Transcript History of radiology

D3
Radiological Imaging Methods
History, overview, principles
3. LF UK Praha
Department of Radiology
2012
This teaching file is an introduction to the study of
radiology and medical imaging methods for medical
students.
History of radiology, overview of different contemporary
imaging methods, their physical principles and future
trends of radiology are presented.
Redaction: Václav Janík, Jan Šprindrich
Discovery of X-rays
Wilhelm Conrad Röntgen
Professor of physics in Würzburg (Germany)
In 1895 he discovered, while experimenting with cathode tubes, a new penetrating
radiation and called it X-rays
The historical first X-ray image of the hand of his wife (exposed 25 min!)
Nobel prize for physics in 1901
Note: In Czech and German these rays are called Röntgen rays – RTG rays
electromagnetic radiation
X - rays
electromagnetic radiation
short wavelength
- flux of photons -
E = h. f
f= c/λ
• penetrating
• nonvisible
• ionizating
History of radiology
1895
Röntgen
X-rays (rtg)
1896
Becquerel
natural radioactivity (α, β, γ)
1898
Mme Curie
Po, Ra
roentgenology
radiology
20. century
1940
F.J.Curie
1941
arteficial radioactivity
nuclear medicine
technics of IR rays
thermography
technics of US
ultrasound - therapy
1950
electronics, semiconductors,TV image intensifier
1960
mikroprocessors, computers
digital image
1970
ultrasonography
1972 Hounsfield, McCormack
CT
1973 Lauterbur
principle of MR imaging
1980
digitalisation
digital methods, MRI
interventional radiology
1990
informatics
PACS, teleradiology
X-ray laboratory in 1900
Rhumkorff´s inductor (high voltage generator), X-ray tube without any
shielding, photographic plate
Biologic effects were not known, radioprotection did not exist.
Many pioneers of radiology died on radiation idnuced cancer.
Historical first X-ray tubes introduced by prof. Röntgen
Modified vaccum Crookes tube with cold cathode, anticathode and anode
Modern X-ray tube - Coolidge tube (since 1918)
+
-
Vacuum tube with heated
cathode filament emitting
electrons which collide with
the metal of anode, giving
rise to the primary beam of
X-rays
Coolidge tube in a protective shield
More than 95% of cinetic
energy of electrons is
transformed to heat.
Contemporary X-ray radiographic room
Contemporary radiology - 21. century
Radiology and medical imaging is a recognized clinical
discipline in all EU countries
Certification in radiology – 5 years
Radiology comprizes nowadays diagnostic as well as
interventional procedures
Higher degree of specialisation in Czech Republic:
pediatric radiology, interventional radiology,
neuroradiology
Related clinical disciplines: nuclear medicine, radiation
oncology ( radiotherapy )
Modern trends in radiology
analog imaging
morfology
digital imaging
function
qualitative evaluation
hybrid systems
interventional methods
ionizing radiation
quantitative evaluation
molecular imaging
miniinvasivity
methods without radiation burden
Radiodiagnostic methods - overview
X-rays
radiography
fluoroscopy
CT
US
ultrasonography
Doppler
IR
MRI
thermography
MRI
MRS
Basic principles of imaging methods
1. Transmission
(X-rays, CT)
S
P
source
pacient
D
detector
μ ≈ λ3 . Zef4
Primary beam of X-rays traverse the patient. In the patient a part of X-rays is
absorbed (photoeffect) and the attenuated beam continues to the detector and
creates the image. Another part is scattered (Compton´s effect)
The degree of absorption depends on the wavelength and on the effective atomic
number of the tissue
The scattered secondary radiation with longer wavelength is propagated in all
directions around the patient.
2. Emission
(NM, thermography)
P
S
D
The source of radiation is situated in the patient and radiation is emerging out
of the patient in all directions
In nuclear medicine a radionuclide is administred in the body and radiations are
registered by detectors outside of the body.
In thermography, the infrared radiation is emitted from the patient and registered
3. Reflection
(Ultrasound methods)
S
PP
D
The ultrasound probe contains both the source and the detector.
Sound waves arasing from the source (UZ probe) are reflected on impedance
interfaces of patient´s body back to the detector (UZ probe).
4. Principle of resonance absorption and emission (MRI)
M
S
D
Radiofrequency pulses are emitted from the source (coil) and irradiate the patient
placed in a strong magnetic field. If the resonance condition is installed the atomic
nuclei of the human body become excited, then the deexcitation signals are coming
back to the detector coil.
Floral
radiography
Soft
technique
Thank
you for
attention !