CONTD)
Cardiac output = 5litres/minute
Aorta = 2.5cm2
2.5cm2= Π R2
Diameter of the aorta= 1.78cm
Velocity =
𝑓𝑙𝑜𝑤
𝑎𝑟𝑒𝑎
=
5𝑙/𝑚𝑖𝑛
2.5𝑐𝑚2 =
5000𝑚𝑙/𝑚𝑖𝑛
2.5𝑐𝑚2 =
5000𝑐𝑚2
/𝑚𝑖𝑛
2.5𝑐𝑚2
= 2000cm/min=20metres/min
= 33cm/sec
28

29. HEMODYNAMICS(CONTD)
Velocity of the capillaries
Cross sectional area of the capillaries=3000cm2
Velocity=
5000𝑐𝑚3
/𝑚𝑖𝑛
3000𝑐𝑚2 = 1.6cm/min = 0.027cm/s
29

30. A GRAPH OF VELOCITY OF BLOOD FLOW
VERSUS BLOOD VESSELS
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31. CONCLUSION
Doppler ultrasound is cheap, less-invasive, non-
ionizing and offers minimal risk of bio-effects.
31

32. REFRENCES
1. Prof. M. A. Aweda. Principles of Doppler Imaging. Lagos University Teaching Hospital.
Lagos. 2012.
2.
J. T. Bushberg, et al. The Essential Physics of Medical Imaging. 2nd Ed. Philadelphia:
Lippincott Williams & Wilkins. 2002.
3. W. Huda, R. Sloan. Review of Radiologic Physics. 3rd ed. Philadelphia: Lippincott
Williams & Wilkins. 2009.
4. Adekunle, O. Akinyanju. Prevention of Stroke in Children with Sickle Cell Anaemia.
Sickle Cell Bulletin. Vol 8. No. 1. Sickle Cell Foundation Nigeria. 2017.
5. Siemens AG. Principles of Ultrasound Imaging. 1999: Med USSE
J. M. Adams. Ultrasound’s Transcranial Doppler Imaging Checks for Risk of Stroke.
2016. Cincinnati Children’s Hospital.
6. http://www.blog.cincinnatichildrens.org/radiology/
W. R. Hendee, E. R. Ritenour. Medical Imaging Physics. 4th Ed. New York: Wiley-Liss.
2002
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33. GRAND MERCI MES AMIS
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