(b) Diaphragms, cones, or a stepless adjustable
collimator shall be used for collimating the useful beam to
the area of clinical interest and shall provide the same
degree of protection as is required of the housing. Cones or
diaphragms, if used, shall be marked with their field size and
the distance at which they are to be used.
(c) The half-value layer (HVL) of the useful beam shall
not be less than as shown in the following table:
Measured
Potential
(kilovolts peak)
Half-value Layer
(millimeters of aluminum
equivalent)
70 and below
1.5
71
2.1
80
2.3
90
2.5
100
2.7
110
3.0
120
3.2
(d) A device shall be provided to terminate the exposure
after a preset time or exposure. It must not be possible for
the device to allow an exposure when preset at "zero" or
"off."
(e) A dead-man type of exposure switch shall be provided,
together with an electrical cord of sufficient length, so that
the operator can stand out of the useful beam and at least two
meters from the animal during all X-ray exposures.
(f) Reproducibility requirements as described under WAC 246-225-090.
(2) Structural shielding. All wall, ceiling, and floor
areas shall be equivalent to or provided with applicable
protective barriers as required in WAC 246-225-030(1).
(3) Operating procedures.
(a) In any application in which the operator is not
located behind a protective barrier, clothing consisting of a
protective apron having a lead-equivalent of not less than
0.25 millimeters shall be worn by the operator and any other
individuals in the room during exposures.
(b) No individual other than the operator shall be in the
X-ray room while exposures are being made unless such
individual's assistance is required.
(c) When an animal or film must be held in position
during radiography, mechanical supporting or restraining
devices should be used. If the animal must be held by an
individual, that individual shall be protected with
appropriate shielding devices, such as protective gloves and
apron, and that individual shall be so positioned that no part
of that individual's body will be struck by the useful beam. The requirements of WAC 246-221-090, Personnel monitoring, and
WAC 246-225-020 (2)(h)(iv) apply to such individuals.