1. Course Coordinator – sekar Lecturer, m.p.t, sports, majmaah university, ministry of higher education, cams, dept of pt&hr, kingdom of saudi arabia LECTURE – 1 – RHPT – 485 READING IN MEDICAL IMAGING LEVEL - 8

2. INTRODUCTION X-RAY  Discovered and named by Dr. W. C. Röentgen at University of Würzburg, 1895  Awarded first Nobel prize for physics, 1901

3. In 1895 Wilhelm Conrad Roentgen discovered X-rays, so paving the way for the development of a new branch of medicine called radiology. Initially, radiology was the science of 'X-rays', but today it involves a variety of imaging techniques to study and investigate patients so that a diagnosis can be achieved. In addition, therapeutic procedures are performed by radiologists under image guidance, a branch also known as interventional radiology.

4. FIRST X-RAY Roentgen’s wife's hand

5. What are the Different Imaging Modalities  Radiography “plain films”  Computed axial tomography “CT”  Magnetic resonance imaging “MRI”  Ultrasound “US”  Interventional radiology “angio”

6. RADIOLOGY TOOLS 6 X- RAY ULTRASOUND NUCLEAR MEDICINE MAGNETIC RESONANCE COMPUTED TOMOGRAPHY

7. HOW IS IMAGING DONE?  IONIZING RADIATION X-ray, CT, Nuclear Medicine  SOUND WAVES Ultrasound  MAGNETIC FIELDS / RADIO WAVES Magnetic Resonance To image the patient a energy source is directed into a volume of tissue and an image is created of the tissue interaction.

8. How to Approach Reading any Image  Identify the patient  When was the image taken  Are these the proper images  The five densities  Are the images technically adequate

9. Radiography – X - Ray  Also called “plain films” or “standard films”  Image formed using broad beam ionizing radiation  The image formed is related to the subjects density  May involve the use of contrast agents Iodinated Barium Air

10.  High Energy Photon --Kilo Electron Volts  Ionizing Radiation  Exposes Film / Detector  Projection Data X-RAY detector X-ray beam X-rays are short-wave electromagnetic radiation produced by accelerating electrons across an evacuated tube onto a tungsten anode using a high voltage.

11. An X-ray tube is similar to a light bulb with a filament and a current to heat the filament. There is also a high voltage to accelerate the electrons from the filament at a target. This collision releases the x-ray radiation that is used to image the patient.

12. X-RAYS PLAIN FILM RADIOGRAPHY - Clinical uses  Chest  Bones  Spine / Extremities / Skull  Soft tissue  Mammography / Abdomen  These are typical body regions that plain x-ray is used to evaluate.

13.  Air / Gas  Soft Tissue / Fluid filled space  Bone  Fat  Metal X - RAY --- FIVE BASIC DENSITIES

14. The x-rays can traverse tissue to create the image. We can only separate the 5 basic densities noted. Air / Gas, Soft tissue / Fluid filled space, Bone, Fat & Metal. Here we see the Air in the lungs, the soft tissue of the heart and the bone density of the ribs. Water will appear of the same density as soft tissue and cannot be separated. Fat is difficult to see on the chest and better noted on abdominal x- rays

15. CONTRAST RADIOGRAPHY  Injection, ingestion, or other placement of opaque material within the body.  Improves visualization and tissue separation.  Can demonstrate functional anatomy and pathology.

16. Administering a contrast agent modifies the image to give more information. Clinical uses :- Typical ones are barium, an inert particulate contrast used in GI tract evaluation. Iodine, a water soluble agent which can be injected into the vascular tree.(ANGIOGRAPHY) + intravenous agents to visualize the renal tract (intravenous pyelogram - IVP) Interventional procedures

17. UPPER GI--(GASTRO INTESTINAL) ORAL BARIUM CONTRAST ARTERIOGRAM INTRAARTERIAL IODINE CONTRAST

18. The contrast agent -Barium- will outline the GI tract, determine size and show patency or obstruction. The contrast agent-Iodine can be injected and is water soluble. In the blood stream, it will outline the vessel and demonstrate anatomy. Iodine is also filtered by the kidney and can show information about tissue function

19. Computed Axial Tomography  Also called CAT scanning or “CT”  Image formed using a rotating thin beam(s) of ionizing radiation  Image “slices” reconstructed by computation  The image formed is related to the subjects density  Image display on computer or multiple films  New technology is multislice helical scanner

20. Involves ionizing radiation. The X-ray tube is rotated around the patient and X-rays pass through them and are detected by photomultiplier tubes at the opposite end of the beam. Different tissues absorb or 'attenuate' the X-ray beam by different amounts. A computer processes the information about the attenuation in each picture element (pixel) into an axial image of the area being examined. In conventional CT the images are acquired a slice at a time with a slice thickness varying from 2 to 10 mm. In helical (spiral) CT the image is acquired volumetrically in a continuous movement with no gaps between the slices imaged. This enables the images to be manipulated in different planes and also allows structures to be viewed in three dimensions.

21. Uses - CT Oncology staging Trauma assessment Guiding biopsies Radiotherapy planning

22. COMPUTED TOMOGRAPHY CT  HIGH ENERGY PHOTON  IONIZING RADIATION  EXPOSES DETECTOR  TOMOGRAPHIC DATA

23. In CT scanning, we are able to get slice images or tomographic. Detectors in the CT scanner count the x-ray photons that traverse the patient from a rotating x-ray tube and use this data to assign a numerical value (CT number) to the tissue within the patient. The computer then assigns a whiteness or blackness to the tissue based on its CT number

24. LT Here the yellow line is showing the level where the CT section is made through the upper abdomen at the level of the liver.

25. Interventional Radiology  Also called angiography or “angio” or “IR”  Image formed using broad beam ionizing radiation (fluoroscopy)  Images acquired using digital detector and processed by computer  The image formed is related to the subjects density  Usually involves the use of iodinated contrast agents and long catheters  Many varied techniques including the use of CT or MRI  Image display on computer or multiple films

26. NUCLEAR MEDICINE  High Energy Photon  Ionizing Radiation --Radiopharmaceutical  Exposes Detector  Projection Data  Dynamic / Physiologic Here we have an example of a nuclear medicine bone scan with anterior and posterior views.

27. This branch of radiology uses radioisotopes for imaging. The radioisotopes produce gamma-rays that are emitted by the patient following intravenous injection of the isotope. The rays are detected by a gamma camera. Radioisotope investigation allows the assessment of function as well as structure. The commonest radioisotope used is technetium, which has a half-life of 6 h. Radioisotopes can be tagged with other substances that are selectively taken up by the parts of the body which are being examined.

28. Common radioisotope investigations Bone scan - Tc phosphonate to look for metastases Lung ventilation - Tc DTPA aerosol, krypton gas Lung perfusion - Tc micro-aggregate albumin to assess perfusion ventilation/perfusion scans for investigation of pulmonary emboli Cardiovascular - thallium scanning to look for cardiac perfusion abnormalities Renal tract - DMSA, DTPA, MAG 3 for assessing renal structure (DMSA) and function (DTPA and MAG 3) Thyroid - iodine or technetium to assess thyroid function/nodules

29. With Nuclear Medicine a radioactive drug is administered, a pharmaceutical portion of the drug has been created to localize to a type of tissue. The radioactive tag of the pharmaceutical serves to identify the site of accumulation. The detector or gamma camera which is similar to a Geiger Counter measures the radiation distribution and maps it to a region.

30. NUCLEAR MEDICINE EXAMPLES  Liver  Bone  PET scan

31. Here the radiopharmaceutical collects in a specific tissue and the radioactivity allows an image from the count of radiation (activity). This can be followed over time to see functional physiology. The PET scan is a scan showing increase in metabolism measured by injecting with a radioactive glucose…. The arrows indicate the lung cancer on the chest x-ray and the pet scan.

32. Ultrasound  Also called “sono” or “echo” or “US”  Image formed by transmitting and receiving high frequency sound waves  Image “slices” reconstructed by computation  The image formed is related to interfaces between tissue areas of differing sound transmission characteristics  Image display on computer or multiple films

33.  Ultrasound does not involve ionizing radiation.  It uses the principle of high-frequency sound waves, which when reflected back from structures in the body can be converted into a grey-scale image.  Ultrasound is a real-time examination, which means that a moving image of the body is seen on a screen, as are the scans.  Doppler ultrasound is used to measure blood flow in vascular structures and depends on the principle that there is a shift in reflected sound frequency from flowing blood in vessels.

34. Advantages Non-ionizing (no radiation) Safe Can be used to follow up patients Images in real-time – instantaneous Can be performed at the bedside Relatively cheap Disadvantages Difficult in obese patients Views are often obscured by air/bowel gas

35. BASIC ULTRASOUND PHYSICS Acoustic Windows  Dense & elastic structures  Liver  Spleen  Fluid-filled structures  Heart  Urinary bladder 35 Typically the ultrasound probe is placed over areas that transmit the sound best for imaging. These regions are called acoustic windows.

36.  Ultrasound Sector Scanning  B Mode-brightness  Most common use  Presents “real time” image The B mode shows intensity of reflection of the image by greater brightness. This is called echogenicity and can be used to separate tissue. The image shows a live screen view as a video feed would show.

37. ULTRASOUND ideal for fluid filled structures Gallbladder Kidney Obstetrics

38. Magnetic Resonance Imaging  Also called “MRI” (used to be NMRI)  Image formed by transmitting and receiving radio waves inside a high magnetic field  Image “slices” reconstructed by computation  The image formed is related to: Scanner settings Patient hydrogen density Patient hydrogen chemical/physical environment  Image display on computer or multiple films

40. MRI is one of the newer imaging modalities that does not involve ionizing radiation. It involves the use of radio-waves and magnetic fields to create an image of the body. The patient is placed in a magnet and a radio-wave applied. The nuclei of hydrogen atoms in water and fat absorb these waves and emit radiofrequency energy and this can be manipulated by computer to produce an image. Imaging can be conducted in several planes, e.g. coronal, sagittal and axial. Imaging depends on the fact that pathological tissues return a different signal to normal tissue and this property is utilized in trying to make a diagnosis from the images.

41. USES - MRI Brain, especially pituitary, posterior fossa Spinal cord Musculoskeletal Abdomen/pelvis gynecological malignancy liver

42. Contra-indications - MRI Pacemakers Metallic foreign bodies etc Claustrophobia

43.  Hydrogen protons in a magnetic field  Radio wave signal transmission  No ionizing radiation  Tomographic data MAGNETIC RESONANCE With magnetic resonance, the tissue response to magnetic fields and radio waves serves as the basis for imaging. The images are slices or tomographic and the plane of section can be determined by the machine.

44. MAGNETIC RESONANCE EXAMPLES  Brain  Spine RTRT Anterior Posterior Anterior Posterior Anterior Posterior  Knee

45. HOSPITAL TERMS X- Ray Plain Film Scout Film Radiograph Computed Tomography Cat Scan CT Nuclear Medicine Nuc Med Ultrasound Sono Sonogram Magnetic Resonance MR MRI Abbreviations used frequently in the medical community.

46. X-Ray  X-ray is emitted from outside the nucleus (electron shells).

47. Ionizing Radiation  Radiation causes ionization of atoms and molecules.  Ionization is the underlying mechanism for most radiation detectors and also is responsible for most radiobiological effects.

48. Biological Effect of Radiation  Why should we protect ourselves from radiation? Direct molecular absorption of energy DNA most susceptible

49. Indirect Action-Radiolysis of WaterIonization Dissociation

50. Free Radical Biological Damage  Cause damage to (DNA/RNA) which become non- functional

51. Somatic Effects  Acute or early (deterministic) within days dose dependent Seen in accidents and nuclear wars Affects acutely bone marrow, GI tract and skin and less neurological system.  Latent or delayed (stochastic). not seen for years cancer, cataract, shortened life span

52. Principals of Radiation Protection  Time  Distance  Shielding

53. TIME The total radiation exposure to an individual is directly proportional to the time he is exposed to the source. Therefore, it is wise to spend no more time than necessary near the source of radiation.

54. DISTANCE The intensity of radiation from a source varies inversely with the square of the distance. Therefore, radiation workers should maximize the distance between themselves and the radiation source.

56. Shielding Lead is most commonly used to shield photons in diagnostic imaging.

57. Angiography

58.  Real time X-ray study  Catheter placed through femoral artery is directed up aorta into the cerebral vessels.  Radio-opaque dye is injected and vessels are visualized  Gold standard for studying cerebral vessels.

59. Angiography AP Right ICA Lateral Right ICA AP Right Vertebral