Dosage Table for Linear Radium Sources

The expression of tissue dosage in terms of roentgens is becoming general in x-ray and radium therapy. For interstitial radium or radon sources, the literature contains data for several satisfactory methods of determining the minimum dose delivered within a volume implanted with needles or seeds in accordance with certain general principles. In the case of single linear sources, however, such as are commonly employed in the treatment of cervical and rectal cancer, information is not so accessible. The most generally used charts, those of Paterson and Parker (1), give the number of milligram-hours necessary to deliver 1,000 rγ at points in a plane perpendicular to the source at its mid-point, up to 3 cm. distance. For positions not in this central plane, or for greater distances, they are not helpful. Sievert (2) and Laurence (3) have presented extensive data, but in rather complicated mathematical forms. Mayneord and Honeyburne (4) have published a general method for drawing isodose curves around any part...