Homework 9 Flashcards
in MRI the component which produces a linear variation in the magnetic field is called the
a. radiofrequency coils
b. gradient coils
c. relaxation timer
d. primary magnet
b. gradient coils
which radiographic imaging technology uses a radionuclide attached to a biologically active molecule?
a. PET
b. MRI
c. ultrasound
d. CT
a. PET
which of the following are advantages to the use of ultrasound for radiotherapy imaging?
a. non-invasive imaging
b. good image resolution
c. good bone visualization
a. non-invasive imaging
which digital imaging technique uses a cassette with a photostimulable luminescent screen similar to film screen radiography?
a. amorphous selenium
b. digital radiography
c. computed radiography
c. computed radiograph
which generation of CT consists of a rotating xray tube and a stationary detector array?
a. fifth generation
b. second generation
c. fourth generation
d. first generation
e. third generation
c. fourth generation
which of the following could be a cuase of a false coincidence signal in a PET image?
a. multiple coincident phtons
b. random coincident phtons
c. scatter coincident phtons
d. all of the answers are correct
d. all of the answers are correct
when a change in the treatment plan occurs during the course of treatment due to the availability of new anatomical data, this is call
a. adaptive planning
b. functional re-planning
c. real time planning
d. all of the above
a. adaptive planning
which imaging modality is best for imagign small differences in soft tissue?
a. PET
b. digital radiography
c. CT
d. magnetic resonance
d. magnetic resonance
what is ture regarding the couch longitudinal travel per rotation when a CT scanner has a pitch of 1.0?
a. the couch distance traveled per rotation equals the beam width
b. the couch distance traveled per roation is less than the beam width
c. the couch distance traveled per rotation exceeds the beam width
a. the couch distance traveled per rotation equals the beam width
what is the pitch for a helical CT scanner where the CT beam width is 6 mm and the table top moves a distance of 3 mm for every rotation?
.5:1
which of the following is NOT an important parameter for selection of radionuclides in PET scanning?
a. half life
b. biological uptake characteristics
c. range of the emitted positron
d. maximum positron enegry
b. biological uptake characteristics
the diameter of the reconstructed CT image is known as the
a. field of view
b. hounsfield number
c. CT number
d. aperture size
a. field of view
in MRI, the tissue signal is a measurement of
a. the portons precessing around the axis of the magnet
b. the protons returning to their equilibrium state
c. protons moving into a higher energy state
b. the protons returning to their equilibrium state
which of the following imaging modalities has the highest spatial resolution?
a. MRI
b. ultrasound
c. CT
d. PET
c. CT
the digital radiography technique where xrays are directly converted into an electric signal is called
a. direct digital radiography
b. digital radiography
c. computed radiography
d. charged coupled radiography
a. direct digital radiography
