Page 236 - Radiation Safety
P. 236
2. Exposure (X)
Measure ionization caused by gamma and x-ray in the air,
not the degree of damage to body tissue.
Old unit: Roentgen;
S.I Unit : Coulombs per kg (C/kg)
1 Roentgen is equivalent to the formation of ions with
charge 2.58 x 10 -4 coulombs per kg. It is equivalent to
absorption of energy in the air of about 0.00869 J/kg air
1 R = 1 ion of charge 2.58 x 10 -4 C/kg
= 1.61 x 10 12 ion pairs / kg
= 0.00869 J / kg air
72
