Biomedical Engineering Reference
In-Depth Information
Fig. 15.10
Attenuation in concrete of X rays produced with
(peak) potential differences from 50 kVp to 400 kVp. (
National
Bureau of Standards Handbook 76
, 1961, Washington, DC.)
Solution
From Table 15.1,
P
=
0.02 mGy wk
-1
for the hall, which is an uncontrolled area. The
1.5 minwk
-1
distance is
d
=
330 mAminwk
-1
. Note that Eq. (15.13) requires these particular units. The use factor
is
U
=
15 ft
=
4.57 m, and the workload is
W
=
220 mA
×
=
1/3 and, from Table 15.2, the occupancy factor is
T
=
1/5. Equation (15.13)
gives
(4.57)
2
0.114
×
0.02
×
10
-3
RmA
-1
min
-1
at 1 m.
Q
=
=
2.16
×
(15.14)
1
3
1
5
330
×
×
