Computed Tomography (CT) Flashcards
A voxel is a three dimensional equivalent of a ______.
pixel
X-ray attenuation depends on:
the density of the tissue
The CT number or Hounsfield unit represents:
the sum of the voxel attenuation along the radiation path.
Filtered back projection improves the quality of the final image by:
reducing blurring
X-rays used in CT have energy from _____ keV (kilo-electronvolts) and a wavelength from 0.018–0.025 nm.
50–70
The Computed Tomography Dose Index (CTDI) is a measure of the dose deposited in a single _____ of the patient. The unit used to measure it is the _____. This unit is expressed as CTDIvol during a medical CT scan.
axial slice,
mGy (milligray).
In order to calculate the total absorbed dose for a complete CT examination, the _____ being scanned must be taken into account.
size of the body
The ______ is the sum of the doses for all organs, multiplied by the respective tissue
weighting factors.
effective dose
During a CT scan, sections of the body are exposed to radiation. The effective dose is the sum of the doses for all organs, multiplied by the respective tissue weighting factors. The unit of measurement for an effective radiation dose is:
millisievert (mSv)
What is an average dose received by an adult patient undergoing one CT scan?
2-5 of the radiation dose unit of measurement.
What is the main advantage of using CT imaging over X-ray imaging?
CT allows visualization in 3D
Which imaging modality uses Housfield units (HU)?
- Ultrasound
- Optical imaging
- Computed tomography
Computed tomography
From a HU calibrated CT image using a black and white scale, the bone will appear:
white
In Computed Tomography imaging, the main purpose of windowing is to:
improve contrast sensitivity
What major technological advancement did CT initiate in diagnostic imaging?
Looking inside the human body, slice by slice, without a scalpel.
