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Spom Imaging
 

Spom Imaging

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    Spom Imaging Spom Imaging Presentation Transcript

    • Imaging Techniques
      • Utilize Ionizing Don’t Utilize Radiation Ionizing Radiation
      • Plain Films MR
      • Fluoroscopy US
      • CT
      • Nuclear Medicine
      • Mammography
    • X-Rays
      • High energy photons
      • Similar to visible light
      • But … have a higher energy and a shorter wavelength
    • Plain Films
      • X-ray tube shoots high energy electrons at a target (Tungsten)
      • When the electrons go around the nucleus of the Tungsten atom, the electrons lose energy
      • This occurs by 2 processes: Bremmstrahlung and K shell Knockout
      • Change in the energy of the electron results in radiation and x-ray formation
    • Plain Films
      • Finally, x-rays are collected on:
      • Photosensitive film (permanent)
      • Digital Imaging Plate (permanent)
      • Fluoroscope (temporary)
    • X-Rays
      • Can’t see the x-rays, only the images
      • Image seen is that part of the patient that blocks the x-ray beam.
      • The denser the material, the more difficult it is for the beam to penetrate the anatomic area
    • X-ray Exposure
      • Not all x-rays that enter the body leave it!
      • Absorbed x-rays can damage DNA, affecting future cells, causing mutations or cell death
      • Keep in mind, x-rays can be diagnostic or therapeutic
    • X-ray Exposure continued
      • X-ray exposure is cumulative
      • It is important to assess the Risk/Benefit ratio
      • 1. Does the patient really need the study?
      • 2. Can the study be done with other non-x-ray diagnostic studies?
      • 3. Can non-vital areas be shielded?
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    • Densities
      • Air - Lungs, Bowel gas
      • Fat - Omentum
      • Soft tissue - Muscle, Solid Organs
      • Bone - Skeleton, Calcifications
      • Metal - Hardware, Contrast
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    • Inspiration Expiration
    • Chest X-Ray Features
      • Symmetry - unilateral vs. bilateral
      • Location - upper, middle, lower, peripheral, central, anterior, posterior
      • Size
      • Number - Single, Multiple
      • Borders - Smooth, Irregular
      • Density - Solid, Air, or Fluid filled, or Combination
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    • Fluoroscopy
      • Live images obtained while a procedure or maneuver is being performed.
      • X-ray beam patient
      • X-ray strikes
      • coupled Fluorescent Plate
      • Image Intensifier
      • coupled TV Camera
      Image
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    • Ultrasound
      • High frequency sound waves sent into tissue and the reflected echoes create an image.
      • Real time images-demonstrate motion –ex. fetal heart beat
      • Doppler images-demonstrate speed and direction of flow in a vessel – ex. carotid artery
    • Ultrasound Continued
      • Thorax - Heart-wall thickness, motion, valves
      • Abdomen - Liver, spleen, pancreas, kidneys, masses, solid, cystic, stones
      • Pelvis - Female-Ovaries, uterus, fetus,
      • Male-Prostate, masses
      • Vasculature - Aorta-Aneurysms
      • Peripheral vessels-DVT
    • Ultrasound Continued
      • Densities:
      • Black - anechoic - low density - fluid
      • Gray - echogenic - medium density - soft tissue
      • White - hyperechoic - high density - calcium
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    • CT
      • In the gantry, there’s a series of small x-ray sensors which rotate. They take multiple x-ray pictures from various angles. Computers interpret the data, compiling the many images obtained. The images appear as cross-sectional slices obtained at many levels.
    • CT continued
      • Advantages
      • Almost all anatomic areas visible
      • Use with or without oral/IV contrast
      • Quick
      • Can differentiate different densities-air/fluid/soft tissue/bone
    • CT continued
      • Disadvantages
      • Ionizing Radiation
      • Cost
      • Not available at all institutions
      • May be hampered by metal/star artifact
    • CT continued
      • Densities- Hounsfield Units
      • Low Attenuation - black (air)
      • High Attenuation - white (bone)
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    • CT/MR
      • Key Features to Assess
      • Asymmetry
      • Masses or mass effect
      • Midline shift
      • Fluid collections
    • CT/MR continued
      • MR Advantages
      • Multiplanar images (axial, coronal, sagittal, oblique)
      • Greater gray/white differentiation
      • More detailed anatomy
      • Better visualization of subacute and chronic bleeds and spinal cord compression (trauma or mets)
      • CT Advantages
      • Availability
      • Speed
      • Cost
      • Can detect calcium and acute bleeds more easily
      • Accommodates patient monitoring equipment
    • MR
      • MR utilizes a magnetic field and radiofrequency antennas (coils) to obtain an image
      • The magnetic field causes all of the protons in the patient’s body to line up
      • Then, a high frequency magnetic pulse shifts them from their straight positions
      • A special antenna listens for the resonance signal each proton gives off
      • Characteristically, they go back to their original positions
    • MR
      • TR/TE
      • Marrow
      • CSF/H20/Disc
      • TR - Repetition Time - length of time needed for protons to realign
      • TE - Echo Time - measure of time for energy absorbed from the radiowave pulse to be reabsorbed
      T2 Long Dark Bright T1 Short Bright Dark
    • MR
      • Bright ( SI )
      • Fat
      • Hemorrhage
      • H2O/ Edema (T2)
      • Dark ( SI )
      • Air
      • Cortical Bone
      • Flowing Blood
      • Fibrous Tissue
      • H2O/ Edema (T1)
    • MR Precautions
      • Strong Magnetic Field-
      • Determine whether patients have:
      • aneurysm clips-head
      • pacemakers
      • artificial valves
      • exposure to metal shards
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    • Interventional Radiology
      • Can be diagnostic or therapeutic
      • Procedures:
      • Angiography-vessel visualization
      • Tube, line, stent, device placement
      • Biopsy
      • Complications:
      • Hemorrhage, embolus, infection
    • Interventional Radiology continued
      • Radiopaque dye (absorbs the x-ray beam) is administered via a catheter.
      • X-ray images reveal the anatomy to be normal or abnormal.
      • Abnormal features include stenosis (blockage), abnormal vessels (AVM), and Tumor Blush
    • Interventional Radiology continued
      • Contrast
      • Same dye used in other x-ray studies, IVP’s, CT’s
      • Dye-clear
      • Metallic taste
      • Warm flush feeling
      • Nausea
      • Ask about prior administration, allergies, and renal function
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    • Nuclear Medicine
      • A small amount of a radioactive isotope is administered to the patient – injected intravenously, inhaled or swallowed. These isotopes attach themselves to certain molecules in the body. Images are obtained to determine the abnormality.
    • Nuclear Medicine continued
      • Bone scan Tec 99m – 4 hours
      • Same amount of radiation as a CXR
      • Isotope excreted in urine
      • Images obtained initially and then 3 hours later. Actual scanning time 30-40 minutes
    • Nuclear Medicine continued
      • Bone Scan Increased uptake in:
      • Acute Fractures
      • Metastatic Disease
      • Growth Plates
    • Nuclear Medicine continued
      • Scans
      • Gallium – infection
      • Hepatobiliary – evaluate liver and gallbladder function and anatomy
      • Liver/Spleen – shape, size, position of organs
      • Thyroid scans – special instructions-
      • discontinue thyroid medication, no I.V. contrast, no seafood or Iodine containing products
    • Nuclear Medicine continued
      • V/Q scan evaluate air and blood flow to lungs
      • TC99m-MAA injected intravenously
      • Xenon-133 inhaled via mask
      • Test for PE, acute or chronic, pre-op lung reserves, effects of granulomatous lung disease, post-op complications, emphysema, heart shunts, congenital abnormalities
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    • Mammography
      • Film/Screen Technique - lower radiation dose
      • 2 views – craniocaudal, cephalad
      • Initial screening at age 40 unless high risk or symptomatic
      • Follow up with Ultrasound, MR (?)
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