Introduction to Medical Introduction to Medical ImagingImaging
From a presentation by From a presentation by
Jeff Benseler, D.O.Jeff Benseler, D.O.
ObjectivesObjectives
How do x-rays create an image of How do x-rays create an image of internal body structures?internal body structures?
What are the 5 basic radiographic What are the 5 basic radiographic densities?densities?
Try your hand at interpreting several Try your hand at interpreting several medical imaging cases.medical imaging cases.
List of diagnostic List of diagnostic imaging studiesimaging studies
Plain x-raysPlain x-rays CT scanCT scan MRIMRI Nuclear imaging/PETNuclear imaging/PET UltrasoundUltrasound MammographyMammography AngiographyAngiography FluoroscopyFluoroscopy
Which of these modalities useionizing radiation?
What are x-rays?
No mass No mass No charge No charge Energy Energy
What is yourdiagnosis?
Basic x-ray physicsBasic x-ray physics
X-rays: a form of electromagnetic energyX-rays: a form of electromagnetic energy Travel at the speed of lightTravel at the speed of light Electromagnetic spectrumElectromagnetic spectrum
Gamma RaysGamma Rays X-raysX-rays Visible lightVisible light Infrared lightInfrared light MicrowavesMicrowaves RadarRadar Radio wavesRadio waves
Three things can happenThree things can happen
X-rays can:X-rays can: PassPass all the way all the way throughthrough the body the body Be deflected or Be deflected or scatteredscattered Be Be absorbedabsorbed
Where on this imagehave x-rays passedthrough the bodyto the greatest degree?
X-rays Passing Through X-rays Passing Through TissueTissue
Depends on the energy of the x-ray Depends on the energy of the x-ray and the atomic number of the tissueand the atomic number of the tissue
Higher energy x-ray - more likely to Higher energy x-ray - more likely to pass throughpass through
Higher atomic number - more likely Higher atomic number - more likely to absorb the x-rayto absorb the x-ray
Diagnosis?
How do x-rays passing How do x-rays passing through the body create an through the body create an
image?image? X-rays that pass through the body to X-rays that pass through the body to
the film render the film dark (black)the film render the film dark (black) X-rays that are totally blocked do not X-rays that are totally blocked do not
reach the film and render the film reach the film and render the film light (white)light (white)
Air = low atomic # = x-rays get Air = low atomic # = x-rays get through = image is darkthrough = image is dark
Metal = high atomic # = x-rays Metal = high atomic # = x-rays blocked = image is light (white)blocked = image is light (white)
5 Basic Radiographic 5 Basic Radiographic DensitiesDensities
AirAir FatFat Soft tissue/fluidSoft tissue/fluid MineralMineral MetalMetal
1.
2.
3.
4.
5.
Name these radiographic densities.
History: “I think my dog swallowed a rock”
Diagnosis: “Yes, he did.”
Diagnosis?
Can you recognizeshapes and density?
Find the pathologyWhat clues do you have?
Medical ImagingMedical Imaging
Primary purpose is to identify pathologic Primary purpose is to identify pathologic conditions.conditions.
Requires recognition of normal anatomy.Requires recognition of normal anatomy.
History: 11 y/o twistinginjury of the foot
Proximal
Distal
1.
2.
3.
Word bank: epiphysis, metaphysis, diaphysis, cortex, medullary cavity
Naming the parts of a long bone
Summary: Summary: How do x-rays create an How do x-rays create an image of internal body structures?image of internal body structures?
X-rays pass through the body to X-rays pass through the body to varying degreesvarying degrees
Higher atomic number structures Higher atomic number structures block x-rays better, example bone.block x-rays better, example bone.
Lower atomic number structures Lower atomic number structures allow x-rays to pass through, allow x-rays to pass through, example: air in the lungs.example: air in the lungs.Question: If x-rays were blocked to the same degree by all bodystructures, could we see the internal parts of the body?
What are the 5 basic What are the 5 basic radiographic densities from radiographic densities from
black to bright white?black to bright white? AirAir FatFat Soft tissue/fluidSoft tissue/fluid Bone/mineralBone/mineral MetalMetal
What densityare the lungs?
Why?
The list: air, fat, soft tissue, mineral and metal
CT scan of the abdomenX-rays used skin
What density is this?
air
Di
Diagnosis?
Radiographic AnalysisRadiographic Analysis
Any structure, normal or pathologic, Any structure, normal or pathologic, should be analyzed for:should be analyzed for:
1.1. SizeSize
2.2. Shape and contourShape and contour
3.3. PositionPosition
4.4. Density (You must know the 5 basic Density (You must know the 5 basic densities)densities)
The anatomical positionThe anatomical position
right left
What densityis this?
Summary questionsSummary questions
What 3 things when an x-ray What 3 things when an x-ray encounters the body?encounters the body?
How is it possible to see the heart on How is it possible to see the heart on an x-ray?an x-ray?
What are the 5 basic radiographic What are the 5 basic radiographic densities?densities?
What three things can you do to What three things can you do to protect yourself from radiation?protect yourself from radiation?
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