Evaluation of mammographic viewbox luminance, illuminance, and color.

Twenty-three viewboxes were evaluated in six mammography facilities. Luminance and illuminance measurements were made with a recently calibrated photometer. Color temperatures were measured with a Minolta color meter. The average luminance for the 23 viewboxes was 2920 nit (lumen/Sr/m2), the lowest value was 1610 nit, and the highest value was 3630 nit. The average illuminance was 40 lux (lumen/m2), with 6 lux as the lowest value, and 97 lux as the highest. The average color temperature was 8400 K with the lowest value of 4900 K, and the highest of 10,900 K.