radiology

1. Historical perspectives
Of
Radiology
Dr Deebika
Vinothprabu

2. History of radiology
 1895 – Wilhelm Conrad Roentgen detects x rays & take first x
ray
 1896 – Antoine Henri Becquerel discovers radioactivity
 1896 – Thomas Alva Edison invents first commercially
available fluoroscope
 1913 – Albert Salmon – mammography
 1927 – Egas Moniz – cerebral angiography
 1950 – David e.kuhl invents PET

3. • 1953 – Sven Ivar Seldinger – seldinger technique
• 1957 – Ian Donald – ultrasound
• 1964 – Charles Dotter – image guided intervention
• 1972 – Godfrey Hounsfield & Allan m.Conmarck – CT
• 1977 – Raymond Vahan Damadian – mri scanner

4. History of X rays
 Discovery of x rays was the beginning
of revolutionary change
 German physicist WILHELM CONRAD
RONTGEN discovers x rays – 1895
 Nobel prize in physics in 1901
 In 2004, international union of pure
and applied chemistry named element
111 as ROENTGENIUM(radio active
element)

5. • In early november he was investigating external effects of
various vacuum tubes.
• While doing experiments with vacuum tubes,he added
aluminium window to permit cathode rays to exit & a
cardboard covering added to protect aluminium from
damage by electrostatic field that is necessary to produce
cathode rays
• Roentgen observed invisible rays caused fluorescent
effect on carboard screen painted with barium
platinocyanide

6. • He investigated various properties of rays
which he called ‘X RAYS’
• He took the very first picture using x rays
of his wife Anna berthas’s hand

7. X RAYS
 part of electromagnetic spectrum
 Wide range of Wavelength
 Deeply penetrating,highly destructive shorter wavelength – HARD X RAYS
 Longer wavelength,lesser penetrating power – SOFT X RAYS
 Soft xrays – used in medical & dental diagnosis
 Ionising radiation
 Carries high energy & deposits a part of it within the body it passes
 Cause biological effects

8. X ray tubes
Crookes tube
-invented by william crookes
-first used x ray tubes
-used untill 1920
-generate electrons by ionization
of residual air in the tube
-used an aluminium cathode,
platinum anode
-unreliable as residual air in tube
absorbed by walls

9. Coolidge tube
• Improved by william coolidge 1913
• Most widely used
• Electrons produced by thermionic effect
• Tungsten filament(cathode) heated by electric current
• High voltage potential between cathode & anode
• Electrons accelerated hit anode

10. X-Ray tube
Filament
Rotor
Vacuum envelopeAnode
Cathode

11. X rays produced due to sudden deceleration of fast moving electrons when they
collide & interact with target anode
99% electron energy converted to heat and 1% into x ray production
Cathode(tungsten filament) is the negative terminal of x ray tube
When current is flowing through it filament gets heated and start emitting electrons by
process called thermionic emission
High voltage applied between cathode and anode
Anode(tungsten disc) is the positive terminal.fast moving electron interact with anode
in 3 ways
1)Interaction with K-shell electron – charecteristic x rays
2)Interaction with nucleus – bremsstrahlung radiation
3)Interaction with outer shell electron – line spectrum

12. In early 1896 in the wave of excitement following
Roentgen’s discovery of x rays, Antoine Henri
Becquerel ,french physicist thought that
phosphorescent materials such as Uranium salts emit
penetrating x ray like radiation when illuminated by
sunlight
Discoverer of radioactivity
1903 – received nobel prize in physics along with
Marie Curie & Pierre Curie

13. Fluoroscopy
• First crude fluoroscope created within
months after x ray discovery
• Use of x rays to produce a moving
image of internal structure of patient
• Fluoroscopy uses continuous x ray
beam that is passed over area of
interest
• Frequently used to evaluate GI
tract,kidney function etc

14. Computerised radiography
• Similar to conventional radiography except that in
place of the flim to create the image,an imaging
plate made of photostimulable phosphor used
• Imaging plate is housed in a special cassette and
placed under the object and xray exposure made
• Imaging plate is run through a special laser
scanner that reads the image

15. Digital x ray
• X ray sensors(digital image capture device)are used
instead of traditional photographic film
• Time efficiency
• Ability to digitally transfer & enhances image
• Less radiation
• Immediate image preview & availability
• Eliminates costly film processing

17. Mammogram
1949 – Raul Leborgne,radiologists
introduced compression technique
Late 50’s –Robert L.Egan,radiologists introduces
a new technique using fine-grain intensifying
screen & industrial film for clearer images
MID 60’s – gain acceptance as screening
tool
german surgeon Albert Salmon attempts to visualize
cancer of breast through radiograph
1913
1949
Late 50’s
MID 60’s

18. – modern day film mammogram invented1969
1993
2000
2011
– mammogram recommended as screening tool by
American Cancer Society
– FDA approves first digital
mammography system
– FDA approves Hologic’s 3D mammography
technology(breast tomosynthesis),proven
clinically superior to digital mammography

19. Ultrasonogram
• Ian Donald – first diagnostic application of usg –
1956,one dimentional A mod (amplitude mode)
• 1963 – B mode(brightness mode)two dimentional
devices constructed
• Turning point in application of ultrasound in medicine
• In mid seventies (kossoff garrett)introduction of real
time ultrasound scanner
• Decade later,doppler effect enabled visualization of
blood circulation

20. • Ultrasound refers to sound waves with frequency too high
for humans to hear
• Images made by sending a pulse of ultrasound into tissue
using ultrasound transducer
• Sound reflected fron parts of tissue recorded as image

21. Modes
A-MODE :
-simplest type
-single transducer scans a line through the body
with echoes plotted on screens function of depth
-therapeutic ultrasound for tumor or calculus for
pinpoint focus of destructive wave energy
B MODE :
Linear array of transducers scan a plane that viewed
as two – dimentional image on screen

22. M – MODE :
M for motion
rapid sequence of B mode scans images
follow each other in sequences ,enable
see & measure range of motion
commonly used to measure cardiac
dimensions & ejection fraction
DOPPLER MODE :
In measuring & visualizing blood flow

23. Doppler effect
• Christian Andreas Doppler(1803-1853),austrian
physicist & mathemetician formulated his theory in
1842
• Observed change in the
frequency of transmitted
waves when relative motion
exists between the source
of wave & an observer

24. • First medical applications of
doppler sonography initiated
during late 1950’s
• First pulsed-wave doppler
equipment developed by
Donald Baker,Dennis Watkins
& John Reid worked on this
project in 1966 produced one
of first pulsed Doppler devices

25. Convex 3.5 MHz
For abdominal and
OB/GYN studies
Micro-convex: 6.5MHz
For transvaginal and
transrectal studies
Ultrasound
machine
Ultrasound
examination

26. 3D USG
Sound waves sent at different angles
Returning echoes processed by sophisticated
computer resulting in three dimentional volume
image of fetus’s surface
First developed by Olaf Von Ramm 1987
OBS - Timing of 3d scan between 26 to 30wks

27. 4D USG
• Similar to 3D usg with the
difference associated with
time
4D allows 3 dimentional
picture in real time
it is reffered to 4D when
baby is moving in 3D

28. Elastography
Maps the elastic properties of soft tissue
Gives diagnostic information about disease
by saying whether tissue is hard or soft
Offers very high contrast between masses
and host tissues
The acoustic radiation force moves the
tissue and detect distorsion by speckle
tracking
Results are quantitative
Found applications in breast,liver
prostate,thyroid

29. Ultrasound therapy
Role in tissue ablation therapy in the form of high intensity focused
ultrasound
Exploits thermal effects of high power ultrasound beams focused on
very small target tissue
Use frequency 0.7 to 3.3 mhz
More precise, easy to handle compared to radiotherapy
In ligament sprains,lithotripsy,cataract,acoustic targeted drug
delivery,cancer therapy,thrombolysis etc

30. Computerized Tomography
Also known as computerized axial tomography[CAT]
Imaging of a cross sectional slice of the body using X-
rays.
Invented by Dr. G. N. Housfield in 1971. Received the
Nobel prize in medicine in 1979.
The method is constructing images from large number of
measurements of x-ray transmission through the patient.
The resulting images are tomographic maps of the X-ray
linear attenuation coefficient.

31. • Hounsfield built a prototype head scanner & tested it on a
preserved human brain later on himself
• In 1971 CT scanning introduced into medical practice with a
successful scan on cerebral cyst patient at Atkinson Morley’s
hospital London
• In 1975 he built a whole body scanner
• In early experiments he used gamma source & it took 9 days to
acquire image data & 2 ½ hrs to reconstruct image
• He replaced gamma source with x ray tube, scan time reduced to 9
hrs

32. ALLAN M.CORMACK
• 1979 – nobel prize shared with
DR.Hounsfield developed
solutions to mathematical
problems in CT

33. • Principle - The density of the tissue passed by x ray
beam can be measured from calculation of the
attenuation coeffient
• Two processes of absorption
photoelectric effect
compton effect
Measure transmission of thin beam of x rays through full
scan of body
Image of that section taken from different angles,allows to
retrieve information on the depth
Consists of square matrix of elements(pixel) & volume

34. CT-First generation
• Single x ray source
• Beam – pencil beam
• Detector rotate slightly
• Translate/rotate scanner
• Duration of time 25 to 30 mins
• Resolution very poor

35. Second generation
• Design – multiple detectors upto 30
• X rays beam – fan shaped
• Translate – rotate
• Duration of scan - <90 secs

36. Third generation
• Design – larger array of detectors
• 300-700 detectors ,circular
• Beam – fan shaped x ray beam
• Tube and detector arrays rotate
around patient
• Rotate rotate scanner
• Duration of scan – 5sec

37. Fourth generation
• Detector – multiple >2000 arranged in outer ring fixed
• Beam – fan shaped
• Rotate – fixed scanner
• Duration of scan few seconds

39. Fifth generation
• X ray tube is a large ring that circles
patient
• Use – cardiac tomography imaging “cine
CT”
• Stationary/stationary geometry

40. Spiral/helical ct
• Design – x ray tube rotates as patient moved smoothly
into x ray scan field
• Source rotation,table translation,data acquition
• Advantages
speed-30 sec for abdomen,chest
improved detections
improved contrast
improved reconstruction
improved 3D images

41. Seventh generation
• Design – multiple detector array
• Turbo charged spiral
• Upto 8 rows of detectors
• Improvement in details
• Cone beam and multiple parallel rows
of detectors
• Reducing scan time,increase z
resolution

42. Attenuation coefficients of several tissues expressed in Hounsfield
units.

43. Magnetic Resonance
Imaging (MRI)

44. 1946 - NMR Discovered by two physicists Felix Bloch &Edward Mills Purcell
1952 - They received nobel prize in physics
1971 - Use of NMR to produce 2D images made by Paul Lauterbur
1976 - First clinical human MRI
2003 - Nobel prize for Lauterbur & Mansfield
Uses strong magnetic fields and radiowaves to form image of the body
Used for medical diagnosis,staging of disease,follow up without exposure to
radiation

45. How it works
First – mri creates steady state of magnetism within human body by
placing the body in a steady magnetic field
Second – mri stimulates body with radiowaves to change the steady
state orientation of protons
Third – mri machine stops the radiowaves & register the body’s
electromagnetic transmission
Fourth – transmitted signal used to construct internal images of body

46. MRI machine

47.  Neuroimaging more sensitive for small tumors,CNS
diseases
guided stereotactic surgery
radiosurgery(av malformations,tumors)
 Cardiovascular
MI,cardiomyopathies,CHD,ironoverload
 Musculoskeletal
spine imaging,joint disease,soft tissue
tumors
 Oncology,Liver,GI tract,functional MRI

48. Specialized applications
 Diffusion MRI
 MR angiography
 MR spectroscopy
 Functional MRI
 Real time MRI
 Interventional MRI
 MR guided focused ultrasound
 Multinuclear imaging
 Molecular imaging by MRI

49. • Advantage – ability to produce images in
axial,coronal,saggital & multiple oblique planes
• Gives best soft tissue contrast of all imaging modalities
• CI – pacemakers,cochlear implants,aneurysm clips,metal
fragments in eye
• Potential advancement – functional
imaging,cardiovascular MRI,MRI guided therapy

50. Nuclear Imaging

51. PET
• Concept of emission and transmission tomography
introduced by David E.Kuhl in late 1950s
• In 1961 James Robertson built the first single plane
PET Scan,nick named “head-shrinker”
• Development of labeled 2FDG was a major factor in
expanding in the scope of PET imaging
• The compound was first administered to two
volunteers in aug 1976,at university of pennsylvania

52. •Modern non invasive imaging technique for quantification of radioactivity in
vivo
•Involves use of radiopharmaceutical injected into body & its accumulation in
body detected,quantified & interpreted
Concept
• radiolabelled biocompound 2-fluoro-2-deoxy-D-glucose injected iv
• uptake of compound followed by breakdown occurs in cells
• tumors have high metabolic rate hence this compound metabolised by
• tumor cells
• FDG metabolised to FDG 6 phosphate
• further not metabolised by tumor cells hence accumulates
• accumulation is quantified

54. Whole body PET

55. Nuclear camera

56. Radionuclide (isotope) scan
• Radionuclide is a chemical which emits a type of
radioactivity called gamma rays
• Tiny amount of radionuclide put into body
• Cells which are more active will take up more of
radionuclide & emits more gamma rays
• Detected by gamma camera,converted into
electrical signal & sent to computer
• Computers builds into different colours/shades of
grey

57. SPECT
(single photon emission computerized
tomography)

58. • Tomographic slice is reconstructed from
photons emitted by the radio isotope in a
nuclear medicine study
• SPECT is 3D Tomographic technique that
uses Gamma Camera data from many
projections and reconstructed in different
planes

59. SPECT Machine

60. THANK YOU