Does improved depth dose characteristics and treatment planning correlate with a gain in therapeutic results? Evidence from past clinical experience using conventional radiation sources.

Experience with the use of external beam conventional radiation over a period of several decades has shown that in every instance where there has been a major advance in the physical delivery of radiation to the tumor (beam energy and characteristics and precise tumor dose delivery) there has been a corresponding major improvement in the treatment results. The advent of megavoltage sources following the invention and use of Cobalt 60 and medical linear accelerator units during the late 1940's and early 1950's and their major impact on tumor control and patient survival in solid tumors such as carcinoma of the prostate, Hodgkin's Disease, head and neck tumors and cancer of the cervix are being discussed. Most recently, the use of computerized tomography and computer systems for treatment planning is likely to show a further improvement in the therapeutic results.