Introduction to Radiology Final part 1.pptx

Best introduction to radiology

1. Introduction to Diagnostic Radiology for HO students JULY, 2024 Dr. Endale F. (Radiologist)

2. The History In 1895, Wilhelm Conrad Röntgen (or Roentgen), working in a darkened laboratory in Würzburg , Germany, noticed that a screen painted with a fluorescent material in the same room, but a few feet from a cathode ray tube he had energized and made lightproof, started to glow (fluoresce) There was no shielding so x-rays were emitted in all directions So……he discovered X-rays ......Nov 8, 1895 For this he was awarded the first Nobel prize in Physics in 1901 .…..

3. . He was doing experiment with cathode ray tube studying their behaviour in completely dark room. When tube was operating he discovered glow caused by fluorescence of plate left on the bench, when he reached for the plate he was shocked to see the images of bones of his hand cast on the plate.

4. Cont,… He called this unknown radiation which was invisible, could penetrate objects, and caused fluorescence x-ray because initially he did not understand its nature.

5. Print of Wilhelm Roentgen's first "medical" X-ray, of his wife's hand, taken on 22 December 1895 One of the first X-ray photographs was made of the hand of Roentgen's wife

6. Cont.…. X-rays are a form of electromagnetic radiation , their frequency and energy being much greater than visible light A high voltage generator supplies the required power to the X-ray tube A collimator is placed at the tube exit port to limit the extent of the X-ray field

7. X-Ray Tube Components Housing Visible part of tube Glass Enclosure (insert) Vacuum Electrodes Cathode Filament Anode Target *

8. X-Ray Tube Principle Filament heated electrons gain energy electrons freed (“boiled” off) Thermionic emission *

9. 8/3/2024 9 Cont… As a medical specialty, radiology can be classified broadly into  Diagnostic radiology and Therapeutic radiology/Radiation Oncology Ionizing radiation is common for both. Changes and developments of diagnostic radiology made areas of the body previously in-accessible to non-surgical exam clearly visible. Ability to accurately image all areas of the body made it possible for interventional & biopsy procedures to be performed using newer methods of diagnostic imaging for guidance .

10. Modalities of imaging in Diagnostic Radiology 8/3/2024 10 Plain film radiography Contrast enhanced radiography Mammography. CT MRI US , etc...

11. Basic principle of imaging 8/3/2024 11 Anatomic description of a particular region of body & its related abnormalitie s ..... So knowledge of anatomy and pathology are important prerequisite.

12. Plain film radiography 8/3/2024 12 Produced by x-ray passing through the patient and exposing radiographic film. Plain film means no contrast material is used to enhance various body structures. Plain film radiography :- Adequate when there is inherent contrast eg chest, skeletal system. Radiographic image is two dimensional representation of three dimensional structure.

13. General Principles of Radiography The energy of the radiation affects its penetrating power ( KVp , mAS ) Higher energy radiation can penetrate thicker and more dense materials The radiation energy and/or exposure time must be controlled to properly image the region of interest

14. Imaging Modalities Several different imaging methods are available to display the final image in radiography: Film Radiography Digital Radiography (DR).. uses flat panel detectors based on direct or indirect conversion of X-rays to charge, which is then processed to produce a digital image Computed Radiography (CR).. uses cassette-based phosphor storage plates (PSP), which are then scanned by the computerized system into a digital format

15. Film Radiography One of the most widely used and oldest imaging mediums in radiography Film contains microscopic material called silver bromide Once exposed to radiation and developed in a darkroom, silver bromide turns to black metallic silver which forms the image

16. Digital Radiography One of the newest forms of radiographic imaging Requiring no film, digital radiographic images are captured using either special phosphor screens or flat panels containing micro-electronic sensors No darkrooms are needed to process film, and captured images can be digitally enhanced for increased detail Images are also easily archived (stored) when in digital form and can be viewed by any authorized personnel's

17. Advantages of Digital Images over use of X-ray film Reduction in exposure Images can be transferred out of the department to other locations No problem finding film storage space Rapid finding of previous images for comparison

18. Production of images 8/3/2024 18 Image production by x-ray result from attenuation of those x –rays by the materials through which they pass. Attenuation :- removal of X-ray from the beam through absorption and scatter. The greater the density of the material the greater its ability to absorb and scatter. Absorption is also influenced by atomic number.

19. Cont... 8/3/2024 19 The denser the structure the greater the attenuation, which results in less blackening of the film.... i.e. fewer x-rays strike the film. Less dense structures attenuate the beam to a lesser degree & result in more blackening of the film ......i.e. more x rays strike the film.

20. Terms 8/3/2024 20 Physical density – number of grams/cc Structures that produce more blackening on a film are referred to as Radiolucent and those that produce less blackening are called radiopaque or radio dense.

21. NB: Objects of metal density are not normally present in the body. Radiologic contrast media and prosthetic knees or hips are examples of metal densities artificially placed in the body

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23. Recording Media 8/3/2024 23 1 X-ray film. 2 Fluoroscopic screen/image intensification system. 3 Photoelectric detector crystals. 4 Xenon detector system. 5 Computer linked detector system that measure actual attenuation.

24. Cont… 8/3/2024 24 X-ray film consists of a plastic sheet coated with a thin emulsion that contains silver bromide & a small amount of silver iodide . This emulsion is sensitive to light and radiation. When the film is exposed to light or to ionizing radiation & it will develop chemical changes within the emulsion resulting in deposition of metallic silver which is black. The amount of blackening on the film depends entirely on the amount of radiation reaching the film & therefore on the amount attenuated or removed by the subject .

25. CT(computed Tomography) scanners & Digital Radiography 8/3/2024 25 Utilize electronic sensors that actually measures the attenuation coefficient of tissue through which X-ray beam has passed and converts this mathematical value into digital shades of gray. The data are fed into computer that plots the location each of those measurements to produce the computer image. This is recorded & displayed on a TV monitor or made into a hard copy(film)by multiformat camera.

26. Factors affecting image quality Image quality Noise Blur or Unsharpness Contrast Distortion & artifact The most common cause of radiographic unsharpness is: Motion

27. Practices for Radiation Safety Radiation safety uses the “as low as reasonably achievable” (or ALARA) principle: … High-quality images should be obtained by using the lowest possible dose to limit the exposure of patients and health care workers. The goal is to prevent deterministic effects and limit stochastic effects.

28. . Stochastic effects …..Damage that may occur at any level of exposure, without a threshold dose. These effects occur by chance, and while their probability increases with an increasing dose, their severity is independent of the dose. Eg : hereditary/genetic/ effects, cancer Deterministic/non-stochastic/ effects … This is damage that occurs when a threshold level is met. Both the probability and the severity of the effect are proportional to increasing dose, where the dose is usually given in one exposure or several exposures over a very short period of time. Eg . Radiation-induced skin burns, Acute radiation syndrome/Radiation poisoning, Cataracts, Sterility, Tumor Necrosis .

29. Cont. Radiation hazards occur as a result of damage to cells caused by radiation Actively dividing cells are particularly sensitive, eg . the gonads and bone marrow The nature and degree of cell damage vary according to: Radiation dose Irradiated volume Type of radiation This damage takes many forms: Cell death Mitotic inhibition Chromosome damage/genetic damage leading to mutation

30. Factors to minimize radiation hazard All health care providers should understand the risks associated with radiation exposure and limit exposure when possible ….. Minimise number of X-rays taken Minimise fluoroscopy screening time Focus beam accurately to area of interest Only trained personnel should operate equipment Minimise use of mobile equipment Use ultrasound whenever possible Gonadal shield protection Only necessary people should be present in a room where X-ray procedures are being performed Staff should wear lead apron All X-ray rooms should have lead lining in their walls, ceilings & floors

31. Radiation safety The radiation leakage rate from the tube normally measured at a distance of 1 meter from the housing and should not exceed an air kerma of 1.00 milligray or 100 mR ( Milli -Roentgen) per hour measured at a distance of 1 meter from the focus Leakage levels should be checked at regular intervals as part of the quality checks on the X-ray unit

32. Special modification of plain film radiography 8/3/2024 32 Fluoroscopy Tomography.

33. Flouroscopy 8/3/2024 33 Is a term used when continuous low power x-ray beam passed through patient to produce a dynamic image that can be viewed on TV monitor A continuous x-ray beam passes through the patient & falls on fluoroscopic screen. The faint light pattern emitted by the fluorescent screen is amplified electronically by an image intensifier, image displayed on TV monitor.

34. Fluoroscopy 8/3/2024 34

35. Uses of flouroscopy 8/3/2024 35 To see: -GI peristalsis - Movement of diaphragm with respiration - Cardiac function - Valve calcification - Localization of chest mass. Fluoroscopy also used to perform & monitor continuous radiographic procedures such as barium studies ,catheter placements.

36. Contrast Examination 8/3/2024 36 Plain film radiography is adequate for situation where natural radiographic contrast exists b/n structures such as the heart & lungs or the bones & adjacent soft tissues. To examine structures that do not have inherent contrast differences from surrounding tissue it is necessary to use one of a variety of contrast agents eg ..GIT,GU, blood vessels Contrasts commonly used:- 1. Barium sulphate GIT 2. organic iodine preparations IV

37. contrast study 8/3/2024 37 Arterial system arteriography Venous system venography Spinal theca mylography Billiary tree cholangiography Salivary gland sailography Urinary tract urography(Iv urogram ) Vascular system angiography Sinogram done to visualize any abnormal opening (sinus) in the body Fistulogram

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40. Mammography. 8/3/2024 40 Is radiography of the breast, Much lower x-ray energies are used in mammography than any other radiographic applications, and consequently modern mammography uses x-ray machines and detector systems specifically designed for breast imaging. Mammography is used for -screening mammography- to screen asymptomatic women for breast cancer -diagnostic mammography -diagnosis of women with breast symptoms such as the presence of a lump.

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42. . 8/3/2024 42 Standard views are CC and MLO views

43. < . QUESTIONS THANK YOU!!!