General Purpose Rad System
Operation
OM-0273R2
7
2.3
MAXIMUM PERMISSIBLE DOSE (MPD)
Various studies of the effects of X-ray radiation have provided a foundation for
establishing the Maximum Permissible Dose (MPD) of X-ray radiation. The
results of these studies have been used by the ICRP to develop
recommendations for MPD. These limits are certainly not easy to define and
from time to time must be updated as new information becomes available.
For occupational exposures, the ICRP recommends that the MPD accumulated
should not exceed of the following limits:
•
Annual effective dose
50 mSv
•
Annual dose for the lens of the eye
150 mSv
•
Annual dose for all other areas
500 mSv
(i.e. red bone marrow, breast, lung,
gonads, skin, and extremities)
2.4
RADIATION PROTECTION
Because exposure to X-ray radiation may be damaging to health, use great
care to provide protection against exposure to the primary beam. Some of the
effects of X-ray radiation are cumulative and may extend over a period of
months or years. The best safety rule for X-ray operator is
“Avoid exposure
to the primary beam at
all times
”
.
Any object in the path of the primary beam produces secondary (scattered)
radiation. The intensity of the secondary radiation is dependent upon the
energy and intensity of the primary beam and the atomic number for the object
material struck by the primary beam. Secondary radiation may be of greater
intensity than that of the radiation reaching the film. Take protective measures
to safeguard against it.
An effective protective measure is the use of lead shielding. To minimize
dangerous exposure, use such items as lead screens, lead impregnated
gloves, aprons, thyroid collars, etc. The lead screen should contain a minimum
of 2.0 mm of lead or equivalent and personal protective devices (aprons,
gloves, etc.) must contain a minimum of 0.25 mm of lead or equivalent. For
confirmation of the local requirements at your site, please refer to your “Local
Radiation Protection Rules” as provided by your Radiation Protection Advisor.
WHILE OPERATING OR SERVICING X-RAY EQUIPMENT,
ALWAYS KEEP A DISTANCE NOT LESS THAN 2 METERS
FROM THE FOCAL SPOT AND X-RAY BEAM, PROTECT
BODY AND DO NOT EXPOSE HANDS, WRISTS, ARMS OR
OTHER PARTS OF THE BODY TO THE PRIMARY BEAM.
