Isoeffect lines using TDF and CRE concepts

In most of the radiotherapy centres the treatment planning is based on isodose lines. Isoeffect lines are also being drawn based on the concepts of TDFs and CREs. It was aimed in this work to find out whether the isoeffect lines based on the concepts of TDFs, CREs and the physical isodose lines are identical in all the treatment situations. Isoeffect lines for a few treatment schedules involving treatment of carcinoma of the bladder, treatment of cancer of the uterine cervix by combined intracavitary and external beam therapies and intracavitary therapy alone have been obtained and compared in the present study. The effect of treatment mode on the isoeffect lines is also studied. It is found that the isodose curves and the isoeffect lines using the TDF and CRE concepts are not identical in all situations. Therefore, the ultimate treatment plans based on theses isoeffect lines will not be exactly the same. The dependence of the isoeffect lines with the variation of the exponents of time and number of fractions used in the empirical relationship for NSD have also been investigated. Clinical trials have been initiated in the case of cancer of the bladder and cervix uterus based on the isodose curves and the isoeffect lines using CRE and TDF concepts.