Supervoltage radiation in the form of two-million-volt roentgen rays, when the quality of radiation delivered is comparable to the quality of the radium beam, has given us our first opportunity to study and evaluate what might be accomplished by a radium bomb of a magnitude of 5,000 gm., providing that much radium were available in the world. In addition to having a quality equivalent to radium-bomb radiation, supervoltage roentgen radiation has several advantages, even if radium were ever found in quantities sufficient for bombs of this magnitude. To begin with, it allows complete shielding for those working with it, without danger of even small amounts of radiation reaching personnel. Radiation delivered by this means, moreover, is developed from a point source, which means that a small tumor can be treated with a sharply defined field. The ease of maneuverability of the equipment is such that treatment may be delivered through ports of special size and shape without endangering either patient or person...