- Sketch a cross-section of a
basic x-ray tube and label the components.
- Describe and explain the
concept of the two electrical quantities, KV
and MA, that are associated with x-ray
production.
- Describe the events that occur
within an x-ray tube that lead to x-ray production.
- Describe a
focal spot, what is it? where is it?
- Name the material used as the
x-ray tube anode for general x-ray imaging
and explain why it is used.
- Name two materials used as the
x-ray tube anode for
mammography and explain why each is used.
- Lookup in a reference the
atomic number (Z) of the two anode
materials used for mammography and describe the significance of Z with
respect to x-ray production.
- Describe the filament and
focusing cup (i.e., the cathode assembly)
of an x-ray tube, including the purpose of two filaments in some x-ray
tubes and the purpose of the focusing cup.
- Name and briefly describe the
process by which electrons are liberated from a
heated filament at the cathode of an x-ray tube.
- Describe the principle factor
that determines the kinetic energy attained by
electrons as they strike the x-ray tube anode. Can it be changed
or adjusted?
- Discuss at least two functions
of the x-ray tube housing.
- Describe the process of
bremsstrahlung production and sketch a
typical spectrum.
- Sketch and compare the three
bremsstrahlung spectra for the following
factors:
50 kV and 50 mA
100 kV and 50 mA
100 kV and 100 mA
- Describe the production of
characteristic radiation and sketch a
typical spectrum.
- Sketch and compare the
characteristic x-ray spectra for a
molybdenum anode operating at 25 kV and 35 kV.
- Sketch and compare the
characteristic x-ray spectra for a
molybdenum anode and a
rhodium anode both operating at 30 kV.
- Identify the adjustable
operating factor(s) that determine(s) the maximum
energy of x-ray photons emitted from an anode.
- Explain why
K x-rays emitted by an atom have higher
energies than L or M x-rays from the same
atom.
- Explain why a high Z element
produces some characteristic x-rays with
energy greater than that of x-rays from a lower Z element, even though
both elements are bombarded by 100 keV electrons.
- Define the expression "efficiency"
of x-ray production and identify the principle factors that affect
efficiency , and estimate its value for a diagnostic x-ray tube.
- Describe how the
efficiency is related to the electron
accelerating voltage (KV).
- Describe the general
relationship between x-ray production efficiency and the
atomic number of the anode material.
- Sketch typical graphs and
describe the variation in output (i.e.,
exposure rate) of an x-ray tube as a function of: 1. tube voltage (KV)
2. tube current (MA). What is the type of mathematical relationship for
each?
- Estimate the
skin entrance exposure to a 23 cm thick
patient for a PA chest radiograph performed at 72 inches using a
technique of 120 kVp and 15 mAs. Use appropriate references as necessary
to obtain typical x-ray tube output data.
- Estimate the
increase in x-ray tube output exposure when
the tube potential (KV) is increased from 60 to 75 kVp. Explain how you
arrived at the answer.
|
