8/12/2019 Radiation Unitrs(Ghufran)

1/14

Ghufran Ali

8/12/2019 Radiation Unitrs(Ghufran)

2/14

8/12/2019 Radiation Unitrs(Ghufran)

3/14

In 1981, the International Commission on

Radiation Units and Measurements (ICRU)

issued standard units based on SI that have

since been adopted by all countries except

the United States. Most U.S. scientificjournals and societies have adopted The

International System, SI, but regulatory

agencies and the American Registry of

Radiologic Technologists (ARRT) have not.

8/12/2019 Radiation Unitrs(Ghufran)

4/14

8/12/2019 Radiation Unitrs(Ghufran)

5/14

Radioactivity Units

International Unit disintegration/sec or Becquerel (Bq)

U.S. UnitCurie (Ci)

10

1 Ci = 3.7 x 10 Bq

Activity

8/12/2019 Radiation Unitrs(Ghufran)

6/14

Exposure

Roentgen (R)

A unit for measuring exposure

Defined for effect in air only

Applies only to gamma and x-rays

Does not relate radiation to the effect on the humanbody

Operating Engineers National HazmatProgram 6

8/12/2019 Radiation Unitrs(Ghufran)

7/14

Radiation Exposure Units

International Unit

Coulomb per kilogram (C/kg)

U.S. UnitRoentgen (R)

defined only for measurement in air

applies only to x and gamma rays up to energies of about 3MeV

1 R = 2.58 x 10-4C/kg

1 mR = 0.258 C/kg

1 R = 258 C/kg

8/12/2019 Radiation Unitrs(Ghufran)

8/14

Radiation Absorbed Dose

Radiation absorbed dose is the amountof energy deposited per unit of tissue.

It is usually measured in ergs per gramor joules per kilogram.

8/12/2019 Radiation Unitrs(Ghufran)

9/14

Radiation Absorbed Dose Units

International UnitGray (Gy)

U.S. UnitRad

1 rad = 0.01 Gy

1 mrad = 0.01 mGy

1 rad = 0.01 Gy

8/12/2019 Radiation Unitrs(Ghufran)

10/14

Radiation Effective Dose Units Effective dose is used to represent how good the

absorbed dose of radiation might be at producing an

effect so it accounts for the effectiveness or quality ofthe radiation.

Effective dose also includes a factor representing the

sensitivity of the tissue to the radiation so it alsoaccounts for how the tissue might react.

8/12/2019 Radiation Unitrs(Ghufran)

11/14

Radiation Effective Dose Units

International Unit sievert (Sv)

U.S. UnitRoentgen Equivalent Man (rem)

1 rem = 0.01 Sv

1 mrem = 0.01 mSv

1 rem = 0.01 Sv

8/12/2019 Radiation Unitrs(Ghufran)

12/14

Type of Ionizing Radiation Quality Factor

X-ray photons 1

Beta particles 1

Gamma photons 1

Thermal neutrons 5

Fast neutrons 20

High-energy external protons 1

Low-energy internal protons 2

Alpha particles 20

8/12/2019 Radiation Unitrs(Ghufran)

13/14

Quantity Customary Symbol SI Symbol

Exposure roentgen R air kerma Gya

Absorbeddose rad rad gray Gyt

Equivalent

dose

rem rem seivert Sv

Radioactivity curie Ci becquerel Bq

8/12/2019 Radiation Unitrs(Ghufran)

14/14

Factor Name Symbol

1024 yotta Y

1021 zetta Z

1018 exa E

1015 peta P

1012 tera T

109 giga G

106 mega M

103 kilo k

102 hecto h

101 deka da

Factor Name Symbol

10-1 deci d

10-2 centi c

10-3 milli m

10-6 micro

10-9 nano n

10-12 pico p

10-15 femto f

10-18 atto a

10-21 zepto z

10-24 yocto y

SI Prefixes