CT COLONOSCOPY

Colonoscopy

1. CT COLONOSCOPY ANOOP A.B BSc MIT INTERN KSHEMA

2. INTRODUCTION CT colonoscopy or virtual colonoscopy is a medical imaging procedure which uses x-rays and computers to produce two and three dimensional image of the colon. It includes images of large intestine,small intestine, rectum C T colonoscopy is mainly used to evaluate colorectal polyp detection, and it may be used for colorectal screening

3. ANATOMY

4. BLOOD SUPPLY

5. INDICATION Screening for polyps Incomplete colonoscopy Colorectal cancer

6. CONTRAINDICATION Pregnancy Presence of barium in the bowel

7. PARIENT PREPARATION Information about the procedure Instruct the patient to remove all the metallic objects from the part of interest The patient will usually be asked to take laxatives or other oral agents at home the day before the procedure .

8. PROCEDURE The patient is placed in a supine position on the examination table. A thin tube is inserted into the rectum , so the air can be pumped through the tube in order to inflate the colon for better viewing

9. The table moves through the scanner to produce a series of two dimensional cross sections along the length of the colon. A computer program puts these images together to create a three-dimensional pictures that can be viewed on the video screen. The patient is asked to hold his/her breath during the scan to avoid distortion on the images

10. The scan is then repeated with the patient lying in a prone position. After the examination , the images produced by the scanner must be processed in to a 3d images. The patient may resume normal activity after the procedure.

11. PROTOCOL PROTOCOL ABDOMEN SCANOGRAM Supain AP Patient position/land mark supain feet first/xiphoid process Start location mediastinum End location Pubic symphysis Slice thickness 5 mm Increment 5 mm Scan direction Caudo -cranial Scan type helical Gantry ankle None Resolution 512x512 matrix Post processing VR,MPR kV 120 mAs 250 Filter standard

12. MOV_0263.mp4

13. POST PROCESSING Three dimensional navigator
3D colon
Fly through

14. THREE DIMENTIONAL NAVIGATOR The navigator advanced visualization software provides a single icon-driven interface for ease of use and interaction with virtual colonoscopy images. It allows
real time navigation of structures
visualization capabilities for viewing inside cavities endoluminal viewing of 3D surface rendered abnormalities of tubular structures eg: polyps,tumors,clots

15. 3D COLON It is intuitive and is intended to provide image visualization of the colon for masses, cancers, polyps and other lesion and allows the user to perform 3D measurements, real time volume rendering.

16. FLY THROUGH The software of the invention splits the entire tubular anatomy into exactly two halves.

The software assigns a virtual camera to each half to perform fly-over navigation .

17. FILMING

18. FILMING

19. COMPLICATIONS No complications

20. POST PROCEDURE CARE No such post procedure care for virtual colonoscopy

21. ADVANTAGES VC is more comfortable than conventional colonoscopy for some people it does not use a colonoscope. No sedation is needed, and the patient can return to his/her usual activities or go home after the procedure with of the aid of any other person. The lack of sedation also lowers the risk of the procedure since some people may have adverse reactions to sedative medications used during conventional colonoscopy. VC provides clearer, more detailed images than the conventional method

22. VC takes less time than the conventional colonoscopy VC provides a secondary benefit of revealing disease or abnormalities outside the colon.

23. DISADVANTAGES The main disadvantage of VC is that a radiologist cannot take tissue samples(biopsy)or remove polyps during VC , so a conventional colonoscopy must be performed if abnormalities are found. Also VC does not show as much detail as a conventional colonoscopy , so polyps smaller than between 2 and 10 mm in diameter may not show up on the images.

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