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Introduction to Medical Imaging

Introduction to Medical Imaging. Instructors: Brian Fleming and Ioana Fleming flembri@pha.jhu.edu, ioana@cs.jhu.edu. Lecture 1. Meet and greet A brief history of everything Break Intro to Death Rays X-Rays. In the Beginning…. Where to put the Leeches. Hippocrates (460 - 377 BCE)

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Introduction to Medical Imaging

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  1. Introduction to Medical Imaging Instructors: Brian Fleming and Ioana Fleming flembri@pha.jhu.edu, ioana@cs.jhu.edu

  2. Lecture 1 • Meet and greet • A brief history of everything • Break • Intro to Death Rays X-Rays

  3. In the Beginning…

  4. Where to put the Leeches • Hippocrates (460 - 377 BCE) • Muscles, skeleton, kidneys • Observation only • Pesky “Oath” prevented human dissection • Aristotle and Friends (4th century BCE) • Animals aren’t people • Herophilos and Erasistratus (4th century BCE) • First human cadavers • Criminals aren’t people either

  5. Where to put the Leeches • Dark Ages - Europe • Balance the “humors” • Bleed, burn, drown, or exorcise • Dark Ages – Arabia/Persia • Avicenna (1020 AD) Canon of Medicine • Premier book of medicine everywhere for 500 years • Ibn Zuhr (1100 AD) • Invented Autopsy and discovered parasites • Would have killed the idea of humors if logic and fact had been considered a valid argument

  6. Where to put the Leeches • Printing Press – 17th century • Sharing of ideas brings renaissance (murder?)

  7. History of Medical Imaging Wilhelm Röntgen (Roentgen) • The father of diagnostic radiology • German physicist (1845-1923) • Discovered x-rays in 1895 • X was for "unknown“ • First Nobel Prize in physics 1901

  8. Discovery of X-rays

  9. How to Irradiate Yourself • Step 1 – Force electrons to go where no electron would ever want to go • In air, would cool by giving off light

  10. How to Irradiate Yourself • Step 2 – Get rid of the air • Air quenches electron escape • Unless you really ramp up the voltage… • Try Neon • Or try nothing…

  11. How to Irradiate Yourself • Step 3 – Run those electrons into a target

  12. “Instant” Success • Nov 8, 1895: Accidental discovery of x-rays • Dec 22, 1895: Bertha’s hand • Dec 28, 1895: first publication of results • Jan 1, 1896: Roentgen mailed copies to leading scientists • Jan 5, 1896: Austrian newspaper story • Jan 23, 1896: society presentation • Feb 8, 1896: 1st clinical use (in US!)

  13. Within One Year ... • 49 serious books on x-rays • 1,044 scientific papers • Known to: • spot cancer • treat cancer • cause cancer • Numerous patents

  14. What it REALLY Did…

  15. Fluoroscopy

  16. Fluorescence

  17. Filmed in X-ray!

  18. Early Popularity of Fluoroscopy • Simple fluoro equipment: • x-ray tube • electrical generator • scintillation screen • Convenience of real-time • Note: early film required 1-2 hours of exposure • (where was intensifier screen????)

  19. Red Goggles • Fluoroscopy images were dim • 1899: Beclere showed that dark adaptation is a function of the retina • 1901: Williams suggested 10-minute dark adaptation • 1916: scientific basis of sensitivity of retinal rods in the range of red light • 1916-1950’s: red goggles standard gear

  20. X-ray Hazards • Early 1896: reports of hair falling out • Early 1896: skin reddening, inflammation • Early 1896: some severe burns (attributed to high voltage in tubes) • Early 1896: delayed burns • 1902: Edison clear on dangers of x-rays • Clarence Dally’s oozing ulcers, lost fingers, left hand, died in 1904 (Edison never x-rayed again) • The use of X-rays for medical purposes (to develop into the field of radiation therapy) was pioneered by Major John Hall-Edwards in Birmingham, England. In 1908, he had to have his left arm amputated owing to the spread of X-ray dermatitis

  21. Some More Landmarks • 1896: Becquerel discovered radioactivity • 1896: stereoradiography developed • 1901: contrast agents described • 1904: lead glass protection devised • 1904: exposure badge invented First angiogram

  22. Coolidge X-ray Tube: 1913 • Properties of new tube: • high vacuum • hot cathode • tungsten-target • Five outstanding properties • accurate adjustment • stable • reproducible • range of x-ray energies • less scattered radiation William Coolidge (expense prevented routine use until 1930’s)

  23. Potter-Bucky Grid: 1913-1920 • Scattered x-rays cause blurring • 1913: Gustav Bucky: metal collimator grid • reduce scatter blur • 1920: Hollis Potter: movable grids • reduce image of grid

  24. Conventional Tomogram: 1929 • Overlapping tissues blur tissue of interest • Jean Kieffer invented conventional tomogram to image an interior slice • to help diagnose his own TB! Only amateur in >100 years to make a significant discovery in medical imaging

  25. Tomography • Much as any light/camera, there is a focal plane • My moving source and camera in opposite directions, focal plane becomes sharp • Basis for almost all modern medical 3-D devices except Ultrasound. • CAT = Computed Axial Tomography • PET = Positron Emission Tomography

  26. Tomography (Again!)

  27. Tomography was hard • So it really wasn’t used all that much… • Until 1972, when computers and motors led to the development of CAT

  28. Impact of X-rays • Widespread detection of tuberculosis in 1917 • 1898: American Roentgen Ray Society • 1927: proof of cell damage caused by x-rays • 1935: radiologist required to interpret radiograph in court (anybody could previously) • Shoe fluoroscopes from 1920’s to 1960’s

  29. Out with the old, In with the nukes • X-rays were (and still are) limited. • Dim, for one (unless subject already dead) • Cannot track temporal events well • Blood flow • Brain activity • Etc • Enter nuclear medicine

  30. Radioactive Decay • Antoine Henri Becquerel (1852 – 1908) • Shared Nobel Prize of 1903 with Marie and Pierre Curie for discovery of radioactivity • Studying phosphorescence in Uranium salts on one side of his desk and the effect of bright sunlight on fluorescent coated photographic plates on the other.

  31. Nuclear Physics in a Slide

  32. Spontaneous Decay • Every atom in the universe has a chance of spontaneously decaying • p+ π0 + e+ • Happens about once every universe • Generally, large isotopes ( > Fe) Alpha decay • Nucleus binding energy is unstable • Mass products have lower mass than parent • 238U  234Th + 4He • Beta Decay = emission of electron or positron • p+ n0 + e+ + ν • Electronic Transmutation – 15O  15N- + e+ + ν • Gamma Decay – excess from β decay

  33. Back to Nuclear Imaging • Radiopharmaceuticals are injected • Biodistribution process causes • absorption, distribution, metabolism, excretion • Radioactive decay occurs, producing: • gamma rays (single photons), or • Single Photon Emission Computed Tomography (SPECT) • positrons (which yield paired photons) • Positron Emission Tomography (PET) • Location and counts are recorded as images

  34. Positron Annihilation • Positrons are Anti-matter (anti-electrons) • When matter and anti-matter collide, they annihilate • Mass energy of electron + positron released as two photons • Total energy = 2*0.511 MeV + extra conserved energy

  35. Nuclear Medicine • Step 1 – Inject patient with a radioactive substance • Alpha, Beta, or Gamma? • PET, SPECT • Step 2 – Wait for body to distribute • Choose radiopharmaceutical depending on target • Step 3 – Take photos, make scrapbook Gallium scintigraphy looks for recurrence of malignant melanoma

  36. Radiopharmaceuticals? Tc = Technitium, In = Indium

  37. Nuclear Medicine LandmarksSingle-photon imaging • 1896: Becquerel discovered radioactivity • 1930’s: Hevesy mapped internal organs • late 1930’s: discovery of technetium • 1946: AEC allowed isotopes for medical use • 1950’s: Anger invented gamma camera • 1968: SPECT introduced by Kuhl • 1980’s: Dual/triple headed SPECT systems

  38. Gamma Camera • For: • planar imaging • SPECT imaging SPECT = single photon emission computed tomography

  39. Commercial Gamma Cameras Siemens Toshiba For planar imaging and SPECT

  40. [Normal male, Tc-99m HMPAO, for cerebral blood flow, Brighamrad]

  41. normal Tc-99m MDP bone scintigram (5 mCi injected dose).

  42. Commercial PET Scanners CTI/Siemens

  43. PET Images Parkinson's Disease Huntington's disease Dopamine receptors Myocardial perfusion

  44. Ultrasound Imaging

  45. Medical Ultrasound • 1940’s – Ultrasound used to ease pain • Dr. George Ludwig, Naval Medical RI, Bethesda • 1949 - Dr. John Wild measures how thick your colon (wall) is • “Father of Medical Ultrasound” • 1953 – Inge Edler asks Carl Hertz if he can use radar to see inside the body. • No, but they use ultrasound to measure heart activity, published in 1954

  46. Medical Ultrasound • 1958 – Prof. Ian Donald treats the wife of one of the directors of Babcock and Wilcox • Asks to visit with R&D to see their toys • Asks to play with ultrasound • Uses it on volunteers to measure ultrasonic properties of various people with illnesses • Publishes "Investigation of Abdominal Masses by Pulsed Ultrasound” • The most important medical imaging paper… EVER • Goes on to study the growth rate of fetuses, first use of US in obstetrics

  47. Medical Ultrasound • 1965: First real-time ultrasound scanner • 1970: commercial systems widespread • mid-1970’s: grayscale and Doppler systems • early-1980’s: phased-array systems • mid-1990’s: 3-D ultrasound

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