ITG SUBJECT: USE OF THE TEXAS INSTRUMENTS MODEL 59 PROGRAMMABLE CALCULATOR IN THE ENFORCEMENT OF THE DIAGNOSTIC X-RAY PERFORMANCE STANDARD

The Federal diagnostic X-ray equipment standard is aimed at reducing patient exposure during X-ray examinations. Its significance lies in the fact that 90 percent of the U.S. population's exposure from manmade sources is attributed to the diagnostic use of X-ray. More than 130 million people are estimated to receive some kind of X-ray examination each year in this country.

In essence, the standard calls for equipment capable of providing more reliable diagnostic information with an increased level of radiation protection. Components covered by the standard are tube-housing assemblies, X-ray controls, X-ray high voltage generators, fluroscopic imaging assemblies, tables, cradles, film changers, cassette holders, and beam-limiting devices.

The standard is directed primarily at the X-ray equipment manufacturer, to produce systems and components that perform in a prescribed way. However, the interconnection of major components to form a diagnostic X-ray and the adjustment and testing of the system are the final steps in the X-ray equipment manufacturing process. The standard takes cognizance of this fact by defining the installer, or assembler, as a manufacturer. An assembler who installs one or more components must meet requirements of the standard applicable to such installation.

A large part of the enforcement of the diagnostic X-ray standard is accomplished through the use of consolidated test procedures and routine test equipment. These procedures and equipment provide efficient means of testing against many performance requirements simultaneously. During an inspection, data is recorded on a field test record for computer calculation and manipulation. Although test results can be obtained by hand calculation, considerable time savings are provided by machine calculation. Thus, test data, which determine compliance of the equipment to the performance standard, must be processed by computation facilities at the *Center for Devices and Radiological Health.* The Texas Instruments Model 59 programmable calculator provides an on- site alternative to obtaining test results. This calculator can provide almost instantaneous on-site test results; it also has an advantage over conventional calculators in that calculation programs many be permanently stored on a magnetic card and entered into the calculators memory when needed. This feature saves considerable time by eliminating multiple steps during the calculation.

This calculator has been provided to regional offices' auditors. Calculation programs have been developed for each specific test procedure used by the field to text X-ray equipment. The calculator provides field personnel with a capability to immediately calculate test results. As a result of this capability, test results and testing techniques can be verified and checked prior to any compliance action against a manufacturer/assembler.