T.O. 33B-1-1
6-152
l. In the case of multiple exposures in an open area in which the beam direction, intensity (kVp, mA) or
attenuating materials are significantly altered, the barrier perimeter shall be re-established as necessary.
m. All information required on the bound utilization log shall be recorded by the radiographer. (Army
only, if a suspected overexposure has occurred). This will include the radiation levels detected at the
barrier.
6.9.19
Design or Modification of Installations.
6.9.19.1
Responsibility for Determining Shielding Requirements.
The structural shielding requirements of any new installation or of an existing one in which changes are contemplated,
may be decided by a health physicist, radiological physicist, or a Nuclear Medicine Science Officer provided it is
approved by the appropriate MAJCOM Headquarters.
6.9.19.2
Data required For Determining Shielding Requirements.
To adequately determine shielding requirements, the following data concerning the source of radiation must be
provided:
a. Type of radiation source (e.g., X-ray or gamma-ray)
b. Maximum and average tube potential (kilovoltage) or the energy of the radiation.
c. Maximum and average tube current (milliamperage) or the source output in roentgens per hour at one
meter (Rhm) from the source.
d. The expected workload in hours per week.
e. The use factors for each wall, floor and ceiling as appropriate. This is the fraction of the workload
during which the useful beam is pointed in the direction under consideration (see Table 6-26).
f. The type of occupancy of all areas which might be affected by the installation (see Table 6-27).
g. The structural details of the building. This will include a dimensioned drawing of the facility, with
notation of the typical distances from the x-ray source to each barrier of the facility, as well as the
expected construction materials for the facility.
Table 6-26. Use Factors (U)*
Enclosed
Installation Use
Exempt All Uses
Collimated Sources
Open Sources
Floors
1
1
1
Walls
1
¼
1
Ceilings
1
1/16
1
* For use as a guide in planning shielding when complete data are not available
