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8. Glossary
Piranha & QABrowser Reference Manual
2014-06/5.5C
162
Framing
In cinefluorography, the registration of the circular image of the output phosphor on the
rectangular film element or frame.
Gantry
The moveable patient table used for CT.
Geometric unsharpness
Unsharpness of the recorded image due to the combined optical effect of finite size of
the radiation source and geometric separation of the anatomic area of interest from the
image receptor and the collimator.
Gray (Gy)
The special name for the SI unit of absorbed dose, kerma, and specific energy imparted
equal to one joule per kilogram. One gray equals one joule per kilogram. The previous
unit of absorbed dose, rad, has been replaced by the gray. One gray equals 100 rad.
Half-value layer (HVL)
Thickness of a specified substance which, when introduced into the path of a given
beam of radiation, reduces the kerma rate by one-half.
SI unit: mm
Heel effect
Non-uniform intensity observed because a small fraction of the X-ray beam emitted in a
direction nearly parallel to the angled target surface must pass through more target
material before escaping from the target than does the major portion of the beam which
is emitted more perpendicularly. (Note: In addition to the non-uniform intensity
the angled target also produces non-uniform image resolution due to variations in
apparent focal spot size as viewed from various positions on the film).
Hounsfield units
See CT number.
Image intensifier
An X-ray image receptor which increases the brightness of a fluoroscopic image by
electronic amplification and image minification.
Image receptor
A system for deriving a diagnostically usable image from the X-rays transmitted by the
patient. Examples: screen film system; stimulable phosphor; solid state detector.
Inherent filtration
Filter between the radiation source and the output window of the X-ray equipment.
See filter.
Initial X-ray tube voltage
In a capacitor discharge X-ray generator, X-ray tube voltage at the beginning of the
loading of the X-ray tube.
Installation
A radiation source with associated equipment, and the space in which it is located.
Interlock
A device used to assure proper and safe use of a radiation installation by monitoring
(usually by electrical devices) the status, presence or position of various associated
Summary of Contents for Piranha
Page 1: ...Reference Manual English Version 5 5C Piranha QABrowser RTI article number 9629050 10 ...
Page 8: ...Introduction Chapter 1 ...
Page 12: ...Description of the Piranha Chapter 2 ...
Page 40: ...Description of the QABrowser Chapter 3 ...
Page 77: ...Measurement Principles Theory Chapter 4 ...
Page 91: ...Measurements with the Piranha System Chapter 5 ...
Page 151: ...Optional Accessories Chapter 6 ...
Page 155: ...Problems and Solutions Chapter 7 ...
Page 161: ...Glossary Chapter 8 ...
Page 181: ...Notes Piranha QABrowser Reference Manual 2014 06 5 5C Notes 177 ...