RIN #20
PERSONAL PROTECTION GUIDELINES FOR
STAFF IN VETERINARY MEDICINE IN A
MULTI-PURPOSE ROOM SET-UP
This RIN provides guidance to owners/operators of veterinary facilities which have multi-purpose rooms in which xray equipment is also used. The purpose is to ensure that other persons working within the multi-purpose room
during the taking of diagnostic x-ray exposures do not receive doses in excess of 1 milliSievert per year (1 mSv/yr), the
Action Level for ionizing radiation, as given in WorkSafeBCs Occupational Health and Safety Regulation (the
Regulation - see Part 7, Div 3). Multi-purpose rooms must be a sufficient size to allow the required separation
distance identified in Personal Protection (below).
Maximum Operating Criteria
 The x-ray unit is operated at up to 70 kVp and 615 mAs per exposure, is equipped with a beamlimiting device and the useful x-ray beam is
directed away from areas occupied by staff.
 The x-ray workload (number of exposures) per
year does not exceed 2000 (~ 165/month).
 The maximum film size (cassette size) is 35 cm x
43 cm (14” x 17”); smaller cassettes are normally
used.
Staff Exposure Assessment
Using the operating criteria given above, the exposure
to unprotected staff within the room due to secondary
radiation at a distance of three meters from the x-ray
tube is calculated to be 0.8 mSv/year. At two meters
distance the exposure to unprotected staff is
calculated at 1.8 mSv/year.
Personal Protection
During x-ray exposure, those workers within the room
not involved in taking the x-ray must stand a minimum
of three meters away from the x-ray tube. Staff who
are outside the room, in adjacent areas, at a minimum
distance of 1.5 meters from the x-ray tube, will not
exceed the Action Level, provided that protection in
the intervening walls meets or exceeds the shielding
equivalent to 2.5cm (1 inch) total thickness of gypsum
wallboard. Both three meters and 1.5 meters distance
from x-ray tube must be clearly indicated and marked
on either the floor or wall(s).
If the workload exceeds the value specified above, the
required distance for staff within the room would
likely be unachievable in a typical multi-purpose setup. A reassessment of protection required will be
necessary.
Consideration should be given to providing portable xray shielding, which can be located between the x-ray
table and the position of the other staff within the
room, to keep doses as low as reasonably achievable.
Those staff members carrying out x-ray procedures
must wear appropriate personal protective equipment
and dosimeters.
Dosimeters must be worn underneath the lead apron
to verify that body doses for x-ray staff are below
Action Level of 1 mSv/year. Additional dosimeters may
be worn to determine doses to other parts of the body
(e.g. head, hands). Contact your dosimetry service
provider for details on appropriate dosimeter types
and wearing methods.
If doses exceed or may exceed 1 mSv/yr, the
employer must establish an exposure control
plan for the worker. The exposure limit for
workers, as specified in the Regulation is 20
mSv/yr. The Regulation also references Health
Canada’s Safety Code 28, “Radiation Protection in
Veterinary Medicine, Recommended Safety
Procedures for Installation and Use of Veterinary
X-ray Equipment”, for specific guidance on
protecting veterinary staff and other persons in
adjacent occupied areas.
Updated: Jan 2014
For further information, please contact:
Radiation Protection | Environmental Health Services
th
LL0073, 655 12 Ave W | Vancouver BC V5Z 4R4
T: 604.707.2442 | F: 604.707.2441 | E: [email protected]