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Profile of Stray Radiation For Table
The diagram below, Fig. 2-4, shows the dependency of the scattered radiation on the
distance from the central beam, height above the floor and kV potential. The decrease of the
scattered radiation is expressed in percent of the central beam exposure rate (100%). The
diagram also shows the decrease of scattered radiation when using protective clothing, also
this expressed in percent of the central beam dose rate.
Fig. 2-4, shows that a higher kV increases the scattered radiation slightly. The diagram also
shows that the best way to minimize the effect of the scattered radiation is an increased
distance to the patient and by using a lead apron.
Central beam exposure parameters used:
KVP: 70, 100, 120 kV
Tube current: 100 mA
Exposure time: 100 ms
Field size: 43x43 cm
Film-Focus distance: 1 m
Patient simulation: 150 mm PMMA
Filter: 0 mm
Central beam dose rate measured on top of PMMA (750 mm from focus).
100,000
Fig. 2-4 Scattered radiation rate expressed in percent of central beam dose rate, with and without
Operator´s Manual
Scattered radiation expressed in percent of central beam dose rate
10,000
1,000
70KV, 1000mm
70KV, 500 mm
100KV, 1000mm
100KV, 500mm
120KV, 1000mm
120KV, 500mm
central Beam dose rate
1000-095-071-EN Rev. 2.1
Page 25
Radiation and X-Ray Tube
0,100
0,010
Percent of central beam dose rate (%)
70KV, 1000mm, Lead apron
100KV, 1000mm, Lead apron
120KV, 1000mm, Lead apron
shielding
Safety
Height above oor (mm)
2000
1500
1000
500
0
0,001
OMNERA 500A
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