ASTM E170-99e1
(Terminology)Standard Terminology Relating to Radiation Measurements and Dosimetry
Standard Terminology Relating to Radiation Measurements and Dosimetry
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Designation:E170–99
Standard Terminology Relating to
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Radiation Measurements and Dosimetry
This standard is issued under the fixed designation E170; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1
e NOTE—Equation 2 was editorially corrected in April 1999.
INTRODUCTION
This terminology generally covers terms that apply to radiation measurements and dosimetry
associatedwithenergydepositionandradiationeffects,ordamage,inmaterialscausedbyinteractions
by high-energy radiation fields. The common radiation fields considered are X-rays, gamma rays,
electrons, alpha particles, neutrons, and mixtures of these fields. This treatment is not intended to be
exhaustive but reflects special and common terms used in technology and applications of interest to
Committee E-10, as for example, in areas of radiation effects on components of nuclear power
reactors, radiation hardness testing of electronics, and radiation processing of materials.
Thisterminologyusesrecommendeddefinitionsandconceptsofquantities,withunits,forradiation
measurements as contained in the International Commission on Radiation Units and Measurements
2
(ICRU) Report 33 on “Radiation Quantities and Units,”April 15, 1980. Those terms that are defined
essentiallyaccordingtotheterminologyofICRUReport33willbefollowedbyICRUinparentheses.
It should also be noted that the units for quantities used are the latest adopted according to the
International System of Units (SI).
2
absorbed dose (D)—Quantity of ionizing radiation energy
µ /r = mass energy absorption coefficient (m /kg).
en
impartedperunitmassofaspecifiedmaterial.TheSIunitof
If bremsstrahlung production within the specified material is
absorbeddoseisthegray(Gy),where1grayisequivalentto
negligible, the mass energy absorption coefficient (µ /r)is
en
the absorption of 1 joule per kilogram of the specified
equal to the mass energy transfer coefficient (µ /r), and
tr
material (1 Gy = 1 J/kg). The mathematical relationship is
absorbeddoseisequaltokermaif,inaddition,chargedparticle
the quotient of de¯ by dm, where de¯ is the mean incremental
equilibrium exists.
energyimpartedbyionizingradiationtomatterofincremen-
˙
absorbed dose rate, D—the absorbed dose in a material per
tal mass dm (see ICRU 33).
incremental time interval, that is, the quotient of d D by d t
D 5 de¯ dm (1)
/
(see ICRU Report 33).
DISCUSSION— The discontinued unit for absorbed dose is the rad (1
˙
D 5dD/dt (3)
rad = 100 erg/g = 0.01 Gy). Absorbed dose is sometimes referred to
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simply as dose. For a photon source under conditions of charged
SI unit: Gy·s .
particle equilibrium, the absorbed dose, D, may be expressed as
DISCUSSION—Theabsorbed-doserateisoftenspecifiedintermsofthe
follows:
average value of D over longer time intervals, for example, in units of
D5F· E· µ /r, (2)
−1 −1
en
Gy·min or Gy·h .
where:
accuracy—the closeness of agreement between a measure-
2
F = particle fluence (particles/m ),
ment result and an accepted reference value (see Terminol-
E = energy of the ionizing radiation (J), and
ogy E456).
activation cross section—the cross section for processes in
which the product nucleus is radioactive (see cross section).
activity, A—ofanamountofradioactivenuclideinaparticular
1
This terminology is under the jurisdiction of ASTM Committee E-10 on
energy state at a given time, the quotient of dN by dt, where
Nuclear Technology and Applications and is the direct responsibility of Subcom-
dN is the expectation value of the number of spontaneous
mittee E10.93 on Editorial.
Current edition approved Jan. 10, 1999. Published February 1999. Originally
nuclear transitions from that energy state in the time interval
published as E170–63. Last previous edition E170–98a.
dt (ICRU).
2
Available from International Commission on Radiation Units and Measure-
ments (ICRU), 7910 Woodmont Ave., Suite 800, Bethesda, MD 20814. A 5dN/dt (4)
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E170–99
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Unit: s reaction rate measured with an identical neutron detector
The special name for the unit of activity is the becquerel enclosed by a particular cadmium cover and exposed in the
(Bq). same neutron field at the same or an equivalent spatial
location.
21
1 Bq 51s (5)
DISCUSSION—In practice, meaningful experimental values can be
DISCUSSION—The former special unit of activity was the curie (Ci).
obtained in an isotropic neutron field by using a cadmium filter
10 21
s ~exactly!. (6) approximately 1 mm thick.
1 Ci 53.7 310
calibrated
...
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