Fundamentals of Diagnostic Medical Ultrasound Scan Physics

1. FUNDAMENTALS OF OBSTETRIC AND
GYNAECOLOGICAL ULTRASOUND
NURSING/MIDWIFERY L400 STUDENTS OF ST. LOUIS UNIHEBS
2015/2016 ACADEMIC YEAR
PART B
Lecture 2
Basic Physics of Ultrasound
1
Nchanji NKEH KENETH
B.TECH/HPD - MDIRT
kennchanji@yahoo.com
Radiology Dept
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class of 2015/2016 Academic year, ST.LOUIS UNIHEBS
WITH MATERIALS FROM AIUM, UKAS, WHO MANUAL OF DIAGNOSTIC ULTRASOUND

2. Anatomy/ physiology of the female
pelvis and associated structures
Study expectations:
At the end of this presentation, the students
should be able to:
1. Note basic of ultrasound physics and terminologies
2. Identify various scan modes, scan planes
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3. Introduction
Basics of ultrasound physics
The ultrasound machine
Review of body sections/planes
Definition of concepts
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4. Basic physics of US
The benefits of medical US scans
cannot be over emphasized
Sound is a form of mechanical wave
that travels in a medium in a straight
line fashion
Some acoustic parameters that
describe the properties of sd are:
Frequency, period, amplitude, power,
intensity, wave length and speed
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5. Frequency ranges
Frequency range name
< 20 Hz infrasound
20 Hz - 20 kHz
Audible sound
> 20 kHz, <1MHz
ultrasound
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6. Speed of sound in diff tissues
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7. When sound travels through a material,
It can be absorbed
Reflected
Transmitted
Or scattered
Principle of US production is based on the
PIEZOELECTRIC EFFECT
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8. HOW IS ULTRASOUND PRODUCED?
use of the ultrasound machine which has
transducers with piezoelectric crystals
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9. US machine/ probes
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10. compiled by Nchanji nkeh keneth, MDI
,nkehkenethnchanji@gmail.com,671459
765, level 400 NSG/MDW class of
2015/2016 Academic year, ST>LOUIS
UNIHEBS 10

11. compiled by Nchanji nkeh keneth, MDI
,nkehkenethnchanji@gmail.com,671459
765, level 400 NSG/MDW class of
2015/2016 Academic year, ST>LOUIS
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12. compiled by Nchanji nkeh keneth, MDI
,nkehkenethnchanji@gmail.com,671459
765, level 400 NSG/MDW class of
2015/2016 Academic year, ST>LOUIS
UNIHEBS 12

13. compiled by Nchanji nkeh keneth, MDI
,nkehkenethnchanji@gmail.com,671459
765, level 400 NSG/MDW class of
2015/2016 Academic year, ST>LOUIS
UNIHEBS 13

14. The US image
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15. Various echogenicity
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16. Echogenicities
Anachoic
Hypoechoic
Hyperechoic
Echogenic
Echopenic
some sttres may be of mixed echogenicities
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17. Body planes/cuts
Sagittal/ mid sagittal
Coronal
Oblique
Transverse plane
Other terminologies are :
Anterior/posterior, superior/inferior,
superficial/deep, proximal/distal,
medial/lateral, cephalic/caudal, left/right
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18. More on tissue presentations
Anechoic.
Describes structures
which offer very
insignificant attenuation
to the ultrasound
waves. Such structures
appear BLACK, with
posterior enhancement.
Ex urinary bladder, gall
bladder, blood vessels,
ventricles, heart
chambers, simple cysts
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Anechoic UB

19. Hypoechoic
This term describes
sttrs, which offer some
limited degree of
attenuation to the
ultrasound beam as it
passes through them.
They thus reflect
some echoes, making
them relatively whiter
when compared to
anachoic sttres
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Hypoechoic structure

20. Echogenic structures
They reflect more
echoes as the US
waves traverse them.
Such tissues have a
higher density
They appear much
brighter compared to
hypoechoic structures.
Ex, liver parenchyma,
muscles etc
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20
Echogenic structure

21. Hyperechoic tissues
They appear bright
white
They are very dense
tissues
They completely stop
the transmission of US
through them
They cause acoustic
shadow artefacts.
Ex bones, calcifications,
metal implants
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22. Commonly encountered
artefacts during USS
acoustic enhancement
Acoustic shadow
Reverberation artefact
Mirror image artefact
Edge shadow artefact
Edge enhancement artefact
Partial volume averaging artifacts.
Details will not be considered now
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23. Beri wi ba’a ghor