Metal-polysiloxane shields for radiation therapy of maxillo-facial tumors

Journal Article · Thu Feb 28 23:00:00 EST 1991 · Medical Physics; (United States)

DOI:https://doi.org/10.1118/1.596724· OSTI ID:5554824

Farahani, M; Eichmiller, F C; McLaughlin, W L ^[1]

---

1. American Dental Association Health Foundation, Paffenberger Research Center, NIST, Gaithersburg, Maryland (USA)

In the treatment of some head and neck lesions with high-intensity radiation (teletherapy), an essential procedure is the application of an individually customized shielding appliance, which is designed, modeled, and formed into a working extra- or intraoral stent for the purpose of sparing healthy tissues. The present state of the art is slow and technique intensive, which can add to patient discomfort and inconvenience during molding and fabrication. A new formulation is described, which offers speed and ease of forming a moldable composite stent especially for intraoral use. Interleaved stacks of calibrated thin radiochromic film strips and soft-tissue-simulating plastic (polystyrene) layers gave a means of mapping one- or two-dimensional profiles of dose distributions adjacent to the high-density shielding materials using a spectrophotometer equipped with a gel scanner or a scanning laser-beam microdensitometer. Tests using collimated gamma-ray beams from a 60Co teletherapy unit were made in order to measure the dose distribution near interfaces of tissue-simulating polymer and the composite stent material with and without mixtures of metals (Ag-Cu and Sn-Sb). These results show that quickly formed composites made of a flexible resin with high concentrations of powdered spherical metal alloys provide effective custom-designed shielding, and, with a thin overlayer of the resin without metal, a diminished back-scattered radiation dose to normal tissues. An example of a successful formulation is a mixture of 90% by weight Ag-Cu alloy powder in a vinyl polysiloxane resin. This material is a moldable putty which, upon polymerization, forms a rigid elastomeric material, providing a half-value layer of {approximately} 2.5 to 2.8 cm for a gamma-ray beam from a 60Co source.

• OSTI ID: 5554824
• Journal Information: Medical Physics; (United States), Journal Name: Medical Physics; (United States) Vol. 18:2; ISSN 0094-2405; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

550603* -- Medicine-- External Radiation in Therapy-- (1980-)
62 RADIOLOGY AND NUCLEAR MEDICINE
ALLOYS
BIOLOGICAL SHIELDING
BODY
BODY AREAS
COBALT
COPPER
DISEASES
ELECTROMAGNETIC RADIATION
ELEMENTS
GAMMA RADIATION
HEAD
IONIZING RADIATIONS
MATERIALS
MEDICINE
METALS
NECK
NEOPLASMS
NUCLEAR MEDICINE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
ORGANIC SILICON COMPOUNDS
POLYMERS
POLYVINYLS
RADIATION PROTECTION
RADIATIONS
RADIOLOGY
RADIOTHERAPY
SHIELDING
SHIELDING MATERIALS
SILOXANES
SILVER
THERAPY
TRANSITION ELEMENTS