8/7/2019 SAIBAL-CT

1/14

COMPUTED

TOMOGRAPHY

Saibal Kumar Kar

3rd Year , B.M.E

Netaji Subhash Engineering College

8/7/2019 SAIBAL-CT

2/14

CONTENTENTS

What is CT

Basic Principle Generation of CT

Image Reconstruction Techniques

CT Detectors

Artifacts in CT

Application of CT

Summary

Referance

8/7/2019 SAIBAL-CT

3/14

What is CT

CT is a digital imaging technique ,produces several axial or sliceor cross-sectional images of different parts of our body such as

bone ,mussels , heart, human brain, etc..It is normally abackproecting image construction procedure.

Tomography is a Greek word which comes from , tomosmeans slice and graphia means describing.

CT was first invented by Dr. G.N.Hounsfield at the CentralResearch Laboratories of EMI Ltd , UK, in 1967 & was firstpublicly announced in 1972.

8/7/2019 SAIBAL-CT

4/14

y CT produces cross-sectional images by measuring the

narrow beam of X-Ray f0r different and direction.

y The main principle of CT depends on Beers-Lamberts

law-y I=Io.e

y CT produces cross-sectional images by measuring the

narrow beam of X-Ray f0r different and direction.

y The main principle of CT depends on Beers-Lamberts

law-y I=Io.e

Basic Principle

8/7/2019 SAIBAL-CT

5/14

Generation of CT:

y 1st Generation : One source coupled with one or two

detectors . It takes 4-5 minutes to construct an image.

y 2nd Generation: One source multidetector (at least 30detectors)system.18-20 seconds required for one image.

y 3rd Generation: One source multidetector(100-300

detectors)system. Here source &the detectors are

coupled. It takes 7-12 seconds.y 4th Generation: One source coupled with 2000 fixed

detectors.Now-a-days this generation is mostly used.

y 5th Generation of CT has also been developed now.

8/7/2019 SAIBAL-CT

6/14

8/7/2019 SAIBAL-CT

7/14

8/7/2019 SAIBAL-CT

8/14

IMAGE RECONSTRUCTIONIMAGE RECONSTRUCTION

y There are 3 processes,

S

imple Back Projection, Interative Method,

Analytical Method.

Now-a-days analytical method is mostly

used.

8/7/2019 SAIBAL-CT

9/14

8/7/2019 SAIBAL-CT

10/14

The main detectors, used in CT, are asfollows,

1.Scintilation crystal with PMT,

2.Inert Gas ionisation detector,

3.Scintilation crystal with Photodiode.

8/7/2019 SAIBAL-CT

11/14

Artifacts of CT:

Artifacts

Patientrelated

PatientMovement

PartialVolume

Scannerrelated

SamplingAccuracy

BeamHardening

Detectornon-

uniformity

8/7/2019 SAIBAL-CT

12/14

CT scan is normally recommended to:

Diagnose muscle and bone disorders, such as bone

tumors and fractures. Pinpoint the location of a tumour, infection or blood clot. Guide procedures such as surgery, biopsy and radiation

therapy. Detect and monitor diseases such as cancer or heart

disease. Detect internal injuries and internal bleeding. CT scanning is useful to get a very detailed 3-D image of

certain parts of the body, such as soft tissues, the pelvis,blood vessels, the lungs, the brain, abdomen, and bones.

8/7/2019 SAIBAL-CT

13/14

SUMMARY

CT image reconstruction technique have been

continuously developed over the years to match

the advancement in new acquisition hardware

and new acquisition technique.

Image explosion from new CT scanners,

advanced visualization are needed to improve

the productivity of radiologists.Faster & better

tools are constantly developed.

8/7/2019 SAIBAL-CT

14/14

REFERANCES

by

1.Biomedical Instrumentation

by R.S.Khandpur.

2.Reference taken from

Dr.Sukumar Roy(HOD-B.M.E),

Mr.Samir Ghosh(FACULTY-B.M.E),

3.www.google.com