mammogram vs radiogram

mammogram

noun
  • An X-ray picture of the breasts (mammaries), used to screen for breast cancer. 

radiogram

noun
  • A radiograph 

  • An entertainment device that combined a radio and a record player or gramophone. 

  • A message, like a telegram, transmitted by radio rather than wires. 

How often have the words mammogram and radiogram occurred in a corpus of books? (source: Google Ngram Viewer )