Document nkqqkxnze1dLMQOrrJdGX4GGG

^ryijrr^Mrfiwympyi 'i & ( LIA23649 ;'- ; ....... -/ March 13, 19^3 SUBJECT! *W BHIELDTO MATERIA13 To Hesfcsr* of the lead Industrie* Association, Xaa.j Several materials have recently appeared ca the market vhlch purport to be "new" radlatloo shielding product*. Ve should like to point out to our members that there 1* Dot now, nor 1* there likely to be Is the near future, anything that It really sev for thl* purpose. Many of these materials contain lead, but In a greatly reduced aount, and therefore require sore material for equai attenuatloo than doe* pure lead. Thl* doe* Dot Imply that there la no use for some of these product*, nor doe* It seas that ve feel they vlll, necessarily, dltplace sheet lead frea It* shielding market, but ve should like to point out that the products should be used vlth knowledge of their limitations. The Instruction sheets vhlch acccepany seme of these products are misleading especially to those vbo are not expert In radiation shielding design. Tor Instance, one manufacturer states that his product contain* 76 per cent of lead by weight and thereby Infers that It Is three-quarter* a* effective a* pur* lead. An example shoving that thl* Is not the case 1* the fact that It vould take a* nuch as a 5-loch thick layer of this product to be equivalent to l/l6-lnch thick lead sheet as a shield for a 150 kv X-ray. Another product vhlch Is "a sand-like ceramic noterial that 1* much lighter than lead but can be used In X-ray rooms and radiation areas" obviously attempts to Infer that It Is a replacement for lead and a lighter weight replacement. This Is simply not true and when one remember* that lead 1* effective In proportion to It* mas* and density, on* may readily reelite that other materials used to replace lead must also provide an equivalent mass to be as effective. As an example let as quota frea the Rational Bureau of Standards Handbook 76 entitled "Medical X-rsy Protection Up to Three Million Volts" wherein l/l6-lnch lead sheet weighing h lbs. per square foot Is listed as equivalent to a 5.3-tnch thick coocrete wall vhlch velgha 65 lb*, a square foot for 150 kv X-ray shielding. This Is a good Indication, of course, that lead Itself 1* probably the most efficient, and certainly the lightest weight, of any other shielding material cccaonly available. The posit loo of government agencies having Jurisdiction In this area Is that SLlmoat any material may be used for radiation shielding provided that it Is used In such a manner as to meet the attenuation requirements specified i CT"-~r-r- 1B IP" 1 < 11 111 w.tp n i f LIA23650 i~lltm I I "Uev" Shielding Material* page 2. by lav. For example, In the case of the materiel previously mentioned. If a physician should vlah to place a 5-loch thick leyer on the door* and vail* of hi* X*ray room lnrteai of using l/l6-Vnch le*l, If tests by an expert certify that the mevjrlol ha* been applied correctly so that there are no bubbles or other gaps, then the government could approve such an Installation. In *uan>ary, ve viet to show that the principle* of radlatloo protection add the materiel-. oral labia for such prevention huve not really changed In spitu of ilile-lir-g o/vnufacturer*' data avccts. There la undoubt edly a p'ace for -tie of these nev products, but sot aa Indiscriminate replaceaa-t of lead. Very truly yours, DCF; ltd Don 0. Fovler Director of Health and Safety 5 s 0 f