BS ISO 15708-1:2017 pdf download

BS ISO 15708-1:2017 pdf download.Non-destructive testing — Radiation methods for computed tomography
1 Scope
This document gives the definitions of terms used in the field of computed tomography (CT). It presents a terminology that is not only CT-specific but which also includes other more generic terms and definitions spanning imaging and radiography. Some of the definitions represent discussion points aimed at refocusing their terms in the specific context of computed tomography.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1 absorption
photoelectric absorption
mode of interaction between photons and matter whereby a photon is absorbed by an atom which then emits an electron whose kinetic energy is exactly equal to the energy-depleted photon’s electron-binding energy
Note 1 to entry: See also Compton scattering (3.6).
3.2 angular increment
angular spacing between adjacent CT projections (3.12)
3.3 artefact
artificial feature which appears on the CT image (3.11) but does not correspond to a physical feature of the object
3.4 beam hardening
spectrum hardening
spectral change of a polychromatic beam caused by preferential attenuation of lower energy photons
Note 1 to entry: See also cupping effect (3.17).
3.5 calibration template
phantom
known reference object that is scanned to assess the performance of a CT system (3.15)
3.6 Compton scattering
mode of interaction between a photon and an electron, where the photon is scattered with reduced energy, and the difference of energy is transferred to the electron, also known as inelastic scattering or incoherent scattering
Note 1 to entry: See also photoelectric absorption (3.1).
3.7 computed tomography
CT
CT computed axial tomography
radiographic scanning technique that uses a number of CT projections (3.12) of an object at different angles in order to allow calculation of a CT image (3.11)
3.8 CT cone beam
scanning mode wherein each CT projection (3.12) is built from a set of ray paths (3.24) emanating from a point source and diverging in two dimensions, thereby forming a cone
3.9 CT data
CT dataset
CT projection (3.12) or CT image (3.11)
3.10 CT grey value
grey level
numerical value assigned to each voxel (3.30) in a CT image (3.11)
Note 1 to entry: This value represents the average linear attenuation coefficient (3.20) of the object volume for that voxel.
3.11 CT image
tomogram
2D or 3D image of the CT grey values (3.10) obtained by reconstruction (3.25)
3.12 CT projection
1D or 2D radiographic image