Table 2.

The simulated exposure rate at outside corridor during occupancy of a patient

Calculations and corrections
Activity taken for measurement=600 MBq
Assumed activity in isolated patient=3700 MBq (by a factor 6.15)
50 cm is measured activity plane. 2 m distance is patient occupied distance
Therefore, correction for inverse square on these readings (0.5/2)2=1/16.0
Outer corridor readings correspond to edge of the wall
To get exposure rates corrected to “middle of the corridor”
There is a correction with inverse square law, namely, (2/3)2=4/9.0
Viewing window level
Room 1 maximum reading=0.58 mR/h
Room 2 maximum reading=0.87 mR/h
0.87 mR/h as highest of the two sets are taken. The simulated exposure rate to correct for patient’s bed position and for 3700 MBq activity=0.87 mR/h × (6.15) × (1/16) × (4/9)=0.148 mR/h
Estimated value for center of the outside corridor, at mid-VW level=1.48 µSv/h
Below viewing window level
Mean maximum recorded exposure rate [Table 1]=0.26 mR/h
Corrected for patient’s bed position and for 3700 MBq activity=0.26 mR/h × (6.15) × (1/16) × (4/9)=0.044 mR/h (0.44 µSv/h)