The indirect or mathematical method of measurement of superficial roentgen-ray dosage as described and introduced by MacKee,1 and Remer and Witherbee2 has for some years held a position of primary importance in dermatologic therapy. While a more scientific method may be desirable and will no doubt be developed, this one, because of the readiness with which it may be adapted to the conditions of office practice, has fulfilled a genuine requirement and has made possible the employment of practical roentgen-ray therapy by many to whom it would otherwise have been denied.
In order that such a method may be universally applicable or in modern terms be "standardized," it is requisite that the formulas by means of which it is applied be composed of factors which remain constant in value under all conditions. It is now recognized, however, that in the formulas originally devised for this method and still