Ct scan

CT scan in brief

1. CT scan CT- Computed Tomography

2. 2D imaging was used – X-rays there was super imposition of structures. less clarity of images Prior to CT

3. Computed : use of computer Tomography: Greek word  tomos   means " slice ",   graphy   means " write ". Computed Tomography is the process of generating a two-dimensional image of a slice or section through a 3-dimensional object (a tomogram) Computed tomography (or computerized axial tomography) is an examination that uses X-ray and computer to obtain a cross-sectional image of the human body.

4. The first commercially CT scanner was invented by Sir Godfrey Hounsfield  in  Hayes, United Kingdom , at EMI Central Research Laboratories using X-rays The first EMI-Scanner was installed in  Atkinson Morley Hospital in Wimbledon, England The first patient brain-scan was done on 1 October 1971. Emi scanner is limited to scanning only brain. HISTORY

5. EMI SCANNER

6. Hounsfield and Cormack got the 1979   Nobel Prize for their contributions to CT. Allan McLeod Cormack 's theoretical calculations on x-ray was used by Hounsfield.

7. Initial sketch of ct machine by Housnfield

8. 1st model of CT machine by Housnfield

9. Housnfield with the 1st constructed CT machine

10. Gantry (scanner system) Patient's table Computer(operation control) Parts of a CT scan machine

11. Scanner system : X ray tube Detector system Collimators Filters

12. X-ray tube : generates x-ray beams Detector : detects the x-rays passing t hr ough the patient's body. Collimator : narrows the beams of x-rays Filters : these are used to filter some rays from entering the patient's body that may be harmful. P arts of G antry

13. 2 types Conventional : scan is taken slice by slice and after slice the scan stops. E.g.. from top of abdomen till the pelvis. This needs the patient to hold their breath. Spiral scan: continuous scan taken in spiral fashion. It is quick. Types

14. Principle

15. When X-rays pass through the human body, some of the rays are absorbed and some pass through the body to produce an image. In plain X-ray imaging, the film directly absorbs penetrated X-rays. In CAT scanning, an electronic device called a " detector array" absorbs the penetrated X-rays, measures the X-ray amount, and transmits the data to a computer system . A sophisticated computer system, in turn, calculates and analyzes data from each detector in each level, and finally reconstructs multiple, two-dimensional, cross-sectional images.

16. Displayed on screen Hounsfield scale( linear transformation reference being distilled water) Range from +1000(bone) to -1000(air/gas) Ct number or Hounsfield scale is a measure of radiodensity . Ct number measured in Hounsfield unit.

17. CT SCAN OF BRAIN

18. An imaging technique of the brain that reveal tumors, blood clots, hemorrhages, or other abnormal anatomy . A series of computerized images of the brain at various levels are taken to reveal normal anatomy or any abnormality.

19. Evaluate acute cranial-facial trauma determine acute stroke Evaluate suspected intracranial hemorrhage Evaluate headache Determine if there is abnormal development of the head and neck Tumours , clots Uses for brain

20. Parameters Scan range starting at base of the skull; ending at vertex of the skull Respiration : shallow breathing Positioning Supine Head immobilized Arms along the sides.

21. CT SCAN OF NECK

22. Patient preparation : Fasting for 4 Hours before the examination . Starting at floor of the mouth Ending at supraclavicular fossa . Respiration suspended in expiration with no swallowing. Parameters

23. Spine, airway ,carotid vessels, salivary and thyroid glands are included. To evaluate parotid or submandibular gland lesions or infections . Head and neck diseases Foreign bodies that are logged in the neck or upper airway Tumours or infections of pharynx vocal cord. Uses

24. CT scan of chest(lungs)

25. Show the size, shape, and position of lungs and other structures in the chest. Follow up on abnormal findings from standard chest x rays. Find the cause of lung symptoms, such as shortness of breath or chest pai n . Diagnose lung diseases such as a tumor , excess fluid around the lungs, or a pulmonary embolism. The test also is used to check for tuberculosis , emphysema and pneumonia Uses

26. CT scan of abdomen

27. To test abdominal pain or swelling Masses and tumours including cancer Injury or infections Kidney stones Appendicitis Alcoholic liver diseases Cancer of pancreas, colon, renal pelvis. Peritoneal fibrosis Uses

28. CT scan of bone

29. Purpose of the Bone CT Scan To identify abnormalities in the spine, such as spinal stenosis that may be causing back pain To detect bone tumors and tumors in the soft tissue surrounding bone s

30. To diagnose osteoporosis , which is common in women after menopause and also may occur in men To evaluate fracture To detect unusual formation of bone To diagnose joint abnormalities .

31. Quick and painless Can help diagnose and guide treatment for a wider range of conditions than plain X-rays Can detect the presence of more serious problems check if a previously treated disease has recurred No superimposition of images. Advantages

32. Small risk of developing cancer in future from exposure to X-rays. Risk is greater for children Uses higher doses of radiation are used in chest , abdomen , so the risks are in general greater than other imaging types Injection of a contrast medium (dye) can cause kidney problems or result in allergic or injection-site reactions in some people Some procedures require anesthesia Disadvantages

33. Requires breath holding which some patients cannot manage. Ct scan of brain can affect nearby bone . There is also risk of childhood cancer and leukaemia in mothers who have imaging during pregnancy. Pregnant women are not allowed for this imaging .

34. Thank you By SHREYA GOPINATH & G.SWATHI