2. CONTENTS
INTRODUCTION
DISCOVERY OF X –RAYS
GAS TUBES, VACUUM TUBES
X- RAY FILMS
EVOLUTION OF DARK ROOM
GROWTH OF DENTAL RADIOLOGY
HISTORY OF PANORAMIC RADIOGRAPHY
HISTORY OF COMPUTED TOMOGRAPHY
HISTORY OF MAGNETIC RESONANCE
IMAGING
3. INTRODUCTION
NOTHING MATERIALIZES AS IF BY MAGIC
OVERNIGHT, EVEN ROENTGEN’S DISCOVERY
DEPENDED UPON THE DEVELOPMENT AND
APPLICATION OF THREE CONVERGING
THOUGHTS; ELECTRICITY ,VACUUM AND
MAGNETISM.
History began long back in 600
BC when thales of miletus,was first to tread the
darkness and obtain the substance from Baltic
shores and named it as electron or amber which
attracted light particles of matter when rubbed.His
work was enlarged upon by Theophrastus ,Pliny and
William Gilbert.
4. Gilbert (1600) classified all things into electric and
non electric and gave the term electricity.
Stephen Gray discovered that current would flow
over conductor to a greater distances.
Abbe Nollet removed the source of high tension from
vacuum and his ‘electric egg `became direct
descendant of discharge tube.
Charles DuFay (1730) discovered two types of
electricity ,i.e. ‘vitreous’ and ‘resinous’ .
Franklin called it ‘positive’ and ‘negative’ electricity.
Otto von Guericke (1648) invented first air pump used
in the formation of vacuum.
5. DISCOVERY OF X-RAYS
Sir William Morgan (1785), while investigating the
discharge of high tension current in perfect vacuum
,obtained a vacuum so high that there was no
discharge .In one of his experiment ,glass cracked
and Morgan observed display of colours ,yellow-
green and followed by red, violet and blue.Unknown
to him he was the first man to produce X-rays.
In 1821 ,Michael Faraday conducted his first
experiment on electric discharges in partially
evacuated glass vessels .He described that ‘voltaic
arc’ was accompanied by fluorescence of gas
remaining within the vessel.
6. Julius Plucker(1859) was first to observe Green
Glass Fluorescence in partially evacuated discharge
tubes.
Wilhelm Hittorf(1870) improved vacuum pumps. He
observed that fluorescent discharge increased in size
as the tube was evacuated and identified the source
of phenomenon as cathode and termed it as ‘cathode
rays’
In 1880s , Sir William Crookes described additional
changes that took place in fluorescence.He reffered to
a ‘molecular’ and ‘emmisive’ ray from tube which
could only be seen when a fluorescent screen placed
in the rays path beyond the tube.He had unknowingly
generated X- rays.
7. Heinrich Hertz denied that cathode rays were
charged particles ,but observed that they could
penetrate matter.Philip Lenard showed that
cathode rays would pass through a special
aluminium window and retained enough energy
outside the tube to cause fluorescent screen to
glow.These rays caused air to glow and glow
extended five centimetres in air and were known
as ‘Lenard’s ray’.Lenard might have been the
discoverer of X- rays had he used barium
platinocyanide instead of less sensitive
fluorescent material keton.He was able to
demonstrate effect of Lenard’s ray on
photographic emulsion.Lenard proposed ‘Inverse
Square Law’.
9. SIR JOSEPH-
JOHN(1856-1940)
In 1895, Jead Perrin
stated cathode rays
were negatively
charged particles.
1896 , John Joseph
resolved the debate
relative to the nature of
cathode rays when he
measured their velocity
and ratio between their
charge and mass and
thereby discovered the
10.
11. Humanity owes honor and gratitude for discovering the
most striking and outstanding property of cathode rays to
Professor Wilhem Conard Roentgen of WURZBERG
,Bavaria(1895).
Roentgen while experimenting and searching for the
invisible light rays turned on a low pressure Crooke’s
tube,completely enclosed in heavy black paper and
applied power to electrodes .
To his surprise, a fluorescent screen, covered with barium
platinocyanide started to glow brightly and interposed
objects cast shadow on screen.
He revealed that rays were produced whenever and
wherever the cathode rays encountered matter and the
rays could penetrate substances opaque to light and
degree of penetration depended upon density of substance
.These rays could not be reflected and refracted and are
unaffected by magnetic or elecricc field.He termed these
rays X- rays as X meant unknown
15. Roentgen accidentally placed his hand between
tube and fluorescent screen only to be surprised
by seeing a faint but stratling image of bones
within his hands on screen.He subsequently
demonstrated that such images of body could be
recorded on photographic plates.
Roentgen proceeded to make the first radiograph
of human body; he placed his wife’s hand on
photographic plates and exposed it to ‘unknown
rays’ for 15 minutes.On developing the outline of
the bones in her hand could be seen.
16. First X ray made in
public. Hand of the
famed
anatomist, Albert von
Kölliker, made during
Roentgen's initial
lecture before the
Würzburg
Physical Medical
Society on January
23, 1896.
17. He published three papers
-A new kind of rays:A preliminary
communication
-A new kind of rays: continued
-Further observations on a new kind of
rays
So complete were his studies that over
next 15 years only the fact that X-rays could be
polarized and defracted were to be added to the
existing information.Roentgen was awarded first
Nobel Prize in physics(1901), a Honorary M.D
Degree from Maximilan University in Wurzberg,
18. First medical radiogph was of Mrs Roentgen’s
First industrial radiograph was of Roentgen’s
shot gun.
It is uncertain who took first dental radiograph
,but the honors are shared between
Germans,Koenig and Walkhoff, Frank Harrison in
Britain and C. Edmund Kells in NEW Jersy, all of
whom were producing crude but recognizable
dental ‘skiagrams’in late winter and early sprigs of
1896.
19. Dr Friedrich Otto Walkhoff; DDS ,MD (1860-1934), a
dentist in Brunschweig, Germany within 14 days of
announcement that Roentgen rays could penetrate
solid substances impervious to light ,had completed
his first dental radiograph.
He took anordinary glass plate wrapped it in rubber
dam put it in his mouth between teeth and tongue and
lay on floor for 25 minutes to expose plate to X-ray
beam, which was too long a procedure and
equipment too costly.
he obtained image of both maxillary and mandibular
teeth (first bite wing).
He continued his experiment and 2 years later in April
1896, he succeeded in making extraoral pictures with
an exposure time of 30 minutes
20.
21. In 1896, Otto Walkhoff and Fritz Giesel established
first dental roentgenologic laboratory in the world.
Dental radiographs were also made by professor
Wilhelm Koeing Wilhelm made series of 14 dental
radiographs of his own mouth.Requiring only 9
minutes of exposure per film ,they showed clearly
fillings in some teeth .he used ‘focus tube’ which
probably the reason he made good pictures early.He
found if cathode rays were reflected by platimum
sheet at 45 degree angle resultant rays was more
penetrating .
Frank Harrison was first to report the occurrence of
radiation hazard.Credit of first published report of a
dental radiograph clearly goes to Harrison.
William J Morton (1845-1920) a New York physician
made first recorded dental radiograph
22. Dr C Edmund Kells (1880) also known as ‘Father
of Dental Radiology’ fitted his office with an
electric equipment ,all of his own design.and took
first intraoral radiograph on live person in 1896.
He established his own dental X-ray apparatus
for holding tube and techniquenfor radiographing
teeth and jaws.He constructed a film holder
made from a thin aluminium plate and gutta
percha that allowed patient to bite into occlusion
.he mentiomed the importance of of keeping film
and object at right angles to X-rays.He was first to
advocate right angle or paralleling technique.
C.Edmund Kells –first denist to use radiography
in root canal therapy on May 10, 1899
23. On march 23,1896 Dr. John Daniel wrote a letter
to editor of Science about hair loss from head of
colleague
Direct relationship between x ray beams and
biologic effects was proved definitely by
controlled experiments of Kienbock.
24. ‘Roentgen Studies’ appeared in America and Europe and
advertisements announced businesses in ‘Roentgen
Photography’ .These ‘radiological chemist’ used
fundamental pieces of apparatus
X- ray machine
X- ray tube
Adustable tube stand
The darkroom
X- ray machine consisted of- induction coil,
interrupter, rheostat
Two basic types of interrupters
1)Mechanical
a)vibrating type
b)mercury type
2. Electrolytic type.
25. X ray tubes used by Roentgen ,Lenard ,crookes were
fixed and stationary vacuum types .so each tube had
to be tested to determine its penetrating qualities
before it could be used on patients.
Procedures used were
Observing colour of fluorescence in energized tube
-low vacuum- dark blue
-high vacuum –more uniform yellow or apple green
colour
By observing amount of spark ‘backed up’ across the
spark gap of the induction coil.
-3 -4 inches spark- soft X-rays
-7 – 10 inches spark- high vacuum ,high penetrating X-
rays
26. Thomas A Edison invented fluoroscope.
Later quality of x-ray beam was estimated by
ability to penetrate varying densities on adevice
called ‘penetrometer’
Another device called’ Qualimeter’ registered the
resistance in secondary circuit of transformer
-high vacuum-high resistance-high
penetrating power
-low vacuum- low resistance- low
penetrating power
27. GAS TUBES
Early vacuum tubes depended upon incomplete
vacuum to provide source of electrons at the cathode.
As the tube was used the gas molecules combined
with or were trapped by vaporized residues from the
anode and cathode which gradually increased the
vacuum. When vacuum became too high no x rays
were produced and tube was considered to be cranky.
VACUUM TUBE
In an effort to eliminate gas and stabilize the operation
of x-ray tubE,J.E Lilienfeld ,an Austrian developed a
tube in 1911 based on field current principles.
28.
29. DEMISE OF GAS TUBE
In 1907 ,that Clyde Snook installed his first X-ray
machine .It was rated at 110 k Vp and 200 m A
Real breakthrough in tube design ,which ushered in the
‘golden age of radiology’ was the development of the
hot cathode tube by William David
Coolidge.,(1913).He used coil of tungsten as a source
of electrons. It permitted:
Greater flexibility in quantity and quality of x rays
produced
Greater tube stability
Smaller tube size
Longer tube life
Direct operation from a transformer
30. X- RAY FILMS
First dental radiograph was taken on a small
glass plate-then Kells and Rollins began to use
photographic film because of adaptability to
tissues.
Early films were handmade and consisted of
glass plates or roll films, cut to proper length and
wrapped in black paper and rubber dam material .
First machine wrapped dental x- ray film packet
,called regular film( Kodak) became commercially
available in 1919.
31. EVOLUTION OF DARK ROOM
Most early darkroom was a closet with or without
running water,of size three and half feet by five
feet.Many of early workers utilized a ‘four bottled’
photographic method of development:
-covering sensitive material with a developing agent
-adding a preservative
-adding an accelerator
-adding a bromide
In 1896 kells described radiographic technique
requiring 5 to 15 minutes exposure and developing
time of 30 to 60 mins
In 1909 ,tank development and standardized
developing solution and procedures were introduced.
Automatic processors were introduced in 1910s.
32. HIGHLIGHTS IN HISTORY OF
DENTAL RADIOLOGY
1895-DISCOVERY OF X-RAYS-
W.C.ROENTGEN
1896-FIRST DENTAL RADIOGRAPH-O.
WALKHOFF
1896-FIRST DENTAL RADIOGRAPH IN
US(SKULL)-W.J.MORTON
1896-FIRST DENTAL RADIOGRAPH IN US
(LIVE)-C.E.KELLS
1901-FIRST PAPER ON DANGERS OF X-
RADIATION-W.H. ROLLINS
1904-INTRODUCTION OF BISECTING
TECHNIQUE-W.A. PRICE
33. 1913-FIRST DENTAL TEXT-H.R.RAPER
1913-FIRST PREWRAPPED DENTAL FILMS-
EASTMAN KODAK COMPANY
1913-FIRST X-RAY TUBE-W.D. COOLIDGE
1920-CONCEPT OF PARALLELING
TECHNIQUE-F. McCORMACK
1923-FIRST DENTAL X- RAY MACHINE-VICTOR
X-RAY CORPORATION OF CHICAGO
1925-INTRODUCTION OF BITEWING
TECHNIQUE-H.R.HARPER
34. 1933- CONCEPT OF ROTATIONAL PANAROMIC
PROPOSED-Dr HISATUGU NUMATA
1947-INTRODUCTION OF LONG CONE
PARALLELING TECHNIQUE-F.G.FITZGERALD
1948- INTRODUCTION OF PANORAMIC
RADIOGRAPHY-Dr. YRJO VELI PAATERO
1955-INTRODUCTION OF D-SPEED FILM
1957- FIRST VARIABLE VOLTAGE DENTAL X-
RAY MACHINE-GENERAL ELETRIC
1960-FIRST PANORAMIC MACHINE
MARKETED-S.S.WHITE AND Co.
35. 1969- Prototype scanner developed –Godfrey
Hounsfield
1978-INTRODUCTION OF DENTAL
XERORADIOGRAPHY
1981-INTRODUCTION OF E-SPEED FILM
1987- INTRODUCTION OF INTRAORAL
DIGITAL RADIOGRAPHY
1987-Denta scan designed
2000-INTRODUCTION OF ‘F’ SPEED FILMS
36. HISTORY OF PANORAMIC
RADIOGRAPHY
Dr H Numata was first to propose and experiment
with this method of panoramic radiography.
He placed curved film in the mouth lingual to
teeth and used aslit or narrow x-ray beam that
rotated around the patient’s jaws to expose the
film.
In 1960s ,S.S. White and Company marketed
first panoramic machine (Panorex).
In 1968, the International Association of Dento-
Maxillofacial Radiology was established.
37.
38. HISTORY OF COMPUTED
RADIOGRAPHY
Three dimensional radiography was introduced in
1917 by Mathematician Radon, who described
the concept that two dimensional or three
dimensional objects could be reconstructed from
infinite set of all its projections.
In 1969 ,Godfrey Hounsfield developed the
prototype scanner .American light source(isotope)
was used.
39. HIGHLIGHTS OF COMPUTED
TOMOGRAPHY
IN 1970, with aid of computer technology ,this
concept was applied clinically by Sir Hounsfield and it
was known as computed tomography(CT).
It was announced in imaging world in 1972
and in astrophysics.1n 1971 fist scanner was installed
. and in 1972 the first commercially viable CT scanner
was invented by Godfrey Newbold in Hayes ,England
at Thorn EMI Central Laboratories using X-rays.
In 1974 first CT system from medical equipment
manufacturer (siretom) was introduced and had
scanning time of 2.5 min.
In 1975,the introduction of CT unit of 5000 series
was announced byEMI ,having scanning time of 18
sec.
40. In 1976 , whole body CT imaging started. Fan
beam introduced.
In i980 , Electron beam CT was introduced by
Andrew Castagnini
In 1987 ,Dr. MICHEAL Rhodes and the
computer science group of multiplanar Diagnostic
Imaging with development of Dentascan .
In 1990 –Helical also called spiral , CT was
introduced.
In 1992 integrated CT angiography was
introduced
41. HISTORY OF MAGNETIC
RESONANCE IMAGING
Felix Bloch and Edward Purcell ,both of whom were
awarded nobel prize in 1952, discovered magnetic
resonance phenomenon independentaly in 1946. In
period between 1950 and 1970, NMR was developed
and used for chemical and physical analysis.
In 1971, Raymond Damadian showed nuclear
relaxation times of tissues and tumors differed, thus
motivating scientists to consider magnetic resonance
for detection of disease.
In 1975, Richard Enst proposed magnetic
resonance imaging using phase and frequency
encoding and Fourier Transform.
On July 3, 1977 first MRI exam was ever performed
on human being. It took almost 5 hours to produce
42. In 1977, Peter Mansfield developed the echo-
planar imaging technique.
In 1987 ,echoplanar imaging technique was
used to perform real –movie imaging of single
cardiac cycle.
In 1992 , functional MRI was developed.
In 2003, Paul C. Lauterbur of university of Illinios
and Sir Peter Mansfield of university of
Nottingham were awarded nobel prize in
medicine for their discoveries concerning
magnetic resonance imaging.MRI is clearly young
but growing science.
43. Text book of dental and maxillofacial radiology-
Freny
Oral radiology principles and interpretation-Paul
W Goaz and Staurt C. white
Dental Radiology –Joen Imacia and Laura- 2nd
edition
