1.1 principles of radiation physics!
D With three-phase equipment, the voltage across the x-ray tube
2 and 3 only drops to zero every 180 degrees
is 87% to 96% of the maximum value
is at nearly constant potential
A
1 only
B
2 only
C
1 and 2 only
D
2 and 3 only
The Correct Answer is: D
With single-phase, full-wave-rectified equipment, the voltage is constantly
changing from 0% to 100% of its maximum value. It drops to 0 every 180
degrees (of the AC waveform); that is, there is 100% voltage ripple. With three-
phase equipment, the voltage ripple is significantly smaller. Three-phase, six-
pulse equipment has a 13% voltage ripple, and three-phase, 12-pulse
equipment has a 3.5% ripple. Therefore, the voltage never falls below 87% to
96.5% of its maximum value with three-phase equipment, and it closely
approaches constant potential [direct current (DC)]. (Carlton and Adler, 4th
ed., pp. 91-93)
b 1 and 2 An increase in the kilovoltage applied to the x-ray tube increases the
percentage of high-energy photons produced.
beam intensity.
patient absorption.
A
1 only
B
1 and 2 only
C
2 and 3 only
D
1, 2, and 3
Page 1 of 7
, 1.1 principles of radiation physics!
he Correct Answer is: B
As the kilovoltage is increased, a greater number of electrons are driven across
to the anode with greater force. Therefore, as energy conversion takes place at
the anode, more high-energy photons are produced. However, because they
are higher-energy photons, there will be less patient absorption. (Fauber, 2nd
ed., p. 58)
answer b Characteristics of x-ray photons include
1 a penetrating effect on all matter
2 an ionizing effect on air
3 travelling at the speed of sound
A
1 only
B
1 and 2 only
C
2 and 3 only
D
1, 2, and 3
he Correct Answer is: B
X-rays are energetic enough to rearrange atoms in materials through which
they pass, and they can, therefore, be hazardous to living tissue.
X-rays are called ionizing radiation because they have the energetic potential
to break apart electrically neutral atoms, resulting in the production of negative
and/or positive ions.
X-rays are infinitesimal bundles of energy called photons that deposit some of
their energy into matter as they travel through it.
This deposition of energy and subsequent ionization has the potential to cause
chemical and biologic damage.
Several of the outstanding properties of x-ray photons are: X-rays are not
perceptible by the senses.
X-rays travel in straight lines. X-rays travel at the speed of light.
X-rays are electrically neutral.
X-rays have a penetrating effect on all matter.
X-rays have a physiological effect on living tissue
. X-rays have an ionizing effect on air.
X-rays have a photographic effect on film emulsion.
X-rays produce fluorescence in certain phosphors.
X-rays cannot be focused.
X-rays have a spectrum of energies. X-rays are unaffected by a magnetic field.
Page 2 of 7
D With three-phase equipment, the voltage across the x-ray tube
2 and 3 only drops to zero every 180 degrees
is 87% to 96% of the maximum value
is at nearly constant potential
A
1 only
B
2 only
C
1 and 2 only
D
2 and 3 only
The Correct Answer is: D
With single-phase, full-wave-rectified equipment, the voltage is constantly
changing from 0% to 100% of its maximum value. It drops to 0 every 180
degrees (of the AC waveform); that is, there is 100% voltage ripple. With three-
phase equipment, the voltage ripple is significantly smaller. Three-phase, six-
pulse equipment has a 13% voltage ripple, and three-phase, 12-pulse
equipment has a 3.5% ripple. Therefore, the voltage never falls below 87% to
96.5% of its maximum value with three-phase equipment, and it closely
approaches constant potential [direct current (DC)]. (Carlton and Adler, 4th
ed., pp. 91-93)
b 1 and 2 An increase in the kilovoltage applied to the x-ray tube increases the
percentage of high-energy photons produced.
beam intensity.
patient absorption.
A
1 only
B
1 and 2 only
C
2 and 3 only
D
1, 2, and 3
Page 1 of 7
, 1.1 principles of radiation physics!
he Correct Answer is: B
As the kilovoltage is increased, a greater number of electrons are driven across
to the anode with greater force. Therefore, as energy conversion takes place at
the anode, more high-energy photons are produced. However, because they
are higher-energy photons, there will be less patient absorption. (Fauber, 2nd
ed., p. 58)
answer b Characteristics of x-ray photons include
1 a penetrating effect on all matter
2 an ionizing effect on air
3 travelling at the speed of sound
A
1 only
B
1 and 2 only
C
2 and 3 only
D
1, 2, and 3
he Correct Answer is: B
X-rays are energetic enough to rearrange atoms in materials through which
they pass, and they can, therefore, be hazardous to living tissue.
X-rays are called ionizing radiation because they have the energetic potential
to break apart electrically neutral atoms, resulting in the production of negative
and/or positive ions.
X-rays are infinitesimal bundles of energy called photons that deposit some of
their energy into matter as they travel through it.
This deposition of energy and subsequent ionization has the potential to cause
chemical and biologic damage.
Several of the outstanding properties of x-ray photons are: X-rays are not
perceptible by the senses.
X-rays travel in straight lines. X-rays travel at the speed of light.
X-rays are electrically neutral.
X-rays have a penetrating effect on all matter.
X-rays have a physiological effect on living tissue
. X-rays have an ionizing effect on air.
X-rays have a photographic effect on film emulsion.
X-rays produce fluorescence in certain phosphors.
X-rays cannot be focused.
X-rays have a spectrum of energies. X-rays are unaffected by a magnetic field.
Page 2 of 7
