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8. Glossary
Piranha & QABrowser Reference Manual
2014-06/5.5C
160
CT number
One of a set of numbers on a linear scale which are related to the linear attenuation
coefficients calculated by a computed tomographic device. One of the specific set of CT
numbers on a scale from -1000 for air to +1000 for bone, with water equal to zero,
which is called a Hounsfield unit.
Curie (Ci)
The previously used special unit of activity equal to 3.7 × 1010 per second. 1 Ci =
3.7 × 10
10
Bq.
Dead man switch
A switch so constructed that a circuit-closing contact can be maintained only by
continuous pressure on the switch.
Dental panoramic radiographic
Direct radiography of a part of or the complete dentition by the use of an intra-oral X-ray
tube. See also Orthopantomography.
Diagnostic source assembly
A diagnostic source housing (X-ray tube housing) assembly with a beam limiting device
attached. This assembly shall be so constructed that the leakage radiation air kerma
measured at a distance of one meter from the source does not exceed 1 mGy (0.1 rad)
in one hour when the source is operated at its leakage technique factors. (See
definition).
Digital radiography
A diagnostic procedure using an appropriate radiation source and an imaging system
which collects processes, stores, recalls, and presents image information in a digital
rather than analogue fashion.
Digital subtraction
An image processing procedure used to improve image contrast by subtracting one
digitized image from another.
Dose equivalent (H)
A quantity, defined for radiation protection purposes, which is the product of the
absorbed dose to the tissue and a quality factor "Q" determined by the properties of the
radiation that produced the absorbed dose. For X-rays, gamma rays, and electrons, Q =
1 and dose equivalent values are numerically equal to absorbed dose values when
consistent units are used for both quantities. The SI unit for dose equivalent is joule per
kilogram. The special name for the SI unit of dose equivalent is sievert (Sv). The
previous special unit of dose equivalent was the rem. One sievert equals 100 rem.
SI unit: Sv = J/kg
Dose rate meter
Radiation meter intended to measure absorbed dose per unit time.
Dosemeter
Radiation meter intended to measure absorbed dose.
Effective dose equivalent (HE)
Quantity used to express the weighted DOSE EQUIVALENT to the whole body when it
is irradiated non uniformly or partially.
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 ...