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1. How does it work? Lecture 1-2

2. Radiology Methods – Principles of Operation and Applications Radiology encompasses a wide range of methods that use different physical principles to visualize internal structures of the body. The main methods include radiography, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound diagnostics (US), and positron emission tomography ( PET

3. Classification of Radiology Diagnostic Methods All methods are categorized into ionizing and non-ionizing techniques.

4. Ionizing Methods Radiography (X-ray) Computed Tomography (CT) Angiography

5. Non-Ionizing Methods Magnetic Resonance Ima Ultrasound (US) diagnostics ging (MRI

6. What the deal Ionizing radiation has enough energy to remove electrons from atoms, creating ions. This process can damage cells and DNA. Non-ionizing radiation does not have enough energy to ionize atoms but can cause thermal and mechanical effects.

7. Imaging Method Imaging Method Type of Radiation X-ray (Radiography) X-ray (Radiography) X-ray CT (Computed Tomography) CT (Computed Tomography) X-ray Scintigraphy (Isotope-based methods) Scintigraphy (Isotope-based methods) Gamma radiation PET (Positron Emission Tomography) PET (Positron Emission Tomography) Gamma radiation MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Radio waves, magnetic field Ultrasound (Sonography) Ultrasound (Sonography) Sound waves Optical Imaging (Infrared Thermography, Endoscopy) Optical Imaging (Infrared Thermography, Endoscopy) Light waves

8. Why Is It Important to Understand These Methods? Patient Safety : Improper use of ionizing methods can cause radiation damage to tissues. Medical Staff Protection : Working with ionizing radiation requires strict safety measures. Principle of Justification : Every use of ionizing radiation must be justified (X-rays should not be performed without necessity).

9. Radiation affects body cells, causing mutations, cellular damage, and even cell death. Acute Radiation Syndrome (ARS) occurs at doses above 1 Sv (Sievert) . Increased Cancer Risk is linked to chronic exposure, even at low doses. Biological Effects : DNA damage → mutations → cancer Blood disorders (leukemia) Cataracts (if eyes are exposed) Fertility issues (if reproductive organs are exposed)

10. Safe and Dangerous Radiation Levels( Radiation doses are measured in millisieverts ( mSv ) or sieverts ( Sv ) . Radiation Dose Effect 0.1 mSv Single chest X-ray dose 2-5 mSv Annual natural background radiation 10 mSv Chest CT scan

11. 50 mSv Maximum annual dose for radiation workers 100 mSv Increased cancer risk threshold 1000 mSv (1 Sv) Acute radiation syndrome (nausea, vomiting) 4-5 Sv 50% mortality without medical treatment 8-10 Sv Near 100% mortality

12. How to Protect Against Radiation? Time : Minimize exposure time. Distance : The farther from the source, the lower the dose. Shielding : Use lead aprons, protective walls.

13. Radiography (X-ray) Wavelength: 0.01–10 nm (X-ray radiation) Applications: Orthopedics, pulmonology, dentistry, traumatology Indications: Bone fractures, lung diseases, dental problems, tumor diagnosis

14. Radiography (X-ray) Contraindications: Pregnancy (relative), high radiation sensitivity Principle of operation: The X-ray tube generates a beam of X-rays that pass through the patient’s body. Different tissues absorb radiation to varying degrees: bones absorb more than soft tissues. The remaining radiation is recorded by the detector, forming an image. Image acquisition: The detector captures transmitted radiation, forming a black-and-white image where dense structures (bones) appear bright, and soft tissues appear darker.

15. Computed Tomography (CT) Wavelength: 0.01–10 nm (X-ray radiation) Applications: Neurosurgery, oncology, traumatology, vascular diagnostics Indications: Tumors, hemorrhages, internal organ pathologies, trauma Contraindications: Pregnancy, allergy to contrast agents (if used) Principle of operation: A rotating X-ray source emits thin layers of X-rays around the patient’s body. Detectors capture data, and a computer converts them into cross-sectional images of the body. Image acquisition: A computer program reconstructs three-dimensional anatomical structures, allowing visualization of the body in different planes.

16. CT

17. Magnetic Resonance Imaging (MRI) Wavelength: Radio waves (0.01–300 m) Applications: Neurology, orthopedics, cardiology, oncology Indications: Brain and spinal cord disorders, joint pathologies, cardiovascular diseases Contraindications: Presence of metallic implants, pacemakers, claustrophobia (relative) Principle of operation: A strong magnetic field affects hydrogen atoms in tissues, altering their energy state. Then, radio waves excite the atoms, causing them to resonate. When atoms return to their original state, they emit radio signals recorded by detectors. Image acquisition: The computer analyzes the signals and creates detailed images of soft tissues, making the method particularly useful for diagnosing brain, joint, and internal organ diseases.

18. MRi

19. Ultrasound (US) Wavelength: 1–20 MHz (ultrasound) Applications: Obstetrics, cardiology, gastroenterology Indications: Pregnancy assessment, internal organ diseases, vascular diagnostics Contraindications: Practically none Principle of operation: Ultrasound waves are emitted by a transducer and penetrate the patient’s body. Different tissues have different acoustic densities, affecting wave reflection. The transducer captures echo signals, which are converted into images. Image acquisition: The computer analyzes the difference between transmitted and reflected signals, forming two-dimensional or three-dimensional images of organs and tissues.

20. Ultrasound

21. Positron Emission Tomography (PET) Wavelength: Gamma radiation (up to 511 keV ) Applications: Oncology, neurology, cardiology Indications: Metastasis detection, functional brain activity research, heart disease diagnostics Contraindications: Pregnancy, kidney failure (when using radiopharmaceuticals) Principle of operation: A radioactive substance is injected into the patient, accumulating in specific tissues. When positrons and electrons annihilate, gamma radiation is emitted and detected. Image acquisition: A special program analyzes the data, creating a distribution map of the radiopharmaceutical, allowing visualization of metabolic processes in the body.

22. Conclusion Each radiology method has its own characteristics, advantages, and limitations. The choice of method depends on the clinical situation, patient characteristics, and the need for specific information about the condition of internal organs and tissues. It is essential to consider indications and contraindications and ensure patient safety during examinations.