Lucency is the medical term used by radiologists to describe the brightness or transparency of an area on an X-ray, CT scan, or MRI. However, there are several other words that can be used as synonyms for lucency. Some of these include transparency, translucency, radiolucency, clarity, and opacity. While transparency and translucency are associated with brightness and lightness, radiolucency and opacity are used to describe how much light passes through an area. Clarity, on the other hand, is a broader term that describes how easily something can be seen or understood. In summary, lucency is just one of many terms used to describe the brightness or transparency of an area on a radiographic image.