Principles of Radiology

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Principles of Radiology

• Daniel Podd RPA-C

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Physics of Radiology

• X-Rays produced by electron beam hitting tungsten
  film target
• Electrons strike film, metallic silver is
  precipitated if no obstruction to beam, resulting
  in bright film
• Obstruction in path of beam prevents silver
  precipitation film remains dark
• The negative of this film is known as the Plain
  X-Ray, or radiograph

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Positive Negative (Developed)
Radiograph, Plain Film
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Radiodensity as a Function of Thickness
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Radiodensity as a Function of Composition with
Thickness Kept Constant
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X-Ray
A-D Radiolucent or Radioopaque?
Why?
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AP CHEST Patient Position
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AP CHEST
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PA CHEST Patient Position
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L Lung R Rib T Trachea  AK Aortic knob A
Ascending aorta H Heart   V Vertebra
P Pulmonary artery S Spleen
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Lateral
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Bullet PA only ?
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Bullet PA Lateral
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PA Chest
Lordotic View
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Fluoroscopy

• Mechanism Continuous below patient, amp- lified
  by intensifier above patient broadcast on
  high-resolution television screen
• Provides live animation
• Imaging reversed vs xray
• Uses Barium swallow to

X-ray beams from
evaluate esophagus,

• small and large intestines, vessel catheter
  guidance

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Fluoroscopy
Spot Film Single X-ray during procedure. Film
developed into negative
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Angiography

• Mechanism Uses X-rays and intravascular
  injection of iodinated contrast to evaluate
  arterial (arteriogram) and venous (venogram)
• systems
• Vasoocclusive
• disease

• Most approaches
• via femoral artery
• or vein

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Computerized Axial Tomography

• Cross-sectional slice radiographs of the body
  using thin beam of X-rays through desired axial
  plane
• Slices up to 1.0 mm that represent density
  values no superimposed images
• Viewed as if facing patient and looking up
  through feet
• Density Less Dense Air, Fat (black)
• More Dense Bone (white)

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CT Scan
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CT Scan Angiography

• 3DCT, 3-Dimensional CT scan
• Injection of IV contrast to enhance vascular
  system
• Useful for aortic aneurysms, coronary heart
  disease, carotid vascular occlusive disease

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CT Scan Angiography
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Ultrasound

• Mechanism High-frequency sound waves beamed
  directed into body, onto organs and their
  interfaces transducer receives and interprets
  reflection of these beams from organs
• Acoustic Impedance beam absorption by tissues,
  based on density and velocity of sound through
  different adjoining tissue types

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Ultrasound

• Image (echo) produced when different neighboring
  tissues reflect different acoustic impedances
• Solid organs, fat, stones Echogenic (white)
• Fluid cysts Anechoic (black)

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Ultrasound
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Ultrasound

• Advantages
• No ionizing radiation
• Applicable to any plane
• Cost-effective
• Portable
• Real-time imaging

Disadvantages 1. Time consuming 2. Poorer quality
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Magnetic Resonance Imaging (MRI)

• Mechanism Patient placed in magnet tunnel
  radio waves passed through body in pulses. Pulses
  returned from tissues, transformed into 2D image
  based on relaxing times T1 T2

• T1
• T2

High Signal (brightness) Low
Signal
fat, medullary bone blood (gray), solid mass, cysts, air, compact bone
tumors, solid masses, CSF, cysts compact bone, blood, fat, air
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MRI

• Advantages vs CT
• Multiplanar scanning
• Better soft-tissue differentiation
• 3. Contrast-free 3DMR
• Contraindications
• Metals, clips, pacemakers

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MRI
T1
T2
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Normal CXR
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Normal CXR
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Enlarged Hila
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Aortic Knob
Hilar Mass (Left)
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Right vs Left Pulmonary Artery

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• Kerley B-Lines
• Fine horizontal opacified
  lines representing pulmonary edema
• Seen in CHF, pulmonary fibrosis, heavy metal
  fibrosis, malignancy

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Blunted Costophrenic Angle
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Lung Mass Cavitation
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Lung Mass Solid Tissue
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Air Space (Alveolar) Disease
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Interstitial Disease
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Alveolar or Interstitial?
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Alveolar or Interstitial?
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Alveolar or Interstitial?
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Lobar Consolidation Right

• Think anatomically
• 3 Lobes

• RLL located Lateral to heart, but anterior to
  diaphragm
• Obliteration of right CoPhS
• Right heart border intact

• RUL and RML located
• Anterior to heart
• Obliteration of
• mediastinum and cardiac
• borders
• Right CoPhS intact

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Lobar Consolidation Left

• LUL lies anterior to heart and superior to
  diaphragm (and LLL)
• Obliteration of left heart border only
• Left hemidiaphragm intact

• LLL located lateral to heart and anterior to
  diaphragm
• Obliteration of left hemidiaphragm
• Left heart border intact

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Where Is This Consolidation?
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Diaphragm
Gastric Bubble
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Diaphragm Expiration vs Inspiration
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Pleura

• Anatomically, the visceral and parietal pleura
  are separated by a potential space, the pleural
  space
• Fluid in this space is known as a Pleural
  Effusion
• Effusions may be large or small, but settle to
  base of lung due to gravity
• Completely obscures aerated lung and
  heart/mediastinum/diaphragm borders

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Pleural Effusion Large
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Pleural Effusion Small
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Pleural Effusion Small (special case)
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Pleural Effusion Small (special case)
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Pneumothorax

• Introduction of air into the normal vacuum of
  pleural space
• Radiographic findings
• 1. Hyperlucent versus aerated lung 2. Passive
  atelectasis of ipsilateral
  lung
• 3. Depression of ipsilateral
  hemidiaphragm
• 4. Mediastinal shift

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Pneumothorax

• Optimal Radiographic Images
• Expiration film
• 2. Lateral decubitus film

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Pneumothorax
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Subtle Pneumothorax
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Pulmonary Embolism

• Lung vessel embolus
• Radiologic findings
• 1. Diminished lung volume
• Elevated ipsilateral
  hemidiaphragm
• Linear/patchy ipsilateral atelectasis
• 2. Completely Normal ! (m/c)
• CXR to rule out other etiologies

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Pulmonary Embolism
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Pulmonary Embolism

• With Infarction
• 1. Hamptons Hump

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Pulmonary Embolism
Further Diagnostics

• Perfusion Test (Q)
• Technetium-99

• Ventilation Test (V)
• Xenon gas

Perfusion/Ventilation mismatch, V/Q Mismatch
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Pulmonary Embolism

• V/Q Scan Interpretation
• Normal Perfusion scan Rules out PE
• Negative/Low Probability scan (slight perfusion
  abnormality or V/Q matching) Non-embolic
  pulmonary abnormalities
• Positive/High Probability V/Q mismatch
• Intermediate/Indeterminate Low High
• Pulmonary Angiogram indicated for 3, 4, or 2 with
  strong clinical evidence

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Pulmonary Angiogram

• Gold Standard

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Helical (Spiral) CT Scan

• Indicated for suspected PE with abnormal CXR
• CT venogram Adding IV contrast for concurrent
  deep leg vein scan

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References

• http//www.vh.org/adult/provider/radiology/icmrad/
  chest/parts/Righthilum.html
• http//www.meddean.luc.edu/lumen/meded/medicine/pu
  lmonar/cxr/atlas/cxratlas_f.htm
• http//www.meddean.luc.edu/lumen/meded/medicine/pu
  lmonar/cxr/atlas/hilar.htm
• http//uwcme.org/site/courses/legacy/threehourtour
  /edema.php
• http//www.meddean.luc.edu/lumen/meded/medicine/pu
  lmonar/cxr/atlas/apwindow1.htm
• http//info.med.yale.edu/casebook/intmed/manditi/t
  est_results.html
• http//www.meddean.luc.edu/lumen/meded/medicine/pu
  lmonar/cxr/atlas/normallabeled.htm
• http//www.premedonline.com/Personal_Page/rad.html
  
• http//sfghed.ucsf.edu/ClinicImages/chest_and_pelv
  is_films.htm
• http//www.virtual.epm.br/material/tis/curr-med/me
  d3/2003/ddi/matdid/cap2.htm

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References

• http//www.virtual.epm.br/material/tis/curr-med/me
  d3/2003/ddi/matdid/cap1.htm
• http//www.fhsu.edu/nursing/cxr/CostoPhrAngCopy.ht
  m
• http//www.aic.cuhk.edu.hk/web8/0122_CONSOLIDATION
  _LATERAL_SEGMENT_RML.jpg
• http//www.med.wayne.edu/diagRadiology/TF/Chest/CH
  04.html
• http//acbrown.com/lung/Lectures/RsVntl/RsVntlMscl
  Dphr.htm
• http//www.nyp.org/masc/images/nl3_ph11.jpg
• http//www.lumen.luc.edu/lumen/MedEd/medicine/pulm
  onar/images/effusion.jpg
• http//brighamrad.harvard.edu/Cases/bwh/hcache/116
  /full.html
• http//www.radiology.co.uk/srs-x/cases/094/a.htm

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References

• http//brighamrad.harvard.edu/Cases/bwh/images/84/
  R54A2.GIF
• http//uwcme.org/site/courses/legacy/threehourtour
  /images/PTXPA.jpg
• http//www.med.wayne.edu/diagRadiology/TF/Chest/CH
  08.html
• http//www.nature.com/ncpcardio/journal/v2/n2/thum
  bs/ncpcardio0118-F2.jpg
• http//www.vh.org/adult/provider/radiology/icmrad/
  nuclear/parts/HiProb.html
• http//www.rochestermedicalcenter.com/images/a015.
  jpg
• http//www.engineering.uiowa.edu/bme185/angiogram
  .gif
• http//www.vh.org/adult/provider/radiology/Electri
  cPE/RadImages/03.RT-Angio.gif
• http//www.usask.ca/medicine/imaging/Clinical/GF.s
  html
• http//health.allrefer.com/pictures-images/pancrea
  tic-cystic-adenoma-ct-scan.html
• http//www.mia.net.au/perrett/info_general/ct_angi
  o/Image2.jpg
• http//www.terarecon.com/gallery/images/us_7_galls
  tones.jpg