Radiological Imaging Methods History, overview, principles 3. LF UK Praha Department of Radiology...
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Transcript of Radiological Imaging Methods History, overview, principles 3. LF UK Praha Department of Radiology...
Radiological Imaging Methods
History, overview, principles
3. LF UK Praha Department of Radiology 2012
D 3
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
X - rays
electromagnetic radiation
short wavelength
- flux of photons -
• penetrating
• nonvisible
• ionizating
E = h. f
f = c / λ
electromagnetic radiation
History of radiology
1895 Röntgen X-rays (rtg) roentgenology
1896 Becquerel natural radioactivity (α, β, γ)
1898 Mme Curie Po, Ra radiology
20. century
1940 F.J.Curie arteficial radioactivity nuclear medicine
1941 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)
Coolidge tube in a protective shield
Vacuum tube with heated cathode filament emitting electrons which collide with the metal of anode, giving rise to the primary beam of X-rays
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 digital imaging
morfology function
qualitative evaluation quantitative evaluation
hybrid systems molecular imaging
interventional methods miniinvasivity
ionizing radiation methods without radiation burden
X-rays US IR MRI
radiography
fluoroscopy
CT
ultrasonography thermography MRI
Doppler MRS
Radiodiagnostic methods - overview
Basic principles of imaging methods1. Transmission
S P D
source pacient detector
(X-rays, CT)
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 tissueThe scattered secondary radiation with longer wavelength is propagated in all directions around the patient.
2. Emission
S
P
D
(NM, thermography)
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
S
D
PP
(Ultrasound methods)
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
PS
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 !