BASIC KNOWLEDGE OF C T SCANNING

 BASIC KNOWLEDGE OF C T SCANNING

INTRODUCTION

 CT SCAN invented by Godfrey Housen Field in 1972, a basic principle of Computed  Tomography (CT) is the BASIC KNOWLEDGE OF C T SCANNING

internal structure of an object can be constructed from multiple cut /slice of the object though X-ray beam,

  • Earlier name C T scan is also known as CAT SCAN (COMPUTERISED AXIAL TOMOGRAPHY)
  • NOW KNOWN AS COMPUTED TOMOGRAPHY  /COMPUTERISED TOMOGRAPHY

CT SCAN  is a digital imaging technique

How to take C T SCANNING -Considered scan planning

1. Positioning of scout

2.Type scan – Axial or helical

3. Slice thickness

4. Increment ( distance between two slices)

5. Exposure factor – KVp, mAs

6. FOV- Field of View

7. Multiple reconstruction use in C T scan ( RECON TYPE –soft, stand std+, delt, chest, bone, abdomen, mediastinum )                             IMAGE FILTER –smooth (S1, S2, S3, S21…) LUNGS WINDOW –(L1, L2, L3…)

8.MPR- (MULTI PLANNER RECONSTRUCTION – 3D)-  AXIAL. CORONAL. SAGGITAL

9. Contrast requirement ( if need )

PARTS OF BODY WHICH ARE SCANNING ON  CT SCAN

BRAIN (GENERAL)

SKULL

CT ANGIOGRAPHY

FACE & NECK

  • FACE & SINUS
  • PETROUS BONE (TEMPORAL BONE –HRCT )
  • ORBITS
  • SALIVARY GLAND, PAROTID GLAGD, SUBMANDIBULAR GLAND
  • PHARYNX
  • LARYNX

 

SPINE ( VERTEBRAL STRUCTURE )

  • CERVICAL SPINE
  • DORSAL/THORACIC SPINE
  • LUMBAR  SPINE
  • SACRAL /COCCYGEAL SPINE AREA

 

CHEST / THORAX

  • CHEST GENERAL
  • CHEST – HRCT (HIGH-RESOLUTION COMPUTED TOMOGRAPHY

 

ABDOMEN & PELVIS

  • ABDOMEN GENERAL
  • LIVER& SPLEEN
  • PANCREAS
  • ADRENAL GLANDS
  • KIDNEYS
  • PELVIS GENERAL

 

JOINTS

  • HIP JOINT
  • SI JOINT
  • SHOULDER JOINTS
  • ELBOW JOINTS
  • WRIST  JOINTS
  • KNEE JOINTS
  • ANKLE JOINTS

 

BASIC KNOWLEDGE OF SCAN  POSITIONING ON CT SCAN

BRAIN

  • BASE OF SKULL TO VERTEX
  • SLICE THICKNESS -5 MM HELICAL / AXIAL
  • CONTRAST IN NEEDED – 30 TO 40 ML

 

FACE & SINUS

  • LOWER JAW TO FRONTAL PART OF BRAIN
  • SLICE THICKNESS – 2-3 MM  (HELICAL IMAGE )
  • CONTRAST 50-60 ML IF REQUIRED

 

NECK

  • LOWER JAW TO INLET OF THORAX
  • SLICE THICKNESS -3 MM
  • INCREMENT  1/2 MM
  • RECONSTRUCTION 1/1.5 MM
  • CONTRAST  50 ML IF REQUIRED

 

ORBITS

  • UPPER JAW TO FRONTAL PART OF BRAIN (ENTIRE ORBITS )
  • SLICE THICKNESS -2-3 MM (HELICAL)
  • CONTRAST 40-50 ML IF REQUIRED

SELLA

  • HYPOPHYSEAL REGION (ENDOCRINOLOGICAL DISEASE )
  • MAINLY  PITUITARY GLAND
  • SLICE THICKNESS – 2/3 MM (HELICAL)
  • CONTRAST 40 -50 ML

PHARYNX

  • LATERAL FROM ORBITAL ROOF TO ROOT OF NECK
  • VISUALIZATION –
  • ENTIRE PHARYNX
  • SLICE THICKNESS -2/3 MM  ( HELICAL)
  • CONTRAST 40-50 ML IF REQUIRED

 

LARYNX

  • FLOOR OF MOUTH TO THORACIC INLET
  • VISUALIZATION– ENTIRE LARYNX
  • SLICE THICKNESS -2/3 MM  (HELICAL)
  • CONTRAST 40 -50 ML IF REQUIRED

 

CHEST / THORAX

  • FRONTAL FROM MID NECK TO UPPER ABD
  • ENTIRE –THORACIC AORTA
  • VENA CAVA
  • HEART
  • THORACIC CAGE (RIBS )
  • LUNGS PARENCHYMA
  • SLICE THICKNESS 3-5 MM
  • CONTRAST -40 -60 ML IF REQUIRED

HRCT- LUNGS

  • ENTIRE LUNGS PARENCHYMA
  • SLICE THICKNESS -1/2 MM ( INCREMENT 5/6 MM )

 

ABDOMEN GENERAL  (SUPINE ARM ABOVE THE HEAD )

  • LOWER CHEST TO SYMPHYSIS PUBIS
  • SLICE THICKNESS- 5 MM ( HELICAL )
  • RECONSTRUCTION  1/2 MM
  • CONTRAST – ORAL, IV, RECTAL  IF REQUIRED BY DOCTORS
  • IMAGE VISUALIZATION
  • DIAPHRAGM
  • ENTIRE LIVER &SPLEEN
  • PANCREAS, ADRENAL GLANDS
  • KIDNEYS
  • URINARY BLADDER 
  • ABDOMINAL WALL; INCLUDING ALL HERNIATION
  • VESSELS  AFTER IV CONTRAST MEDIA TAKEN

 

PELVIS  ( SUPINE ARM ABOVE THE HEAD )

  • FRONTAL FROM ILIAC CREST TO PROXIMAL PARTS OF FEMUR
  •  SLICE THICKNESS- 3/5 MM ( HELICAL )
  • RECONSTRUCTION  1/2 MM
  • VISUALIZATION-WHOLE PELVIC RING
  • ENTIRE ILIAC BONES
  • ISCHIAL BONE
  • PUBIC SYMPHYSIS
  • URINARY BLADDER
  • ALL PERI PELVIC MUSCLE
  • VESSELS AFTER  IV CONTRAST MEDIA TAKEN

 

KUB

  • LOWER CHEST TO PUBIC SYMPHYSIS
  • SLICE THICKNESS -3/5 MM ( HELICAL )

VISUALIZATION –

  • KIDNEYS
  • URETERS
  • BLADDER
  • CONTRAST 50/60 ML IF REQUIRED
  • NOTE – URINE FULL BLADDER AS SOON AS POSSIBLE.

 

WRIST JOINT

  • ENTIRE WRIST
  • SLICE THICKNESS -2 MM ( HELICAL )
  • INCREMENT 1/2 MM

 

KNEE JOINT

  • ENTIRE KNEE
  • SLICE THICKNESS -2 MM
  • INCREMENT  1/2 MM

 

ANKLE JOINT

  • ABOVE THE TALOTIBIAL JOINT THROUGH  MID FOOT
  • THICKNESS -2 MM
  • INCREMENT  1/2 MM

 

SHOULDER JOINT

  • FROM JUST ABOVE THE ACROMIO CLAVICULAR JOINT TO SCAPULAR TIP
  • THICKNESS -2 MM  INCREMENT 1/2 MM

 

CERVICAL SPINE

  • FROM CRANIOCERVICAL JUNCTION( CVJ)TO MID OF T1
  • SLICE THICKNESS -3 MM
  • INCREMENT 1/2 MM
  • RECONSTRUCTION 1 MM

 

DORSAL SPINE

  • FROM C7 TO L1
  • SLICE THICKNESS -3 MM
  • INCREMENT 1/2 MM
  • RECONSTRUCTION 1 MM  

 

LUMBAR SPINE

  • FROM T12 TO S1
  • SLICE THICKNESS -3 MM
  • INCREMENT -1/2 MM
  • RECONSTRUCTION 1 MM

NOTE-IV CONTRAST, ORAL CONTRAST, RECTAL CONTRAST ALWAYS TAKEN EMPTY STOMACH 5/6 HOUR RESTRAINT FROM FOOD or LIQUID DIET.

(WATER CAN BE TAKEN )

CT CONTRAST AGENTS USED TO HIGHLIGHT SPECIFIC AREA, SO THAT ORGAN, BLOOD VESSELS OR TISSUES OR ANY  LESION VISUALISE MORE  CLEAR.

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BASIC KNOWLEDGE OF C T SCAN

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