X-Ray Exposure Protection
4.0 Radiation Exposure Protection
Although occupational radiation doses at Virginia Tech are very low and current occupational limits provide a very low risk of injury, the administration at Virginia Tech recognizes that it is sensible to avoid unnecessary exposure. It is therefore the policy of Virginia Tech to reduce occupational exposures to a level that is as low as reasonably achievable (ALARA). This will be accomplished through sound radiation protection planning and practice, and a commitment to policies that promote vigilance against unsafe practice.
4.1 Radiation Exposure Limits
Radiation workers shall not receive a dose in one calendar quarter over the following limits:
- Deep Dose Equivalent 1,250 millirem (mrem)
- Lens Dose Equivalent 3,750 mrem
- Shallow Dose Equivalent (skin of body) 12,500 mrem
- Shallow Dose Equivalent (extremities) 12,500 mrem
Individuals under 18 years of age are not permitted to receive a dose greater than 10% of the above limits.
The maximum permissible whole-body dose to a declared pregnant radiation worker during the pregnancy must not exceed 500 mrem.
Radiation levels in unrestricted areas shall not exceed 2 mrem/hr or 100 mrem/yr.
4.2 Personnel Monitoring
All personnel who enter an area where it is likely they will receive greater than 25% of the maximum occupational dose limit shall wear a personnel monitoring device.
The need for a personnel monitoring device will be determined by the Radiation Safety Office. That office will supervise the ordering, distribution, and collection of personnel monitoring devices.
Whole-body personnel monitoring devices will be worn routinely on the shirt pocket or collar. The position of the monitoring device shall remain constant during a reporting period.
Personnel monitoring devices designed to measure beta or low-energy X or gamma radiation shall not be worn inside of a pocket or obstructed in any manner.
When not in use, personnel monitoring devices shall be stored in an area where they will not be exposed to ionizing radiation above background levels.
Personnel monitoring devices shall not be deliberately exposed to radiation except under the supervision of a Radiation Safety Officer.
Personnel monitoring devices are not to be worn during non-occupational exposures such as medical X-rays.
When a lead apron or thyroid shield is worn, the monitoring device shall be worn on the outside of the protective device at the collar.
Declared pregnant radiation workers shall wear a whole-body personnel monitoring device during the pregnancy.
4.2.1 Specific Requirements
- Diagnostic - All users shall wear a whole-body monitoring device. Fluoroscopy users will also wear a ring badge.
- Analytical - Users of open-beam analytical X-ray equipment that conduct alignment of the system are required to wear a ring badge. Badges are not required for users of closed systems.
- Cabinet - All users shall wear a whole-body badge.
- Miscellaneous - Personnel monitoring is not required.
4.3 Exposure Records
The Radiation Safety Office will maintain exposure records and will provide exposure results as necessary, usually on an annual basis. The office will provide a radiation exposure report to the worker, or an employer at the request of the worker.
The Radiation Safety Office will supply the worker with a written report if a dose over 25% of the occupational limits is received.
4.4 Pregnant Authorized Users
A user has the option to formally declare a pregnancy to their supervisor in order to take advantage of reduced occupational exposure limits for the entire term of the pregnancy. This declaration is voluntary and can be kept confidential. The RSO is available to answer any questions that may arise whether or not a formal declaration of pregnancy is made. To become a declared pregnant worker the supervisor needs the following information:
- Estimated date of conception
- Expected date of birth
Pregnant authorized users shall:
- Wear a whole-body personnel monitoring device if working with penetrating X-ray producing equipment.
- Wear a second whole-body monitoring device under a lead apron at waist level, when a lead apron is required to be worn.
- Not be required to hold patients, animals or film cassettes during an X-ray exposure.
- Be informed of her radiation exposure on a quarterly basis.
Pregnant authorized users should:
- Notify the Radiation Safety Officer as soon as her pregnancy is known (confidentiality will be maintained).
- Limit her exposure to less than 500 mrem during the pregnancy.
- Keep her exposure to the very lowest practical level by reducing the amount of time spent in a radiation area, increasing the distance from a radiation source, and using shielding.
- Inform her obstetrician about her work with X-ray producing equipment.
4.5 X-Ray Exams of Pregnant or Potentially Pregnant Women
A sign bearing the words or similar words "Caution: If you are pregnant or think you are pregnant, please inform the technologist before X-rays are taken" shall be conspicuously posted in the X-ray room.
Before ordering X-rays of the abdominal or pelvic area of a fertile woman, the examining physician will order a pregnancy test unless a medical situation precludes the testing (e.g. medical emergencies).
The X-ray technologist will check the requisition for the results of the pregnancy test before taking X-rays of the abdominal or pelvic area of a fertile woman. If a pregnancy test has not been performed, the technologist will refer the patient back to the examining physician.
The physician's approval to X-ray pregnant women is not required when X-rays of areas other than the abdominal or pelvic area are ordered, provided the abdomen is shielded on all sides by 0.25 mm lead equivalency.
The abdominal and pelvic area of fertile women shall be covered with a lead apron of 0.25 mm lead equivalency when X-rays are ordered for areas other than the abdominal or pelvic region.
Fertile women should consider pregnancy testing before receiving bone density scans. Women in their childbearing years who participate in research studies involving DXA scans will be required to undergo a pregnancy test, and receive a negative result (not pregnant), before a scan is performed. Women who are pregnant will be advised to consult with their personal physician as to the advisability of their continued participation in the study, and if cleared by their physician, they may undergo the scan.
4.6 Posting
Each area or room where fixed diagnostic, analytical, or cabinet X-ray equipment is located shall be conspicuously posted with:
- A sign bearing the radiation symbol and the words (or similar words) "CAUTION: X-RAY EQUIPMENT."
- State Form RH-F-12 "Notice to Employees - Standards for Protection Against Radiation: Notices, Instructions and Reports to Workers; Inspections."
- A notice that describes where the University Radiation Safety Manual, registration, surveys, and inspections may be examined.
- Procedures to be followed if there is a radiological emergency.
- Each area or room where mobile X-ray equipment is used shall be temporarily posted with a "Caution: X-ray Equipment" sign.
- No area posting is required for Miscellaneous X-ray equipment.
4.6.1 Removal of Notices
Any sign, notice, warning or label applied by the Radiation Safety Office to equipment or the facilities of a licensed user shall not be removed, defaced, or concealed without written permission from the Radiation Safety Office.
4.7 Inspections
All licensed activities are subject to inspection by the Radiation Safety Office. Inspections may be announced or unannounced and will be conducted at least every year. Miscellaneous x-ray systems are inspected at least every five years and administrative checks are made every year.
A written report specifying any deficiencies will be sent to the Laboratory Authority who must correct the deficiencies within the time specified in the report, unless a variance or an extension of time has been granted by the Radiation Safety Committee. A Laboratory Authority who disagrees with the deficiencies specified in the report may appeal in writing to the Chairman of the Radiation Safety Committee and request a hearing before the Committee.