from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The passing of a light through the walls of a body part or organ to facilitate medical inspection.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The examination of a body part, or a tissue sample, by shining light through it
from The Century Dictionary and Cyclopedia
- n. A shining through; the process of causing light to pass through; specifically, in medicine, the throwing of a strong light through an organ or portion of the body as a means of diagnosis.
trans- + illumination (Wiktionary)
With direct transillumination, frosted glass should not be used.