Copy of Clinical Skill Diagnostic Imaging Approach Smst 2

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Clinical Skill

General Approach to Diagnostic

Imaging

ELYSANTI DWI MARTADIANIRADIOLOGY DEPARTMENT , UDAYANA SCHOOL OF MEDICINE/

SANGLAH GENERAL HOSPITALDENPASAR


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Diagnostic Imaging

Technique to make body imaging fordiagnostic purpose


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IMAGING MODALITY

Using ionizingradiation 1.Radiography :

a. plain radiographb. with contrast agent

2.Computerized X-ray tomography(CT Scan )

3. Radioisotop scanning= nuclear medicine= radionuclide scanning= scintiscanning


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IMAGING MODALITY

Without

ionizing

radiation

1. Ultrasound (US)

2. Magnetic ResonanceImaging (MRI)


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X-Ray

X-ray : part of electromagnetic wave Discovered by Conrad Roentgen (1895)

Short wavelenght can penetrate materials

without transmit visible light High voltage electric current passing across

the vacuum tube induced a stream of

electrons from cathode to strike a metal target(anode ) produced X-ray (1%) and heat (99%)


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How does x-ray produced ?

High voltage

electric current

passing across the

vacuum tube

induced a stream ofelectrons from

cathode to strike a

metal target(anode ) produced X-ray

(1%) and heat (99%)


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Radiation Hazard

Very large dose damage to humantissue.

Local tissue necrosis

Damage to the sensitive reproductive cell fetal deformity / sterility

Cancerous growth / leukaemia

Be carefull : pregnancy !


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Simple / Plain Radiography

X-ray beam is passed through the patienton to a photographic plate

Depend on the region that needs toexamine

Head , chest, abdomen, spine,limb etc


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RADIOGRAPHY


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Head

Radiograph


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Chest

radiograph


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AbdominalRadiograph/

BOF


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Limb / extremity Radiograph


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Spine Radiograph


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Contrast Radiography Contrast agent introduced into various

organ cavities, vein and arteries.

Upper Gastrointestinal (UGI) : gaster ,duodenum

Barium follow through : yeyunum, ileum(small bowel)

Barium enema/ colon in loop : large bowel

Invasive : Intravenous Urography /IVUArteriography


16/42Contrast study BOF


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Arteriography


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Radiography

ADVANTAGE

General overview

Low cost

Widely available

DISADVANTAGE

Minimal ability to

differentiate softtissue density

Cross-sectionalimaging ability (-)

Ionizing radiation

(+)


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Computed Tomography / CT Scan


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Computed Tomography /CT scan

Developed & introduced by Godfrey Hounsfield (1972)

X-ray fall not on the film x-ray but on to detectors

Detectors convert x-ray photon into scintillations

quantified & recorded digitally into computer

produced different readings data as the x-ray beam

traverse round the patient.


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CT Scan

Giving information about tissue density that is

equal with amount of x-ray absorbed by thetissue

More x-ray photons are absorbed by denser

tissue) HU ( Hounsfield Unit)

Demonstrate human body in the cross sectionalimage (slices)


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Head CT


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Chest CT


24/42Abdominal CT CT SCAN


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CT SCAN

Disadvantage

Ionizing radiation (+),higher than simple x-ray

Not portable

If using contrast :potensial nephrotoxic

Advantage

High quality image Anatomic overlapp (-)

Can differentatevarious tissue density

Widely available

High cost


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Radioisotope Scanning

Radioisotope : radioactive that

disintegrates spontaneusly, emittingradiation which includes gamma radiation

Half life : time taken for radioactive activityto fall by one-half ( i.e 6 hr for 99Tc)

Example : 123I , 125I, 131I,99Tc


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Radioisotope scanning

Particular isotopes selectively taken up byparticular organs using radiofarmaka

Radioisotop + radiofarmaka injected /

inhaled isotope release gamma raygamma ray is catched by gamma camerapicture that shows hot-spot or cold area,

depend on the uptake by the organs.


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Radionuclide Scanning

Giving information about physiological/ metabolic state.

Patient : source of radiation patient

isolation is important Low resolution anatomical picture

Price : medium high cost


30/42Bone Scintigraphy / Bone scan


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ULTRASONOGRAPHY

Can differentiate : solid from cytic

structure

Can not use for evaluate boneand air-filled structure


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USMACHINE


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US of the solid structure ( liver)


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US OF THE CYSTIC STRUCTURE : GALLBLADDER


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ULTRASOUND

ADVANTAGE DISADVANTAGE

Real-timetomographicimaging

Inexpensive

Portable

No ionizingradiation

Operatordependent

Can not evaluatebowel / bones

Soft tissue

resolution


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Magnetic Resonance Imaging/ MRI

MAGNETIC RESONANCE IMAGING


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MAGNETIC RESONANCE IMAGING/ MRI

Cross sectional imaging technique Strong magnetic field & multiple

radiofrequency generate image

Can evaluate almost every part of the body,especially soft tissue ( brain, muscle, spinalcord , etc)


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MRI

MRI


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MRI

ADVANTAGE DISADVANTAGE

Very goodresolution & softtissue contrast

Multiplanar

No ionizingradiation

Expensive Not good enough for

evaluating bone

Not portable Not widely available

Contraindication forpatient withpacemaker/ vascularstent/ vascular clip

S


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Summary There are many imaging modalities that

have their own advantage anddisadvantage

Conventional radiography, CT scan andradioisotope scan give ionizing radiation,but US and MRI do not give ionizingradiation

Sometimes one imaging modality is not

adequate, so that needs additionalexamination with other modality.


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THANK YOU

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Copy of Clinical Skill Diagnostic Imaging Approach Smst 2