Review Assignment 1 Flashcards
Which of the following is the collection element in Direct Digital Radiography (DDR) systems?
TFTs
During CR plate processing, what component directs phosphorescent light toward the photodiode?
the cylindrical mirror directs phosphorescent light toward the photodiode
Why does the scintillation crystal require a hermetic seal?
the scintillation crystal requires a hermetic seal to prevent the crystal from encountering air or moisture.
The appearance of the patellar fracture on the lateral knee x-ray image would primarily be attributed to?
transmitted x-rays incident on the receptor
Sensitivity may be increased by?
- increasing detector chamber size in radiation detection devices.
- increasing the voltage exerted across the anode and cathode in gas filled radiation detection devices.
- increasing electronic amplification of signal produced by the transducer.
What colour light is used to erase a PSP of any residual latent image prior to reuse?
white
Which interactions with an attenuator result in a loss of intensity by the x-ray beam?
photoelectric absorption, filtration and compton scattering
True or false: the probability of Compton scattering occurring is independent of incident x-ray photon energy?
false
What does the reflective layer of the CR receptor do?
reflects light forwards, back towards there light guides
the doping agent in computed radiography photostimulable phosphor is?
europium
If radiation detection Device A has a faster resolving time than Device B, which is more accurate?
Device A is more accurate than Device B if there are no differences in their characteristics other than resolving time
True or false: sensitivity of radiation devices are inherent and cannot be modified?
false
which components are present in Direct digital radiography systems?
Amorphous silicon and amorphous selenium
what 2 factors contribute to the absolute efficiency of a radiation detector?
- the transducer should have sufficient stopping power to absorb the radiation
- Transducer should be optimally positioned relative to the radiation source
Which of the gas filled radiation detectors would be most suited to measuring the integrity of radiation barriers in a medical imaging department?
Ionization chambers
True or false: The probability of Compton scattering in bone at 85 keV is greater than the probability of Photoelectric absorption in bone at the same photon energy.
True
Personal radiation dosimetry badges provide a radiation dose reading on the basis of which of the following principles?
thermoluminescence and scintillation
According to Safety Code 35, the half value layer of aluminum for an x-ray tube voltage of 80kV is 2.9mm. Upon testing, it is discovered that your machine has a HVL value of 3mm at 80kV. Is this acceptable?
Yes
Why is it recommended to process the CR phosphor as soon as possible after exposure?
It is recommended to process the CR phosphor as soon as possible after exposure because electrons start returning to the ground state over time, causing the latent image to begin to fade.
When an x-ray photon is incident on human tissue, at which of the following photon energies is the probability of photoelectric absorption the highest?
60 keV
True or false: Filtration of the primary x-ray beam is only necessary at low kV settings.
false
true or false: Both x-radiation and light are emitted isotropically.
true
List the primary reason Lithium Fluoride is the phosphor of choice in TLDs.
It has a crystal density similar to soft tissue density, and Z number that exhibits x-ray absorption properties similar to those in soft tissue
True or false: a homogenous x-ray beam is reduced in both intensity and quality as it penetrates through matter?
false
A Geiger counter operates in which of the radiation detector modes?
detection/pulse
Photostimulable phosphors used in computed radiography are made of?
Barium Fluorohalides
