8. Glossary
Barracuda & QABrowser Reference Manual
2012-10/4.3A
200
Phantom
In medical radiology, object behaving in essentially the same manner as tissue, with
respect to absorption or scattering of the ionizing radiation in question. Phantom are
used, for example, for simulating practical conditions of measurement:
- for purposes of radiation protection,
- for evaluating the performances to the diagnostic systems with respect to the
radiation or to the object,
- for dosimetry.
Pixel
A two-dimensional picture element in the presented image.
Practical Peak Voltage (PPV)
The PPV is the constant potential producing the same image contrast as the waveform
under test. PPV is defined in the IEC 61676 standard as: "The PRACTICAL PEAK
VOLTAGE is based on the concept that the radiation generated by a high voltage of
any waveform produces the same AIR KERMA contrast behind a specified PHANTOM
as a radiation generated by an equivalent constant potential. The constant potential
producing the same contrast as the waveform under test is defined as PRACTICAL
PEAK VOLTAGE".
Primary protective barrier
See protective barrier
Protective apron
An apron made of radiation absorbing materials, used to reduce radiation exposure.
Protective barrier
A barrier of radiation absorbing material(s) used to reduce radiation exposure.
Protective glove
A glove made of radiation absorbing materials used to reduce radiation exposure.
Rad
The previously used special unit of absorbed dose. It is equal to 100 ergs per gram. 1
rad = 0.01 Gy (10
-2
gray).
Radiation (ionizing)
Any electromagnetic or particulate radiation capable of producing ions, directly or
indirectly, by interaction with matter. Examples are X-ray photons, charged atomic
particles and other ions, and neutrons.
Ripple factor
The variation in the high-voltage expressed as the percentage of the maximum
high-voltage across the X-ray tube during X-ray production: Ripple factor (%) = 100 x
(Vmax - Vmin)/Vmax
Leakage radiation
All radiation coming from within the source assembly except for the useful beam.
(Note: Leakage radiation includes the portion of the radiation coming directly from the
source and not absorbed by the source assembly, as well as the scattered radiation
produced within the source assembly).
Scattered radiation
Radiation that, during passage through matter is changed in direction. (It is usually
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