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?