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 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 methods 1. Transmission SP D source pacient detector (X-rays, CT) μ ≈ λ 3. Zef 4 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 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 P 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 !