Computed Tomography (CT)
What is CT and what is it used for? - correct answer ✔✔CT uses diagnostic x-rays to create cross-
sectional images of the human body. It uses mathematical algorithms to combine these images together.
It's helpful in obtaining of volume of information so we can see structures in 3 dimensions. It's extremely
helpful with cancers to be able to detect the size and shape of a mass.
What are the components of the equipment? - correct answer ✔✔Gantry: Gantry includes the couch
(table) and support, scanner housing, x ray tube, and detectors.
Computer: displays images
Operating console: CT can have up to three operating consoles.
How does the equipment work? - correct answer ✔✔The x-ray tube is pulsed and has a fan shaped/
narrow beam. It has a rotating tube that is opposite of the detector. The tube has a small focal spot. The
detector sends data to the computer and measures the attenuation coefficient. The computer receives,
process, displays and stores data. It also displays the technique, and allows for post processing.
What are housefield units? - correct answer ✔✔tissue density values and measure the thickness of
tissue that can be used for contrast, and detection of diseases.
What are the limitations of CT? - correct answer ✔✔-While the machine is helical, 360 data is not
required
- Motion can cause streaking of the image
- Metal objects attenuate 100% of the beam
- Beam hardening causes broad dark bands/streaks
- Partial volume effect (smaller structures get hidden)
- ring artifacts
- higher dose
- high cost
What are the advantages of CT? - correct answer ✔✔-acquire more images fast
What is CT and what is it used for? - correct answer ✔✔CT uses diagnostic x-rays to create cross-
sectional images of the human body. It uses mathematical algorithms to combine these images together.
It's helpful in obtaining of volume of information so we can see structures in 3 dimensions. It's extremely
helpful with cancers to be able to detect the size and shape of a mass.
What are the components of the equipment? - correct answer ✔✔Gantry: Gantry includes the couch
(table) and support, scanner housing, x ray tube, and detectors.
Computer: displays images
Operating console: CT can have up to three operating consoles.
How does the equipment work? - correct answer ✔✔The x-ray tube is pulsed and has a fan shaped/
narrow beam. It has a rotating tube that is opposite of the detector. The tube has a small focal spot. The
detector sends data to the computer and measures the attenuation coefficient. The computer receives,
process, displays and stores data. It also displays the technique, and allows for post processing.
What are housefield units? - correct answer ✔✔tissue density values and measure the thickness of
tissue that can be used for contrast, and detection of diseases.
What are the limitations of CT? - correct answer ✔✔-While the machine is helical, 360 data is not
required
- Motion can cause streaking of the image
- Metal objects attenuate 100% of the beam
- Beam hardening causes broad dark bands/streaks
- Partial volume effect (smaller structures get hidden)
- ring artifacts
- higher dose
- high cost
What are the advantages of CT? - correct answer ✔✔-acquire more images fast
