Flashcards in Getting To Know CT Deck (20)
In 1901, who was awarded the first Nobel Prize in Physics?
Wilhelm Conrad Röntgen for the discovery of x-rays
What were some reasons to develop tomographic imaging techniques?
Conventional radiographs superimposed anatomy
Conventional radiographs are limited in their ability to show the difference between tissues with similar densities
Physicians wanted to be able to see inside a patient in a manner similar to surgical exploration
What were used in tomographic systems before the first CT scanners existed?
Conventional tomography was NOT clinically useful because:
Images were often too blurry
Took too long to make an image
Images lacked detail
Detectors were incorporated into CT scanner designs to replace film because detectors:
Converted the x-ray attenuation information into an electrical signal which could be used by a computer
When was the first commercial CT scanner available?
A thick x-ray beam that not only spreads to the sides of the patient table but also diverges along the length of the patient table
MDCT scanners were first attempted by:
EMI in the 1970s
What kind of information can be obtained with PET/CT?
Images with metabolic information (PET)
Images with high-resolution anatomical information (CT)
Which cross-sectional orientations of an abdomen can be directly scanned in CT?
What's the difference between CT and conventional radiography?
Arrange MR imaging, CT imaging, and plain film x-ray imaging in order from best to worst in their ability to differentiate soft tissues in the body
MRI > CT > X-ray
What is the set safe level of exposure to ionizing radiation?
None, must be as low as possible given the clinical goal
Which imaging modalities uses ionizing radiation?
Any modalities using x-rays (conventional radiography, mammography, computed tomography)
In the oncology department, CT may be used to:
Collect an image used for therapy planning
Verify patient and tumor position prior to therapeutic radiation
Initially diagnose presence of malignancy
What can be found in the nucleus of an atom?
Protons and neutrons
The x-ray beam produced by a CT x-ray tube is composed of what type of radiation(s)?
Almost 100% bremsstrahlung radiation
The extent of the attenuation of an x-ray beam is dependent upon:
Energy of the x-ray photon
Atomic number of the atoms in the tissues penetrated by the beam
Density of electrons of the atoms in the tissues
A dense structure will attenuate an x-ray beam _____ than a structure that is not dense.