FOR IMMEDIATE RELEASE:                  Roger Rensberger
March 16, 1994                          (301) 975-2762

                                        TN-5970

                  SHIELD FOR RADIATION THERAPY DEVELOPED
                         IN DENTAL PROGRAM AT NIST


     A dental researcher at the National Institute of Standards
and Technology has invented a new shielding material and method
for protecting healthy body tissues from radiation during
therapy.

     The shielding is easy to fabricate and can be used for the
treatment of tumors or lesions in the mouth or on the body.  It
is easily molded and can be altered to fit the contours and
configurations required by dentists and radiotherapy technicians.

     "The new technique is simpler and less time consuming than
current shielding processes," says Frederick E. Eichmiller,
inventor and associate director of the American Dental
Association Health Foundation Paffenbarger Research Center at
NIST.

     Fabrication requires only a single appointment for a
procedure that is done directly on the patient and, in most
cases, can be completed in less than one hour.  Eichmiller notes
that this is a major improvement over current materials and
techniques that require multiple appointments and considerable
expertise.

     Eichmiller says that he was looking for a way to meet two
critical dental requirements.  Patients need a shield to protect
the salivary glands (important in helping reduce oral decay)
that can be destroyed by radiation.  Dentists and therapists also
need a shielding device that can be made easily in outpatient
facilities.

     The shields are made from two layers of elastomeric
polymers, such as vinyl polysiloxane that is commonly used for
dental impressions.  It sets to form a rubber-like material.  One
layer is filled to approximately 95 percent by weight with heavy
metal powders of silver, tin or copper that diffuse the
radiation.

     For external application, the body surface area over the
lesion or tumor is outlined with a washable ink.  A thin layer of
polymer without metal is rolled to the desired thickness like a
pie crust and placed on the patient, then molded to anatomical
contour.  The ink lines transfer to the polymer and serve as a
trim guide and for locating the treatment window.

     A layer of metal-filled polymer is then rolled to the
desired thickness, placed over the unfilled material on the
patient, and molded to contour.  A dental adhesive applied to the
first layer holds the two together.  Excess material is removed,
and the treatment window is cut through the shield.  The required
thickness of the polymer layers depends on the power and type of
radiation source.

     In-mouth shields are fabricated in much the same way as a
dental impression.  Unfilled material is placed in the patient's
mouth and molded to fit the treatment area.  The unfilled polymer
is covered with a filled layer and then trimmed for patient
comfort.

     Eichmiller says, "I would not have been able to develop the
new shielding method outside of NIST.  By working here, I was
able to draw upon the expertise of NIST metallurgists, polymer
scientists and radiation physicists."

     A license to manufacture the new shielding material has been
issued by the ADAHF to the L.D. Caulk Division of Dentsply
International, in Milford, Del.  The Veterans Administration is
conducting clinical trials.  According to Eichmiller, the product
should be on the market in approximately two years.

     Support for the project was provided by the National
Institute of Dental Research through the Center of Excellence for
Materials Science Research at NIST.  The center is co-directed by
Rafael L. Bowen, director of the ADAHF Paffenbarger Research
Center at NIST, and John A. Tesk, leader of the NIST Dental and
Medical Materials Group.

     As a non-regulatory agency of the Commerce Department's
Technology Administration, NIST promotes U.S. economic growth by
working with industry to develop and apply technology,
measurements and standards.

                                   -30-

NOTE TO EDITORS:  The NIST dental materials program is a long-
standing model of cooperation between the private sector and
government.  Researchers from the dental profession, industry and
government have worked together at NIST for more than 65 years to
improve dental materials and devices.

     NIDR, one of the National Institutes of Health, Bethesda,
Md., is the primary sponsor of dental research and related
training in the United States.  The Center of Excellence for
Materials Science Research at NIST is one of three centers funded
by NIDR to advance the science and art of dental health care
through the improvement of restorative and preventive dental
materials.