CT EQUIPMENTS

CT EQUIPMENTS

1. CT EQUIPMENTS Dr. Niranjan Patil Prof. Department of Radio-diagnosis DY Patil Medical College and Hospital Kolhapur

2. Components of CT Scanner X-ray tube Collimators Detector. Filters. High frequency generators. Patient couch. GANTRY DATA ACQUISITION SYSTEM OPERATING CONSOLE

3. CT Gantry: The CT scanner gantry is a moveable frame that contains the x-ray tube, including: 1.collimators 2. filters. 3. detectors. 4. data acquisition system. 5. positioning laser.

4. Xray tube: Xray Tubes operates with 3 phase or high frequency generators and rotating anode CT tube is a vacuum tube. The main part of any x-ray tube are anode & cathode. Anode is made of tungsten, rhenium & molybdenum alloy. In Modern CT scanner, the anode is made of tungsten. When electrons leave the cathode and hit the anode,99% heat is generated and 1% X-rays will be produced. The X-ray tube is mounted with its anode cathode axis parallel to the axis of rotation so that it reduce heel effect.

5. CT Collimator: Collimator is used to reduce the size and shape of the beam as well as remove the scattered photons. Collimator types : 1.Pre patient collimator 2.Post patient collimator

6. Between tube & patient. It constrain size of beam Design to minimize beam divergence It reduce scatter radiation that reaches to the detector array and enhance the contrast but does not influence patient dose . Between patient & detector This collimator restrict the xray field viewed by detector array. It defines the slice thickness when coupled with pre patient collimator Pre patient collimators : Post patient collimator:

7. Dectectors : 1.A detector can capture ,absorb & convert xray photon to an electrical signal. 2. Small size with good resolution 1.Scintillation detectors : This detectors convert the xray into visible light photons . Uses scintillation crystal coupled to photomultiplier tube to convert light to electron. Material used: 1.Sodium iodide 2. Bismuth germanium oxide 3. Cesium iodide 4. Cadmium Tungstate This detector has photodiodes which convert light photon into electric signal. Two types of detectors are used :

8. 2. Gas filled detectors: Material Used :1. Xenon 2. Krypton Xenon detectors are filled with xenon gases Xenon detectors have anode and cathode . When voltage is applied to these electrodes, the ionized gas causes the electrons to attach to the tungsten plates, producing an electronic signal.

9. Filters : Filters is placed between xray source and object Bowtie shapped filter is used for beam shaping Absorbs low energy xray Reduce pt dose Provides uniform beam

10. Patient support couch: Made of carbon fibre Slightly curved or flat Capable of moving up and down It does not interfere with xray beam transmission transmission &pt imaging.

11. Laser system: It is mounted at the scanner bore of the CT gantry. To identify the centre of the scan plane.

12. Ct scan principle: The internal structure of an object can be reconstructed from multiple projections of the object . The images are acquired by rotation of xray tube around the patient’s body. A series of xray images are taken from different angles around the body. The transmitted radiation is measured by the detectors &produce electrical impulse according to intensity of the xray . The attenuation value of the tissue is then calculated by computer The computer processes the data and creates cross sectional images of bones, blood vessel ,& soft tissue.

13. Operating console: It is master control centre of CT scanner Permits control of all scan parameter. It is used to input all of the factors related to taking a scan , such as slice thickness, movement of the patient couch, and radiographic factors. The console facilitates image manipulation, postprocessing, filming and networking such as PACS.(Picture archiving and communication system) Used to adjust contrast and brightness to view images.

14. Data acquisition system: Xray photons Detector detects intensity Current = voltage Analog signal=digital form Processed& reconstructed in the computer