What is the initial setup for lead apron attenuation testing?

The initial setup for lead apron attenuation testing involves placing a Keithley ion chamber in the beam at a negative source-to-image distance (SID), specifically at -40 SID. This method allows for a precise measurement of the radiation exposure passing through the lead apron. The ion chamber effectively measures the intensity of radiation, which can then be compared with and without the apron to determine the level of attenuation provided by the lead.

This configuration is particularly important because the negative SID indicates that the chamber is positioned behind the lead apron, thereby enabling the assessment of how much radiation is absorbed by the lead material. Proper calibration of the setup also ensures that the electrical response of the ion chamber accurately reflects the radiation exposure.

Regarding the other options, they do not align with the standardized methodology for testing lead apron attenuation. For example, varying voltages or high mAs with low kVp configurations could introduce inconsistencies that would affect the accuracy of the attenuation measurement. Similarly, using a lead foil above the ion chamber at a longer SID would not provide the direct assessment needed to evaluate the apron’s protective qualities effectively.