In dermatologic roentgen therapy it is routine procedure to shield the normal skin. On large areas this is easily accomplished by the use of lead foil and lead rubber sheets, and by means of variously sized cones.
When the lesions to be treated, however, are small and solitary, and particularly when large roentgen-ray dosage is required (either in one exposure or serially), then these lesions must be screened closely and accurately. Examples of such lesions are keloids, verrucae, synovial cysts, angiomas, and malignant neoplasms.
After several frustrating experiences in attempting to shape accurate shields for keloids, a search was made through textbooks and journals for the description of such a procedure. The only papers dealing with shielding of the skin are those describing moldable materials as substitutes for sheet lead. Merritt,1 in 1937, described a plastic lead. (This was soon abandoned because the material was sticky,