The future of radiation therapy

Since the development of one‐ and two‐million volt x‐ray machines in the 1930s, which led to the reduction of both skin erythema and bone necrosis as well as an increase in depth dose, medical physicists have worked steadily to develop radiation sources and techniques for increasing the therapeutic ratios for most solid tumors. [...]proton‐beam therapy (PBT) provides treatment plans with higher therapeutic ratios, which may result in reduced radiation toxicities, but evidence that PBT offers patients longer survival times is in short supply. Clearly, differences in survival times and levels of toxicity for PBT as compared with those for x rays are likely to be small. [...]to obtain statistically valid comparisons would require that relatively large numbers of patients be studied over long periods of time, and that the methodology of the randomized prospective clinical trial (RPCT) be employed.