Exposure reduction through faster speed film-screen systems and a review of A.L.A.R.A. (as low as reasonably achievable).
One of the most talked about and recognized practices for dose reduction is the "as low as reasonably achievable" (A.L.A.R.A.) concept initiated by the International Commission on Radiological Protection. Many new technologists, however, are neither familiar with the concept nor recognize how important their part is in its implementation. In addition, some experienced technologists may need to refresh their knowledge of certain practices and how they relate to the A.L.A.R.A. concept. This article reviews the literature and presents new data on exposure technique reduction through film-screen speed combinations. The latest 250- and 600-speed film-screen combinations were obtained from leading manufacturers and tested to determine what new techniques would provide adequate radiographs using lower exposures. Comparisons were made between the 100- and 250-speed systems and the 400- and 600-speed systems. These comparisons were objectively based on aluminum stepwedge exposures measured by densitometry and subjectively based on exposure of 3M phantoms utilizing the newly established techniques with the higher speed film-screen system compared to the original techniques using the lower speed film-screen system. It was found that using a 250-speed system instead of a 100-speed system will reduce exposure dose by 36 to 60 per cent; using a 600-speed system in place of a 400-speed system exposure dose is reduced by 31 to 63 per cent. There is no apparent loss of resolution for either film-screen combination.
Vernon Jubilee Hospital, British Columbia.
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D001955:British Columbia; D006801:Humans; D016273:Occupational Exposure / Q000517:prevention & control / Q000592:standards; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation / Q000592:standards*; D011859:Radiography / Q000009:adverse effects / Q000592:standards*; D013679:Technology, Radiologic / Q000592:standards*; D014962:X-Ray Film / Q000592:standards