Alexander Graham Bell is best known for inventing the telephone.  However, it was Bell that first suggested implanting radioactive  sources for treatment of cancer in 1903. Dear Dr. Sowers,      I understand from you that the Roentgen rays, and the rays emitted by radium, have been found to have a marked effect upon external cancers, but that the effects upon deep-seated cancers have not this far proved satisfactory.      It has occurred to me that one reason for the unsatisfactory nature of these latter experiments arises from the fact that the rays have been applied externally, thus having to pass through healthy tissues of various depths in order to reach the cancerous matter.      The Crookes' tube, from which the Roentgen rays are emitted, is of course too bulky to be admitted into the middle of a mass of cancer, but there is not reason why a tiny fragment of radium sealed up in a fine glass tube should not be inserted into the very heart of the cancer, thus acting upon the diseased material.  Would it not be worth while making experiments along this line? [Signed} Alexander Graham Bell