QSA Global, Inc.
40 North Avenue Burlington, MA 01803
888.272.2242
781.272.2000
qsa-global.com
Operations Manual
MAN-038 March 2019
Page 9 of 100
Table 4 - Selected attenuation data
Material Approximate
Material
Density
(g/cm
3
)
Approximate Half Value Thickness
Inches (mm)
Cobalt-60
Concrete 2.35
2.400 (61.0)
Steel 7.80
0.827 (21.0)
Lead 11.34
0.500 (12.7)
Tungsten 17.80
0.310 (7.9)
DU 18.70
0.270 (6.8)
1.4 Operating
Distance
The distance between the remote control and the exposure head is determined by summing the length of
the remote control conduits plus the total length of source guide tubes used, and normally should not
exceed 47 ft (14.2 m) with standard 25 ft. controls.
Standard lengths of remote controls: 25 ft (7.6 m), 35 ft (10.7 m), 50 ft (15 m)
Standard lengths of guide tubes (projection sheaths): 7 ft (2.1 m) - three guide tubes, 21 ft total (6.4 m)
WARNING
The total length of source guide tubes utilized
must be shorter
in length than the remote controls to
ensure the source assembly will project into the working position.
e.g. When using 25 ft (7.6 m) remote controls, a maximum of three 7 ft (2.1 m) source guide tubes can
be used with a combined length of 21 ft (6.4 m).
Conversely, when using 35 ft (10.7 m) remote controls, a maximum of four 7 ft (2.1 m) source guide
tubes can be utilized.
When using 50 ft (15 m) remote controls, a maximum of six 7 ft (2.1 m) source guide tubes can be
utilized. This limitation is due to the weight and friction of remote control cable length.