U.S. Nuclear Regulatory Commission
Technical Assistance Request, Use of Portable Shields for a High Dose Rate Afterloader Facility at Washington Hospital Center, Washington, D.C.
Title: Technical Assistance Request, Use of Portable
Shields for a High Dose Rate Afterloader Facility at
Washington Hospital Center, Washington, D.C.
See the memorandum from J. E. Glenn to R. R. Bellamy dated
June 25, 1992. This NMSS memo responds to a technical
assistance request from Region I, dated March 26, 1992,
concerning Washington Hospital Center's request to relocate
their high dose rate afterloader to a new location and use
portable lead shadow shields to obtain compliance with the
dose limits of 10 CFR 20.1301 for members of the public.
The request was reviewed and the following guidance is
Although NRC's Policy and Guidance Directive, FC 86-4, for
licensing high dose rate afterloaders presumes the
necessary room shielding is obtained by the use of
appropriate fixed wall, floor, and ceiling materials, it
does not explicitly require it. However, portable shield
should not be permitted as a permanent means of providing
shielding for high dose rate afterloading facilities. This
requirement is consistent with the recommendations
contained in the most recent draft of the AAPM Task Group
on Remote Afterloading Systems.
Washington Hospital Center may be allowed to use the
portable shields on a temporary or emergency basis to
insure patient care is not impacted. If portable shield
are used, a positive method of ensuring the shield (s) are
correctly positioned for each treatment must be provided,
and "per patient" surveys must be performed for each
treatment to insure that exposure rates in unrestricted
areas comply with 10 CFR 20. The licensee would be
expected to commit to the installation of appropriate
permanent shielding within a reasonable period of time.
The hospital must be made aware that the use of a
cantilevered shield for limiting the exposure to the
adjacent uncontrolled area above the treatment room may
raise additional safety concerns about patient injury from
improper design, maintenance, or mishandling during
positioning of the shield.
After review of the technical assistance request, the
licensee apparently omitted any description of the area
security for the treatment room. Such a description is
required by V (c) of FC 86-4. Since the licensee is
proposing to locate the high dose rate afterloader with an
existing superficial treatment machine, it is essential
that they implement and describe a means of assuring that
only one of the two radiation producing devices can be
operated at a time. Also, the proposed shadow shield for
the door and window would appear to obscure observation of
the patient during treatment. If this is the case, the
licensee must provide an alternate means of viewing the
patient during treatment.
Regulatory references: 10 CFR 20.1301, 10 CFR 20.1302
Subject codes: 4.4, 5.3, 7.1, 12.8
Applicability: Byproduct Material