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

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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